<![CDATA[Ambon City a high level of vulnerability to floods due to steep topography, extreme rainfall, and land use that exceeds land capability. Floods pose a serious threat to community safety and cause damage to infrastructure. Risk reduction requires an accurate and well-implemented early warning system. This study aims to analyze the spatial level of flood disaster risk, examine the distribution of extreme rainfall during rainfall events, and assess the accuracy of the Impact-Based Forecast and Warning Services System (IBFWS). The research method includes spatial analysis using a Geographic Information System (GIS) through an overlay approach of three risk components: hazard, vulnerability, and capacity. The study also applies Inverse Distance Weighting (IDW) methods for spatial interpolation of 24-hour rainfall data from the events on May 11 and May 30, 2023, and conducts spatial validation of the IBFWS prediction results against actual landslide occurrences. The results show that 75.6% of Ambon City falls into the high-risk category for floods. Multiple linear regression analysis indicates that slope gradient is the most significant variable influencing floods hazard, with an R² value of 90.6% and an S value of 0.120. Spatial validation and field verification demonstrate that the accuracy of the IBFWS reached 94% for the floods event on May 11 and 100% for the event on May 30, 2023. These findings indicate that the IBFWS functions as a reliable early warning system to support floods disaster risk reduction in Ambon City.]]>
