伊犁河支流大西沟河水与地下水转化关系研究

A study of the conversion between the Daxigou river and groundwater

开展河流和地下水转换关系研究对于区域水资源合理开发利用具有重要意义。文章以大西沟河水与地下水转换关系为目标,在分析地下水动力场的基础上,通过水化学类型、溶解性总固体(TDS)、氯离子(Cl^-)等水化学以及环境同位素^(18)O、D、T等指标作为示踪剂,分析大西沟河和地下水的转换关系和转化强度。结果表明:研究区河流和地下水化学类型主要为HCO_3—Ca,水化学类型空间分布特征相似; TDS和Cl^-浓度表现为先增加后下降,但地下水的变化幅度大于河水。通过对大西沟河水和地下水中的水化学和环境同位素指标对比分析,发现研究区河流与地下水之间补给排泄关系具有明显的分段性;从河流出山口到下游地区,河水和地下水之间发生了三次转化关系:在山前倾斜砾质平原区以河水入渗补给地下水为主,补给量占该段潜水径流量的56%;到了细土平原区出现地下水补给河水地段,补给源为承压水越流补给潜水后的混合水体,潜水和承压水补给比例占该段河水径流量的20. 4%与58. 4%;风成沙漠区河水沿途渗漏补给地下水直至河流断流。本次研究结果为建立研究区水循环演化模式和水资源合理开发利用提供了理论和技术支持。

A study of the conversion between a river and groundwater is of great significance for the rational development and utilization of regional water resources.Based on the analyses of the conversion between the Daxigou River water and groundwater,this paper analyzes the groundwater dynamic field and uses hydrochemical type,dissolved total solids(TDS),chloride(Cl-)and environmental isotopes18O,D,T and other indicators as tracers to examine the conversion relationship between the Daxigou River and groundwater and their transformation intensity.The results show that the hydrochemical types of rivers and groundwater in the study area are mainly of HCO3-Ca type,and the spatial distribution characteristics of the hydrochemical types are similar.The concentrations of TDS and Cl-increase first and then decrease,but the variation in groundwater is greater than that of the river water.The comparative analysis of hydrochemistry and environmental isotope indexes in the Daxigou river water and groundwater reveals that the supply and discharge relationship between rivers and groundwater in the study area is characterized by obvious segmentation.From river exit to downstream,conversion of the river water and groundwater occur three times.In the sloped gravel plain area in front of the mountains,the river water infiltrates into the groundwater,and the recharge accounts for 56%of the submarine runoff.In the fine soil plain area,the groundwater recharges the river water,and the recharge source is from the mixed water body in the unconfined aquifer which is a leakage recharge from the confined aquifer.The proportion from the unconfined and confined aquifers accounts for 20.4%and58.4%of the river runoff,respectively.The river in the windy desert area supplies the groundwater until the river is zero-flow.The results of this study may provide theoretical and technical support for the establishment of the water cycle evolution model and the rational development and utilization of water resources of the study area.