How Hydrological Structural Connectivity Controls Red Soil Erosion During Multiple‐Intermittent Rainfalls

Abstract Hydrological structural connectivity is key to regulating hillslope erosion, but its formation and interactions with runoff‐sediment dynamics during intermittent rainfall remain unclear. Through simulated intermittent rainfall (three consecutive rainfall events with a 1‐day interval between each, intensities: 30, 60, 90 mm hr −1 ) combined with overland‐flow hydraulics measurements and high‐resolution UAV photogrammetry, this study reveals how hydrological structural connectivity dynamically controls erosion. Runoff‐sediment responses showed strong intensity dependence. At 30 mm hr −1 the runoff coefficient rose continuously, whereas under higher intensities it increased and then stabilized. Soil loss rates rose steadily at low intensity, followed a “rise‐then‐fall” pattern at medium intensity, and declined at high intensity. Connectivity strengthened with rainfall progression, but its growth rate declined as intensity increased. The key structural connectivity index |RF| rose with intensity (36.71, 39.36, 41.52 under 30, 60, 90 mm hr −1 , respectively; ×10 −6 ), while its growth rate decreases significantly (18.58%, 9.96%, 1.02%), showing earlier stabilization under high intensity. |RF| exhibits significant positive correlations with surface runoff, hydrodynamic parameters, and key rill morphological parameters, indicating that connectivity influences erosion processes by regulating flow pathways and convergence efficiency. Under low rainfall intensity, erosion promotes connectivity development, whereas under high rainfall intensity, an early‐established highly connected network constrains further erosion. As rainfall intensity increased, the erosion system shifts gradually from an “erosion‐driven connectivity development” regime to a “connectivity‐controlled erosion regulation” regime. This study reveals the nonlinear responses of hillslope erosion from a connectivity perspective, offering a theoretical basis for mechanism understanding and targeted conservation strategies.