Quantitative hydrological response to climate change and human activities in North and South Sources in upper stream of Qiantang River Basin, East China

Study region: The North and South Sources in the upper stream of Qiantang River Basin, China.Study focus: Identifying the relative contribution of climate change and human activities to runoff variation is essential for an enhanced understanding on efficient management of regional water resources. We used multiplied abrupt change testing methods to determine the baseline period (BP) and two variation periods (VP1 and VP2) and used six Budyko-based methods to detect the quantitative hydrological response to climate change and human activities.New hydrological insights for the region: The annual mean runoff of North Source witnessed a decrease in VP1 before it increased during VP2, while it continued to increase in South Source. The climate change dominated the runoff variation in the North Source, while it was human activities that was the main driver for South Source.The human-induced effect contributed to runoff decline in North Source, while it led to the continuous runoff increasing in South Source. It shows that the runoff change due to climate was more sensitive to precipitation than potential evapotranspiration. The land use analysis illustrates that human-induced runoff changes were composed of two aspects: 1) the increased proportion of woodland and decreased ratio of farmland reduced runoff; 2) the increased percentage of town-and-country-land increased runoff. The former influence was relatively limited compared to the latter, as well as the climate change.

Automated summary

This study focuses on the North and South Sources in the upper stream of Qiantang River Basin, China, and aims to identify the relative contribution of climate change and human activities to runoff variation. The results show that climate change dominated the runoff variation in the North Source, while human activities were the main driver for the South Source. Human-induced effects led to a decline in runoff in the North Source, while it contributed to continuous runoff increase in the South Source. The findings also indicate that runoff change due to climate change is more sensitive to precipitation than potential evapotranspiration.