Hurricane-triggered cascading hazards: Geomorphic responses and flood hazard dynamics in a tropical mountain region

In tropical mountains, extreme hydrometeorological hazards have the potential to produce significant geomorphic changes that influence flood hazard dynamics. Although considerable research has been devoted to the geomorphic response of catchments to flood in temperate areas, comparatively little attention has been paid to the geomorphic and hydrological impacts of hurricanes in tropical mountainous areas. It is thus crucial to identify and quantify the differential response of catchments to these events and to integrate those changes into the corresponding flood hazard analyses. In this study, we address three key research questions: (1) What are the geomorphic impacts triggered by hurricanes in mountainous regions at the river reach scale? (2) To what extent do neighboring catchments differ in their response to hurricanes? (3) How do hurricane-induced geomorphic changes influence flood hazard dynamics? For that, we investigate the geomorphic response and flood hazard of two catchments in the Sierra de las Minas (Guatemala), Pasabien and Jones, by analyzing their response to cascading events triggered by Hurricane Mitch in 1998 and Hurricanes Eta and Iota in 2020. We use an integrated approach that combines UAV and satellite-based remote sensing analyses, field-based evidence and physically based modeling to analyze landform and flood extent changes after the events. The overall results indicate that hurricanes have the capacity to impact flood hazard dynamics as they play a key role in landscape evolution, and that the storm characteristics, together with physiographic characteristics of the catchment, condition their differential geomorphic impact . These results have strong implications for disaster risk reduction, especially in the light of the ongoing urbanization process and the increasing frequency of hydrometeorological extreme in tropical mountains. • Hurricanes Eta-Iota triggered divergent geomorphic responses and flood hazards in adjacent catchments. • Catchment physiography controls landslide susceptibility and post-hurricane channel response. • Hurricanes Eta-Iota mobilized vast coarse sediment, driving river widening, avulsion, and floodplain change. • An integrated multi-method approach reconstructs cascading hazards in data-scarce tropical mountain regions.