A Groundwater Management Tool for Solving the Pumping Yields Minimization Problem: A Case Study in the Heihe River Basin

Abstract

Declining groundwater levels caused by over-exploitation in the middle reaches of the Heihe River basin have raised concerns with respect to the sustainability of the aquifer system. The groundwater depletion in the Daman irrigation district is particularly serious suffering ~20 m drawdown of groundwater level since 1980s. In this paper, a transient groundwater flow model was constructed and calibrated to simulate the groundwater dynamics in Daman irrigation district. A groundwater management tool has been developed to prevent further drawdown of groundwater level in conjunction with the flow model for this area. The response matrix method is used to transform a groundwater management problem into an optimization function. As a highly efficient and reliable method, the simplex method is used to solve the optimization problem. In the case of Daman irrigation district, the optimization problem is to maximize the pumping yields subject to the groundwater level constraints. To verify the effectiveness of the groundwater management tool, three different groundwater level constraints are assigned for the system control. The results indicate that the groundwater management tool is capable of identifying the optimal pumping yields for satisfying the given constraints. Further, the cultivated area which could be sustained by the optimized yearly pumping yields is calculated under the assumption of normal account of diverted water from the Heihe River. The results suggest two plausible solutions to approach the sustainable pumping yield. Although this study focus on the Heihe River Basin, it illustrates a general modeling framework for the sustainability of groundwater flow systems.