Building ANN-Based Regional Multi-Step-Ahead Flood Inundation Forecast Models

A regional inundation early warning system is crucial to alleviating flood risks and reducing loss of life and property. This study aims to provide real-time multi-step-ahead forecasting of flood inundation maps during storm events for flood early warnings in inundation-prone regions. For decades, the Kemaman River Basin, located on the east coast of the West Malaysia Peninsular, has suffered from monsoon floods that have caused serious damage. The downstream region with an area of approximately 100 km(2) located on the east side of this basin is selected as the study area. We explore and implement a hybrid ANN-based regional flood inundation forecast system in the study area. The system combines two popular artificial neural networksthe self-organizing map (SOM) and the recurrent nonlinear autoregressive with exogenous inputs (RNARX)to sequentially produce regional flood inundation maps during storm events. The results show that: (1) the 4 x 4 SOM network can effectively cluster regional inundation depths; (2) RNARX networks can accurately forecast the long-term (3-12 h) regional average inundation depths; and (3) the hybrid models can produce adequate real-time regional flood inundation maps. The proposed ANN-based model was shown to very quickly carry out multi-step-ahead forecasting of area-wide inundation depths with sufficient lead time (up to 12 h) and can visualize the forecasted results on Google Earth using user devices to help decision makers and residents take precautionary measures against flooding.