Developing integrated hydrologic modeling and flood mitigation strategies for the Takwi Creek Watershed, Philippines

Effective flood mitigation strategies are essential for safeguarding communities and minimizing economic losses, particularly in watersheds vulnerable to flash flooding. This study presents an integrated approach to hydrologic modeling and flood mitigation planning for the Takwi Creek Watershed in Pampanga, Philippines—an area highly susceptible to flooding due to its physiographic characteristics and climatic conditions. Using the Hydrologic Modeling System (HEC-HMS), a comprehensive model was developed from physical parameters, topographic data, and historical hydrometeorological records. The model was calibrated and verified against observed streamflow data from Typhoon Peping and Typhoon Santi events, ensuring reliability in simulating rainfall–runoff dynamics under various scenarios. Rainfall–runoff analyses revealed significant sensitivity to land-use changes, soil type, and rainfall intensity. Scenario testing of structural (e.g., channel widening, levees, retention basins) and non-structural (e.g., floodplain zoning, public awareness) measures demonstrated notable reductions in peak outflow—up to 6.1% in extreme events—and increased temporary storage capacity. Findings underscore the value of integrating advanced hydrologic modeling with community-informed strategies for sustainable flood risk management. The approach provides a decision-support framework applicable to other flood-prone watersheds in the Philippines and beyond. The methodological framework draws upon recent advances in optimization-based approaches for water system operation (Phumiphan et al., Water 16:816, 2024; Gonthong et al., Int J Geomate 29:113–120, 2025) and incorporates considerations for infrastructure design under changing climate conditions (Nuannukul et al., ARPN J Eng Appl Sci 16:1035–1043, 2021).