Separating variance in the runoff in Beijing's river system under climate change and human activities

Identifying the individual contributions of factors impacting the water resources in Beijing plays crucial roles in planning water management for resolving water shortage problems and for the sustainable utilization of water resources. In this study, four statistical methods, the Mann-Kendall test, double mass curve method, modified slope changing ratio of accumulative quantity method, and generalized linear model, were employed to detect the individual contributions of climate change and human activities on the variation of runoff in Beijing from 1961 to 2017. Our results showed that the annual runoff declined significantly during the entire study period. The mean temperature increased significantly, while the annual precipitation did not change significantly, over the entire study period. An abrupt change was detected in 1977 with a change in runoff. During the period of change, climate change contributed 20.0% to the increase in runoff, while human activities contributed 120% to the decline in runoff from 1978 to 2017. Furthermore, we partitioned the contributions of human activities into eight social and economic factors. These factors explained 55.29% of the total contributions of human activities. The economic factors, the changes in the arable land area and accumulative construction area, and the change in urbanization rate contributed 15.94%, 18.37%, and 6.05% to the total variation in runoff, respectively. Finally, the South-to-North Water Transfer Project contributed 5.19% of the change in runoff. Our study provides the individual contributions of the specific impact factors to runoff in Beijing and may help policy-makers to devise targeted water resource management plans.

Automated summary

The study reveals that climate change and human activities have significant impacts on runoff in Beijing, with human activities contributing more to the decline in runoff compared to climate change. Economic factors, changes in arable land area, and urbanization rate are identified as major contributing factors to the variation in runoff caused by human activities.