Evolution and Periodicity of Watershed-scale Runoff: Insight from the Spatiotemporal Variety in Intensive Anthropogenic Activities Region

The analysis of runoff evolution is crucial for the effective management and utilization of water resources, as well as for agricultural regulation within watersheds. However, the spatiotemporal evolution and periodicity of runoff at the watershed scale, particularly under intensive anthropogenic influences, remain insufficiently documented. In this study, the Mann-Kendall test, Pettitt test, R/S analysis and wavelet analysis were applied to runoff data spanning 20 years (2002–2021) in the Yiluo River watershed. The results revealed an increasing trend in runoff from 2009 to 2015, followed by a decreasing trend from 2005 to 2009. Abrupt change points were identified in 2004, 2008, and 2020. The findings indicate a weak long-term increase in runoff within the Yiluo River watershed. Additionally, periodicity analyses revealed runoff cycles of approximately 1 year and 5 years. Intensive anthropogenic activities significantly influenced the spatiotemporal evolution and periodicity of runoff, primarily through changes in land use, including increased cropland and impervious surfaces at the watershed scale. Our results study provide a quantitative understanding of runoff regulation at the watershed scale and offer a valuable reference for future research.