Application of Rainfall Frequency Analysis on Studying Rainfall Distribution Characteristics of Chia-Nan Plain Area in Southern Taiwan

This study aims at studying the rainfall distribution characteristics of Chia-Nan plain area, by using different statistical analyses such as normal distribution, log-normal distribution, extreme value type I distribution, Pearson type Ⅲdistribution, and log-Pearson type Ⅲ distribution. 178 stations having annual rainfall data over ten years were selected to perform frequency analysis. Results showed that the log-Pearson type Ⅲ distribution performed the best in probability distribution, occupying 50% of the total station number. This study also applied principal component analysis to derive two principal components of the rainfall spatial distribution. Results indicated that the eigenvalues of the two principal components were capable of explaining 73% of the total variance of annual rainfall, with first principal component occupied 55.7% and the second principal component occupied 17.5%. These two components can be used to replace most of the original variables in satisfying the requirement of component independence and data reduction.