基于同位素技术的且末车尔臣河流域地下水补给来源分析

为了更加合理地利用及开发塔里木盆地南部且末县车尔臣河流域地下水资源,利用和田及乌鲁木齐2个监测站点多年大气降水同位素数据,拟合出当地大气降水线LMWL:δD=7.5δ18O+5.9(n=178,R2=0.9526)。通过不同地貌单元地表水与地下水同位素(δD、δ18O、T)变化特征及Cl-δ18O相对变化规律,结合当地水文地质条件,探究了且末县车尔臣河流域地下水补给来源。研究表明:沿河流方向,研究区不同地貌单元地下水均受到冰川雪融水及高山降雨补给,补给源区为南部高山区。此外,灌区人为修建水渠、机民井等节水设施,地表水与浅层地下水发生混合,地下水还受到了河水、农田灌溉水渗漏补给;绿洲带承压水δD、δ18O、T值均偏低,反映地下水受到高海拔水源的早期补给且更新较慢;在沙漠一带地下水T值偏低,δD、δ18O值接近当地大气降水线,推测此段地下水还受到了局部大气降水补给。

An Analysis of the Groundwater Recharge Source of Cherchen River Basin in Qianma County

In order to make a more reasonable use of groundwater resources in the Cherchen River Basin in the southern part of the Tarim Basin,this paper uses the multi-year atmospheric precipitation isotope data from two monitoring stations in Hetian and Urumqi to fit the local atmospheric precipitation line LMW:δD=7.5δ18O+5.9(n=178,R2=0.9526).Combined with the local hydro-geological conditions,this paper explores the groundwater supply source of Cherchen River Basin in Tianma County by using the variation characteristics of surface water and groundwater isotopes(δD,δ18O,T)of different geomorphic units and the relative change rule of Cl-δ18O.The results show that the groundwater of different geomorphic units in the study area is mainly supplied by glacial snowmelt water and alpine rainfall,and the source area is the southern high mountain area.In addition,in recent years,water-saving facilities such as canals and civil wells are built to divert water for irrigation,so that the groundwater in the irrigation area is also supplied by a large number of canal system diversion water and seepage of backwater from farmland irrigation.In the desert area,the T isotopes of groundwater are low,and theδD andδ18O values are close to the local atmospheric precipitation line,so it is speculated that the groundwater in this section is also recharged by local atmospheric precipitation.