Groundwater simulation for efficient water resources management in Zhangye Oasis, Northwest China

Human activities, especially groundwater exploitation for agricultural production, have resulted in an excessive decline of the groundwater level and posed a serious threat of aquifer overdraft in the arid and semi-arid region of northwest China. For the purpose of managing water resources effectively, this study applied the Visual MODFLOW package to simulate the aquifer changes under various agricultural scenarios from 2009 to 2018 in Zhangye Oasis, the middle reaches of the Heihe River Basin, Northwest China. In addition to current conditions, limited irrigation and channel leakage prevention, which represent the essential trend of today’s irrigation, were set as future water-saving agricultural scenarios. As the results show, under current water resource management conditions, groundwater levels fall at an alarming rate of 1 m/year in irrigation areas and 0.2 m/year in non-irrigation areas; moreover, the annual groundwater budget in the oasis will be −7.64 × 10⁸ m³. In addition, taking agricultural water saving measures can alleviate the groundwater problems efficiently, and the most promising water resource management for the Zhangye oasis could be decreasing the irrigation quota and the leakage coefficient of the canal system to 80 % of the current level and 0.3, respectively. Contrast of the two optimal scenarios indicates that limited irrigation is more effective than channel leakage prevention for groundwater protection in the Zhangye Oasis.