Pengembangan Strategi Naturebased Solution (NbS) untuk Mitigasi Resiko Banjir pada Sub-DAS Pagedungan

Abstract

Flooding is one of the most frequent hydrometeorological disasters, influenced by land use changes, soil characteristics, and rainfall intensity. The Pagedungan Sub-watershed in Situbondo Regency has a relatively high flood risk due to the dominance of built-up areas, low soil infiltration capacity, and limited drainage systems. This study aims to analyze flood vulnerability under existing conditions and evaluate the effectiveness of Nature-Based Solutions (NbS) in flood risk mitigation. The method used is hydrological modeling with the InVEST Urban Flood Risk Mitigation (UFRM) model, utilizing rainfall, land cover, and Hydrologic Soil Group (HSG) data as inputs. The results indicate that the existing condition has an average runoff depth of 93.13 mm and a total runoff retention volume of 5.561.075,43 m³, reflecting limited water retention capacity. The implementation of NbS scenario 1, consisting of upstream reforestation, reduces runoff depth to 89.49 mm and increases retention volume by 7.17%. Meanwhile, scenario 2, involving retention ponds in downstream areas, reduces runoff depth to 92.70 mm with a retention increase of 2.16%. The combined scenario shows the most optimal results, with a runoff depth of 89.25 mm and a retention increase of 9.11%. In conclusion, Nature-Based Solutions are effective in reducing surface runoff and enhancing water retention capacity. The integrated application of NbS, particularly the combination of upstream reforestation and retention ponds, provides the most optimal results for flood risk mitigation in the Pagedungan Sub watershed.