GIS-BASED FLOOD SUSCEPTIBILITY MAPPING AT UNIVERSITAS 17 AGUSTUS 1945 SAMARINDA

Flooding and temporary waterlogging are recurring environmental concerns on the campus of Universitas 17 Agustus 1945 Samarinda, East Kalimantan, Indonesia, particularly in low-lying and highly impervious areas. This study aimed to map flood susceptibility within the 12.01 ha campus by integrating rainfall, slope, elevation, distance to drainage, and land use using a Geographic Information System (GIS)-based weighted overlay approach. Each parameter was classified, scored, weighted, and spatially integrated to delineate low, moderate, and high susceptibility zones. Field validation was conducted at 36 purposively selected observation points by comparing predicted susceptibility classes with observed inundation conditions. The results showed that 3.45 ha (28.7%) of the campus had low susceptibility, 5.62 ha (46.8%) moderate susceptibility, and 2.94 ha (24.5%) high susceptibility. High-susceptibility zones were concentrated in low-lying areas with gentle slopes, extensive impervious surfaces, and proximity to drainage corridors, particularly around the parking area, canteen, and student activity center. Thirty of the 36 validation points corresponded with field observations, yielding an overall agreement of 83.3%. The six mismatched points suggest that local inundation processes are not fully represented by the selected spatial parameters. These findings demonstrate that the GIS-based approach suitably identifies relative flood susceptibility and supports the prioritization of drainage improvements and environmental management interventions within the campus.