Modeling for Design Storm Rainfall with Two Peaks

Abstract

This paper proposes a model for design storm rainfall with several peaks. It was applied to the observed rainfall patterns of which the characteristics were analyzed by using data observed in Kyoto and Hikone. The results obtained are summarized as follows:
1) More than half of the heavy rainfall events observed consisted of storms with a single peak, and those with less than 2 peaks accounted for 90% of the whole event.
2) A new model for design storms with 2 peaks was shown by utilizing Sherman's intensity curve for a single peak storm. This model has 4 parameters.
3) These unknown parameters were determined by solving non-linear simultaneous equations by the Newton-Raphson, Regula Falsi and Continuation methods, for example. In addition, a simplified 3-parameter model instead of a 4-parameter one turned out to be useful when an optimal combination of 4 parameters was difficult to identify.
4) The model was applied to all the rainfall patterns of 2 peaks observed in Kyoto and proved to be useful and practical.