Disproportionate contributions and spatiotemporal patterns of extreme rainfall and erosivity events across mainland China

Extreme rainfall events are increasingly influencing soil erosion across mainland China, yet their contribution to total rainfall erosivity and spatiotemporal patterns remains insufficiently quantified. Using hourly data from 2,200 meteorological stations with at least 15 years of records, we analyzed over nine million rainfall events to assess the disproportionate role of extremes nationwide and within six major soil and water conservation regions. On average, only 9% of erosivity events accounted for 80% of total rainfall erosivity, whereas 25% of rainfall events were needed to reach the same proportion of total precipitation. Hotspots of extreme erosivity were identified in the Sichuan Basin, the western part of the Northern Rock Soil region, the southeastern Northwestern Loess Plateau, and the northwestern Southern Red Soil regions, where abundant moisture and regional terrain facilitate short-duration, high-intensity convective storms. Analysis of the 20 largest erosivity events showed slightly lower total rainfall but much higher peak intensities and shorter durations than the largest rainfall events. About 20–30% of stations exhibited temporal mismatches between the peak months of precipitation (MAX_P) and rainfall erosivity (MAX_E), mainly because erosivity is strongly governed by peak intensity, which is inversely related to rainfall duration. Short-lived convective storms, more frequent in summer (June–August) under enhanced thermal convection, generate much stronger erosive power than prolonged stratiform rainfall. Consequently, MAX_E tends to occur more often in summer than MAX_P. These findings highlight the disproportionate contribution of extreme rainfall to annual erosivity and underscore the need to incorporate high-resolution rainfall intensity and seasonality into erosion risk assessments and management strategies.