Abstract:

 Climate warming and human activities have a major impact on the spatial and temporal characteristics of surface runoff in the Shiyang river basin, and the adaptive management of water resources in the basin is facing serious challenges. With three independent drainage Dajinghe river system, Liuhe river system and Xidahe river system as the research object, the statistical method analyzed the average flow evolution in 1960−2020, using Mann-Kendall test and Pettitt test to determine the runoff sequence mutation point, set the combination of climate and land use change, and used SWAT model to identify the runoff variation in Shiyang river basin, addressing the unequal allocation of water resources. The results showed that: (1) from 1960 to 2020, the annual average runoff decline rate of Xidahe river, Liuhe river and Dajing river system was 0.01m³·s⁻¹, 0.07m³·s⁻¹, 0.01m³·s⁻¹ respectively. The runoff years for the Liuhe river and Xidahe river were in 1973 and 2002, respectively, while the Dajing river system was in its natural state. (2) The SWAT model had a good adaptability to the Shiyang river basin, and the determination coefficient and the Nash efficiency coefficient were both higher than 0.50. (3) From 1960 to 2020, the contribution of precipitation, average temperature, relative humidity, solar radiation and average wind speed to the annual average runoff were 75%, 53%, 55%, 55%, and 52%, respectively. The contribution of land use change to the annual average runoff was 17%. The coupled contribution of six influence factors to annual average runoff reduction was 67%, indicating that climate change had great influence on runoff in Shiyang river basin. The research results could provide a reference for the adaptive management of watershed water resources.

Key words: Fonsens evolution features, SWAT model, Mutation analysis, Attribution analysis, Shiyang river basin