D. Amalia, Y.A. Setiyowati, A.A. Rofikha
Ambon City, an island province in Indonesia, is highly vulnerable to flooding due to its steep topography and increased rainfall intensity resulting from climate change. This study provides a quantitative evaluation of the implemented green-grey infrastructure in the Wai Batu Merah Watershed and examines its contribution to enhancing Ambon City's flood resilience through the application of Integrated Flood Risk Management (IFRM) strategies. The methodology involved hydraulic modeling using HEC-RAS to compare flood inundation for a 25-year return period before and after implementing interventions, including check dams, retention ponds, and Geomat slope stabilization. Additionally, a comprehensive assessment was conducted using the World Meteorological Organization's (WMO) IFRM framework. The results demonstrate that the green-grey solution significantly reduced the flood inundation area by 13.97 hectares (47.2%) and increased the river's discharge capacity from approximately ±50 m3/s to ±140 m3/s. The IFRM analysis yielded a "moderate"resilience index of 55.67%, indicating effective structural measures but gaps in non-structural aspects. In conclusion, while the hybrid infrastructure has proven highly effective in mitigating immediate flood hazards, achieving long-term resilience requires strengthening non-structural measures, such as land-use regulation, public awareness, and wetland restoration. © 2026 Published under licence by IOP Publishing Ltd.
Water Resources Engineering Department, Faculty of Engineering, Universitas Brawijaya, Malang, Indonesia; Maluku River Basin Organization, Directorate General of Water Resources, Ministry of Public Works, Maluku, Indonesia
