Flood early warning systems are crucial for reducing flood risks by predicting river conditions and the time available for mitigation. Floods in Bima City, Indonesia are caused by heavy rainfall and topography. This study used hydrology and hydraulic analysis to determine the maximum river capacity and available mitigation time. The results show that the Padolo River can handle up to 66 m3/s of floods with a maximum rainfall depth of 24 mm, giving residents around 2 hours of warning before flooding occurs.