Abstract
We have investigated flood runoff processes on hillslopes in a small mountainous basin through variations in the time-varying parameters of the nonlinear relationship between basin storage and dischange. The results indicated that the relationship could be characterized by the predominant flow-states on the hillslopes ; namely, throughflows, or fast flows as represented by gully runoff.
In this paper, a storage-type model of theflood runoff analysis, taking into consideration these characteristics, and its method for identification using nonlinear filtering are described.
A model, in which storage Sc, was used to join the relationship between basin storage and'discharge when throughflows predominate and that when fast flows (represented by gully flow) predominate, was introduced. It was shown that Sc, could be estimated by nonlinear filtering with only rainfall and discharge data. The method of identifying the parameters using Sc, are also shown.
It was concluded, from the simulations, that the three parameters of the model are easily identified by nonlinear filtering, and the model shows a remarkable performance in flood runoff analysis in a small mountainous basin.
