Application of tank, NAM, ARMA and neural network models to flood forecasting

Two lumped conceptual hydrological models, namely tank and NAM and a neural network model are applied to flood forecasting in two river basins in Thai land, the Wichianburi on the Pasak River and the Tha Wang Pha on the Nan Ri ver using the flood forecasting procedure developed in this study. The tank and NAM models were calibrated and verified and found to give similar resu lts. The results were found to improve significantly by coupling stochastic and deterministic models (tank and NAM) for updating forecast output. The neural network (NN) model was compared with the tank and NAM models. The NN model does not require knowledge of catchment characteristics and internal hydrological processes. The training process or calibration is relatively simple and less time consuming compared with the extensive calibration effo rt required by the tank and NAM models. The NN model gives good forecasts b ased on available rainfall; evaporation and runoff data. The black-box natu re of the NN model and the need for selecting parameters based on trial and error or rule-of-thumb, however, characterizes its inherent weakness. The performance of the three models was evaluated statistically. Copyright (C) 2000 John Wiley & Sons, Ltd.