Evolution of sediment after a decade of the Wenchuan earthquake: a case study in a protected debris flow catchment in Wenchuan County, China

The Wenchuan earthquake brought abundant sediment in the seismic area. The evolution of sediment caused catastrophic debris flow when the rainfall reached the threshold during the past decade. The massive debris flow still occurred frequently in recent years. The question is whether these frequent disasters are related to the evolution of the sediment and what role the check dam plays in it. This study investigates the evolution of sediment and how it is affected by the effect of check dam in a protected catchment. We analyze the evolution of sediment during the 2019 and 2020 debris flow in Chutou gully by using several investigation methods. The interaction between the evolution of sediment and the effects of check dams are assessed on the basis of the results of sediment evolution and innovative methods. We present the effects of check dam under different conditions through the well-balanced numerical method. Results show that the evolution of sediment remains active in recent years, and we should focus on the debris flow protection in the seismic area. Check dams are essential protection for the debris flows, which impact sediment evolution remarkably. The storage capacity and the stability of check dams should be focused to prevent the subsequent debris flow.