生态输水工程对塔里木河中下游地区地下水循环特征的影响

利用环境同位素技术结合水化学特征,对塔里木河中下游地区生态输水影响下地下水循环规律进行监测分析。结果显示:塔里木河中下游各断面地下水p H值变化不大,矿化度和各离子差异明显,地下水水样以Na+、Cl+占绝对优势;矿化度较低的断面其离子浓度变化较小,反之,矿化度高的断面其离子浓度变化幅度较大;塔里木河中游δ2H和δ18O变化趋势基本一致,随着距河道距离的增大,δ18O的值呈增大趋势,下游H、O同位素变化波动较大,下游各样点距河道最近处(即50m处)H、O同位素最小,随着距河道距离的增大,H、O同位素亦呈增大趋势变化;塔里木河中下游地下水、地表水中δ2H和δ18O之间均呈明显的线性关系,中游地表水补给是地下水的主要来源;下游地下水中H、O同位素则普遍高于地表水,说明水体受到严重的蒸发作用,导致同位素富集外,也说明存在地下水对河水的补给。

Study on the circulation of groundwater influenced by water delivery engineering at the middle and lower tarim river

To disclose the relationship between the circulation of groundwater and Ecological Water Delivery Engineering,the study tries to monitor and analyze the circulating characteristics of groundwater at the middle and lower Tarim River by means of the technology of environmental isotopes as well as water chemistry. The result shows that,the p H value changed little from section to section at the middle and lower Tarim River while the salinity and ions at different sections were significantly different.Besides,the Na^＋,Cl^＋were far superior numerically of all the ions in groundwater samples. The concentrations of ions were always low in the monitoring section where the total dissolved solids value was small,and vice versa; the changing trends of δ^2H and δ^18O at the middle reaches of Tarim River were consistent,and the value of δ^18O in groundwater increased along with the increasing of the distance of monitoring wells away from watercourse. Isotopic variational scope of δ^2H and δ^18O was larger in downstream than that in middle reaches; the sampling points at the lower to the nearest watercourse（ i. e.50 m away from the watercourse） the values of δ^2H and δ^18O correspond closely to the theoretical minimum,and meanwhile,the values of δ^2H and δ^18O show a trend of increase as the distance from watercourse was increasing; the relationship between values of δ^2H and that of δ^18O existing in the groundwater and surface water respectively was a linear correlation,indicating that the watercourse is the source of water to groundwater which is similar to the case in the middle reaches; the values of δ^2H and δ^18O in groundwater were generally higher than those in river channel,which means the discharging way of groundwater is severely evaporation.