DEVELOPMENT OF REGIONAL RAINFALL INTENSITY-DURATION-FREQUENCY CURVES BASED ON SCALING PROPERTIES

This study developed a regional Intensity?Duration?Frequency (IDF) relationship for ungauged locations based on the scaling theory. The scaling properties of extreme rainfall are examined to establish scaling relationship behaviors of statistical moments over different durations. The results show that a rainfall property in time does follow a simple scaling process. A scale invariance concept is explored for disaggregation (or downscaling) of rainfall intensity from low to high resolution and is applied to the derivation of scaling IDF curves. These curves are developed for ungauged sites based on scaling of the Extreme Value type 1 (EV1) or Gumbel probability distributions. The spatial distribution maps of three parameters: the scaling exponent and two statistical parameters are constructed. By using these maps, the IDF relationships are deduced from only daily rainfall with the scaling approach, which shows good agreements in comparison with the IDF curves obtained from traditional techniques.