Flood Vulnerability Assessment of Binahaan River Basin Using Morphometric Analysis Based on Quantum Geographic Information System and Remote Sensing

Morphometric analysis has been conducted to measure a river basin's linear, aerial, and relief aspects. Studies showed that basin morphometry has a relationship with the hydrologic phenomenon of a river basin, thus influencing occurrences of floods, run-off, erosion, and channel abrasion. The Binahaan River in Leyte, Philippines, has a history of frequent flooding events that average more than one damage-causing event yearly. The study aimed to determine the morphometric parameters of the Binahaan River basin and evaluate their implications for hydrologic processes, most specifically, flooding, using a Geographic Information System (GIS) to delineate, extract, and analyze the parameters. The study revealed the flood susceptibility ranking of the sub-catchments: High (catchments 6 and 7), Intermediate (catchments 1 and 5), and Low (catchments 2, 3, and 4). Catchments 6 and 7 were noted to have high basin relief, relief ratio, ruggedness number, and mean bifurcation ratio with low circularity ratio and compactness coefficient. Validation through interviews and georeferencing with existing flood hazard maps also mainly showed the same results. The study presented that morphometric analysis and GIS can be utilized to analyze drainage basins comprising large areas with time constraints but still yield accurate data.