Impact of changes in water management on hydrology and environment: A case study in North China

Irrigation projects often result in many far-reaching environmental changes. This paper considers the case of the Hetao Irrigation District, the largest irrigation project along the Yellow River in China, and studies the impacts of agricultural water management on the hydrology and the environment. Long-term data (1954-2013) concerning irrigation, drainage, soil salinity, groundwater, and the environment of Wuliangsuhai Wetland, the lake that receives the drainage water, were collected and analyzed. The findings show that uncontrolled irrigation and the absence of effective drainage initially resulted in a rising groundwater table, worsening soil salinization, and the expansion of the lake, which is an important internationally recognized wetland. The completion of an artificial drainage system and the implementation of water-saving practices have had promising effects on lowering the groundwater table and controlling soil salinity. However, the risk of soil salinity is still threatening the irrigation system because salt is continuously accumulating within it and the total dissolved salts (TDS) in the groundwater are increasing. For better soil salinity control, more effective drainage is necessary to drain more salt and lower the water table, but this may harm the natural vegetation and the eco-environment of the Wuliangsuhai Lake because the non-point-source pollution from agricultural drainage has resulted in a serious eco-crisis in the Wuliangsuhai Lake. The results show that it is important to ensure there is a certain amount of low-TDS drainage water to protect the Wuliangsuhai Lake environment. Therefore, a balance must be achieved among soil salinity control, groundwater quality, favorable conditions for natural vegetation, and wetland protection. Further research is needed to develop optimal agricultural water management strategies, especially in the context of the ongoing water-saving renovation program.