Regional flood frequency estimation using log Pearson type III distribution parameters for coastal N.S.W. streams

Multiple regression on catchment characteristics is used to obtain regional equations of the Log Pearson Type III descriptive parLiineters, mean, standard deviation and skew coefficient for the annual flood series. The estimates of the descriptive parameters are incorporated into a regional design flood estimation model which utilizes the Log Pearson Type III frequency factors listed in Table 9.3 of Australian Hainfall and Runoff. The resulting equation provides estimates of peak discharge of specified occurrence frequency. Eighty-four variables including arithmetic and logarithmic transformations were investigated. From this list seven (three geomorphic, three climatic and one regional) are recommended for use in future research in the region utilizing multiple regression techniques. Tv/o sets of regional equations are recommended for mean and standard deviation. No significant relationship was obtained to estimate a skew coefficient.