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2021, 13 (4) Online: 31 August 2021
• Progress, problems and prospects of palynology in reconstructing environmental change in inland arid areas of Asia
• YongTao Zhao,YunFa Miao,Yan Lei,XianYong Cao,MingXing Xiang
• DOI: 10.3724/SP.J.1226.2021.20049.
• 2021, Vol.13 (4): 271–291 Abstract ( 88) HTML ( 15) PDF (5371 KB) ( 99 )
• Studying the climatic and environmental changes on different time scales in inland arid regions of Asia can greatly improve our understanding of climatic influences for the Qinghai-Tibet Plateau in the context of global change. Pollen, as a remnant of seed plants, is sensitive to environmental factors including precipitation, temperature and altitude, and is a classic proxy in environmental reconstruction. In the last two decades, great progress in the application of palynology to inland areas of Asia has highlighted the role of palynology in paleoclimatic and paleoenvironmental research. The main progress is as follows. (1) On the tectonic time scale of the late Cenozoic, the palaeoclimatological sequence has been established on the basis of pollen percentage, concentration and taxon. Pollen data have revealed a continuous enhancement of drought in the inland arid region of Asia, in contrast to evidence acquired based on other proxies. (2) In the late Quaternary, an increase in herbaceous plants further supports the intensification of drought associated with global cooling. In more detail, the palynological record shows a glacial-interglacial pattern consistent with changes in global ice volume. (3) The Holocene pollen record has been established at a high resolution and across a wide range of inland areas. In general, it presents an arid grassland environment in the early Holocene, followed by the development of woody plants in the mid- to late-Holocene climate optimum. This pattern is related to moisture changes in areas dominated by the westerlies. There are also significant regional differences in the pattern and amplitude of vegetation response to the Holocene environment. (4) Modern pollen studies based on vegetation surveys, meteorological data and statistics show that topsoil palynology can better reflect regional vegetation types (e.g., grassland, meadow, desert). Drier climates yield higher pollen contents of drought-tolerant plants such as Chenopodioideae, Ephedra, and Nitriaria, while contents of Artemisia and Poaceae are greater under humid climates. Besides these achievements, problems remain in palynological research: for example, pollen extraction, identification, interpretation, and quantitative reconstruction. In the future, we encourage strengthened interdisciplinary cooperation to improve experimental methods and innovation. Firstly, we should strengthen palynological classification and improve the skill of identification; secondly, laboratory experiments are needed to better constrain pollen transport dynamics in water and air; thirdly, more rigorous mathematical principles will improve the reliability of reconstructions and deepen the knowledge of plant geography; and finally, new areas and methods in palynology should be explored, for example DNA, UV-B and isotopic analysis. It is expected that palynology will continue to develop, and we hope it will continue to play an important role in the study of past climatic and environmental changes.

• 10Be exposure ages of Quaternary Glaciers in Antarctica
• WangJing Ni,ZhiGang Zhang,JingXue Guo,XueYuan Tang
• DOI: 10.3724/SP.J.1226.2021.20043.
• 2021, Vol.13 (4): 292–298 Abstract ( 35) HTML ( 2) PDF (2909 KB) ( 77 )
• In situ terrestrial cosmogenic nuclides (TCN) have been widely applied to date the ages of Quaternary glacial deposits in Antarctica and plays an important role in reconstructing the glacial evolution and climate change. It helps to understand the Antarctic ice sheet's evolution process in Quaternary and shed light on the application of Cosmogenic Nuclide exposure dating technique in glacial geomorphology. In this paper, we retrieved 495 10Be age samples in Antarctica from literature published between 2004 and 2020 and recalculated the TCN ages using version 3.0 online calculator of Cosmic-Ray Produced Nuclide Systematics on Earth (CRONUS-Earth). Several conclusions can be drawn from the results: (1) 75% of the exposure ages are younger than 400 ka, and 91% younger than 1,100 ka. Northern Antarctic Peninsula exposure result is visibly younger than the main glaciers area in East Antarctica due to climate change and geological evaluation since the LGM (Last Glacial Maximum). (2) TCN ages are relevant to the samples' relative positions in the Antarctic continent, but a relationship between their ages and elevations is yet to be determined based on the collected data.

• Ground temperature variation and its response to climate change on the northern Tibetan Plateau
• GuoNing Wan,MeiXue Yang,XueJia Wang
• DOI: 10.3724/SP.J.1226.2021.20024.
• 2021, Vol.13 (4): 299–313 Abstract ( 37) HTML ( 7) PDF (12729 KB) ( 55 )
• Ground temperature plays a significant role in the interaction between the land surface and atmosphere on the Tibetan Plateau (TP). Under the background of temperature warming, the TP has witnessed an accelerated warming trend in frozen ground temperature, an increasing active layer thickness, and the melting of underground ice. Based on high-resolution ground temperature data observed from 1997 to 2012 on the northern TP, the trend of ground temperature at each observation site and its response to climate change were analyzed. The results showed that while the ground temperature at different soil depths showed a strong warming trend over the observation period, the warming in winter is more significant than that in summer. The warming rate of daily minimum ground temperature was greater than that of daily maximum ground temperature at the TTH and MS3608 sites. During the study period, thawing occurred earlier, whereas freezing happened later, resulting in shortened freezing season and a thinner frozen layer at the BJ site. And a zero-curtain effect develops when the soil begins to thaw or freeze in spring and autumn. From 1997 to 2012, the average summer air temperature and precipitation in summer and winter from six meteorological stations along the Qinghai-Tibet highway also demonstrated an increasing trend, with a more significant temperature increase in winter than in summer. The ground temperature showed an obvious response to air temperature warming, but the trend varied significantly with soil depths due to soil heterogeneity.

• Application of geodetector in sensitivity analysis of reference crop evapotranspiration spatial changes in Northwest China
• WenJu Cheng,HaiYang Xi,Sindikubwabo Celestin
• DOI: 10.3724/SP.J.1226.2021.20038.
• 2021, Vol.13 (4): 314–325 Abstract ( 35) HTML ( 2) PDF (4642 KB) ( 70 )
• Reference crop evapotranspiration (ET0) is an important parameter in the research of farmland irrigation management, crop water demand estimation and water balance in scarce data areas, therefore, it is very important to study the factors affecting the spatial variation of ET0. In this paper, the Penman-Monteith formula was used to calculate ET0 which is the dependent variable of elevation (Elev), daily maximum temperature (Tmax), daily minimum temperature (Tmin), daily average temperature (Tmean), wind speed (U2), sunshine duration (SD) and relative humidity (RH). The sensitivity analysis of ET0 was performed using a Geodetector method based on spatial stratified heterogeneity. The applicability of Geodetector in sensitivity analysis of ET0 was verified by comparing it with existing research results. Results show that RH, Tmax, SD, and Tmean are the main factors affecting ET0 in Northwest China, and RH has the best explanatory power for the spatial distribution of ET0. Geodetector has a unique advantage in sensitivity analysis, because it can analyze the synergistic effect of two factors on the change of ET0. The interactive detector of Geodetector revealed that the synergistic effect of RH and Tmean on ET0 is very significant, and can explain 89% of the spatial variation of ET0. This research provides a new method for sensitivity analysis of ET0 changes.

• Ecophysiological responses to drought stress in Populus euphratica
• ChunYan Zhao,JianHua Si,Qi Feng,TengFei Yu,Huan Luo,Jie Qin
• DOI: 10.3724/SP.J.1226.2021.20025.
• 2021, Vol.13 (4): 326–336 Abstract ( 41) HTML ( 4) PDF (6610 KB) ( 86 )
• Ecophysiological responses to drought stress of Populus euphratica in Alashan Desert Eco-hydrology Experimental Research Station were investigated. Results show that under mild and moderate drought stress, stomatal length, aperture, area and density is likely to decrease in the early days, but afterwards this is likely to recovery with treatment over the passage of treatment time. Under severe drought stress, these properties appear to decline continuously. However, after 45 days of drought-stress treatment, the decline is not as noticeable as before, indicating that Populus euphratica could possibly reduce water evaporation by shutting down the stoma, leading to an improvement in its water use efficiency with better survival under drought stress conditions. The leaf area first decreases, and then increases under mild and moderate drought stress conditions, with the average values under different degree of stress found to be approximately 129.52, 120.08, 116.63 and 107.28 cm2, respectively. Under moderate stress conditions, the leaf water potential appears to show a continuous decline where the average values under different degree of stress are found to be -1.27, -1.85, -4.29 and -4.80 MPa, respectively. In terms of proline content, the results demonstrate that this factor appears to increase significantly under moderate and severe drought stress conditions. Especially under severe drought stress condition, the content is found to be more than 700 μg/g. Ranging over average values of 14.64 and 15.90 nmol/g under moderate and severe drought stress, respectively, Malondialdehyde content is found to increase quite rapidly under moderate and severe drought stress conditions at first, which then appears to decrease gradually with the treatment over time.

• The driving force of water resource stress change based on the STIRPAT model: take Zhangye City as a case study
• Xia Tang,XinYuan Wang,Lei Feng
• DOI: 10.3724/SP.J.1226.2021.20093.
• 2021, Vol.13 (4): 337–348 Abstract ( 32) HTML ( 3) PDF (1998 KB) ( 66 )
• A prominent contradiction between supply and demand of water resources has restricted local development in social and economic aspects of Zhangye City, located in a typical arid region of China. Our study quantified the Water Resource Stress Index (WRSI) from 2003 to 2017 and examined the factors of population, urbanization level, GDP per capita, Engel coefficient, and water consumption per unit of GDP by using the extended stochastic impact by regression on population, affluence and technology (STIRPAT) model to find the key factors that impact WRSI of Zhangye City to relieve the pressure on water resources. The ridge regression method is applied to improve this model to eliminate multicollinearity problems. The WRSI system was developed from the following three aspects: water resources utilization (WR), regional economic development water use (WU), and water environment stress (WE). Results show that the WRSI index has fallen from 0.81 (2003) to 0.17 (2017), with an average annual decreased rate of 9.8%. Moreover, the absolute values of normalized coefficients demonstrate that the Engel coefficient has the largest positive contribution to increase WRSI with an elastic coefficient of 0.2709, followed by water consumption per unit of GDP and population with elastic coefficients of 0.0971 and 0.0387, respectively. In contrast, the urbanization level and GDP per capita can decrease WRSI by -0.2449 and -0.089, respectively. The decline of WRSI was attributed to water-saving society construction which included the improvement of water saving technology and the adjustment of agricultural planting structures. Furthermore, this study demonstrated the feasibility of evaluating the driving forces affecting WRSI by using the STIRPAT model and ridge regression analysis.

2021, Vol.13 No.3 No.2 No.1
2020, Vol.12 No.6 No.5 No.4 No.3 No.2 No.1
2019, Vol.11 No.6 No.5 No.4 No.3 No.2 No.1
2018, Vol.10 No.6 No.5 No.4 No.3 No.2 No.1
2017, Vol.9 No.6 No.5 No.4 No.3 No.2 No.1
2016, Vol.8 No.6 No.5 No.4 No.3 No.2 No.1
2015, Vol.7 No.6 No.5 No.4 No.3 No.2
• Constitutive models and salt migration mechanisms of saline frozen soil and the-state-of-the-practice countermeasures in cold regions
• YuanMing Lai,ZheMin You,Jing Zhang
• DOI:10.3724/SP.J.1226.2021.20045
• 2021, 13 (1): 1–17 Abstract (521) HTML (23846) PDF (4971 KB) (513)
• A series of saline soil-related problems, including salt expansion and collapse, frost heave and thaw settlement, threaten the safety of the road traffic and the built infrastructure in cold regions. This article presents a comprehensive review of the physical and mechanical properties, salt migration mechanisms of saline soil in cold environment, and the countermeasures in practice. It is organized as follows: (1) The basic physical characteristics; (2) The strength criteria and constitutive models; (3) Water and salt migration characteristics and mechanisms; and (4) Countermeasures of frost heave and salt expansion. The review provides a holistic perspective for recent progress in the strength characteristics, mechanisms of frost heave and salt expansion, engineering countermeasures of saline soil in cold regions. Future research is proposed on issues such as the effects of salt erosion on concrete and salt corrosion of metal under the joint action of evaporation and freeze-thaw cycles.

• Seed germination and seedling growth of Pycnanthus angolensis (Welw.) Warb., African false nutmeg
• Sakpere A.M.A.
• DOI:10.3724/SP.J.1226.2019.00350.
• 2019, 11 (5): 350–359 Abstract (4434) HTML (30921) PDF (2153 KB) (370)
• This study investigated the germination behavior and seedling growth of Pycnanthus angolensis seeds. The germination study was carried out in the laboratory and included pretreatment studies and observation of the seed-germination process. For each treatment, three replications of 20 seeds were sown in a transparent plastic germination box (12cm $×$ 22cm $×$ 5cm) lined with moistened filter paper at room temperature. To monitor seedling growth, seedlings were transplanted into pots filled with topsoil and laid out in a completely randomized design. Ten seedlings replicated thrice were measured monthly; and the shoot height, leaf area, and root length, as well as the fresh and dry weights of the seedlings, were recorded. Results showed that mechanically scarified seeds exhibited the significantly highest germination percent (83.33%, P <0.005), followed by control seeds (70.83%), whereas seeds treated with 98% sulphuric acid (H2SO4) displayed the lowest germination percent (1.67). The endospermous seeds exhibited cryptogeal germination, while seeds stored for a month (with or without arils) failed to germinate. During seed germination, radicle protrusion continued with a pseudo-opening of the root, through which the brownish cotyledonary petiole was emitted, thus releasing the plumule at the posterior position. Moreover, P. angolensis exhibited a slow growth rate, attaining a shoot height of 73 cm within a year. The highest positive change in leaf number and area was recorded in the fourth month, a period during which the least change in shoot height occurred. The study concluded that mechanical scarification of the seeds ensured significant and faster germination than chemical scarification or no treatment at all. Additionally, P. angolensis displayed a cryptogeal germination, with the seedling growth of the tree species observed to be slow.

• Study of thermal properties of supraglacial debris and degree-day factors on Lirung Glacier, Nepal
• Mohan Bahadur Chand,Rijan Bhakta Kayastha
• DOI:10.3724/SP.J.1226.2018.00357
• 2018, 10 (5): 357–368 Abstract (418) HTML (14864) PDF (4797 KB) (304)
• The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons. Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon (2013), winter (2013), and pre-monsoon (2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors (DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of ?20.81 °C/m, 4.05 °C/m, and ?7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.

• Research on pile performance and state-of-the-art practice in cold regions
• JianKun Liu, TengFei Wang, Zhi Wen
• DOI:10.3724/SP.J.1226.2018.00001
• 2018, 10 (1): 1–11 Abstract (759) PDF (3430 KB) (303)
• A pile foundation is commonly adopted in geotechnical engineering to support structures, and its application has been extended to cold-regions engineering. In past decades, a host of scholars investigated pile behaviors and proposed design guidelines for seasonally frozen ground or permafrost. This paper reviews the research with respect to pile performance and engineering practice in cold regions, organized as follows: (1) creep tests and bearing capacity, (2) frost-jacking hazards, (3) laterally loaded piles, (4) dynamic responses, (5) refreezing due to concrete-hydration heat, and (6) improved countermeasures and design methods. We first summarize previous research and recent progress; then, predict the development trend of pile foundations in cold regions and recommend further research.
• Theoretical expressions for soil particle detachment rate due to saltation bombardment in wind erosion
• XuYang Liu,WenXiao Ning,ZhenTing Wang
• DOI:10.3724/SP.J.1226.2020.00234
• 2020, 12 (4): 234–241 Abstract (177) HTML (14574) PDF (1421 KB) (301)
• Saltation bombardment is a dominate dust emission mechanism in wind erosion. For loose surfaces, splash entrainment has been well understood theoretically. However, the mass loss predictions of cohesive soils are generally empirical in most wind erosion models. In this study, the soil particle detachment of a bare, smooth, dry, and uncrusted soil surface caused by saltation bombardment is modeled by means of classical mechanics. It is shown that detachment rate can be analytically expressed in terms of the kinetic energy or mass flux of saltating grains and several common mechanical parameters of soils, including Poisson's ratio, Young's modulus, cohesion and friction angle. The novel expressions can describe dust emission rate from cohesive surfaces and are helpful to quantify the anti-erodibility of soil. It is proposed that the mechanical properties of soils should be appropriately included in physically-based wind erosion models.

• Frost susceptibility of soils―A confusing concept that can misguide geotechnical design in cold regions
• DaiChao Sheng
• DOI:10.3724/SP.J.1226.2021.20051
• 2021, 13 (2): 87–94 Abstract (116) HTML (13265) PDF (3999 KB) (294)
• Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.

• Thickness estimation of the Longbasaba Glacier: methods and application
• GuangLi He,JunFeng Wei,Xin Wang
• DOI:10.3724/SP.J.1226.2020.00477
• 2020, 12 (6): 477–490 Abstract (93) HTML (8769) PDF (4573 KB) (278)
• A total of 71,177 glaciers exist on the Qinghai-Tibet Plateau, according to the Randolph Glacier Inventory (RGI 6.0). Despite their large number, glacier ice thickness data are relatively scarce. This study utilizes digital elevation model data and ground-penetrating radar thickness measurements to estimate the distribution and variation of ice thickness of the Longbasaba Glacier using Glacier bed Topography (GlabTop), a full-width expansion model, and the Huss and Farinotti (HF) model. Results show that the average absolute deviations of GlabTop, the full-width expansion model, and the HF model are 9.8, 15.5, and 10.9 m, respectively, indicating that GlabTop performs the best in simulating glacier thickness distribution. During 1980-2015, the Longbasaba Glacier thinned by an average of 7.9±1.3 m or 0.23±0.04 m/a, and its ice volume shrunk by 0.28±0.04 km3 with an average reduction rate of 0.0081±0.0001 km3/a. In the investigation period, the area and volume of Longbasaba Lake expanded at rates of 0.12±0.01 km2/a and 0.0132±0.0018 km3/a, respectively. This proglacial lake could potentially extend up to 5,000 m from the lake dam.

• Aeolian processes on sandy desertification of an alpine meadow: A wind tunnel experiment
• ZhiShan An,KeCun Zhang,LiHai Tan,BaiCheng Niu,YanPing Yu
• DOI:10.3724/SP.J.1226.2020.00012.
• 2020, 12 (1): 12–21 Abstract (113) HTML (7798) PDF (6304 KB) (271)
• In recent years, the desertification of alpine meadows has become a serious ecological problem and has gradually become a threat to regional economic activities in Maqu County. To reveal the mechanism for sandy desertification of alpine meadows, we conducted wind tunnel experiments on aeolian processes over sandy alpine meadows. Results show that the sand-flux profile of mix-sized sediment decays exponentially with increasing height. However, the profile pattern of a group of uniform-sized particles depends on the experimental wind speeds. The profile pattern of all the groups studied can be expressed by exponential decay functions when the wind speed is less than or equal to 16 m/s. while that for all the groups studied can be expressed by a Gaussian distribution function when the wind speed is above 16 m/s. The average saltation heights of mixed sands at wind speeds of 12 m/s, 16 m/s, 20 m/s, and 24 m/s were 2.74, 4.19, 5.28, and 6.12 cm, respectively. The mean grain size basically first decreases and then increases with increasing height under different wind speeds. The sorting improves with increasing wind speed, while the kurtosis and skewness show relationships with only the characteristics of the parent soil.

• Spatial distribution of supraglacial debris thickness on glaciers of the China-Pakistan Economic Corridor and surroundings
• YaJie Zheng,Yong Zhang,Ju Gu,Xin Wang,ZongLi Jiang,JunFeng Wei
• DOI:10.3724/SP.J.1226.2020.00447
• 2020, 12 (6): 447–460 Abstract (110) HTML (3289) PDF (6723 KB) (270)
• Debris-covered glaciers, characterized by the presence of supraglacial debris mantles in their ablation zones, are widespread in the China-Pakistan Economic Corridor (CPEC) and surroundings. For these glaciers, thin debris layers accelerate the melting of underlying ice compared to that of bare ice, while thick debris layers retard ice melting, called debris-cover effect. Knowledge about the thickness and thermal properties of debris cover on CPEC glaciers is still unclear, making it difficult to assess the regional debris-cover effect. In this study, thermal resistance of the debris layer estimated from remotely sensed data reveals that about 54.0% of CPEC glaciers are debris-covered glaciers, on which the total debris-covered area is about 5,072 km2, accounting for 14.0% of the total glacier area of the study region. We find that marked difference in the extent and thickness of debris cover is apparent from region to region, as well as the debris-cover effect. 53.3% of the total debris-covered area of the study region is concentrated in Karakoram, followed by Pamir with 30.2% of the total debris-covered area. As revealed by the thermal resistance, the debris thickness is thick in Hindu Kush on average, with the mean thermal resistance of 7.0×10-2 ((m2?K)/W), followed by Karakoram, while the thickness in western Himalaya is thin with the mean value of 2.0×10-2 ((m2?K)/W). Our findings provide a basis for better assessments of changes in debris-covered glaciers and their associated hydrological impacts in the CPEC and surroundings.

• Qualitative and quantitative phytochemical analysis of selected mosses with different alcoholic solvents
• Kehinde O. Olasoji,Amos M. Makinde,Bolajoko A. Akinpelu,Musibau O. Isa
• DOI:10.3724/SP.J.1226.2019.00382.
• 2019, 11 (5): 382–388 Abstract (189) HTML (1715) PDF (670 KB) (260)
• This study was conducted to investigate the qualitative and quantitative phytochemical content of the crude extracts of Archidium ohioense, Pelekium gratum, and Hyophila involuta with different alcoholic solvents (ethanol, methanol, Seaman's Schnapps, fresh oil-palm wine, and fresh Raffia-palm wine). The mosses were collected from their natural populations on the central campus of the Obafemi Awolowo University, Ile-Ife, Nigeria. The yield of the extracts was weighed for all the solvents, and the qualitative and quantitative evaluations of the extracts were carried out using standard methods. The results of phytochemical analysis of the crude extracts from the mosses showed the presence of saponins, cardiac glycosides, triterpenes, alkaloids, flavonoids, and steroids. The quantitative phytochemical analysis of the crude extracts showed that ethanolic extracts of Hyophila involuta had the highest flavonoid content (288.37±0.10 mg RE/g), and Raffia-palm-wine extracts of Hyophila involuta had the highest saponin content (224.70±0.02 mg/g), while the methanolic extract of Archidium ohioense had the highest cardiac glycosides content (63.71±0.14 mg/g), and the Raffia-palm wine extract of Hyophila involuta had the highest alkaloids content (102.50±0.12 mg/g). Raffia- and oil-palm wines were observed to be the most effective solvents for all the mosses studied, followed by Seaman's Schnapp, while methanol and ethanol were less effective. The study concluded that the extracts of the mosses studied contain pharmacologically active constituents that can be used for therapeutic purposes.

• Soil freezing process and different expressions for the soil-freezing characteristic curve
• JunPing Ren, Sai K. Vanapalli, Zhong Han
• DOI:10.3724/SP.J.1226.2017.00221
• 2017, 9 (3): 221–228 Abstract (243) PDF (4411 KB) (259)
• The soil-freezing characteristic curve (SFCC), which represents the relationship between unfrozen water content and sub-freezing temperature (or suction at ice-water interface) in a freezing soil, can be used for understanding the transportation of heat, water, and solute in frozen soils. In this paper, the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve (SWCC) of unfrozen unsaturated soil are reviewed. Based on similar characteristics between SWCC and SFCC, a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes. Various SFCC expressions from the literature are summarized. Four widely used expressions (i.e., power relationship, exponential relationship, van Genuchten 1980 equation and Fredlund and Xing 1994 equation) are evaluated using published experimental data on four different soils (i.e., sandy loam, silt, clay, and saline silt). Results show that the exponential relationship and van Genuchten (1980) equation are more suitable for sandy soils. The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes; however, it exhibits limitations when fitting the saline silt data. The Fredlund and Xing (1994) equation is suitable for fitting the SFCCs for all soils studied in this paper.
• Characteristics of permafrost degradation in Northeast China and its ecological effects: A review
• ShanShan Chen,ShuYing Zang,Li Sun
• DOI:10.3724/SP.J.1226.2020.00001.
• 2020, 12 (1): 1–11 Abstract (185) HTML (509) PDF (1207 KB) (258)

• A nonlinear interface structural damage model between ice crystal and frozen clay soil
• Sheng Shi,Feng Zhang,KangWei Tang,DeCheng Feng,XuFeng Lu
• DOI:10.3724/SP.J.1226.2021.20050
• 2021, 13 (2): 150–166 Abstract (81) HTML (13696) PDF (10701 KB) (251)
• The shear properties of ice-frozen soil interface are important when studying the constitutive model of frozen soil and slope stability in cold regions. In this research, a series of cryogenic direct shear tests for ice-frozen clay soil interface were conducted. Based on experimental results, a nonlinear interface structural damage model is proposed to describe the shear properties of ice-frozen clay soil interface. Firstly, the cementation and friction structural properties of frozen soil materials were analyzed, and a structural parameter of the ice-frozen clay soil interface is proposed based on the cryogenic direct shear test results. Secondly, a structural coefficient ratio is proposed to describe the structural development degree of ice-frozen clay soil interface under load, which is able to normalize the shear stress of ice-frozen clay soil interface, and the normalized data can be described by the Duncan-Chang model. Finally, the tangent stiffness of ice-frozen clay soil interface is calculated, which can be applied to the mechanics analysis of frozen soil. Also, the shear stress of ice-frozen clay soil interface calculated by the proposed model is compared with test results.

• Characteristics and changes of permafrost along the engineering corridor of National Highway 214 in the eastern Qinghai-Tibet Plateau
• Yu Sheng,JiChun Wu,Wei Cao,JianHong Fang,AnHua Xu,ErXing Peng
• DOI:10.3724/SP.J.1226.2020.00503
• 2020, 12 (6): 503–516 Abstract (243) HTML (2116) PDF (7387 KB) (238)
• Due to a series of linear projects built along National Highway 214, the second "Permafrost Engineering Corridor" on the Qinghai-Tibet Plateau has formed. In this paper, by overcoming the problems of data decentralization and standard inconsistency, permafrost characteristics and changes along the engineering corridor are systematically summarized based on the survey and monitoring data. The results show that: 1) Being controlled by elevation, the permafrost is distributed in flake discontinuity with mountains as the center along the line. The total length of the road section in permafrost regions is 365 km, of which the total length of the permafrost section of National Highway 214 is 216.7 km, and the total length of the permafrost section of Gong-Yu Expressway is 197.3 km. The mean annual ground temperature (MAGT) is higher than -1.5 °C, and permafrost with MAGT lower than -1.5 °C is only distributed in the sections at Bayan Har Mountain and E'la Mountain. There are obvious differences in the distribution of ground ice in the different sections along the engineering corridor. The sections with high ice content are mainly located in Zuimatan, Duogerong Plain and the top of north and south slope of Bayan Har Mountain. The permafrost thickness is controlled by the ground temperature, and permafrost thickness increases with the decrease of the ground temperature, with the change rate of about 37 m/°C. 2) Local factors (topography, landform, vegetation and lithology) affect the degradation process of permafrost, and then affect the distribution, ground temperature, thickness and ice content of permafrost. Asphalt pavement has greatly changed the heat exchange balance of the original ground, resulting in serious degradation of the permafrost. Due to the influence of roadbed direction trend, the phenomenon of shady-sunny slope is very significant in most sections along the line. The warming range of permafrost under the roadbed is gradually smaller with the increase of depth, so the thawing settlement of the shallow section with high ice-content permafrost is more significant.

• Proline and soluble sugars accumulation in three pepper species (Capsicum spp) in response to water stress imposed at different stages of growth
• DOI:10.3724/SP.J.1226.2016.00205
• 2016, 8 (3): 205–211 Abstract (173) PDF (325 KB) (234)
• Drought is a major production constraint for major fruits and vegetable crops in the tropics.This study was conducted to investigate the effect of limited water supply at three growth stages (vegetative,flowering and fruiting) on the accumulation of proline and soluble sugars in three pepper species.Seeds of the three pepper species,Capsicum chinense Jacq.,C.annuum L.and C.frutescens L.were raised in a nursery and the seedlings were transplanted into seventy two plastic pots arranged in a randomized complete block design with three replicates,25 days after planting.Four water treatments,200 mL of water supplied twice daily (W1),once in every three days (W2),once in every five days (W3),and zero water supplied throughout growing period (W0) were imposed at three vegetative,flowering,and fruiting growth stages.Data were collected on relative water content,free proline and total soluble sugar.Data collected were subjected to analysis of variance and means were separated using Duncan's multiple range test.Results show that the concentration of proline and soluble sugar in leaves of the three pepper species were found to be remarkable at the different stages of growth in the stressed plants.
• Influence of proximity to the Qinghai-Tibet highway and railway on variations of soil heavy metal concentrations and bacterial community diversity on the Tibetan Plateau
• Xia Zhao,JunFeng Wang,Yun Wang,Xiang Lu,ShaoFang Liu,YuBao Zhang,ZhiHong Guo,ZhongKui Xie,RuoYu Wang
• DOI:10.3724/SP.J.1226.2019.00407.
• 2019, 11 (6): 407–418 Abstract (172) HTML (1876) PDF (4670 KB) (234)
• An understanding of soil microbial communities is crucial in roadside soil environmental assessments. The 16S rRNA sequencing of a stressed microbial community in soil adjacent to the Qinghai-Tibet Highway (QTH) revealed that the accumulation of heavy metals (over about 10 years) has affected the diversity of bacterial abundance and microbial community structure. The proximity of a sampling site to the QTH/Qinghai-Tibet Railway (QTR), which is effectively a measure of the density of human engineering, was the dominant factor influencing bacterial community diversity. The diversity of bacterial communities shows that 16S rRNA gene abundance decreased in relation to proximity to the QTH and QTR in both alpine wetland and meadow areas. The dominant phyla across all samples were Actinobacteria and Proteobacteria. The concentration of Cr and Cd in the soil were positively correlated with proximity to the QTH and QTR (MC/WC sampling sites), and Ni, Co, and V were positively correlated with proximity to the QTH and QTR (MA/WA sampling sites). The results presented in this study provide an insight into the relationships among heavy metals and soil microbial communities, and have important implications for assessing and predicting the impacts of human-induced activities from the QTH and QTR in such an extreme and fragile environment.

• Cracking in an expansive soil under freeze–thaw cycles
• Yang Lu, SiHong Liu
• DOI:10.3724/SP.J.1226.2017.00392
• 2017, 9 (4): 392–397 Abstract (208) PDF (2977 KB) (223)
• Expansive soils located in cold regions can easily endure the action of frost heaving and cyclic freezing–thawing. Cracking can also occur in expansive clayey soils under freeze–thaw cycles, of which little attention has been paid on this issue. In this study, laboratory experiment and cracking analysis were performed on an expansive soil. Crack patterns were quantitatively analyzed using the fractal concept. The relationships among crack pattern, water loss, number of freeze–thaw cycles, and fractal dimension were discussed. It was found that crack patterns on the surface exhibit a hierarchical network structure that is fractal at a statistical level. Cracks induced by freeze–thaw cycles are shorter, more irregularly oriented, and slowly evolves from an irregularly rectilinear pattern towards a polygonal or quasi–hexagonal one; water loss, closely related to specimen thickness, plays a significant role in the process of soil cracking; crack development under freeze-thaw cycles are not only attributed to capillary effect, but also to expansion and absorption effects.
• Cutting of Phragmites australis as a lake restoration technique: Productivity calculation and nutrient removal in Wuliangsuhai Lake, northern China
• Jan Felix Köbbing, Niels Thevs, Stefan Zerbe
• DOI:10.3724/SP.J.1226.2016.00400
• 2016, 8 (5): 400–410 Abstract (149) PDF (2545 KB) (223)
• Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed (Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100,000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth.
• Comparative study of probable maximum precipitation and isohyetal maps for mountainous regions, Pakistan
• Muhammad Waseem Boota, Ghulam Nabi, Tanveer Abbas, HuiJun Jin, Ayesha Yousaf, Muhammad Azeem Boota
• DOI:10.3724/SP.J.1226.2018.00055
• 2018, 10 (1): 55–68 Abstract (134) PDF (4789 KB) (220)
• Probable maximum precipitation (PMP) is widely used by hydrologists for appraisal of probable maximum flood (PMF) used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper, PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III (LP-III) distribution. Goodness of fit (GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall (HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor (Km) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and Km values varies from 2.54 to 4.68. The coefficient of variability (Cv) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization (MM) approach. In the hydro-meteorological approach, moisture maximization (MM) and wind moisture maximization (WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.
• An evaluation of soil moisture from AMSR-E over source area of the Yellow River, China
• TangTang Zhang,Mekonnen Gebremichael,Akash Koppa,XianHong Meng,Qun Du,Jun Wen
• DOI:10.3724/SP.J.1226.2019.00461.
• 2019, 11 (6): 461–469 Abstract (194) HTML (1698) PDF (2806 KB) (217)
• In this study, in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture products from NASA (National Aeronautics and Space Administration), JAXA (Japanese Aerospace Exploration Agency) and VUA (Vrije University Amsterdam and NASA) over Maqu County, Source Area of the Yellow River (SAYR), China. Results show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area, with a minimum RMSE (root mean square error) of 0.08 (0.10) m3/m3 and smallest absolute error of 0.07 (0.08) m3/m3 at the grassland area with ascending (descending) data. Therefore, the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR. The VUA soil moisture product shows that soil moisture presents a declining trend from east south (0.42 m3/m3) to west north (0.23 m3/m3), with good agreement with a general precipitation distribution. The center of SAYR presents extreme wetness (0.60 m3/m3) during the whole study period, especially in July, while the head of SAYR presents a high level soil moisture (0.23 m3/m3) in July, August and September.

• A review on the ambit and prospects of C3 and C4 plants in Nigeria
• DOI:10.3724/SP.J.1226.2017.00587
• 2017, 9 (6): 587–598 Abstract (106) PDF (2416 KB) (216)
• Despite the enormous applications of photosynthesis in global carbon budget and food security, photosynthesis research has not been adequately explored as a research focus in Nigeria. Previous works on C3 and C4 plants in Nigeria were mainly on the use of anatomical characteristics to delimit plant species into their respective pathways, with no attention being paid to its applications. In this review, past and present knowledge gaps in this area of study are elucidated. Information used in this review were sourced from referred research articles and books in reputable journals. The results revealed that C3 and C4 plants are distributed among 21 genera and 11 families in Nigeria. In addition there is dearth of informatio such that only three genera have been classified based on diverse photosynthetic pathways with no information found on the physiological and biochemical characterization of these genera. Moreover, further research is also suggested for tackling new challenges in the area of food productivity and climate change.
• Characteristics of climate and melt runoff in the Koxkar Glacier River Basin, south slope of the Tianshan Mountains, Northwest China
• Min Xu,HaiDong Han,ShiChang Kang,Hua Tao
• DOI:10.3724/SP.J.1226.2019.00435.
• 2019, 11 (6): 435–447 Abstract (111) HTML (1873) PDF (5258 KB) (216)
• Hydrology of the high glacierized region in the Tianshan Mountains is an important water resource for arid and semiarid areas of China, even Central Asia. The hydrological process is complex to understand, due to the high variability in climate and the lack of hydrometeorological data. Based on field observations, the present study analyzes the meteorological and hydrological characteristics of the Koxkar Glacier River Basin during 2008-2011; and the factors influencing climate impact on glacier hydrology are discussed. The results show that precipitation at the terminus of the glacier was 426.2 mm, 471.8 mm, 624.9 mm, and 532 mm in 2008, 2009, 2010, and 2011, respectively. Discharge increases starting in May, reaches its highest value in July and August, and then starts to decrease. The mean annual discharge was 118.23×106 m3 during the four years observed, with 87.0% occurring in the ablation season (May-September). During the study period, the runoff in August accounted for 29% of total streamflow, followed by July (22%) and June (14%). The runoff exhibited obviously high interannual variability from April to September, induced by drastic changes in climate factors. Discharge autocorrelations are very high for all the years. The climate factors show different influences on discharge. The highest correlation R between daily temperature and discharge was for a time lag of 2-3 days on the Koxkar Glacier (0.66-0.76). The daily depth of runoff to daily temperature and daily water vapor pressure had an R 2 value of 0.56 and 0.69, respectively, which could be described by an exponential function. A closer relationship is found between runoff and either temperature or water vapor pressure on a monthly scale; the R 2 values are 0.65 and 0.78, respectively. The study helps us to understand the mechanisms of the hydrological-meteorological system of typical regional glaciers and to provide a reference for glacier-runoff simulations and water-resource management.

• Estimating interaction between surface water and groundwater in a permafrost region of the northern Tibetan Plateau using heat tracing method
• TanGuang Gao,Jie Liu,TingJun Zhang,ShiChang Kang,ChuanKun Liu,ShuFa Wang,Mika Sillanpää,YuLan Zhang
• DOI:10.3724/SP.J.1226.2020.00071.
• 2020, 12 (2): 71–82 Abstract (168) HTML (441) PDF (4245 KB) (214)
• Understanding the interaction between groundwater and surface water in permafrost regions is essential to study flood frequencies and river water quality, especially in the high latitude/altitude basins. The application of heat tracing method, based on oscillating streambed temperature signals, is a promising geophysical method for identifying and quantifying the interaction between groundwater and surface water. Analytical analysis based on a one-dimensional convective-conductive heat transport equation combined with the fiber-optic distributed temperature sensing method was applied on a streambed of a mountainous permafrost region in the Yeniugou Basin, located in the upper Heihe River on the northern Tibetan Plateau. The results indicated that low connectivity existed between the stream and groundwater in permafrost regions. The interaction between surface water and groundwater increased with the thawing of the active layer. This study demonstrates that the heat tracing method can be applied to study surface water-groundwater interaction over temporal and spatial scales in permafrost regions.

• Artificially frozen ground and related engineering technology in Japan
• Satoshi Akagawa
• DOI:10.3724/SP.J.1226.2021.20046
• 2021, 13 (2): 77–86 Abstract (189) HTML (32228) PDF (8720 KB) (213)
• Since the 1970's, frozen ground has been developing near the Tokyo Bay area around liquefied natural gas (LNG) in-ground storage tanks. For disaster prevention purposes, the tanks are constructed below the ground surface. Since the temperature of the liquid stored in the tanks is -162 °C the soil surrounding the tanks freezes. Since this frozen ground has existed for almost half a century, we have permafrost near Tokyo. The development of artificial frozen ground may cause frost heaving, resulting in frost heave forces that may cause structural damage of adjacent LNG in-ground storage tanks. Therefore, the demand for frozen ground engineering increased and consequently we now have advanced technology in this area. Fortunately, we use this engineering technology and artificial ground freezing for civil engineering, especially in big and crowded cities like Tokyo. This paper provides a summary of the testing apparatus, test methods, and assessment methods for frost heaving.

• Laboratory and field performance of recycled aggregate base in a seasonally cold region
• Tuncer B. Edil, Bora Cetin, Ali Soleimanbeigi
• DOI:10.3724/SP.J.1226.2017.00183
• 2017, 9 (3): 183–191 Abstract (189) PDF (757 KB) (211)
• The objective of this project was to characterize the freeze-thaw properties of recycled concrete (RCA) and asphalt (RAP) as unbound base and to assess how they behaved in the field for nearly 8 years. This paper includes an examination of existing information, laboratory studies of freeze-thaw behavior, and evaluation of data from MnROAD field-test sections in a seasonally cold region, i.e., in Minnesota, USA. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. One test section included 100% RAP, another 100% RCA, a third one a 50/50 blend of RCA/natural aggregate, and a fourth one only natural aggregate (Class 5) as a control. The stiffness (i.e., elastic modulus) was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation, along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance. The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a, as well as by field-scale tests incorporating a falling-weight deflectometer. Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory, and the change in their resilient modulus was measured. In the field-test sections constructed with the same materials as the base course, temperature, moisture, and field modulus (from falling-weight deflectometer tests) were monitored seasonally for nearly 8 years. From the temperatures in the base course layer, the number of freeze-thaw cycles experienced in the field was determined for each test section. Inferences were made relative to modulus change versus freeze-thaw cycles. Conclusions were drawn for long-term field performances of the recycled base (RAB) in comparison to natural aggregate.
• Altitude pattern of carbon stocks in desert grasslands of an arid land region
• Rong Yang, JunQia Kong, ZeYu Du, YongZhong Su
• DOI:10.3724/SP.J.1226.2018.00404
• 2018, 10 (5): 404–412 Abstract (119) HTML (601) PDF (4973 KB) (205)
• For estimating the altitude-distribution pattern of carbon stocks in desert grasslands and analyzing the possible mechanism for this distribution, a detailed study was performed through a series of field vegetation surveys and soil samplings from 90 vegetation plots and 45 soil profiles at 9 sites of the Hexi Corridor region, Northwestern China. Aboveground, belowground, and litter-fall biomass-carbon stocks ranged from 43 to 109, 23 to 64, and 5 to 20 g/m2, with mean values of 80.82, 44.91, and 12.15 g/m2, respectively. Soil-carbon stocks varied between 2.88 and 3.98 kg/m2, with a mean value of 3.43 kg/m2 in the 0–100-cm soil layer. Both biomass- and soil-carbon stocks had an increasing tendency corresponding to the altitudinal gradient. A significantly negative correlation was found between soil-carbon stock and mean annual temperature, with further better correlations between soil- and biomass-carbon stocks, and mean annual precipitation. Furthermore, soil carbon was found to be positively correlated with soil-silt and -clay content, and negatively correlated with soil bulk density and the volume percent of gravel. It can be concluded that variations in soil texture and climate condition were the key factors influencing the altitudinal pattern of carbon stocks in this desert-grassland ecosystem. Thus, by using the linear-regression functions between altitude and carbon stocks, approximately 4.18 Tg carbon were predicted from the 1,260 km2 of desert grasslands in the study area.

• Analysis of structural characteristics and spatial distribution of the national intangible cultural heritage in China and its policy implications
• BaiCui Xu,JingHu Pan
• DOI:10.3724/SP.J.1226.2019.00389.
• 2019, 11 (5): 389–406 Abstract (166) HTML (821) PDF (4506 KB) (205)
• Based on an investigation of four published batches listing 3,140 national intangible cultural heritage (ICH) projects in China and using GIS and some quantitative analysis methods, the spatial structure was investigated and the characteristics and distribution discussed. The distribution of ICHs in China is agglomerative and spatially dependent. From the view of ICH type, each type is distributed in different places, for different reasons, with history being the most important one we found. Nationwide, high-density cores are located in the Beijing-Tianjin-Hebei region and the Yangtze River Delta region. High densities of ICH are concentrated in flat, water-rich regions where broad-leaved forests dominate plains and low mountain areas—areas that have fertile soil, pleasant weather, a long history of culture, ethnic agglomeration, and development. This paper suggests that development of the ICH should be based on discovering unknown items, to break the existing pattern of strong cohesion and high density, and to seek a balanced development of the whole.

• Relationship between ponding and topographic factors along the China-Russia Crude Oil Pipeline in permafrost regions
• MingTang Chai,YanHu Mu,GuoYu Li,Wei Ma,Fei Wang
• DOI:10.3724/SP.J.1226.2019.00419.
• 2019, 11 (6): 419–427 Abstract (178) HTML (585) PDF (4231 KB) (190)
• The original landform along the China-Russia Crude Oil Pipeline (CRCOP, line 2) was disturbed during installation of pavement for the pipeline. Forest and vegetation coverage is dense, and runoff develops along the pipe. Since the operation of the CRCOP (line 2) began in 2018, ponding has appeared on both sides of the pipeline. If there is no drainage, ponding can hardly dissipate, due to the low permeability of the permafrost layer. With the supply of surface flow and the transportation of oil at positive temperatures, ponding promotes an increase in temperature and changes the boundary thermal conditions of the pipeline. Meanwhile, when the ponding freezes and thaws, frost heave threatens operational safety of the pipeline. Furthermore, the ponding can affect the thermal condition of line 1. In this paper, the distribution of ponding along the CRCOP was obtained by field investigation. The type and cause of ponding were summarized, and the catchment and stream order were extracted by the Digital Elevation Model (DEM). According to the statistical results in attributes for topographic factors, it is known that ponding along the pipeline is relative to elevation, slope, aspect, and the Topographic Wetness Index (TWI). Water easily accumulates at altitudes of 300-450 m, slopes within 3°-5°, aspect in the northeast or south, TWI within 13-16, flow direction in north-east-south, and flow length within 90-150 km. This paper proposes a theoretical basis for the cause and characteristics of ponding along the pipeline.

• Evaluating effects of Dielectric Models on the surface soil moisture retrieval in the Qinghai-Tibet Plateau
• Rong Liu,Xin Wang,ZuoLiang Wang,Jun Wen
• DOI:10.3724/SP.J.1226.2021.20067
• 2021, 13 (1): 62–76 Abstract (168) HTML (3504) PDF (7208 KB) (190)
• Based on the measurement of L-band ground-based microwave radiometer (ELBARA-III type) in the Qinghai-Tibet Plateau and the $τ-ω$ radiative transfer model, this research evaluated the effects of four soil dielectric models, i.e., Wang-Schmugge, Mironov, Dobson, and Four-phase, on the L-band microwave brightness temperature simulation and soil moisture retrieval. The results show that with the same vegetation and roughness parameterization scheme, the four soil dielectric models display obvious differences in microwave brightness temperature simulation. When the soil moisture is less than 0.23 m3/m3, the simulated microwave brightness temperature in Wang-Schmugge model is significantly different from that of the other three models, with maximum differences of horizontal polarization and vertical polarization reaching 8.0 K and 4.4 K, respectively; when the soil moisture is greater than 0.23 m3/m3, the simulated microwave brightness temperature of Four-phase significantly exceeds that of the other three models; when the soil moisture is saturated, maximum differences in simulated microwave brightness temperature with horizontal polarization and vertical polarization are 6.1 K and 4.8 K respectively, and the four soil dielectric models are more variable in the microwave brightness temperature simulation with horizontal polarization than that with vertical polarization. As for the soil moisture retrieval based on the four dielectric models, the comparison study shows that, under the condition of horizontal polarization, Wang-Schmugge model can reduce the degree of retrieved soil moisture underestimating the observed soil moisture more effectively than other parameterization schemes, while under the condition of vertical polarization, the Mironov model can reduce the degree of retrieved soil moisture overestimating the observed soil moisture. Finally, based on the Wang-Schmugge model and FengYun-3C observation data, the spatial distribution of soil moisture in the study area is retrieved.

• Biodiversity, productivity, and temporal stability in a natural grassland ecosystem of China
• Bing Liu, WenZhi Zhao, YangYang Meng, Chan Liu
• DOI:10.3724/SP.J.1226.2018.00293
• 2018, 10 (4): 293–304 Abstract (145) HTML (22) PDF (1767 KB) (187)
• Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass, and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China.

• Influence of fines content on the anti-frost properties of coarse-grained soil
• TianLiang Wang, ZuRun Yue, TieCheng Sun, JinChuang Hua
• DOI:10.3724/SP.J.1226.2015.00407
• 2015, 7 (4): 407–413 Abstract (117) PDF (4001 KB) (185)
• This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows:(1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles,the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engineering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions.
• Processes of runoff in seasonally-frozen ground about a forested catchment of semiarid mountains
• PengFei Lin,ZhiBin He,Jun Du,LongFei Chen,Xi Zhu,QuanYan Tian
• DOI:10.3724/SP.J.1226.2020.00272.
• 2020, 12 (5): 272–283 Abstract (92) HTML (12) PDF (5854 KB) (185)
• Climate warming increases the variability in runoff of semiarid mountains where seasonally-frozen ground is widely distributed. However, what is not well understood are the processes of runoff, hydrological drivers, and freeze-thaw cycles in seasonally-frozen ground in semiarid mountains. To understand how freeze-thaw cycles affect runoff processes in seasonally-frozen ground, we monitored hydrological processes in a typical headwater catchment with seasonally-frozen ground in Qilian Mountain, China, from 2002 to 2017. We analyzed the responses of runoff to temperature, precipitation, and seasonally-frozen ground to quantify process characteristics and driving factors. The results show that annual runoff was 88.5 mm accounting for 25.6% of rainfall, mainly concentrated in May to October, with baseflow of 36.44 mm. Peak runoff occurred in June, August, and September, i.e., accounting for spring and summer floods. Runoff during the spring flood was produced by a mix of rainfall, melting snow, and melting seasonally-frozen ground, and had a significant correlation with air temperature. Runoff was mainly due to precipitation accumulation during the summer flood. Air temperature, average soil temperature at 0-50 cm depth, and frozen soil depth variable explained 59.60% of the variation of runoff in the thawing period, while precipitation variable explained 21.9%. Thawing-period runoff and soil temperature had a >0.6 correlation coefficient (P <0.05). In the rainfall-period, runoff was also affected by temperature, soil moisture, and precipitation, which explained 33.6%, 34.1% and 18.1%, respectively. Our results show that increasing temperature and precipitation will have an irreversible impact on the hydrological regime in mountainous basins where seasonally-frozen ground is widely distributed.

• Zhangmu and Gyirong ports under the threat of glacial lake outburst flood
• MiaoMiao Qi,ShiYin Liu,YongPeng Gao
• DOI:10.3724/SP.J.1226.2020.00461
• 2020, 12 (6): 461–476 Abstract (105) HTML (722) PDF (11802 KB) (184)
• The Himalayas are prone to glacial lake outburst floods, which can pose a severe threat to downstream villages and infrastructure. The Zhangmu and Gyirong land treaty ports are located on the China-Nepal border in the central Himalayas. In recent years, the expansion of glacial lakes has increased the threat of these two port regions. This article describes the results of mapping the glacial lakes larger than 0.01 km2 in the Zhangmu and Gyirong port regions and analyzes their change. It provides a comprehensive assessment of potentially dangerous glacial lakes and predicts the development of future glacial lakes. From 1988 to 2019, the glacial lakes in these port regions underwent "expansion", and moraine-dammed lakes show the most significant expansion trend. A total of eleven potentially dangerous glacial lakes are identified based on the assessment criteria and historical outburst events; most expanded by more than 150% from 1988 to 2019, with some by over 500%. The Cirenmaco, a moraine-dammed lake, is extremely prone to overtopping due to ice avalanches or the melting of dead ice in the dam. For other large lakes, such as the Jialongco, Gangxico and Galongco, ice avalanches may likely cause the lakes to burst besides self-destructive failure. The potential dangers of the Youmojianco glacial lakes, including lakes Nos. 9, 10 and 11, will increase in the future. In addition, the glacier-bed topography model predicts that 113 glacial lakes with a size larger than 0.01 km2, a total area of 11.88 km2 and a total volume of 6.37×109 m3 will form in the study area by the end of the 21 century. Due to global warming, the glacial lakes in the Zhangmu and Gyirong port regions will continue to grow in the short term, and hence the risk of glacial lake outburst floods will increase.

• Surface-deformation monitoring in the permafrost regions over the Tibetan Plateau, using Sentinel-1 data
• ZhenMing Wu, Lin Zhao, Lin Liu, Rui Zhu, ZeShen Gao, YongPing Qiao, LiMing Tian, HuaYun Zhou, MeiZhen Xie
• DOI:10.3724/SP.J.1226.2018.00114
• 2018, 10 (2): 114–125 Abstract (148) PDF (2925 KB) (183)
• Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to measure surface deformation over the Tibetan Plateau. However, the accuracy and applicability of the D-InSAR method are not well estimated due to the lack of in-situ validation. In this paper, we mapped the seasonal and long-term displacement of Tanggula (TGL) and Liangdaohe (LDH) permafrost regions with a stack of Sentinel-1 acquisitions using the Small Baseline Subset InSAR (SBAS-InSAR) method. In the TGL region, with its dry soils and sparse vegetation, the InSAR-derived surface-deformation trend was consistent with ground-based leveling results; long-term changes of the active layer showed a settlement rate of around 1 to 3 mm/a due to the melting of ground ice, indicating a degrading permafrost in this area. Around half of the deformation was picked up on monitoring, in contrast with in-situ measurements in LDH, implying that the D-InSAR method remarkably underestimated the surface-deformation. This phenomenon may be induced by the large soil-water content, high vegetation coverage, or a combination of these two factors in this region. This study demonstrates that surface deformation could be mapped accurately for a specific region with Sentinel-1 C-band data, such as in the TGL region. Moreover, although the D-InSAR technology provides an efficient solution for broad surface-deformation monitoring in permafrost regions, it shows a poor performance in the region with high soil-water content and dense vegetation coverage.
• Effects of intercropping on rhizosphere soil microorganisms and root exudates of Lanzhou lily (Lilium davidii var. unicolor)
• CuiPing Hua, YaJun Wang, ZhongKui Xie, ZhiHong Guo, YuBao Zhang, Yang Qiu, Le Wang
• DOI:10.3724/SP.J.1226.2018.00159
• 2018, 10 (2): 159–168 Abstract (158) PDF (1727 KB) (183)
• Both yield and quality of Lanzhou lily (Lilium davidii var. unicolor) are seriously affected by continuous cropping. We attempted to understand the effects of intercropping on the obstacles associated with continuous cropping of Lanzhou lily (Lilium davidii var. unicolor). The changes of rhizosphere microbial biomass and diversity in interplanting and monoculturing systems were studied by using the Illumina HiSeq sequencing technique. The contents and composition of lily root exudates were measured by gas chromatography–mass spectrometer (GC–MS). The intercropping results of Lanzhou lily showed: (1) There was no difference in the composition of the rhizosphere soil microbes at the phylum level, but the relative abundance of the microbes decreased; and the relative abundance of harmful fungi such as Fusarium sp. increased. The relative abundance of Pleosporales sp. and other beneficial bacteria were reduced. After OTU (operational taxonomic unit) clustering, there were some beneficial bacteria, such as Chaetomium sp., in the lily rhizosphere soil in the interplanting system that had not existed in the single-cropping system. We did not find harmful bacteria that had existed in the single-cropping systm in the rhizosphere soil of interplanting system. The above results indicated that the changes of relative abundance of soil fungi and bacteria in lily rhizosphere soil was not conducive to improving the ecological structure of rhizosphere soil microbes. At the same time, the microbial composition change is very complex—beneficial and yet inadequate at the same time. (2) Root exudates provide a matrix for the growth of microorganisms. Combined with the detection of root exudates, the decrease in the composition of the root exudates of the lily was probably the reason for the decrease of the relative abundance of microbes after intercropping. At the same time, the decrease of the relative content of phenolic compounds, which inhibit the growth of microorganisms, did not increase the relative content of rhizosphere soil microorganisms. Changes in amino acids and total sugars may be responsible for the growth of Fusarium sp.. The results showed that the intercropping pattern did not noticeably alleviate the obstacle to continuous cropping of Lanzhou lily, and the change of microbial biomass and diversity was even unfavorable. However, the emergence of some beneficial bacteria, the disappearance of harmful fungi, and other changes with intercropping are in favor of alleviation of obstacles to continuous cropping of Lanzhou lily.
• An improvement of soil temperature simulations on the Tibetan Plateau
• SiQiong Luo, BoLi Chen, ShiHua Lyu, XueWei Fang, JingYuan Wang, XianHong Meng, LunYu Shang, ShaoYing Wang, Di Ma
• DOI:10.3724/SP.J.1226.2018.00080
• 2018, 10 (1): 80–94 Abstract (122) PDF (6264 KB) (183)
• The simulation of soil temperature on the Tibetan Plateau (TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5 (CLM3.5) and Regional Climatic Model 4 (RegCM4). The improved CLM3.5 and RegCM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.
• High-resolution mass spectrometric characterization of dissolved organic matter from warm and cold periods in the NEEM ice core
• JianZhong Xu, Amanda Grannas, CunDe Xiao, ZhiHeng Du, Amanda Willoughby, Patrick Hatcher, YanQing An
• DOI:10.3724/SP.J.1226.2018.00038
• 2018, 10 (1): 38–46 Abstract (131) PDF (3711 KB) (181)
• Dissolved organic matter (DOM) is an important component of ice cores but is currently poorly characterized. DOM from one Holocene sample (HS, aged at 1600-4500 B.P.) and one Last Glacial Maximum sample (LS, aged at 21000-25000 B.P.) from the North Greenland Eemian Ice Drilling (NEEM) ice core were analyzed by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). CHO compounds contributed 50% of the compounds identified in negative-ionization mode in these two samples, with significant contributions from organic N, S, and P compounds, likely suggesting that marine DOM was an important source in these samples. Overall, the chemical compositions are similar between these two samples, suggesting their consistent DOM sources. However, subtle differences in the DOM between these two samples are apparent and could indicate differences in source strength or chemistry occurring through both pre- and post-depositional processes. For example, higher relative amounts of condensed carbon compounds in the HS DOM (5%), compared to the LS DOM (2%), suggest potentially important contributions from terrestrial sources. Greater incorporation of P in the observed DOM in the LS DOM (22%), compared to the HS DOM (13%), indicate more active microbiological processes that likely contribute to phosphorus incorporation into the DOM pool. Although these two samples present only a preliminary analysis of DOM in glacial/interglacial periods, the data indicate a need to expand the analysis into a broader range of ice-core samples, geographical locations, and glacial/interglacial periods.
• Measurement for coordinated development of "four modernizations" and its efficiency of prefecture level cities or above in China
• JingHu Pan, YanXing Hu
• DOI:10.3724/SP.J.1226.2016.00163
• 2016, 8 (2): 163–176 Abstract (117) PDF (697 KB) (180)
• The efficient and coordinated development of industrialization,urbanization,informatization and agricultural modernization(so called "Sihua Tongbu" in China,and hereinafter referred to as "four modernizations") is not only a practical need but also an important strategic direction of integrating urban-rural development and regional development in recent China.This paper evaluated the comprehensive,coupling and coordinated developmental indices of "four modernizations" of China's 343 prefecture-level administrative units,and calculated their efficiency of "four modernizations" in 2001 and 2011.The efficiency evaluation index system was established.The efficiencies and their changing trend during the period 2001-2011 were investigated using the data envelopment analysis(DEA) model.Spatial-temporal pattern of the efficiency of China's prefecture-level units was explored by using exploratory spatial data analysis(ESDA).Finally,the main influencing factors were revealed with the aid of geographically weighted regression(GWR) model.Results indicate that the comprehensive,coupling and coordinated developmental indices and efficiency of "four modernizations" of China's prefecture-level administrative units have obvious spatial differences and show diverse regional patterns.Overall,the efficiency is relatively low,and only few units with small urban populations and economic scale are in DEA efficiencies.The efficiency changing trends were decreasing during 2001-2011,with a transfer of high efficiency areas from inland to eastern coastal areas.The difference between urban and rural per capita investment in fixed assets boasts the greatest influence on the efficiency.
• Numerical simulation of artificial ground freezing in a fluid-saturated rock mass with account for filtration and mechanical processes
• Ivan A. Panteleev, Anastasiia A. Kostina, Oleg A. Plekhov, Lev Yu. Levin
• DOI:10.3724/SP.J.1226.2017.00363
• 2017, 9 (4): 363–377 Abstract (144) PDF (1995 KB) (178)
• This study is devoted to the numerical simulation of the artificial ground freezing process in a fluid-saturated rock mass of the potassium salt deposit. A coupled model of nonstationary thermal conductivity, filtration and thermo-poroelasticity, which takes into account dependence of the physical properties on temperature and pressure, is proposed on the basis of the accepted hypotheses. The considered area is a cylinder with a depth of 256 meters and diameter of 26.5 meters and includes 13 layers with different thermophysical and filtration properties. Numerical simulation was carried out by the finite-element method. It has been shown that substantial ice wall formation occurs non-uniformly along the layers. This can be connected with geometry of the freezing wells and with difference in physical properties. The average width of the ice wall in each layer was calculated. It was demonstrated that two toroidal convective cells induced by thermogravitational convection were created from the very beginning of the freezing process. The effect of the constant seepage flow on the ice wall formation was investigated. It was shown that the presence of the slow flow lead to the delay in ice wall closure. In case of the flow with a velocity of more than 30 mm per day, closure of the ice wall was not observed at all in the foreseeable time.
• Constitutive models and salt migration mechanisms of saline frozen soil and the-state-of-the-practice countermeasures in cold regions
• YuanMing Lai,ZheMin You,Jing Zhang
• DOI:10.3724/SP.J.1226.2021.20045
• 2021, 13 (1): 1–17 Abstract (521) HTML (23846) PDF (4971 KB) (513)
• A series of saline soil-related problems, including salt expansion and collapse, frost heave and thaw settlement, threaten the safety of the road traffic and the built infrastructure in cold regions. This article presents a comprehensive review of the physical and mechanical properties, salt migration mechanisms of saline soil in cold environment, and the countermeasures in practice. It is organized as follows: (1) The basic physical characteristics; (2) The strength criteria and constitutive models; (3) Water and salt migration characteristics and mechanisms; and (4) Countermeasures of frost heave and salt expansion. The review provides a holistic perspective for recent progress in the strength characteristics, mechanisms of frost heave and salt expansion, engineering countermeasures of saline soil in cold regions. Future research is proposed on issues such as the effects of salt erosion on concrete and salt corrosion of metal under the joint action of evaporation and freeze-thaw cycles.

• Seed germination and seedling growth of Pycnanthus angolensis (Welw.) Warb., African false nutmeg
• Sakpere A.M.A.
• DOI:10.3724/SP.J.1226.2019.00350.
• 2019, 11 (5): 350–359 Abstract (4434) HTML (30921) PDF (2153 KB) (370)
• This study investigated the germination behavior and seedling growth of Pycnanthus angolensis seeds. The germination study was carried out in the laboratory and included pretreatment studies and observation of the seed-germination process. For each treatment, three replications of 20 seeds were sown in a transparent plastic germination box (12cm $×$ 22cm $×$ 5cm) lined with moistened filter paper at room temperature. To monitor seedling growth, seedlings were transplanted into pots filled with topsoil and laid out in a completely randomized design. Ten seedlings replicated thrice were measured monthly; and the shoot height, leaf area, and root length, as well as the fresh and dry weights of the seedlings, were recorded. Results showed that mechanically scarified seeds exhibited the significantly highest germination percent (83.33%, P <0.005), followed by control seeds (70.83%), whereas seeds treated with 98% sulphuric acid (H2SO4) displayed the lowest germination percent (1.67). The endospermous seeds exhibited cryptogeal germination, while seeds stored for a month (with or without arils) failed to germinate. During seed germination, radicle protrusion continued with a pseudo-opening of the root, through which the brownish cotyledonary petiole was emitted, thus releasing the plumule at the posterior position. Moreover, P. angolensis exhibited a slow growth rate, attaining a shoot height of 73 cm within a year. The highest positive change in leaf number and area was recorded in the fourth month, a period during which the least change in shoot height occurred. The study concluded that mechanical scarification of the seeds ensured significant and faster germination than chemical scarification or no treatment at all. Additionally, P. angolensis displayed a cryptogeal germination, with the seedling growth of the tree species observed to be slow.

• Study of thermal properties of supraglacial debris and degree-day factors on Lirung Glacier, Nepal
• Mohan Bahadur Chand,Rijan Bhakta Kayastha
• DOI:10.3724/SP.J.1226.2018.00357
• 2018, 10 (5): 357–368 Abstract (418) HTML (14864) PDF (4797 KB) (304)
• The extensive debris that covers glaciers in the ablation zone of the Himalayan region plays an important part in regulating ablation rates and water availability for the downstream region. The melt rate of ice is determined by the amount of heat conducted through debris material lying over the ice. This study presents the vertical temperature gradients, thermal properties in terms of thermal diffusivity and thermal conductivity, and positive degree-day factors for the debris-covered portion of Lirung Glacier in Langtang Valley, Nepal Himalaya using field-based measurements from three different seasons. Field measurements include debris temperatures at different debris thicknesses, air temperature, and ice melt during the monsoon (2013), winter (2013), and pre-monsoon (2014) seasons. We used a thermal equation to estimate thermal diffusivity and thermal conductivity, and degree-day factors (DDF) were calculated from cumulative positive temperature and ice melt of the measurement period. Our analysis of debris temperature profiles at different depths of debris show the daily linear gradients of ?20.81 °C/m, 4.05 °C/m, and ?7.79 °C/m in the monsoon, winter, and pre-monsoon seasons, respectively. The values of thermal diffusivity and thermal conductivity in the monsoon season were 10 times greater than in the winter season. The large difference in these values is attributed to surface temperature and moisture content within the debris. Similarly, we found higher values of DDFs at thinner debris for the pre-monsoon season than in the monsoon season although we observed less melting during the pre-monsoon season. This is attributed to higher cumulative temperature during the monsoon season than in the pre-monsoon season. Our study advances our understanding of heat conductivity through debris material in different seasons, which supports estimating ice melt and discharge from glacierized river basins with debris-covered glaciers in the Himalayan region.

• Research on pile performance and state-of-the-art practice in cold regions
• JianKun Liu, TengFei Wang, Zhi Wen
• DOI:10.3724/SP.J.1226.2018.00001
• 2018, 10 (1): 1–11 Abstract (759) PDF (3430 KB) (303)
• A pile foundation is commonly adopted in geotechnical engineering to support structures, and its application has been extended to cold-regions engineering. In past decades, a host of scholars investigated pile behaviors and proposed design guidelines for seasonally frozen ground or permafrost. This paper reviews the research with respect to pile performance and engineering practice in cold regions, organized as follows: (1) creep tests and bearing capacity, (2) frost-jacking hazards, (3) laterally loaded piles, (4) dynamic responses, (5) refreezing due to concrete-hydration heat, and (6) improved countermeasures and design methods. We first summarize previous research and recent progress; then, predict the development trend of pile foundations in cold regions and recommend further research.
• Theoretical expressions for soil particle detachment rate due to saltation bombardment in wind erosion
• XuYang Liu,WenXiao Ning,ZhenTing Wang
• DOI:10.3724/SP.J.1226.2020.00234
• 2020, 12 (4): 234–241 Abstract (177) HTML (14574) PDF (1421 KB) (301)
• Saltation bombardment is a dominate dust emission mechanism in wind erosion. For loose surfaces, splash entrainment has been well understood theoretically. However, the mass loss predictions of cohesive soils are generally empirical in most wind erosion models. In this study, the soil particle detachment of a bare, smooth, dry, and uncrusted soil surface caused by saltation bombardment is modeled by means of classical mechanics. It is shown that detachment rate can be analytically expressed in terms of the kinetic energy or mass flux of saltating grains and several common mechanical parameters of soils, including Poisson's ratio, Young's modulus, cohesion and friction angle. The novel expressions can describe dust emission rate from cohesive surfaces and are helpful to quantify the anti-erodibility of soil. It is proposed that the mechanical properties of soils should be appropriately included in physically-based wind erosion models.

• Frost susceptibility of soils―A confusing concept that can misguide geotechnical design in cold regions
• DaiChao Sheng
• DOI:10.3724/SP.J.1226.2021.20051
• 2021, 13 (2): 87–94 Abstract (116) HTML (13265) PDF (3999 KB) (294)
• Frost susceptibility is a concept widely used in cold region geotechnical design, to quantify the capacity of a soil in generating frost heave and frost damage. The laboratory test used to verify frost susceptibility of a soil is based on the measurement of frost heave generated in the soil under specific conditions. In reality this concept is, however, more related to the soil's potential to thaw weakening than to frost heave. Recent experimental studies show that frost non-susceptible soils like clean sand and clean gavel can also generate much ice segregation and frost heave if the conditions are favourable, hence challenging the usefulness and suitability of soil classification based on frost susceptibility. It is further shown that the concept is not suitable for design scenarios where frost heave itself is a serious hazard, such as in high-speed rail embankments.

• Thickness estimation of the Longbasaba Glacier: methods and application
• GuangLi He,JunFeng Wei,Xin Wang
• DOI:10.3724/SP.J.1226.2020.00477
• 2020, 12 (6): 477–490 Abstract (93) HTML (8769) PDF (4573 KB) (278)
• A total of 71,177 glaciers exist on the Qinghai-Tibet Plateau, according to the Randolph Glacier Inventory (RGI 6.0). Despite their large number, glacier ice thickness data are relatively scarce. This study utilizes digital elevation model data and ground-penetrating radar thickness measurements to estimate the distribution and variation of ice thickness of the Longbasaba Glacier using Glacier bed Topography (GlabTop), a full-width expansion model, and the Huss and Farinotti (HF) model. Results show that the average absolute deviations of GlabTop, the full-width expansion model, and the HF model are 9.8, 15.5, and 10.9 m, respectively, indicating that GlabTop performs the best in simulating glacier thickness distribution. During 1980-2015, the Longbasaba Glacier thinned by an average of 7.9±1.3 m or 0.23±0.04 m/a, and its ice volume shrunk by 0.28±0.04 km3 with an average reduction rate of 0.0081±0.0001 km3/a. In the investigation period, the area and volume of Longbasaba Lake expanded at rates of 0.12±0.01 km2/a and 0.0132±0.0018 km3/a, respectively. This proglacial lake could potentially extend up to 5,000 m from the lake dam.

• Aeolian processes on sandy desertification of an alpine meadow: A wind tunnel experiment
• ZhiShan An,KeCun Zhang,LiHai Tan,BaiCheng Niu,YanPing Yu
• DOI:10.3724/SP.J.1226.2020.00012.
• 2020, 12 (1): 12–21 Abstract (113) HTML (7798) PDF (6304 KB) (271)
• In recent years, the desertification of alpine meadows has become a serious ecological problem and has gradually become a threat to regional economic activities in Maqu County. To reveal the mechanism for sandy desertification of alpine meadows, we conducted wind tunnel experiments on aeolian processes over sandy alpine meadows. Results show that the sand-flux profile of mix-sized sediment decays exponentially with increasing height. However, the profile pattern of a group of uniform-sized particles depends on the experimental wind speeds. The profile pattern of all the groups studied can be expressed by exponential decay functions when the wind speed is less than or equal to 16 m/s. while that for all the groups studied can be expressed by a Gaussian distribution function when the wind speed is above 16 m/s. The average saltation heights of mixed sands at wind speeds of 12 m/s, 16 m/s, 20 m/s, and 24 m/s were 2.74, 4.19, 5.28, and 6.12 cm, respectively. The mean grain size basically first decreases and then increases with increasing height under different wind speeds. The sorting improves with increasing wind speed, while the kurtosis and skewness show relationships with only the characteristics of the parent soil.

• Spatial distribution of supraglacial debris thickness on glaciers of the China-Pakistan Economic Corridor and surroundings
• YaJie Zheng,Yong Zhang,Ju Gu,Xin Wang,ZongLi Jiang,JunFeng Wei
• DOI:10.3724/SP.J.1226.2020.00447
• 2020, 12 (6): 447–460 Abstract (110) HTML (3289) PDF (6723 KB) (270)
• Debris-covered glaciers, characterized by the presence of supraglacial debris mantles in their ablation zones, are widespread in the China-Pakistan Economic Corridor (CPEC) and surroundings. For these glaciers, thin debris layers accelerate the melting of underlying ice compared to that of bare ice, while thick debris layers retard ice melting, called debris-cover effect. Knowledge about the thickness and thermal properties of debris cover on CPEC glaciers is still unclear, making it difficult to assess the regional debris-cover effect. In this study, thermal resistance of the debris layer estimated from remotely sensed data reveals that about 54.0% of CPEC glaciers are debris-covered glaciers, on which the total debris-covered area is about 5,072 km2, accounting for 14.0% of the total glacier area of the study region. We find that marked difference in the extent and thickness of debris cover is apparent from region to region, as well as the debris-cover effect. 53.3% of the total debris-covered area of the study region is concentrated in Karakoram, followed by Pamir with 30.2% of the total debris-covered area. As revealed by the thermal resistance, the debris thickness is thick in Hindu Kush on average, with the mean thermal resistance of 7.0×10-2 ((m2?K)/W), followed by Karakoram, while the thickness in western Himalaya is thin with the mean value of 2.0×10-2 ((m2?K)/W). Our findings provide a basis for better assessments of changes in debris-covered glaciers and their associated hydrological impacts in the CPEC and surroundings.

• Qualitative and quantitative phytochemical analysis of selected mosses with different alcoholic solvents
• Kehinde O. Olasoji,Amos M. Makinde,Bolajoko A. Akinpelu,Musibau O. Isa
• DOI:10.3724/SP.J.1226.2019.00382.
• 2019, 11 (5): 382–388 Abstract (189) HTML (1715) PDF (670 KB) (260)
• This study was conducted to investigate the qualitative and quantitative phytochemical content of the crude extracts of Archidium ohioense, Pelekium gratum, and Hyophila involuta with different alcoholic solvents (ethanol, methanol, Seaman's Schnapps, fresh oil-palm wine, and fresh Raffia-palm wine). The mosses were collected from their natural populations on the central campus of the Obafemi Awolowo University, Ile-Ife, Nigeria. The yield of the extracts was weighed for all the solvents, and the qualitative and quantitative evaluations of the extracts were carried out using standard methods. The results of phytochemical analysis of the crude extracts from the mosses showed the presence of saponins, cardiac glycosides, triterpenes, alkaloids, flavonoids, and steroids. The quantitative phytochemical analysis of the crude extracts showed that ethanolic extracts of Hyophila involuta had the highest flavonoid content (288.37±0.10 mg RE/g), and Raffia-palm-wine extracts of Hyophila involuta had the highest saponin content (224.70±0.02 mg/g), while the methanolic extract of Archidium ohioense had the highest cardiac glycosides content (63.71±0.14 mg/g), and the Raffia-palm wine extract of Hyophila involuta had the highest alkaloids content (102.50±0.12 mg/g). Raffia- and oil-palm wines were observed to be the most effective solvents for all the mosses studied, followed by Seaman's Schnapp, while methanol and ethanol were less effective. The study concluded that the extracts of the mosses studied contain pharmacologically active constituents that can be used for therapeutic purposes.

• Soil freezing process and different expressions for the soil-freezing characteristic curve
• JunPing Ren, Sai K. Vanapalli, Zhong Han
• DOI:10.3724/SP.J.1226.2017.00221
• 2017, 9 (3): 221–228 Abstract (243) PDF (4411 KB) (259)
• The soil-freezing characteristic curve (SFCC), which represents the relationship between unfrozen water content and sub-freezing temperature (or suction at ice-water interface) in a freezing soil, can be used for understanding the transportation of heat, water, and solute in frozen soils. In this paper, the soil freezing process and the similarity between the SFCC of saturated frozen soil and soil-water characteristic curve (SWCC) of unfrozen unsaturated soil are reviewed. Based on similar characteristics between SWCC and SFCC, a conceptual SFCC is drawn for illustrating the main features of soil freezing and thawing processes. Various SFCC expressions from the literature are summarized. Four widely used expressions (i.e., power relationship, exponential relationship, van Genuchten 1980 equation and Fredlund and Xing 1994 equation) are evaluated using published experimental data on four different soils (i.e., sandy loam, silt, clay, and saline silt). Results show that the exponential relationship and van Genuchten (1980) equation are more suitable for sandy soils. The simple power relationship can be used to reasonably best-fit the SFCC for soils with different particle sizes; however, it exhibits limitations when fitting the saline silt data. The Fredlund and Xing (1994) equation is suitable for fitting the SFCCs for all soils studied in this paper.
• Characteristics of permafrost degradation in Northeast China and its ecological effects: A review
• ShanShan Chen,ShuYing Zang,Li Sun
• DOI:10.3724/SP.J.1226.2020.00001.
• 2020, 12 (1): 1–11 Abstract (185) HTML (509) PDF (1207 KB) (258)

• A nonlinear interface structural damage model between ice crystal and frozen clay soil
• Sheng Shi,Feng Zhang,KangWei Tang,DeCheng Feng,XuFeng Lu
• DOI:10.3724/SP.J.1226.2021.20050
• 2021, 13 (2): 150–166 Abstract (81) HTML (13696) PDF (10701 KB) (251)
• The shear properties of ice-frozen soil interface are important when studying the constitutive model of frozen soil and slope stability in cold regions. In this research, a series of cryogenic direct shear tests for ice-frozen clay soil interface were conducted. Based on experimental results, a nonlinear interface structural damage model is proposed to describe the shear properties of ice-frozen clay soil interface. Firstly, the cementation and friction structural properties of frozen soil materials were analyzed, and a structural parameter of the ice-frozen clay soil interface is proposed based on the cryogenic direct shear test results. Secondly, a structural coefficient ratio is proposed to describe the structural development degree of ice-frozen clay soil interface under load, which is able to normalize the shear stress of ice-frozen clay soil interface, and the normalized data can be described by the Duncan-Chang model. Finally, the tangent stiffness of ice-frozen clay soil interface is calculated, which can be applied to the mechanics analysis of frozen soil. Also, the shear stress of ice-frozen clay soil interface calculated by the proposed model is compared with test results.

• Characteristics and changes of permafrost along the engineering corridor of National Highway 214 in the eastern Qinghai-Tibet Plateau
• Yu Sheng,JiChun Wu,Wei Cao,JianHong Fang,AnHua Xu,ErXing Peng
• DOI:10.3724/SP.J.1226.2020.00503
• 2020, 12 (6): 503–516 Abstract (243) HTML (2116) PDF (7387 KB) (238)
• Due to a series of linear projects built along National Highway 214, the second "Permafrost Engineering Corridor" on the Qinghai-Tibet Plateau has formed. In this paper, by overcoming the problems of data decentralization and standard inconsistency, permafrost characteristics and changes along the engineering corridor are systematically summarized based on the survey and monitoring data. The results show that: 1) Being controlled by elevation, the permafrost is distributed in flake discontinuity with mountains as the center along the line. The total length of the road section in permafrost regions is 365 km, of which the total length of the permafrost section of National Highway 214 is 216.7 km, and the total length of the permafrost section of Gong-Yu Expressway is 197.3 km. The mean annual ground temperature (MAGT) is higher than -1.5 °C, and permafrost with MAGT lower than -1.5 °C is only distributed in the sections at Bayan Har Mountain and E'la Mountain. There are obvious differences in the distribution of ground ice in the different sections along the engineering corridor. The sections with high ice content are mainly located in Zuimatan, Duogerong Plain and the top of north and south slope of Bayan Har Mountain. The permafrost thickness is controlled by the ground temperature, and permafrost thickness increases with the decrease of the ground temperature, with the change rate of about 37 m/°C. 2) Local factors (topography, landform, vegetation and lithology) affect the degradation process of permafrost, and then affect the distribution, ground temperature, thickness and ice content of permafrost. Asphalt pavement has greatly changed the heat exchange balance of the original ground, resulting in serious degradation of the permafrost. Due to the influence of roadbed direction trend, the phenomenon of shady-sunny slope is very significant in most sections along the line. The warming range of permafrost under the roadbed is gradually smaller with the increase of depth, so the thawing settlement of the shallow section with high ice-content permafrost is more significant.

• Proline and soluble sugars accumulation in three pepper species (Capsicum spp) in response to water stress imposed at different stages of growth
• DOI:10.3724/SP.J.1226.2016.00205
• 2016, 8 (3): 205–211 Abstract (173) PDF (325 KB) (234)
• Drought is a major production constraint for major fruits and vegetable crops in the tropics.This study was conducted to investigate the effect of limited water supply at three growth stages (vegetative,flowering and fruiting) on the accumulation of proline and soluble sugars in three pepper species.Seeds of the three pepper species,Capsicum chinense Jacq.,C.annuum L.and C.frutescens L.were raised in a nursery and the seedlings were transplanted into seventy two plastic pots arranged in a randomized complete block design with three replicates,25 days after planting.Four water treatments,200 mL of water supplied twice daily (W1),once in every three days (W2),once in every five days (W3),and zero water supplied throughout growing period (W0) were imposed at three vegetative,flowering,and fruiting growth stages.Data were collected on relative water content,free proline and total soluble sugar.Data collected were subjected to analysis of variance and means were separated using Duncan's multiple range test.Results show that the concentration of proline and soluble sugar in leaves of the three pepper species were found to be remarkable at the different stages of growth in the stressed plants.
• Influence of proximity to the Qinghai-Tibet highway and railway on variations of soil heavy metal concentrations and bacterial community diversity on the Tibetan Plateau
• Xia Zhao,JunFeng Wang,Yun Wang,Xiang Lu,ShaoFang Liu,YuBao Zhang,ZhiHong Guo,ZhongKui Xie,RuoYu Wang
• DOI:10.3724/SP.J.1226.2019.00407.
• 2019, 11 (6): 407–418 Abstract (172) HTML (1876) PDF (4670 KB) (234)
• An understanding of soil microbial communities is crucial in roadside soil environmental assessments. The 16S rRNA sequencing of a stressed microbial community in soil adjacent to the Qinghai-Tibet Highway (QTH) revealed that the accumulation of heavy metals (over about 10 years) has affected the diversity of bacterial abundance and microbial community structure. The proximity of a sampling site to the QTH/Qinghai-Tibet Railway (QTR), which is effectively a measure of the density of human engineering, was the dominant factor influencing bacterial community diversity. The diversity of bacterial communities shows that 16S rRNA gene abundance decreased in relation to proximity to the QTH and QTR in both alpine wetland and meadow areas. The dominant phyla across all samples were Actinobacteria and Proteobacteria. The concentration of Cr and Cd in the soil were positively correlated with proximity to the QTH and QTR (MC/WC sampling sites), and Ni, Co, and V were positively correlated with proximity to the QTH and QTR (MA/WA sampling sites). The results presented in this study provide an insight into the relationships among heavy metals and soil microbial communities, and have important implications for assessing and predicting the impacts of human-induced activities from the QTH and QTR in such an extreme and fragile environment.

• Cracking in an expansive soil under freeze–thaw cycles
• Yang Lu, SiHong Liu
• DOI:10.3724/SP.J.1226.2017.00392
• 2017, 9 (4): 392–397 Abstract (208) PDF (2977 KB) (223)
• Expansive soils located in cold regions can easily endure the action of frost heaving and cyclic freezing–thawing. Cracking can also occur in expansive clayey soils under freeze–thaw cycles, of which little attention has been paid on this issue. In this study, laboratory experiment and cracking analysis were performed on an expansive soil. Crack patterns were quantitatively analyzed using the fractal concept. The relationships among crack pattern, water loss, number of freeze–thaw cycles, and fractal dimension were discussed. It was found that crack patterns on the surface exhibit a hierarchical network structure that is fractal at a statistical level. Cracks induced by freeze–thaw cycles are shorter, more irregularly oriented, and slowly evolves from an irregularly rectilinear pattern towards a polygonal or quasi–hexagonal one; water loss, closely related to specimen thickness, plays a significant role in the process of soil cracking; crack development under freeze-thaw cycles are not only attributed to capillary effect, but also to expansion and absorption effects.
• Cutting of Phragmites australis as a lake restoration technique: Productivity calculation and nutrient removal in Wuliangsuhai Lake, northern China
• Jan Felix Köbbing, Niels Thevs, Stefan Zerbe
• DOI:10.3724/SP.J.1226.2016.00400
• 2016, 8 (5): 400–410 Abstract (149) PDF (2545 KB) (223)
• Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed (Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100,000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth.
• Comparative study of probable maximum precipitation and isohyetal maps for mountainous regions, Pakistan
• Muhammad Waseem Boota, Ghulam Nabi, Tanveer Abbas, HuiJun Jin, Ayesha Yousaf, Muhammad Azeem Boota
• DOI:10.3724/SP.J.1226.2018.00055
• 2018, 10 (1): 55–68 Abstract (134) PDF (4789 KB) (220)
• Probable maximum precipitation (PMP) is widely used by hydrologists for appraisal of probable maximum flood (PMF) used for soil and water conservation structures, and design of dam spillways. A number of methods such as empirical, statistical and dynamic are used to estimate PMP, the most favored being statistical and hydro-meteorological. In this paper, PMP estimation in mountainous regions of Pakistan is studied using statistical as well as physically based hydro-meteorological approaches. Daily precipitation, dew point, wind speed and temperature data is processed to estimate PMP for a one-day duration. Maximum precipitation for different return periods is estimated by using statistical approaches such as Gumble and Log-Pearson type-III (LP-III) distribution. Goodness of fit (GOF) test, chi-square test, correlation coefficient and coefficient of determination were applied to Gumble and LP-III distributions. Results reveal that among statistical approaches, Gumble distribution performed the best result compared to LP-III distribution. Isohyetal maps of the study area at different return periods are produced by using the GIS tool, and PMP in mountainous regions varies from 150 to 320 mm at an average value of 230.83 mm. The ratio of PMP for one-day duration to highest observed rainfall (HOR) varied from 1.08 to 1.29 with an average value of 1.18. An appropriate frequency factor (Km) is very important which is a function of mean for observed precipitation and PMP for 1-day duration, and Km values varies from 2.54 to 4.68. The coefficient of variability (Cv) varies from minimum value of 28% to maximum value of 43.35%. It was concluded that the statistical approach gives higher results compared to moisture maximization (MM) approach. In the hydro-meteorological approach, moisture maximization (MM) and wind moisture maximization (WMM) techniques were applied and it was concluded that wind moisture maximization approach gives higher results of PMP as compared to moisture maximization approach as well as for Hershfield technique. Therefore, it is suggested that MM approach is the most favored in the study area for PMP estimation, which leads to acceptable results, compared to WMM and statistical approaches.
• An evaluation of soil moisture from AMSR-E over source area of the Yellow River, China
• TangTang Zhang,Mekonnen Gebremichael,Akash Koppa,XianHong Meng,Qun Du,Jun Wen
• DOI:10.3724/SP.J.1226.2019.00461.
• 2019, 11 (6): 461–469 Abstract (194) HTML (1698) PDF (2806 KB) (217)
• In this study, in-situ soil moisture measurements are used to evaluate the accuracy of three AMSR-E soil moisture products from NASA (National Aeronautics and Space Administration), JAXA (Japanese Aerospace Exploration Agency) and VUA (Vrije University Amsterdam and NASA) over Maqu County, Source Area of the Yellow River (SAYR), China. Results show that the VUA soil moisture product performs the best among the three AMSR-E soil moisture products in the study area, with a minimum RMSE (root mean square error) of 0.08 (0.10) m3/m3 and smallest absolute error of 0.07 (0.08) m3/m3 at the grassland area with ascending (descending) data. Therefore, the VUA soil moisture product is used to describe the spatial variation of soil moisture during the 2010 growing season over SAYR. The VUA soil moisture product shows that soil moisture presents a declining trend from east south (0.42 m3/m3) to west north (0.23 m3/m3), with good agreement with a general precipitation distribution. The center of SAYR presents extreme wetness (0.60 m3/m3) during the whole study period, especially in July, while the head of SAYR presents a high level soil moisture (0.23 m3/m3) in July, August and September.

• A review on the ambit and prospects of C3 and C4 plants in Nigeria
• DOI:10.3724/SP.J.1226.2017.00587
• 2017, 9 (6): 587–598 Abstract (106) PDF (2416 KB) (216)
• Despite the enormous applications of photosynthesis in global carbon budget and food security, photosynthesis research has not been adequately explored as a research focus in Nigeria. Previous works on C3 and C4 plants in Nigeria were mainly on the use of anatomical characteristics to delimit plant species into their respective pathways, with no attention being paid to its applications. In this review, past and present knowledge gaps in this area of study are elucidated. Information used in this review were sourced from referred research articles and books in reputable journals. The results revealed that C3 and C4 plants are distributed among 21 genera and 11 families in Nigeria. In addition there is dearth of informatio such that only three genera have been classified based on diverse photosynthetic pathways with no information found on the physiological and biochemical characterization of these genera. Moreover, further research is also suggested for tackling new challenges in the area of food productivity and climate change.
• Characteristics of climate and melt runoff in the Koxkar Glacier River Basin, south slope of the Tianshan Mountains, Northwest China
• Min Xu,HaiDong Han,ShiChang Kang,Hua Tao
• DOI:10.3724/SP.J.1226.2019.00435.
• 2019, 11 (6): 435–447 Abstract (111) HTML (1873) PDF (5258 KB) (216)
• Hydrology of the high glacierized region in the Tianshan Mountains is an important water resource for arid and semiarid areas of China, even Central Asia. The hydrological process is complex to understand, due to the high variability in climate and the lack of hydrometeorological data. Based on field observations, the present study analyzes the meteorological and hydrological characteristics of the Koxkar Glacier River Basin during 2008-2011; and the factors influencing climate impact on glacier hydrology are discussed. The results show that precipitation at the terminus of the glacier was 426.2 mm, 471.8 mm, 624.9 mm, and 532 mm in 2008, 2009, 2010, and 2011, respectively. Discharge increases starting in May, reaches its highest value in July and August, and then starts to decrease. The mean annual discharge was 118.23×106 m3 during the four years observed, with 87.0% occurring in the ablation season (May-September). During the study period, the runoff in August accounted for 29% of total streamflow, followed by July (22%) and June (14%). The runoff exhibited obviously high interannual variability from April to September, induced by drastic changes in climate factors. Discharge autocorrelations are very high for all the years. The climate factors show different influences on discharge. The highest correlation R between daily temperature and discharge was for a time lag of 2-3 days on the Koxkar Glacier (0.66-0.76). The daily depth of runoff to daily temperature and daily water vapor pressure had an R 2 value of 0.56 and 0.69, respectively, which could be described by an exponential function. A closer relationship is found between runoff and either temperature or water vapor pressure on a monthly scale; the R 2 values are 0.65 and 0.78, respectively. The study helps us to understand the mechanisms of the hydrological-meteorological system of typical regional glaciers and to provide a reference for glacier-runoff simulations and water-resource management.

• Estimating interaction between surface water and groundwater in a permafrost region of the northern Tibetan Plateau using heat tracing method
• TanGuang Gao,Jie Liu,TingJun Zhang,ShiChang Kang,ChuanKun Liu,ShuFa Wang,Mika Sillanpää,YuLan Zhang
• DOI:10.3724/SP.J.1226.2020.00071.
• 2020, 12 (2): 71–82 Abstract (168) HTML (441) PDF (4245 KB) (214)
• Understanding the interaction between groundwater and surface water in permafrost regions is essential to study flood frequencies and river water quality, especially in the high latitude/altitude basins. The application of heat tracing method, based on oscillating streambed temperature signals, is a promising geophysical method for identifying and quantifying the interaction between groundwater and surface water. Analytical analysis based on a one-dimensional convective-conductive heat transport equation combined with the fiber-optic distributed temperature sensing method was applied on a streambed of a mountainous permafrost region in the Yeniugou Basin, located in the upper Heihe River on the northern Tibetan Plateau. The results indicated that low connectivity existed between the stream and groundwater in permafrost regions. The interaction between surface water and groundwater increased with the thawing of the active layer. This study demonstrates that the heat tracing method can be applied to study surface water-groundwater interaction over temporal and spatial scales in permafrost regions.

• Artificially frozen ground and related engineering technology in Japan
• Satoshi Akagawa
• DOI:10.3724/SP.J.1226.2021.20046
• 2021, 13 (2): 77–86 Abstract (189) HTML (32228) PDF (8720 KB) (213)
• Since the 1970's, frozen ground has been developing near the Tokyo Bay area around liquefied natural gas (LNG) in-ground storage tanks. For disaster prevention purposes, the tanks are constructed below the ground surface. Since the temperature of the liquid stored in the tanks is -162 °C the soil surrounding the tanks freezes. Since this frozen ground has existed for almost half a century, we have permafrost near Tokyo. The development of artificial frozen ground may cause frost heaving, resulting in frost heave forces that may cause structural damage of adjacent LNG in-ground storage tanks. Therefore, the demand for frozen ground engineering increased and consequently we now have advanced technology in this area. Fortunately, we use this engineering technology and artificial ground freezing for civil engineering, especially in big and crowded cities like Tokyo. This paper provides a summary of the testing apparatus, test methods, and assessment methods for frost heaving.

• Laboratory and field performance of recycled aggregate base in a seasonally cold region
• Tuncer B. Edil, Bora Cetin, Ali Soleimanbeigi
• DOI:10.3724/SP.J.1226.2017.00183
• 2017, 9 (3): 183–191 Abstract (189) PDF (757 KB) (211)
• The objective of this project was to characterize the freeze-thaw properties of recycled concrete (RCA) and asphalt (RAP) as unbound base and to assess how they behaved in the field for nearly 8 years. This paper includes an examination of existing information, laboratory studies of freeze-thaw behavior, and evaluation of data from MnROAD field-test sections in a seasonally cold region, i.e., in Minnesota, USA. Test sections were constructed using recycled materials in the granular base layers at the MnROAD test facility. One test section included 100% RAP, another 100% RCA, a third one a 50/50 blend of RCA/natural aggregate, and a fourth one only natural aggregate (Class 5) as a control. The stiffness (i.e., elastic modulus) was monitored during construction and throughout the pavement life by the Minnesota Department of Transportation, along with the variation of temperatures and moisture regimes in the pavement to determine their effects on pavement performance. The resilient modulus of each material was determined by bench-scale testing in accordance with NCHRP 1-28a, as well as by field-scale tests incorporating a falling-weight deflectometer. Specimens were subjected to as many as 20 cycles of freeze-thaw in the laboratory, and the change in their resilient modulus was measured. In the field-test sections constructed with the same materials as the base course, temperature, moisture, and field modulus (from falling-weight deflectometer tests) were monitored seasonally for nearly 8 years. From the temperatures in the base course layer, the number of freeze-thaw cycles experienced in the field was determined for each test section. Inferences were made relative to modulus change versus freeze-thaw cycles. Conclusions were drawn for long-term field performances of the recycled base (RAB) in comparison to natural aggregate.
• Altitude pattern of carbon stocks in desert grasslands of an arid land region
• Rong Yang, JunQia Kong, ZeYu Du, YongZhong Su
• DOI:10.3724/SP.J.1226.2018.00404
• 2018, 10 (5): 404–412 Abstract (119) HTML (601) PDF (4973 KB) (205)
• For estimating the altitude-distribution pattern of carbon stocks in desert grasslands and analyzing the possible mechanism for this distribution, a detailed study was performed through a series of field vegetation surveys and soil samplings from 90 vegetation plots and 45 soil profiles at 9 sites of the Hexi Corridor region, Northwestern China. Aboveground, belowground, and litter-fall biomass-carbon stocks ranged from 43 to 109, 23 to 64, and 5 to 20 g/m2, with mean values of 80.82, 44.91, and 12.15 g/m2, respectively. Soil-carbon stocks varied between 2.88 and 3.98 kg/m2, with a mean value of 3.43 kg/m2 in the 0–100-cm soil layer. Both biomass- and soil-carbon stocks had an increasing tendency corresponding to the altitudinal gradient. A significantly negative correlation was found between soil-carbon stock and mean annual temperature, with further better correlations between soil- and biomass-carbon stocks, and mean annual precipitation. Furthermore, soil carbon was found to be positively correlated with soil-silt and -clay content, and negatively correlated with soil bulk density and the volume percent of gravel. It can be concluded that variations in soil texture and climate condition were the key factors influencing the altitudinal pattern of carbon stocks in this desert-grassland ecosystem. Thus, by using the linear-regression functions between altitude and carbon stocks, approximately 4.18 Tg carbon were predicted from the 1,260 km2 of desert grasslands in the study area.

• Analysis of structural characteristics and spatial distribution of the national intangible cultural heritage in China and its policy implications
• BaiCui Xu,JingHu Pan
• DOI:10.3724/SP.J.1226.2019.00389.
• 2019, 11 (5): 389–406 Abstract (166) HTML (821) PDF (4506 KB) (205)
• Based on an investigation of four published batches listing 3,140 national intangible cultural heritage (ICH) projects in China and using GIS and some quantitative analysis methods, the spatial structure was investigated and the characteristics and distribution discussed. The distribution of ICHs in China is agglomerative and spatially dependent. From the view of ICH type, each type is distributed in different places, for different reasons, with history being the most important one we found. Nationwide, high-density cores are located in the Beijing-Tianjin-Hebei region and the Yangtze River Delta region. High densities of ICH are concentrated in flat, water-rich regions where broad-leaved forests dominate plains and low mountain areas—areas that have fertile soil, pleasant weather, a long history of culture, ethnic agglomeration, and development. This paper suggests that development of the ICH should be based on discovering unknown items, to break the existing pattern of strong cohesion and high density, and to seek a balanced development of the whole.

• Relationship between ponding and topographic factors along the China-Russia Crude Oil Pipeline in permafrost regions
• MingTang Chai,YanHu Mu,GuoYu Li,Wei Ma,Fei Wang
• DOI:10.3724/SP.J.1226.2019.00419.
• 2019, 11 (6): 419–427 Abstract (178) HTML (585) PDF (4231 KB) (190)
• The original landform along the China-Russia Crude Oil Pipeline (CRCOP, line 2) was disturbed during installation of pavement for the pipeline. Forest and vegetation coverage is dense, and runoff develops along the pipe. Since the operation of the CRCOP (line 2) began in 2018, ponding has appeared on both sides of the pipeline. If there is no drainage, ponding can hardly dissipate, due to the low permeability of the permafrost layer. With the supply of surface flow and the transportation of oil at positive temperatures, ponding promotes an increase in temperature and changes the boundary thermal conditions of the pipeline. Meanwhile, when the ponding freezes and thaws, frost heave threatens operational safety of the pipeline. Furthermore, the ponding can affect the thermal condition of line 1. In this paper, the distribution of ponding along the CRCOP was obtained by field investigation. The type and cause of ponding were summarized, and the catchment and stream order were extracted by the Digital Elevation Model (DEM). According to the statistical results in attributes for topographic factors, it is known that ponding along the pipeline is relative to elevation, slope, aspect, and the Topographic Wetness Index (TWI). Water easily accumulates at altitudes of 300-450 m, slopes within 3°-5°, aspect in the northeast or south, TWI within 13-16, flow direction in north-east-south, and flow length within 90-150 km. This paper proposes a theoretical basis for the cause and characteristics of ponding along the pipeline.

• Evaluating effects of Dielectric Models on the surface soil moisture retrieval in the Qinghai-Tibet Plateau
• Rong Liu,Xin Wang,ZuoLiang Wang,Jun Wen
• DOI:10.3724/SP.J.1226.2021.20067
• 2021, 13 (1): 62–76 Abstract (168) HTML (3504) PDF (7208 KB) (190)
• Based on the measurement of L-band ground-based microwave radiometer (ELBARA-III type) in the Qinghai-Tibet Plateau and the $τ-ω$ radiative transfer model, this research evaluated the effects of four soil dielectric models, i.e., Wang-Schmugge, Mironov, Dobson, and Four-phase, on the L-band microwave brightness temperature simulation and soil moisture retrieval. The results show that with the same vegetation and roughness parameterization scheme, the four soil dielectric models display obvious differences in microwave brightness temperature simulation. When the soil moisture is less than 0.23 m3/m3, the simulated microwave brightness temperature in Wang-Schmugge model is significantly different from that of the other three models, with maximum differences of horizontal polarization and vertical polarization reaching 8.0 K and 4.4 K, respectively; when the soil moisture is greater than 0.23 m3/m3, the simulated microwave brightness temperature of Four-phase significantly exceeds that of the other three models; when the soil moisture is saturated, maximum differences in simulated microwave brightness temperature with horizontal polarization and vertical polarization are 6.1 K and 4.8 K respectively, and the four soil dielectric models are more variable in the microwave brightness temperature simulation with horizontal polarization than that with vertical polarization. As for the soil moisture retrieval based on the four dielectric models, the comparison study shows that, under the condition of horizontal polarization, Wang-Schmugge model can reduce the degree of retrieved soil moisture underestimating the observed soil moisture more effectively than other parameterization schemes, while under the condition of vertical polarization, the Mironov model can reduce the degree of retrieved soil moisture overestimating the observed soil moisture. Finally, based on the Wang-Schmugge model and FengYun-3C observation data, the spatial distribution of soil moisture in the study area is retrieved.

• Biodiversity, productivity, and temporal stability in a natural grassland ecosystem of China
• Bing Liu, WenZhi Zhao, YangYang Meng, Chan Liu
• DOI:10.3724/SP.J.1226.2018.00293
• 2018, 10 (4): 293–304 Abstract (145) HTML (22) PDF (1767 KB) (187)
• Understanding the effect of biodiversity on ecosystem function is critical to promoting the sustainability of ecosystems and species conservation in natural ecosystems. We observed species composition, species richness and aboveground biomass, and simulated the competitive assemblages in a natural grassland ecosystem of China, aiming to test some assumptions and predictions about biodiversity–stability relationships. Our results show that aboveground productivity and temporal stability increased significantly with increasing species richness, and via a combination of overyielding, species asynchrony, and portfolio effects. Species interactions resulted in overyielding caused by trait-independent complementarity, and were not offset by a negative dominance effect and trait-dependent complementarity effect. Therefore, the mechanisms underlying the biodiversity effect shifted from the selection effect to the complementarity effect as diversity increased, and both effects were coexisted but the complementarity effect represent a mechanism that facilitates long term species coexistence in a natural grassland ecosystem of China.

• Influence of fines content on the anti-frost properties of coarse-grained soil
• TianLiang Wang, ZuRun Yue, TieCheng Sun, JinChuang Hua
• DOI:10.3724/SP.J.1226.2015.00407
• 2015, 7 (4): 407–413 Abstract (117) PDF (4001 KB) (185)
• This paper aims to determine the optimal fines content of coarse-grained soil required to simultaneously achieve weaker frost susceptibility and better bearing capacity. We studied the frost susceptibility and strength properties of coarse-grained soil by means of frost heaving tests and static triaxial tests, and the results are as follows:(1) the freezing temperature of coarse-grained soil decreased gradually and then leveled off with incremental increases in the percent content of fines; (2) the fines content proved to be an important factor influencing the frost heave susceptibility and strength properties of coarse-grained soil. With incremental increases in the percent content of fines, the frost heave ratio increased gradually and the cohesion function of fines effectively enhanced the shear strength of coarse-grained soil before freeze-thaw, but the frost susceptibility of fines weakened the shear strength of coarse-grained soil after freeze-thaw; (3) with increasing numbers of freeze-thaw cycles,the shear strength of coarse-grained soil decreased and then stabilized after the ninth freeze-thaw cycle, and therefore the mechanical indexes of the ninth freeze-thaw cycle are recommended for the engineering design values; and (4) considering frost susceptibility and strength properties as a whole, the optimal fines content of 5% is recommended for railway subgrade coarse-grained soil fillings in frozen regions.
• Processes of runoff in seasonally-frozen ground about a forested catchment of semiarid mountains
• PengFei Lin,ZhiBin He,Jun Du,LongFei Chen,Xi Zhu,QuanYan Tian
• DOI:10.3724/SP.J.1226.2020.00272.
• 2020, 12 (5): 272–283 Abstract (92) HTML (12) PDF (5854 KB) (185)
• Climate warming increases the variability in runoff of semiarid mountains where seasonally-frozen ground is widely distributed. However, what is not well understood are the processes of runoff, hydrological drivers, and freeze-thaw cycles in seasonally-frozen ground in semiarid mountains. To understand how freeze-thaw cycles affect runoff processes in seasonally-frozen ground, we monitored hydrological processes in a typical headwater catchment with seasonally-frozen ground in Qilian Mountain, China, from 2002 to 2017. We analyzed the responses of runoff to temperature, precipitation, and seasonally-frozen ground to quantify process characteristics and driving factors. The results show that annual runoff was 88.5 mm accounting for 25.6% of rainfall, mainly concentrated in May to October, with baseflow of 36.44 mm. Peak runoff occurred in June, August, and September, i.e., accounting for spring and summer floods. Runoff during the spring flood was produced by a mix of rainfall, melting snow, and melting seasonally-frozen ground, and had a significant correlation with air temperature. Runoff was mainly due to precipitation accumulation during the summer flood. Air temperature, average soil temperature at 0-50 cm depth, and frozen soil depth variable explained 59.60% of the variation of runoff in the thawing period, while precipitation variable explained 21.9%. Thawing-period runoff and soil temperature had a >0.6 correlation coefficient (P <0.05). In the rainfall-period, runoff was also affected by temperature, soil moisture, and precipitation, which explained 33.6%, 34.1% and 18.1%, respectively. Our results show that increasing temperature and precipitation will have an irreversible impact on the hydrological regime in mountainous basins where seasonally-frozen ground is widely distributed.

• Zhangmu and Gyirong ports under the threat of glacial lake outburst flood
• MiaoMiao Qi,ShiYin Liu,YongPeng Gao
• DOI:10.3724/SP.J.1226.2020.00461
• 2020, 12 (6): 461–476 Abstract (105) HTML (722) PDF (11802 KB) (184)
• The Himalayas are prone to glacial lake outburst floods, which can pose a severe threat to downstream villages and infrastructure. The Zhangmu and Gyirong land treaty ports are located on the China-Nepal border in the central Himalayas. In recent years, the expansion of glacial lakes has increased the threat of these two port regions. This article describes the results of mapping the glacial lakes larger than 0.01 km2 in the Zhangmu and Gyirong port regions and analyzes their change. It provides a comprehensive assessment of potentially dangerous glacial lakes and predicts the development of future glacial lakes. From 1988 to 2019, the glacial lakes in these port regions underwent "expansion", and moraine-dammed lakes show the most significant expansion trend. A total of eleven potentially dangerous glacial lakes are identified based on the assessment criteria and historical outburst events; most expanded by more than 150% from 1988 to 2019, with some by over 500%. The Cirenmaco, a moraine-dammed lake, is extremely prone to overtopping due to ice avalanches or the melting of dead ice in the dam. For other large lakes, such as the Jialongco, Gangxico and Galongco, ice avalanches may likely cause the lakes to burst besides self-destructive failure. The potential dangers of the Youmojianco glacial lakes, including lakes Nos. 9, 10 and 11, will increase in the future. In addition, the glacier-bed topography model predicts that 113 glacial lakes with a size larger than 0.01 km2, a total area of 11.88 km2 and a total volume of 6.37×109 m3 will form in the study area by the end of the 21 century. Due to global warming, the glacial lakes in the Zhangmu and Gyirong port regions will continue to grow in the short term, and hence the risk of glacial lake outburst floods will increase.

• Surface-deformation monitoring in the permafrost regions over the Tibetan Plateau, using Sentinel-1 data
• ZhenMing Wu, Lin Zhao, Lin Liu, Rui Zhu, ZeShen Gao, YongPing Qiao, LiMing Tian, HuaYun Zhou, MeiZhen Xie
• DOI:10.3724/SP.J.1226.2018.00114
• 2018, 10 (2): 114–125 Abstract (148) PDF (2925 KB) (183)
• Differential Interferometric Synthetic Aperture Radar (D-InSAR) has been widely used to measure surface deformation over the Tibetan Plateau. However, the accuracy and applicability of the D-InSAR method are not well estimated due to the lack of in-situ validation. In this paper, we mapped the seasonal and long-term displacement of Tanggula (TGL) and Liangdaohe (LDH) permafrost regions with a stack of Sentinel-1 acquisitions using the Small Baseline Subset InSAR (SBAS-InSAR) method. In the TGL region, with its dry soils and sparse vegetation, the InSAR-derived surface-deformation trend was consistent with ground-based leveling results; long-term changes of the active layer showed a settlement rate of around 1 to 3 mm/a due to the melting of ground ice, indicating a degrading permafrost in this area. Around half of the deformation was picked up on monitoring, in contrast with in-situ measurements in LDH, implying that the D-InSAR method remarkably underestimated the surface-deformation. This phenomenon may be induced by the large soil-water content, high vegetation coverage, or a combination of these two factors in this region. This study demonstrates that surface deformation could be mapped accurately for a specific region with Sentinel-1 C-band data, such as in the TGL region. Moreover, although the D-InSAR technology provides an efficient solution for broad surface-deformation monitoring in permafrost regions, it shows a poor performance in the region with high soil-water content and dense vegetation coverage.
• Effects of intercropping on rhizosphere soil microorganisms and root exudates of Lanzhou lily (Lilium davidii var. unicolor)
• CuiPing Hua, YaJun Wang, ZhongKui Xie, ZhiHong Guo, YuBao Zhang, Yang Qiu, Le Wang
• DOI:10.3724/SP.J.1226.2018.00159
• 2018, 10 (2): 159–168 Abstract (158) PDF (1727 KB) (183)
• Both yield and quality of Lanzhou lily (Lilium davidii var. unicolor) are seriously affected by continuous cropping. We attempted to understand the effects of intercropping on the obstacles associated with continuous cropping of Lanzhou lily (Lilium davidii var. unicolor). The changes of rhizosphere microbial biomass and diversity in interplanting and monoculturing systems were studied by using the Illumina HiSeq sequencing technique. The contents and composition of lily root exudates were measured by gas chromatography–mass spectrometer (GC–MS). The intercropping results of Lanzhou lily showed: (1) There was no difference in the composition of the rhizosphere soil microbes at the phylum level, but the relative abundance of the microbes decreased; and the relative abundance of harmful fungi such as Fusarium sp. increased. The relative abundance of Pleosporales sp. and other beneficial bacteria were reduced. After OTU (operational taxonomic unit) clustering, there were some beneficial bacteria, such as Chaetomium sp., in the lily rhizosphere soil in the interplanting system that had not existed in the single-cropping system. We did not find harmful bacteria that had existed in the single-cropping systm in the rhizosphere soil of interplanting system. The above results indicated that the changes of relative abundance of soil fungi and bacteria in lily rhizosphere soil was not conducive to improving the ecological structure of rhizosphere soil microbes. At the same time, the microbial composition change is very complex—beneficial and yet inadequate at the same time. (2) Root exudates provide a matrix for the growth of microorganisms. Combined with the detection of root exudates, the decrease in the composition of the root exudates of the lily was probably the reason for the decrease of the relative abundance of microbes after intercropping. At the same time, the decrease of the relative content of phenolic compounds, which inhibit the growth of microorganisms, did not increase the relative content of rhizosphere soil microorganisms. Changes in amino acids and total sugars may be responsible for the growth of Fusarium sp.. The results showed that the intercropping pattern did not noticeably alleviate the obstacle to continuous cropping of Lanzhou lily, and the change of microbial biomass and diversity was even unfavorable. However, the emergence of some beneficial bacteria, the disappearance of harmful fungi, and other changes with intercropping are in favor of alleviation of obstacles to continuous cropping of Lanzhou lily.
• An improvement of soil temperature simulations on the Tibetan Plateau
• SiQiong Luo, BoLi Chen, ShiHua Lyu, XueWei Fang, JingYuan Wang, XianHong Meng, LunYu Shang, ShaoYing Wang, Di Ma
• DOI:10.3724/SP.J.1226.2018.00080
• 2018, 10 (1): 80–94 Abstract (122) PDF (6264 KB) (183)
• The simulation of soil temperature on the Tibetan Plateau (TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5 (CLM3.5) and Regional Climatic Model 4 (RegCM4). The improved CLM3.5 and RegCM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.
• High-resolution mass spectrometric characterization of dissolved organic matter from warm and cold periods in the NEEM ice core
• JianZhong Xu, Amanda Grannas, CunDe Xiao, ZhiHeng Du, Amanda Willoughby, Patrick Hatcher, YanQing An
• DOI:10.3724/SP.J.1226.2018.00038
• 2018, 10 (1): 38–46 Abstract (131) PDF (3711 KB) (181)
• Dissolved organic matter (DOM) is an important component of ice cores but is currently poorly characterized. DOM from one Holocene sample (HS, aged at 1600-4500 B.P.) and one Last Glacial Maximum sample (LS, aged at 21000-25000 B.P.) from the North Greenland Eemian Ice Drilling (NEEM) ice core were analyzed by ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). CHO compounds contributed 50% of the compounds identified in negative-ionization mode in these two samples, with significant contributions from organic N, S, and P compounds, likely suggesting that marine DOM was an important source in these samples. Overall, the chemical compositions are similar between these two samples, suggesting their consistent DOM sources. However, subtle differences in the DOM between these two samples are apparent and could indicate differences in source strength or chemistry occurring through both pre- and post-depositional processes. For example, higher relative amounts of condensed carbon compounds in the HS DOM (5%), compared to the LS DOM (2%), suggest potentially important contributions from terrestrial sources. Greater incorporation of P in the observed DOM in the LS DOM (22%), compared to the HS DOM (13%), indicate more active microbiological processes that likely contribute to phosphorus incorporation into the DOM pool. Although these two samples present only a preliminary analysis of DOM in glacial/interglacial periods, the data indicate a need to expand the analysis into a broader range of ice-core samples, geographical locations, and glacial/interglacial periods.
• Measurement for coordinated development of "four modernizations" and its efficiency of prefecture level cities or above in China
• JingHu Pan, YanXing Hu
• DOI:10.3724/SP.J.1226.2016.00163
• 2016, 8 (2): 163–176 Abstract (117) PDF (697 KB) (180)
• The efficient and coordinated development of industrialization,urbanization,informatization and agricultural modernization(so called "Sihua Tongbu" in China,and hereinafter referred to as "four modernizations") is not only a practical need but also an important strategic direction of integrating urban-rural development and regional development in recent China.This paper evaluated the comprehensive,coupling and coordinated developmental indices of "four modernizations" of China's 343 prefecture-level administrative units,and calculated their efficiency of "four modernizations" in 2001 and 2011.The efficiency evaluation index system was established.The efficiencies and their changing trend during the period 2001-2011 were investigated using the data envelopment analysis(DEA) model.Spatial-temporal pattern of the efficiency of China's prefecture-level units was explored by using exploratory spatial data analysis(ESDA).Finally,the main influencing factors were revealed with the aid of geographically weighted regression(GWR) model.Results indicate that the comprehensive,coupling and coordinated developmental indices and efficiency of "four modernizations" of China's prefecture-level administrative units have obvious spatial differences and show diverse regional patterns.Overall,the efficiency is relatively low,and only few units with small urban populations and economic scale are in DEA efficiencies.The efficiency changing trends were decreasing during 2001-2011,with a transfer of high efficiency areas from inland to eastern coastal areas.The difference between urban and rural per capita investment in fixed assets boasts the greatest influence on the efficiency.
• Numerical simulation of artificial ground freezing in a fluid-saturated rock mass with account for filtration and mechanical processes
• Ivan A. Panteleev, Anastasiia A. Kostina, Oleg A. Plekhov, Lev Yu. Levin
• DOI:10.3724/SP.J.1226.2017.00363
• 2017, 9 (4): 363–377 Abstract (144) PDF (1995 KB) (178)
• This study is devoted to the numerical simulation of the artificial ground freezing process in a fluid-saturated rock mass of the potassium salt deposit. A coupled model of nonstationary thermal conductivity, filtration and thermo-poroelasticity, which takes into account dependence of the physical properties on temperature and pressure, is proposed on the basis of the accepted hypotheses. The considered area is a cylinder with a depth of 256 meters and diameter of 26.5 meters and includes 13 layers with different thermophysical and filtration properties. Numerical simulation was carried out by the finite-element method. It has been shown that substantial ice wall formation occurs non-uniformly along the layers. This can be connected with geometry of the freezing wells and with difference in physical properties. The average width of the ice wall in each layer was calculated. It was demonstrated that two toroidal convective cells induced by thermogravitational convection were created from the very beginning of the freezing process. The effect of the constant seepage flow on the ice wall formation was investigated. It was shown that the presence of the slow flow lead to the delay in ice wall closure. In case of the flow with a velocity of more than 30 mm per day, closure of the ice wall was not observed at all in the foreseeable time.