COMMUNITY INVOLVEMENT IN BUILDING AND TESTING A FLASH-FLOOD MODEL FOR SIMULATING FLOOD FREQUENCY

In rural El Salvador, flash-flood hazards are not prioritized in disaster risk reduction planning due to their frequent occurrence and ephemeral nature as well as the presence of many other natural hazards. Flash floods are known to be incredibly dangerous, cause significant damage to homes and property, and hinder travel. Two communities in El Salvador face particular flash-flood challenges during heavy rainfall due to infrastructure and land-use changes that exacerbate flooding. A National Science Foundation International Research Experience for Students funded project, in collaboration with Lutheran World Relief in El Salvador and Sistema Nacional de Protección Civil, Prevención y Mitigación de Desastres (“Civil Protection”), provided US graduate students with an opportunity to monitor and model flash-flooding events. Students applied the Water Evaluation and Planning (WEAP) model in a novel way using 15-minute interval rainfall data in the communities of La Claros and Monseñor Óscar Romero. Students collaborated with local residents and Civil Protection to help constrain model variables and identify real-life contributing factors, like built structures, that influence flooding. In addition to populating the model with precipitation histories from a project weather station and field data (mapping and soil-hydraulic testing), students met with the Comisión Comunal de Protección Civil (CCPC) in each community to ascertain the nature of the flooding, how the flooding has changed over time, and to recruit citizen observers to record flooding events for testing the models. Results demonstrated the effects of different drainage routes on the severity of flooding into La Claros and Monseñor Óscar Romero. The scenario-based model outputs are useful tools for Civil Protection, development organizations like Lutheran World Relief, and community committees in charge of making emergency management decisions.