Attribution Analysis of Blue-green Water Change in Jinghe River Basin Driven by Duality

Jinghe River Basin is located in the middle of the Loess Plateau and is one of the birthplaces of China’s agricultural and animal husbandry civilization. Studying the change law of blue and green water in the basin provides an important idea for water resources allocation and water recycling in the Loess Plateau,and provides a guarantee for the final realization of the overall goal of“ecological protection and high-quality development of the Yellow River Basin.”Based on SWAT（Soil and Water Assessment Tool）hydrological model and SUFI-2algorithm,firstly,the spatial distribution difference of blue-green water resources in Jinghe River Basin in typical years is analyzed. Secondly,the scenario setting method is adopted to set scenarios by fixing climate elements and land use elements respectively,so as to quantitatively analyze the impact of two driving factors such as climate change and land use change on blue-green water change in Jinghe River Basin. The simulation results show that:（1） the typical years are determined by Pearson Type III frequency curve method:1997 is a dry year,2010 is a flat year and 2003 is a wet year.（2） The amount of blue-green water in wet years is the most abundant:the amount of blue-green water in wet years is 5.4 times that in dry years and 1.8 times that in normal years.The amount of green water is 1.4 times that in dry years and1.1 times that in normal years. The green water coefficient is the highest in dry years and the lowest in wet years.（3） The runoff of Zhangjiashan Hydrological Station from 1979 to 2019 is analyzed by Mann Kendall mutation test,sliding t test and cumulative anomaly method. The results show that 1996 is the mutation year of runoff of Zhangjiashan Hydrological station.（4） From 1979 to 2019,land use change had little impact on the temporal and spatial distribution of blue and green water in the Jinghe River Basin,and had a greater impact under climate change:the blue water volume and green water volume increased by 1.97 and 21.48 mm respectively,and the green water coefficient increased by 0.52%. The change trend of blue and green water under the joint change of the two was consistent with that under climate change,which showed that climate change had a stronger impact on the amount of blue and green water resources in the Jinghe River Basin.