Regional rainfall intensity formulas based on scaling property of rainfall

This work developed regional Intensity-Duration-Frequency (IDF) formulas for non-recording sites based on the scaling theory. Forty-six recording raingauges over northern Taiwan provide the data set for analysis. The temporal scaling properties of annual maximum rainfall series for various durations were first investigated. The hypothesis of piecewise simple scaling combined with Gumbel distribution was used to develop the IDF scaling formulas. Since most of parameters in IDF scaling formulas can be estimated from the annual 1-day maximum series, these parameters were regionalized based on the relationship between the scaling exponent and the average of annual 1-day maximum rainfall. Three scaling homogeneous regions were classified by different scaling regimes and regional IDF scaling formulas were developed in each region. The analyzed results reveal that the regional IDF scaling formulas proposed herein resulted in reasonable simulations and verifications.