Simulation of flood flow in a river system using artificial neural networks

Artificial neural networks (ANNs) provide a quick and flexible means of developing flood flow simulation models. All important criterion for the wider applicability of the ANNs is the ability to gencralise the events outside the range of training data sets. With respect to flood flow simulation, the ability to extrapolate beyond the range of calibrated data sets is of crucial importance. This study explores methods for improving generalisation of the ANNs using three different flood events data sets from the Neckar River in Germany. An ANN-based model is formulated to simulate flows at certain locations in the river reach, based on the flows at upstream locations. Network training data sets consist of time series of flows from observation stations. Simulated flows from a one-dimensional hydrodynamic numerical model are integrated for network training and validation, at a river section where no measurements arc available. Network structures with different activation functions are considered for improving gencralisation. The training algorithm involved backpropagation with the Levenberg-Marquardt approximation. The ability of the trained networks to extrapolate is assessed using flow data beyond the range of the training data sets. The results of this study indicate that the ANN in a Suitable configuration can extend forecasting capability to a certain extent beyond the range of calibrated data sets.