Sediment transport evolution and impact on vegetation recovery in the Hanping village landslide–debris flow disaster chain in Shaanxi, China

Abstract

The landslide–debris flow disaster chain, as a severe mode of slope material transport, significantly impacts regional geomorphological evolution and ecosystems. To better understand the long-term effects of sediment dynamics in the landslide–debris flow disaster chain, this study took the Hanping village landslide–debris flow disaster chain as a case study. By combining field investigations with dynamic simulations, the formation and evolutionary process of the disaster chain was reconstructed. A multisource remote sensing observation scheme integrating unmanned aerial vehicle and satellite remote sensing data was subsequently developed, which further revealed the characteristics of sediment transport and vegetation recovery over a prolonged postdisaster period. Our findings indicate that the formation and evolution of the disaster chain can be divided into four stages: landslide instability, landslide–debris flow transition, debris flow transport, and debris flow deposition. The transformation mechanism of the disaster chain is driven by the blockage failure effect at the bedrock narrows, followed by collision-induced disintegration that reduces particle size and increases water content. The deposits formed during different stages of the dynamic process exhibit significant compositional differences. Multisource remote sensing observations revealed significant spatiotemporal variations, with postdisaster deformation concentrated in channels and depositional regions. The time series deformation results further indicated that surface runoff induced by heavy rainfall exacerbated sediment transport, leading to notable deformation anomalies, with different material compositions exhibiting distinct transport patterns. Postdisaster monitoring revealed a significant increase in vegetation recovery, with an 80 % increase in vegetation area in the two years after the disaster (April 2022–March 2024). The proportion of areas with good recovery increased from 18.52 % to 41.34 % between 2022 and 2023. Moreover, a generalized feedback mechanism model describing sediment transport and vegetation recovery in landslide–debris flow disaster chains was proposed. This study, from a disaster evolutionary perspective, innovatively integrates numerical simulation with multisource remote sensing techniques to reveals the relationship between sediment transport and vegetation recovery, providing a foundation for ecological recovery efforts.