Impacts of Climate Change and Human Activities on Runoff in the Dongbing River Basin

KONG Fanhua

doi:10.3969/j.issn.1004-7328.2026.06.002

Abstract：Climate change and human activities have affected surface runoff in the Dongbing River Basin,the main inflow river of Dongfeng Reservoir,resulting in a gradual decrease in inflow and posing a threat to the water supply security of downtown Yuxi City.To analyze the quantitative impacts of climate change and human activities on runoff in the Dongbing River Basin,this paper is based on observed runoff data from Dayizi Hydrological Station and precipitation data from Anhua and Dayizi rain gauge stations from 1980 to 2024.Methods including water balance,statistical analysis,and separation evaluation were applied to analyze the evolution characteristics of rainfall-runoff in the basin and to quantify the contribution of climate change and human activities to runoff variations.The main results are as follows:The multi-year average natural runoff of the Dongbing River Basin is 31.88 million m³,with a coefficient of variation(Cv)of 0.35.The multi-year average total water consumption shows an increasing trend,dominated by agricultural water use;The basin's multi-year average precipitation is 942 mm,with a Cv of 0.15.The runoff coefficient is positively correlated with precipitation,indicating that rainfall is an important factor affecting runoff in the Dongbing River Basin.However,the intra-annual distribution of rainfall and runoff is highly uneven,and runoff peaks lag behind precipitation peaks;Both precipitation and runoff exhibit significant decreasing trends,with abrupt change points around 2008 and 2003,respectively;Climate change and human activities jointly contributed to the reduction of runoff in the Dongbing River Basin,with contribution rates of 53.0％and 47.0％,respectively.The results of this study provide scientific reference for the protection of the Dongfeng Reservoir water source and for scheduling water supply security in downtown Yuxi City.