Integrated Modeling of Conjunctive Water Use in a Canal-Well Irrigation District in the Lower Yellow River Basin, China

Abstract

The Yellow River Basin is a closed basin under serious stress with dense population, intensive agriculture, and excess water withdrawals. Low water use efficiency and groundwater overexploitation are threatening the sustainable development of the basin. This paper describes a coupled modeling approach to analyze sustainable management strategies in surface–groundwater conjunctive use irrigation districts in the lower Yellow River Basin. An appropriate irrigation schedule and an optimal range of groundwater levels are first established using the soil water atmosphere plant (SWAP) model with data from an irrigation experiment station. The integrated surface water and groundwater model was then set up using modified soil and water assessment tool (SWAT2000) and modular three-dimensional groundwater flow model (MODFLOW) models. The two models were connected through standardized simulation grids and calibrated using field measurements. Five scenarios that were designed according to different well-canal irrigation supply ratios and the irrigation schedule determined by SWAP were tested using the integrated modeling approach. It is proved that conjunctive management strategies of canal diversions and tube-well pumps can effectively reduce phreatic evaporation losses, increase water use efficiency, and sustain groundwater levels while maintaining crop yields at current levels.