Flood is a natural hazard that resulted from combination of hydrological and meteorological factors. It occurs when a normally dry land areas are temporary inundated due to overflowing of water at the natural or artificial confines of a river, including groundwater caused by prolonged or heavy rainfall. Hydrologists define flood as a sudden increase in water discharge that caused a sudden peak in the water level. Once flood is over, the water level will drop back to near-constant base flow or no flow. As summarized by Martini and Loat (2007), flooding is when water and/or sediments exist at unwanted areas other than the water body. Whereas, Ward (1978), defined flood as a body of water which is not normally submerged. A flood model of a particular river basin for example simulates the real flood events that have occurred using the actual hydrological input data, the basin's hydraulic characteristics and boundary conditions.