Effects of precipitation concentration and human activities on city runoff changes

Abstract Under the dual influence of precipitation and human activity, urban runoff has changed significantly. To evaluate how these two factors may affect city runoff, we used hydro statistical methods to provide a scientific basis for the evolution of urban flood control and non-point source pollution. This study took Guangzhou city as an example and examined the characteristic changes of runoff from 1970 to 2020. The results showed that the concentration of precipitation in Guangzhou City varied between 0.25 and 0.63 during 1970–2020, with a mean value of 0.47, and abrupt changes in runoff occurred in 2013 and 2016. We also found that the impact of human activities on runoff was greater than that of the concentration of precipitation from to 2014–2016, contributing 82.3% while the contribution of precipitation concentration was 11.7%. The impact of precipitation concentration on runoff was more obvious during 2017–2020, contributing up to 98% of the change in runoff compared to only 2% for human activities, and runoff increased with increasing precipitation concentration. The combined effect of precipitation concentration and human activities has a certain impact on urban runoff, and each has a different impact on urban runoff in different periods. This research provides a scientific basis for alleviating urban flood.