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.