Groundwater circulation relative to water quality and vegetation in an arid transitional zone linking oasis, desert and river  

作　　者：HUANG TianMing PANG ZhongHe CHEN YaNing KONG YanLong 

机构地区：[1]Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences [2]State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences

出　　处：《Chinese Science Bulletin》2013年第25期3088-3097,共10页

基　　金：supported by the National Natural Science Foundation of China (41202183, 40872162 and 40672171);the China Postdoctoral Science Foundation Funded Project (2012T50136 and 20110490581)

摘　　要：In groundwater-dependent ecosystems, groundwater circulation controls the overall water quality and ecosystem dynamics. Groundwater and vegetation across a 30-km groundwater transect linking oasis, desert and river in an extremely arid area were investigated with a series of soil profiles drilled into the unsaturated zone to understand groundwater circulation and its control on groundwater quality and surface vegetation in the extremely arid Lower Tarim River, NW China. Measurements have included water-table depth, water chemistry and water isotopes (2H, 18O, 3H) for 15 water samples, soil moisture and chloride content for 11 soil profiles, and vegetation investigation. Results show that the groundwater in desert zone is characterized by slow recharge rate (pre-modern water), great water-table depth (6.17-9.43 m) and high salinity (15.32-26.50 g/L), while that in oasis (uncultivated land) and riparian zone is characterized by relatively fast recharge rate (modern water), small groundwater-table depth (3.56-8.36 m) and low salinity (1.25-1.95 g/L). Stable isotopes show that secondary evaporation takes place during irrigation in oasis. The vegetation characteristics (coverage, richness, evenness and number of plants) are closely related to soil moisture and water-table depth. Groundwater recharge from irrigation in oasis and from river in riparian zone sustains a better ecosystem than that in the desert area, where lateral and vertical groundwater recharge is limited. The more evapotranspirative enrichment may occur in the vegetated and water-rich riparian zone as compared to desert. This study also demonstrates the effectiveness of environmental tracers in studying ecohydrological processes in arid regions.In groundwater-dependent ecosystems, groundwater circulation controls the overall water quality and ecosystem dynamics. Groundwater and vegetation across a 30-km groundwater transect linking oasis, desert and river in an extremely arid area were investigated with a series of soil profiles drilled into the unsaturated zone to understand groundwater circulation and its control on groundwater quality and surface vegetation in the extremely arid Lower Tarim River, NW China. Measurements have included water-table depth, water chemistry and water isotopes （2H, 18O, 3H） for 15 water samples, soil moisture and chloride content for 11 soil profiles, and vegetation investigation. Results show that the groundwater in desert zone is characterized by slow recharge rate （pre-modern water）, great water-table depth （6.17-9.43 m） and high salinity （15.32-26.50 g/L）, while that in oasis （uncultivated land） and riparian zone is characterized by relatively fast recharge rate （modern water）, small groundwater-table depth （3.56-8.36 m） and low salinity （1.25-1.95 g/L）. Stable isotopes show that secondary evaporation takes place during irrigation in oasis. The vegetation characteristics （coverage, richness, evenness and number of plants） are closely related to soil moisture and water-table depth. Groundwater recharge from irrigation in oasis and from river in riparian zone sustains a better ecosystem than that in the desert area, where lateral and vertical groundwater recharge is limited. The more evapotranspirative enrichment may occur in the vegetated and water-rich riparian zone as compared to desert. This study also demonstrates the effectiveness of environmental tracers in studying ecohydrological processes in arid regions.

关 键 词：地下水循环 极端干旱区 地表植被 河流断面 沙漠区 绿洲 连接 生态系统动力学 

分 类 号：P641[天文地球—地质矿产勘探] X24[天文地球—地质学]