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2019, 11 (1) Online: 01 February 2019 Previous issue Next issue
  • Intersection-pavement de-icing: comprehensive review and the state of the practice
  • Yang ZhaoHui Joey
  • DOI: 10.3724/SP.J.1226.2019.00001
  • 2019, Vol.11 (1): 1–12 Abstract ( 110) HTML ( 14) PDF (925 KB) ( 48 )
  • Winter maintenance operations are crucial for pedestrian and motorist safety and public mobility on urban streets and highways in cold regions, especially during winter storms. This study provides a comprehensive literature review of existing deicing technologies, with emphasis on electrical resistance-heating deicing technologies for possible applications in areas with concentrated traffic, such as street intersections and crosswalks. A thorough review of existing and emerging deicing technology for snow/ice melting was conducted. The performance of various deicing methods was evaluated and the installation and operation cost of the electrical resistance-heating methods compared. Finally, current state of the practice of intersection/crosswalk winter maintenance was surveyed among state departments of transportation in North America. The intersection/crosswalk winter maintenance procedure adopted by the State of Alaska Department of Transportation and Public Facilities was described, and the annual winter maintenance and operation cost per intersection was estimated. It was found that the annual energy cost of an electrical resistance-heating method such as the carbon-fiber-tape deicing technology is about the same as the average annual maintenance and operation cost of current practice. In addition, an automatic electrical resistance-heating deicing system will bring benefits such as minimized delay time and improved safety for pedestrian and vehicular traffic in an urban application.

  • The changing process and trend of ground temperature around tower foundations of Qinghai-Tibet Power Transmission line
  • YanLi Xie, QiHao Yu, YanHui You, ZhongQiu Zhang, TingTao Gou
  • DOI: 10.3724/SP.J.1226.2019.00013
  • 2019, Vol.11 (1): 13–0020 Abstract ( 64) HTML ( 9) PDF (10529 KB) ( 34 )
  • After the construction of Qinghai-Tibet Highway and Railway, the Qinghai-Tibet Power Transmission (QTPT) line is another major permafrost engineering project with new types of engineering structures. The changing process and trend of ground temperature around tower foundations are crucial for the stability of QTPT. We analyzed the change characteristics and tendencies of the ground temperature based on field monitoring data from 2010 to 2014. The results reveal that soil around the tower foundations froze and connected with the artificial permafrost induced during the construction of footings after the first freezing period, and the soil below the original permafrost table kept freezing in subsequent thawing periods. The ground temperature lowered to that of natural fields, fast or slowly for tower foundations with thermosyphons, while for tower foundations without thermosyphons, the increase in ground temperature resulted in higher temperature than that of natural fields. Also, the permafrost temperature and ice content are significant factors that influence the ground temperature around tower foundations. Specifically, the ground temperature around tower foundations in warm and ice-rich permafrost regions decreased slowly, while that in cold and ice poor permafrost regions cooled faster. Moreover, foundations types impacted the ground temperature, which consisted of different technical processes during construction and variant of tower footing structures. The revealed changing process and trend of the ground temperature is beneficial for evaluating the thermal regime evolution around tower foundations in the context of climate change.

  • The analysis of heat and water fluxes in frozen silty soil
  • DaHu Rui,Ming Lu,Kunio Watanabe,Jun Zhang
  • DOI: 10.3724/SP.J.1226.2019.00021
  • 2019, Vol.11 (1): 21–28 Abstract ( 73) HTML ( 7) PDF (2368 KB) ( 25 )
  • In this paper, based on the basic equations of water flow and heat transfer, the hydrothermal coupling model is established. The numerical model was realized in COMSOL Multiphysics software, and simulation results are compared with the experimental results of Watanabe and Wake (2008) to verify the effectiveness of the model. Through the calculation, we can obtain the dynamic changes of heat and water fluxes, thermal and hydrological properties, matric potential and temperature gradient in unsaturated freezing soil; and these variables are unmeasurable in practice.

  • Vulnerability and adaptation of an oasis social–ecological system affected by glacier change in an arid region of northwestern China
  • JianPing Yang, Man Li, ChunPing Tan, HongJu Chen, Qin Ji
  • DOI: 10.3724/SP.J.1226.2019.00029
  • 2019, Vol.11 (1): 29–0040 Abstract ( 66) HTML ( 4) PDF (11448 KB) ( 29 )
  • The Hexi Inland River Basin in an arid region of northwestern China was chosen as the study area for this research. The authors define the vulnerability of an oasis social-ecological system to glacier change; select 16 indicators from natural and socioeconomic systems according to exposure, sensitivity, and adaptive capacity; and construct a vulnerability-assessment indicator system aimed at an inland river basin in the arid region of Northwestern China. Vulnerability of the oasis social-ecological system affected by glacier change in the study area is evaluated by Spatial Principal Component Analysis (SPCA) under the circumstance of glacier change. The key factors affecting the vulnerability are analyzed. The vulnerability of the oasis social-ecological system in the Hexi Inland River Basin affected by glacier change is of more than medium grade, accounting for about 48.0% of the total number of counties in the study area. In terms of the spatial pattern of the vulnerability, the oasis economic belt is the most vulnerable. With the rapid development of the area's society and economy, the exposure of the system to glacial changes is significantly increased; and an increase in glacial meltwater is not enough to overcome the impact of increased exposure, which is the main reason for the high vulnerability. Based on the result of the vulnerability analysis and combined with the present industrial structure in the Hexi Inland River Basin, near-, medium-, and long-term adaptation initiatives are put forward in the article.

  • Accumulation and geochemical evidence for the Little Ice Age episode in eastern Antarctica
  • ChuanJin Li,JiaWen Ren,CunDe Xiao,MingHu Ding,AiHong Xie,ZhiHeng Du,XiangYu Ma,DaHe Qin
  • DOI: 10.3724/SP.J.1226.2019.00050
  • 2019, Vol.11 (1): 50–61 Abstract ( 51) HTML ( 5) PDF (2724 KB) ( 18 )
  • Data on accumulation and concentration of chemical compounds recorded in an essentially unexplored area (Dome Argus) of the Indian Ocean sector of eastern Antarctica during the past 2,680 years (680 B.C. to 1999 A.D.) are presented. During the first 1,700 years (680 B.C. to 1000 A.D.), the accumulation data shows a slightly decreasing trend, while chemical ions appear to be stable, representing a stable climatic condition. An intensive increasing trend of the accumulation occurred during the 12th to 14th century. The period from 15th to 19th century was characterized by a rapid reducing accumulation and concentrations of volatile compounds suffering post-depositional loss linked to sparse precipitation amount, which was temporally consistent with the Little Ice Age (LIA) episode. Comparison between observed accumulation rates with other eastern Antarctic ice cores show a consistent decreasing trend during LIA, while sea salt and dust-originated ions increased due to sea ice extent and intensified atmospheric transportation. Distribution of volcanic originated sulfate over the Antarctic continent show a significant change during the 15th century, coincident with the onset of the LIA. These results are important for the assessment of Antarctic continent mass balance and associated interpretation of the Dome A deep ice core records.

  • How changes of groundwater level affect the desert riparian forest ecosystem in the Ejina Oasis, Northwest China
  • HaiYang Xi,JingTian Zhang,Qi Feng,Lu Zhang,JianHua Si,TengFei Yu
  • DOI: 10.3724/SP.J.1226.2019.00062
  • 2019, Vol.11 (1): 62–80 Abstract ( 123) HTML ( 4) PDF (10223 KB) ( 29 )
  • Groundwater is a key factor controlling the growth of vegetation in desert riparian systems. It is important to recognise how groundwater changes affect the riparian forest ecosystem. This information will not only help us to understand the ecological and hydrological process of the riparian forest but also provide support for ecological recovery of riparian forests and water-resources management of arid inland river basins. This study aims to estimate the suitability of the Water Vegetation Energy and Solute Modelling (WAVES) model to simulate the Ejina Desert riparian forest ecosystem changes, China, to assess effects of groundwater-depth change on the canopy leaf area index (LAI) and water budgets, and to ascertain the suitable groundwater depth for preserving the stability and structure of desert riparian forest. Results demonstrated that the WAVES model can simulate changes to ecological and hydrological processes. The annual mean water consumption of a Tamarix chinensis riparian forest was less than that of a Populus euphratica riparian forest, and the canopy LAI of the desert riparian forest should increase as groundwater depth decreases. Groundwater changes could significantly influence water budgets for T. chinensis and P. euphratica riparian forests and show the positive and negative effects on vegetation growth and water budgets of riparian forests. Maintaining the annual mean groundwater depth at around 1.7?2.7 m is critical for healthy riparian forest growth. This study highlights the importance of considering groundwater-change impacts on desert riparian vegetation and water-balance applications in ecological restoration and efficient water-resource management in the Heihe River Basin.

  • Increase in medium-size rainfall events will enhance the C-sequestration capacity of biological soil crusts
  • CuiHua Huang,Fei Peng,Itaru Shibata,Jun Luo,Xian Xue,Kinya Akashi,Atsushi Tsunekawa,Tao Wang
  • DOI: 10.3724/SP.J.1226.2019.00081
  • 2019, Vol.11 (1): 81–92 Abstract ( 60) HTML ( 2) PDF (3973 KB) ( 21 )
  • Biological soil crusts (BSCs) play important roles in the carbon (C) balance in arid regions. Net C balance of BSCs is strongly dependent on rainfall and consequent activation of microbes in the BSCs. The compensation-rainfall size for BSCs (the minimum rainfall amount for a positive net C balance) is assumed to be different with BSCs of different developmental stages. A field experiment with simulated rainfall amount (SRA) of 0, 1, 5, 10, 20, and 40 mm was conducted to examine the C fluxes and compensation-rainfall size of BSCs in different parts of fixed dunes in the ecotone between the Badain Jaran Desert and the Minqin Oasis. We found algae?lichen crust on the interdunes and crest, algae crust on the leeward side, and lichen?moss crust on the windward. Even a small rainfall (1 mm) can activate both photosynthesis and respiration of all types of BSCs. The gross ecosystem production, ecosystem respiration, and net ecosystem exchange were significantly affected by SRA, hours after the simulated rainfall, position on a dune, and their interactions. The rapid activation of photosynthesis provides a C source and therefore could be responsible for the increase of C efflux after each rewetting. C-uptake and -emission capacity of all the BSCs positively correlated with rainfall size, with the lowest C fluxes on the leeward side. The compensation rainfall for a net C uptake was 3.80, 15.54, 8.62, and 1.88 mm for BSCs on the interdunes, the leeward side, the crest, and the windward side, respectively. The whole dune started to show a net C uptake with an SRA of 5 mm and maximized with an SRA of about 30 mm. The compensation-rainfall size is negatively correlated with chlorophyll content. Our results suggest that BSCs will be favored in terms of C balance, and sand dune stabilization could be sustained with an increasing frequency of 5?10 mm rainfall events in the desert?oasis transitional zone.