Chain effects of landslide activity intensity decay on landslide sediment transfer and debris flow activity

In earthquake-affected zones, the spatiotemporal succession of landslide activity intensity influences the capacity of the landslide sediment supply for debris flows, thereby affecting their activity. However, the driving mechanisms behind the spatiotemporal succession of landslide activity intensity remain unclear. In particular, the chain effects of this evolution on landslide sediment transfer and debris flow activity are not fully understood. In this study, we monitored the prolonged changes in landslide activity intensity and landslide sediment transfer potential. we subsequently analyzed the driving mechanism of the succession of landslide activity intensity and observed the close relationship between the succession of landslide activity intensity and sediment transfer as well as debris flow activity. In the first 5 years following the Wenchuan earthquake, intense tectonic activity and extreme rainfall events dominated the landslide destabilization probabilities, resulting in exceptionally high sediment transfer potential in the Yingxiu–Caopo regions, Sichuan Province, China. Subsequently, the combined impacts of rainfall, curvature, slope, and aspect gradually increased, resulting in the regions with higher landslide activity intensity progressively advancing to these nonriparian regions, which consequently induced a corresponding change in areas with higher landslide sediment transfer potential. The spatiotemporal evolution of landslide activity intensity has led to a linear decay in the potential for landslide-derived sediment supply to channels, consequently resulting in a corresponding linear decline in debris flow activity.