Flood vulnerability analysis using geographic information system and weighted scoring approaches in the Silat Sub-watershed, West Kalimantan

ABSTRACT Graphical abstract illustrating flood vulnerability mapping in the Silat Sub-watershed using GIS-based weighted scoring analysis integrating rainfall, slope, soil type, land use, and watershed shape. Flood vulnerability is classified into five categories: very low (lessthan131), low (131-210), moderate (211-290), high (291-370), and very high (greaterthan370). The dominant contributing factors include high rainfall, oxisol soil type, settlements, and mining land use. The study emphasizes spatial management, forest rehabilitation, and community-based early warning systems for flood mitigation. Changes in land cover and hydrological conditions in a watershed significantly affect flood frequency. Although several studies have analyzed land-cover changes, flood hydrographs, and flow dynamics in the Kapuas Watershed, no research has specifically mapped flood vulnerability in the Silat Sub-watershed by integrating morphometric parameters, soil type, rainfall, and land use within a single GIS-based and weighted-scoring analytical framework. This study aims to fill that gap by analyzing flood vulnerability in the Silat Sub-watershed, which forms part of the Kapuas Watershed, using Geographic Information System and Weighted Scoring methods. The data used include rainfall, slope gradient, soil type, land cover, and watershed shape. The results show that the flood vulnerability in the Silat Sub-watershed is classified into five categories: very low (131), low (131–210), moderate (211–290), high (291–370), and very high (370). The most influential factors on flood vulnerability are rainfall (very high category), oxisol soil type (very high vulnerability), and land use dominated by settlements and mining. The slightly oval watershed shape helps reduces the potential for runoff concentration compared to broader shapes. These findings emphasize the importance of integrating spatial management, forest rehabilitation, and community-based early warning systems to strengthen flood mitigation efforts.