生态输水条件下塔里木河下游断面尺度地下水流数值模拟

由于中国西北地区地表水资源有限,地下水则成为重要的备用水资源,而地表水和地下水转化过程及其耦合模拟是水资源开发利用和科学评价的基础,因此,为了准确反映塔里木河下游间歇性生态输水后地下水的动态变化,以塔里木河下游英苏断面为例,基于Boussinesq方程建立了改进的地下水动力学(GH-D2)模型,模拟了塔里木河下游绿色走廊典型断面地下水对全时段(2000-2015年)间歇性生态输水的响应过程。结果表明,尽管Boussinesq方程的GH解能较好地模拟地下水位的瞬态变化,但模拟地下水位多年变化的结果并不理想,而改进的GH-D2模型考虑了间歇性生态输水对地下水位变化的滞后效应,对长时间尺度地下水位变化的模拟具有较好的效果。与GH和GH-D1模型相比,GH-D2模型模拟的地下水位值更接近于观测值,这将对塔里木河下游实施科学合理的生态输水计划以及生态恢复和重建策略提供关键的技术支撑。

Numerical simulation of groundwater flow at cross-section scale in the lower reaches of Tarim River under the condition of ecological water conveyance

Owing to limited surface water,groundwater is a critical water resource in the northwest China. Conversion process and its coupling simulation of surface water and groundwater are the foundation of water resources development,utilization,and scientific evaluation. In order to accurately reflect the dynamic changes of groundwater after ecological water conveyance,the groundwater level in Yingsu section of the lower reaches of the Tarim River was studied monthly for consecutive years. We proposed an improved groundwater dynamic (GH-D2) model based on Boussinesq equation to simulate the response of groundwater level fluctuation in the typical section of the green corridor to intermittent ecological water conveyance (2000-2015). The results show that although the GH solution of Boussinesq equation can well simulate the transient change of groundwater level,it is not ideal in simulating the multiyear changes in intermittent water conveyance river. The improved GH-D2 model takes into account the delayed effect of intermittent ecological water conveyance on the change of groundwater level,and performs well in the simulation of long-term changes. Compared with GH and GH-D1 models,the groundwater level simulated by GH-D2 model is more approaching to the observed value. This study will provide crucial technical support for the implementation of a scientific and rational ecological water conveyance project and for the ecological restoration and reconstruction strategy in the lower reaches of Tarim River.