Abstract:Many novel techniques for reconstructing rainfall-runoff processes require hydrometeorologic and geomorphologic information for modelling. However, certain information is not always measurable. In this paper, we employ a special recurrent neural network to reconstruct the rainfall-runoff process by using collected rainfall data. In addition, we propose an indirect system identification to overcome the drawback of a traditional, time-consuming trial-and-error search. The indirect system identification is an efficient method to recognize the structure of a recurrent neural network. The unit hydrograph can be derived directly from the weights of the network due to a state-space form embedded in the recurrent neural network. This improves the link between the weights of the network and the physical concepts that most neural networks fail to connect.The case studies of 41 events from 1966 to 1997 have been implemented in Taiwan's Wu-Tu watershed, where the runoff path-lines are short and steep. Two recurrent neural networks and one state-space model are utilized to simulate the rainfall-runoff processes for comparison. The results are validated by four criteria: coefficient of efficiency; peak discharge error; time to peak arrival error; total discharge volume error. The resulting data from the recurrent neural network reveal that the neural network proposed herein is appropriate for hydrological systems.