DEVELOPMENT OF A DAILY RAINFALL GENERATION MODEL

Abstract

The daily rainfall data of 5 stations of Upper Lusi basin, Indonesia have been analysed in this study. The statistical characteristics of wet spells, dry spells and rainfall amounts on wet days have been analysed for individual stations and mean areal rainfall over the basin. The performance of transition probability matrix method for single station rainfall generation has been evaluated. On the basis of this study the following conclusions can be drawn. 1. Wet spells follow exponential distribution•. 2. Dry spells follow geometric distribution (special case of negative binomial distribution). 3. Rainfall amounts follow Pearson type III or log Pearson type III distributions. However for fitting these distribution, the time period should not be more than 3 months, 4. The performance of transition probability matrix is satisfactory for single station rainfall generation. Further efforts should be made to develop daily rainfall generation model based on alternating renewal process. It is a preliminary study in the area of synthetic generation of rainfall. Meteorological and climatological aspects have not been incorperated and studied in detail. Consideration of meteorological aspects should be made in further studies.