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China Water Conservancy Hydropower Science (2020)

Study on Ecological Security and Groundwater Level Regulation in Arid Areas

Study on Ecological Security and Groundwater Level Regulation in Arid Areas

Titre : Study on Ecological Security and Groundwater Level Regulation in Arid Areas

Auteur : 汪勇;

Grade : Doctoral Dissertation 2020

Université : China Water Conservancy Hydropower Science

Résumé partiel
Large-scale study of ecological hydrology in arid area began with the study on rational use of water resources and ecological environment protection in the northwest region of the major projects of the National Science and Technology Research Program of the Ninth Five-Year Plan(1996-2000)in China.After years of research,a unified understanding of the hydrological cycle and ecological pattern in the arid regions has been formed.Rainfall production in mountainous areas,runoff consumption in plain areas,inland river flow recharges groundwater ;vegetation pattern depends on the water table,which characterizes the landscapes of oasis,transition zone and desert,within different distances from an inland river.The development and utilization of water resources has changed the groundwater subsurface flow field,and the structure of the ecological circle has also changed.Therefore,the safety of the ecosystem depends on the stability of the groundwater subsurface flow field.The key is to maintain a certain transition zone between the oasis and deserts,so that the oasis and the desert maintain a safe distance.According to the theory of the ecological layer structure,this requires a transition zone to maintain a certain depth of groundwater.Oasis safety is the core of ecological protection in in arid areas.Irrigation is a common form of water resources development and utilization in arid areas.This is the process of water concentration in oasis,which may have a major impact on the ecological security of the oasis.On the one hand,due to the concentration of water resources to the oasis,the groundwater level at the outer edge of the subsurface flow field has decreased,resulting in the disappearance of vegetation degradation in the interlaced transition zone of the oasis,the reduction of the transition zone,and the desert to the oasis.On the other hand,the irrigation and drainage is not smooth,resulting in a sharp rise in the groundwater level inside the oasis,resulting in secondary salinization.For example,in the Heihe River Basin,compared with the 1970s,the area of the transition zone around the oasis decreased by 6,972 km2,the desert expanded by 14,281 km2 in the 1990s,and the transition zone area subsided.Compared with the 1990s,the area of arable land increased by 732 km2,and the transition zone with only a small area decreased by 4127 km2,and the desert expanded by 8280 km2.At the same time,the area of secondary salinization continued to expand,reaching a cumulative 722.22 km2.It is estimated that the total evaporation loss due to salinization and the amount of salinized water is about 692~822 million m3/y.This kind of ecological problem caused by desertification and salinization caused by changes in groundwater level(depth),both internally and externally,seriously threatens the ecological security of the oasis.

Mots clés : Arid area; Transition zone; Shallow Groundwater Active Layer; Salinization; Desertification; Groundwater regulation;

Présentation (CNKI)

Page publiée le 3 juin 2021