Building ANN-based regional multi-step-ahead flood inundation forecast models

Abstract

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 theWestMalaysia Peninsular, has suffered from monsoon floods that have caused serious damage. The downstreamregion with an area of approximately 100 km2 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 systemin the study area. The systemcombines two popular artificial neural networks-the self-organizing map (SOM) and the recurrent nonlinear autoregressivewith exogenous inputs (RNARX)-to sequentially produce regional flood inundationmaps during stormevents. The results show that: (1) the 4 × 4 SOMnetwork 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 proposedANN-basedmodelwas shown to very quickly carry outmulti-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.