The researchers analyzed the runoff variations in Yishuhe River Basin to help with flood control and drought relief. They looked at 60 years of data from 2 hydrometric stations and 23 precipitation stations. The study found that the annual runoff in the basin is unevenly distributed, with most runoff occurring in four consecutive months. The monthly maximum precipitation usually happens in August. Over time, the annual runoff has been decreasing at two stations, with a significant reduction trend in Yihe River starting in 1966 and 2013.