A simple multifractal model for rainfall IDF analysis in China

The rainfall Intensity-Duration-Frequency (IDF) curves is one of the most commonly tools used in water resources engineering. A simple multifractal rainfall model with multifractal behavior approved by Andreas Langousis is used to estimate the IDF curves in this paper. The model is composed of exterior and interior process with constant duration D and “bare” intensity I_D´. Using high resolution data of rainfall record, Langousis gives the conclusion that the results of the IDF curves tends insensitive to the length of data record. So, in this paper, the 6 years rainfall data at 5-min resolution at Nanxiong station, Guangdong province, China, are applied with the model to estimate the IDF curves. Compared to the traditional parametric models, it reduces the amount of parameters required to be calculated, and 6 years of high resolution rainfall data is capable to estimate the IDF curves. 22 years maxima annual daily rainfall data are fitted by the Pearson-3(P3) distribution to obtain the daily rainfall intensities for different return period T. The results are similar to 24h rainfall intensities of the multifractal model with T ≤ 100 years. The study is of significant practical importance in China for the regions lacking of long sufficient rainfall data.