Study on reciprocal relationship among water amount-water quality-water efficiency based on the SWAT_WAQER model : —A case study of the Yulin catchment

In order to quantitatively analyze the interrelationship among total water consumption, water use efficiency and river water quality, this paper takes the Yulin Basin as the study object and constructs a “quantity-quality-efficiency” joint regulation model based on SWAT_WAQER, and calibrates runoff and water quality. By setting five scenarios of industrial water use efficiency and agricultural irrigation water use efficiency, the SWAT_WAQER model is used to simulate and analyze the total water consumption, pollution emission, and response state of water quality of river cross-sections under each scenario, and to analyze the interaction among them. The results show that the SWAT_WAQER model constructed in this paper performs well and it is applicable for changes in national economy water consumption, pollutants discharged into rivers and river water quality concentration under different water conservation scenarios. In the Yulin Basin, water consumption of per CNY 10,000 of industrial added value, industrial water consumption and river water quality up-to-standard rate show a linkage relationship of simultaneous decrease and simultaneous increase; water efficiency of irrigation, irrigation water use and water quality up-to-standard rate show a linkage relationship of “as one falls, another rises”; changes in water consumption of per CNY 10,000 of industrial added value have obvious influence on river water quality concentration, but changes in water efficiency of irrigation have limited influence on river water quality concentration.