Flood Vulnerability Assessment in Ambon City: A Morphometric Approach of Wai Batu Merah and Wai Tomu Watershed
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Abstract
Ambon City faces high flood vulnerability due to heavy annual rainfall, complex topography, and rapid urbanization. This study evaluates the influence of morphometric parameters on flood susceptibility in the Wai Batu Merah and Wai Tomu watersheds by analyzing the bifurcation ratio (Rb), drainage density (Dd), and texture ratio (Rt). Morphometric parameters were derived from 8-meter resolution DEMNAS data and calculated using a GIS based quantitative approach. The results show that Rb values range from 1.3 to 2.0 reflecting a complex stream network influenced by structural deformation, which triggers a rapid hydrological response. Dd values exhibit a clear spatiial contrast ranging from 2.7 to 7.0; sub-watersheds WT3 and WT4 display the highest densities, associated with impermeable lithology and steep slopes, potentially generating high surface runoff and rapid peak discharge. Meanwhile, Rt is dominated by very coarse classes, indicating runoff accumulation susceptibility within the Ambon volcanic rock and coral limestone units. Sub-watersheds WT3, WT4, BM1, BM2, and BM6 are identified as high priority areas for mitigation. This study addresses the research gap in flood risk mapping for data scarce regions by demonstrating that integrated morphometric analysis provides a precise scientific basis for watershed management prioritization. These findings serve as a strategic foundation for spatial planning and vegetation conservation to minimize disaster risks in complex urban geological settings.
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References
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