IMPROVEMENT OF SYNTHESIS PROBABILITY METHOD BY CONSIDERING PROBABILITY DISTRIBUTIONS OF RAINFALL DEPENDING ON DURATION OF RAINFALL

Abstract

 The synthesis probability method, which estimates T-year annual maximum flood peak discharge considering spatio-temporal distribution of rainfall, has the assumption of independency between total precipitation and its spatio-temporal distribution. This research improved the method to consider a relation between the two by using conditional probability distributions of total precipitation given rainfall duration. The improved method was applied to the Yura-gawa river basin and performed more reasonable estimation of T-year annual maximum flood peak discharge than the original method.