塔里木河下游第五次应急输水后地下水恢复量的计算

依据塔里木河下游应急输水前与第五次第一阶段输水后地下水的监测资料,分析了输水前后地下水位的响应特征:地下水位在应急输水前持续下降,呈近似水平状态;输水后则由于接受了河道渗漏的补给,地下水位表现出逐次回升的趋势且受输水的影响,宽度(距离河道)也随之加大。在此基础上,逐断面拟合了第五(I)次输水后地下水位与离河距离的二次多项式方程,同时运用地下水水均衡的原理,推导了计算地下水净恢复量的数学公式,并以此为工具对第五(I)次输水后地下水的净恢复量进行了计算。

Calculation of Groundwater Recharge Volume after the Fifth Emergency Water Transfer to the Lower Reaches of the Tarim River, Xinjiang

Tarim River is the longest inland river in China.It is located at the north of the Tarim Basin.However,the river flow in the 357-km-long section of the lower reaches had been cut off since 1972.The groundwater level had declined from 2.9～7.0m to 8.1～12.9m.In order to protect the eco-environment and save the existing vegetation in the lower Tarim River,a total volume of 13.8×10⁸m3 of water was delivered to the lower reaches from May 2000 to July 2003, in five times.Based on groundwater monitoring data before and after the fifth water transfer,this paper analyses the features of responses of groundwater table pre- and post-delivery of water to the lower reaches of the Tarim River.Before water transfer,the groundwater table was generally a horizontal line but after that,it presented a binary polynomial curve. The relationgship of ground-water table and distance from the river was thus expressed binary polynomial.Furthermore,the calculative formula of groundwater recharge volume was established by means of groundwater balance.The results of calculation showed that the average depth of groundwater has come back respectively from 9.0m to 3.0m and from 9.0m to 7.4m at Yingsu section and Yiganbujima section in the vicinities of the river(0～1000m).The total volume of groundwater recharged was 8.01×10⁸m3 after the fifth water transpfer.All these can provide referenced index for the evaluation of benefits from water transfer.