Observations and computational multi‐phase modelling in tropical river settings show complex channel changes downstream from rainfall‐triggered landslides

摘要: Alluvial river channels respond to changes in sediment supply by adjusting their geometry. Landslide sediment delivery and geomorphic response of river channels during floods are poorly understood and rarely examined in tropical settings. We investigate the impact of landslides on channel geomorphic changes during an extreme typhoon‐induced flood event in the Philippines, specifically the complex geomorphic response of the Antamok River to Typhoon Mangkhut in September 2018, which triggered >500 landslides in the Ambalanga catchment. The catchment has a legacy of anthropogenic modifications, such as extensive small‐scale (artisanal) mining and tailings storage facilities (TSFs) from large‐scale mining activities. We use a novel mix of mapping and computational modelling approaches to test the hypothesis that landslide sediment delivery is a major control on channel geomorphic change. Pre …