Estimation of groundwater recharge during the ecological water conveyance in the lower reaches of Tarim River

本文通过对塔里木河下游断流河道2000～2007年九次生态输水期间九个地下水监测断面40口监测井地下水埋深变化监测数据的分析，首先探讨了生态输水以来地下水埋深变化的规律。结果表明:在九次输水的影响下，地下水埋深总体有显著抬升。运用SPSS统计软件对监测数据进行的回归分析表明，抬升幅度与输水持续时间和输水量大小成显著正相关关系，横向和纵向上还表现出地下水埋深抬升幅度随距输水源距离改变而变化的正相关关系。其次,依据九次生态输水期间地下水埋深监测数据，拟合了输水后地下水埋深与离河距离关系的曲线方程，进而对塔里木河下游断流河道输水后地下水的补给量及其变化特征进行了计算和分析，探讨了生态输水的横向影响范围及其变化特点。结果表明：塔里木河下游区域输水后地下水总净补给量为78 438.1×104m3，占总下泄水量的35.72％。九次输水过程中，除第二次输水和第六次输水外，其余各次输水期间，地下水净补给量都呈下降趋势。表明随着生态输水的实施，地下水的补给量逐渐减小并趋于动态平衡，生态输水产生的生态效益呈逐渐减小的趋势。对输水后横向影响范围的分析表明，横向影响范围与输水量大小和持续时间密切相关。随着输水的进行，各断面横向影响范围呈明显扩大趋势，纵向上沿河道至上而下，影响范围呈现出逐渐减小的趋势。最后，运用灰色理论对输水后地下水位埋深的预测表明随着未来输水工程的持续，地下水埋深呈缓慢上升的趋势。预测每次输水量为 时，地下水位将以0.04m-0.40m 速度抬升，且随着纵向距离的增大地下水位上升趋势由大变小。塔里木河下游断流河段河道两侧地下水位恢复是一个与输水量和输水时间关系密切的上下波动的周期性过程，且要河道两侧地下水位恢复到适合天然植被生长所需范围需要经过一个艰难而漫长的过程。The regulation of variation of risen amplitude of the groundwater depth after ecological water transport in the lower reaches of the Tarim River are firstly analyzed based on the monitored data of the nine stream water conveyance to the river section where the stream flow was cut-off more than 30 years and of the nine groundwater-monitoring sections and forty monitoring wells in the lower reaches of the Tarim River from 2000 to 2007.The results showed that the groundwater depth of the groundwater-monitoring sections has lift obviously after eight times of stream water conveyance.Statistical analysis on the variation of risen amplitude of the groundwater depth by regression analysis using SPSS 13.0 reveals that there is positive correlation between the risen amplitude and the duration and the quantity of the ecological water transport. Secondly,Based on the monitored data of the nine groundwater-monitoring sections and forty monitoring wells of the nine stream water conveyances in the lower reaches of the Tarim River from 2000 to 2007,this paper analyses the response features of groundwater depth after eight stream water conveyances.Then the variation characteristics of the volume of recharged groundwater and influenced range after ecological water conveyance are analyzed. The results showed that The total net volume of recharged groundwater was 78 438.1×104 m3 after ecological water conveyance. The ratio of the volume of recharged groundwater to the volume of output water is 35.72 percent.Except duration of the second and sixth water conveyance, The ratio of the volume of recharged groundwater to the volume of output water is fall down. It showed that the volume of recharged groundwater is decreased and close to a homeostasis and the ecological benefit of stream water conveyance is decreased with the ecological water conveyance’s going on.Analysis on transverse influence range of the groundwater during ecological water conveyance showed that it is strongly in relation to the volume of output water and duration of water transport. Both in transverse and lengthwayst the influence range of the groundwater is extended remarably positively correlate with the stream water conveyance. Lastly, Use the grey theory model,under predicting that there are similar conditions in the environment and modeling environment,Accurately prediction the groundwater depth change in Tarim River under the same delivery water amount in future. The results showed that the groundwater depth will lift slowly with the ecological water conveyance’s going on. The groundwater depth will lift 0.04m to 0.40m after the volume of output water is during every ecological water transport,and the lift amplitude of the groundwater depth will decrease in lengthways.It will be a long time to make the groundwater depth in the river banks lift to the rational groundwater table