Regional flood inundation nowcast using hybrid SOM and dynamic neural networks

Abstract

summary This study proposes a hybrid SOM–R-NARX methodology for nowcasting multi-step-ahead regional flood inundation maps during typhoon events. The core idea is to form a meaningful topology of inundation maps and then real-time update the selected inundation map according to a forecasted total inundated volume. The methodology includes three major schemes: (1) configuring the self-organizing map (SOM) to categorize a large number of regional inundation maps into a meaningful topology; (2) building a recurrent configuration of nonlinear autoregressive with exogenous inputs (R-NARX) to forecast the total inundated volume; and (3) adjusting the weights of the selected neuron in the constructed SOM based on the forecasted total inundated volume to obtain a real-time adapted regional inundation map. The proposed models are trained and tested based on a large number of inundation data sets collected in an inundation-prone region (270 km 2 ) in the Yilan County, Taiwan. The results show that (1) the SOM–R-NARX model can suitably forecast multi-step-ahead regional inundation maps; and (2) the SOM–R-NARX model consistently outperforms the comparative model in providing regional inundation maps with smaller forecast errors and higher correlation (RMSE 0.9 in most cases). The proposed modelling approach offers an insightful and promising methodology for real-time forecasting 2-dimensional visible inundation maps during storm events. 2014 Elsevier B.V. All rights reserved.