Straw measures attenuate the differences in surface-subsurface flow and sediment yield under four rainfall patterns on red soil sloping farmlands of southern China

The intra-event dynamics of rainfall processes significantly alter surface-subsurface flow generation and sediment yield on sloping farmland. However, the effectiveness of straw mulching in regulating these rainfall-induced erosion processes remains inadequately understood. Over a 5-year observation period in this study, 127 rainfall events were classified into advanced (AP), intermediate (IP), delayed (DP), and uniform (UP) patterns. AP events, characterized by the highest intensity and shorter duration, whereas DP, with the greatest total rainfall and longest duration, also drove severe runoff and soil loss. Straw mulching attenuates the hydrological and sedimentary disparities induced by different rainfall patterns. Under AP rainfalls, compared with plowing bare land, tillage with straw mulching (TSM) reduced surface runoff rate (SFR) and sentiment concentration (SC) by 78.6 %, 97.1 %, respectively, and increased subsurface flow rate (SSFR) by 1.9 times. Power function analyses revealed that rainfall intensity patterns and straw mulching jointly shaped rainfall-runoff-erosion coupling, with measures with straw maintaining flatter relationships that stabilized hydrological and sediment responses under variable and extreme storms. By increasing subsurface flow and soil water content, the straw mulching strengthens soil water management and increases water availability, which enhances the climate adaptability and resilience of sloping farmlands under the increased frequency of extreme rainfall and drought events. • We studied surface-subsurface flow and sediment yield under different RIP patterns. • Runoff and sediment yield process was dominated by RIP in no-straw measures. • Straw mulching diminished the impacts of RIP on runoff and sediment yield. • The coupling effects of surface-subsurface flow were emphasized under four SCTs.