The researchers studied long-term trends in annual runoff in the Baiyangdian watershed. They found that upper reaches had a more significant decreasing trend than lower reaches. The Shahe watershed had a slower decreasing trend compared to Tanghe and Jumahe watersheds. Overall, annual runoff is decreasing and may continue to do so in the future. Climate change may be impacting runoff in the Shahe watershed, while human activities may be affecting the Jumahe watershed. The increase in air temperature could be contributing to changes in evapotranspiration.