FLOOD HAZARD MAPPING IN THE FLOODPLAIN OF MALINGON RIVER, VALENCIA CITY, MINDANAO, PHILIPPINES

摘要

Flooding becomes one of the most challenging natural calamities in the Philippines today risking the lives and properties of the affected communities. Loss of lives and livelihoods due to flood hazards made the government to consider the need of research aiming to mitigate flood impacts and to increase the level of awareness thereby creating more adaptive and resilient communities. This study involved the combined technologies of Geographic Information System (GIS). Light Detection and Ranging (LiDAR)-derived digital elevation model (DEM) and the families of hydrologic models like Hydrologic Engineering Center-Hydrologic Modeling System and -River Analysis System (HEC-HMS and HEC-RAS). The aim was to determine the amount and timing of precipitation-runoff relationships in the upstream watershed, and performing two-dimensional hydraulic calculation in the floodplain of Malingon River in Valencia City. Mindanao. Philippines. Models were calibrated and the generated flood hazard maps were validated using actual datasets gathered from the field. Maps for different scenarios like 2-year. 5-year, 10-year. 25-year, 50-year and 100-year return periods were generated. Statistical analysis of features like buildings and other infrastructures exposed to different level of flood hazards was likewise conducted. Output of the study served as important basis to a more informed decision and a science-based recommendations in formulating local and regional policies statements for more effective and cost-efficient management strategies relative to flood hazards.