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2022, 14 (4) 发布日期: 2022-08-31 上一期
2022, Vol.14 No.3 No.2 No.1
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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
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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
  • Light-absorbing impurities on Keqikaer Glacier in western Tien Shan: concentrations and potential impact on albedo reduction
  • YuLan Zhang, ShiChang Kang, Min Xu, Michael Sprenger, TanGuang Gao, ZhiYuan Cong, ChaoLiu Li, JunMing Guo, ZhiQiang Xu, Yang Li, Gang Li, XiaoFei Li, YaJun Liu, HaiDong Han
  • DOI:10.3724/SP.J.1226.2017.00097
  • 2017, 9 (2): 97–111 摘要 (492) PDF (1325 KB) (3393)
  • Light-absorbing impurities on glaciers are important factors that influence glacial surface albedo and accelerate glacier melt. In this study, the quantity of light-absorbing impurities on Keqikaer Glacier in western Tien Shan, Central Asia, was measured. We found that the average concentrations of black carbon was 2,180 ng/g, with a range from 250 ng/g to more than 10,000 ng/g. The average concentrations of organic carbon and mineral dust were 1,738 ng/g and 194 μg/g, respectively. Based on simulations performed with the Snow Ice Aerosol Radiative model simulations, black carbon and dust are responsible for approximately 64% and 9%, respectively, of the albedo reduction, and are associated with instantaneous radiative forcing of 323.18 W/m2 (ranging from 142.16 to 619.25 W/m2) and 24.05 W/m2 (ranging from 0.15 to 69.77 W/m2), respectively. For different scenarios, the albedo and radiative forcing effect of black carbon is considerably greater than that of dust. The estimated radiative forcing at Keqikaer Glacier is higher than most similar values estimated by previous studies on the Tibetan Plateau, perhaps as a result of black carbon enrichment by melt scavenging. Light-absorbing impurities deposited on Keqikaer Glacier appear to mainly originate from central Asia, Siberia, western China (including the Taklimakan Desert) and parts of South Asia in summer, and from the Middle East and Central Asia in winter. A footprint analysis indicates that a large fraction (>60%) of the black carbon contributions on Keqikaer Glacier comes from anthropogenic sources. These results provide a scientific basis for regional mitigation efforts to reduce black carbon.
  • 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 摘要 (1041) PDF (4411 KB) (1582)
  • 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.
  • Atmospheric insight to climatic signals of δ18O in a Laohugou ice core in the northeastern Tibetan Plateau during 1960-2006
  • WenTao Du, ShiChang Kang, Xiang Qin, XiaoQing Cui, WeiJun Sun
  • DOI:10.3724/SP.J.1226.2016.00367
  • 2016, 8 (5): 367–377 摘要 (433) PDF (6039 KB) (1285)
  • Ice documentation and response to prominent warming, especially after the 1990s, is further investigated because it is concerned whether ice records have absence. A δ18O series of a Laohugou (LHG) shallow ice core (20.12 m) in the northeastern Tibetan Plateau was reconstructed covering the period of 1960-2006. The ice core δ18O record had significant positive correlations with the warm season (May-September) air temperatures at adjacent meteorological stations and the 500 hPa temperatures in boreal China, indicating that the δ18O record could be considered a credible proxy of regional temperature. A clear, cold temperature event in 1967 and rapid warming after the 1990s were captured in the LHG δ18O series, revealing that it could record extreme air-temperature events on both regional and global scales. The LHG δ18O variations had evident positive correlations with both the summer surface outgoing longwave radiation (OLR) in the Mongolia region and the summer meridional wind at 500 hPa in the LHG region during 1960-2006, suggesting that the increased OLR in the Mongolia region might have intensified the Mongolia Low and expanded the pressure gradient to the LHG region (the Shulehe High), which would have pushed the westerlies further north and suppressed southward incursions of cold air into the LHG region, and thus augmented the temperature rise. The regional atmospheric circulation difference (1985-2006 minus 1960-1984) suggested that the anticyclone in the Mongolia region might have developed the easterly wind, which transported warmer air from the east toward the LHG region and weakened the cold penetration of the westerlies, resulting in the temperature rise since the middle 1980s.
  • Uncertainty analysis of runoff and sedimentation in a forested watershed using sequential uncertainty fitting method
  • Tanveer Abbas, Ghulam Nabi, Muhammad W. Boota, Fiaz Hussain, Muhammad I. Azam, HuiJun Jin, Muhammad Faisal
  • DOI:10.3724/SP.J.1226.2016.00297
  • 2016, 8 (4): 297–310 摘要 (538) PDF (4685 KB) (882)
  • The Soil and Water Assessment Tool (SWAT) was implemented in a small forested watershed of the Soan River Basin in northern Pakistan through application of the sequential uncertainty fitting (SUFI-2) method to investigate the associated uncertainty in runoff and sediment load estimation. The model was calibrated for a 10-year period (1991-2000) with an initial 4-year warm-up period (1987-1990), and was validated for the subsequent 10-year period (2001-2010). The model evaluation indices R2 (the coefficient of determination), NS (the Nash-Sutcliffe efficiency), and PBIAS (percent bias) for stream flows simulation indicated that there was a good agreement between the measured and simulated flows. To assess the uncertainty in the model outputs, p-factor (a 95% prediction uncertainty, 95PPU) and r-factors (average wideness width of the 95PPU band divided by the standard deviation of the observed values) were taken into account. The 95PPU band bracketed 72% of the observed data during the calibration and 67% during the validation. The r-factor was 0.81 during the calibration and 0.68 during the validation. For monthly sediment yield, the model evaluation coefficients (R2 and NS) for the calibration were computed as 0.81 and 0.79, respectively; for validation, they were 0.78 and 0.74, respectively. Meanwhile, the 95PPU covered more than 60% of the observed sediment data during calibration and validation. Moreover, improved model prediction and parameter estimation were observed with the increased number of iterations. However, the model performance became worse after the fourth iterations due to an unreasonable parameter estimation. Overall results indicated the applicability of the SWAT model with moderate levels of uncertainty during the calibration and high levels during the validation. Thus, this calibrated SWAT model can be used for assessment of water balance components, climate change studies, and land use management practices.
  • 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 摘要 (687) PDF (4789 KB) (878)
  • 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.
  • 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 摘要 (591) PDF (4001 KB) (876)
  • 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.
  • A review on the ambit and prospects of C3 and C4 plants in Nigeria
  • Abdulwakeel Ayokun-nun Ajao, Oludare Oladipo Agboola, Sefiu Adekilekun Saheed
  • DOI:10.3724/SP.J.1226.2017.00587
  • 2017, 9 (6): 587–598 摘要 (414) PDF (2416 KB) (867)
  • 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.
  • Spatiotemporal change of carbon storage in the Loess Plateau of northern Shaanxi, based on the InVEST Model
  • ShaoYang Liu, NingKe Hu, Jin Zhang, ZhiChao Lv
  • DOI:10.3724/SP.J.1226.2018.00240
  • 2018, 10 (3): 240–250 摘要 (784) PDF (3607 KB) (865)
  • In recent years, land use and land cover have under gone tremendous change on the Loess Plateau, leading to temporal and spatial variation over many ecological factors, such as carbon storage. Based on four series of land-use data from remote-sensing imaging, spatiotemporal changes of land-use types and volume changes were analyzed. Combined with carbon-stock-assessment modules of the InVEST (integrated valuation ecosystem services and tradeoffs) model, the carbon-storage change was estimated and analyzed at the subcounty and subbasin scales. The results show that (1) cultivated land and grassland area decreased, while woodland and urban land area increased in northern Shaanxi; (2) the average carbon storage in Huangling County and the Beiluo River Basin is the largest, while that of Yuyang County and the Xinshui River Basin is the minimum, and that of Wuqi County showed the greatest growth; (3) carbon storage in the study area showed a definite decrease in 2000, but in general has increased from 1995 to 2010; (4) carbon-storage figures of subbasins and counties are all restricted by the natural status and land-use landscape of the whole study area. From the results, it can be seen that the effect of ecological policies is remarkable. This study has important implications for the rational planning of land use, adjustment of the ecosystem carbon cycle, and related policies.
  • 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 摘要 (700) PDF (2925 KB) (806)
  • 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.