Territorial Decision Support System Based on IDF Curves’ Parameters Regionalization

The Frequency – Duration – Intensity (IDF) curves are essential in designing channel and rainwater drainage systems, and their unavailability is a real issue for the designers of such structures. This paper aims to perform a large-scale regionalization analysis of the IDF curves’ parameters on the Moroccan rainfall network. The parameters for this study were derived from rainfall distribution greater than 24 h and analyzed using the ordinary co-kriging interpolator. The outcome provided spatial distribution maps that estimate IDF curves’ parameters for any location within the study area. The latter are obtained using the Montana law equation i (T) = a (T)*t^(b(T)), with the variables: the return period T, the rainfall duration t, and the precipitation intensity i. The IDF curves’ parameters analysis revealed that average precipitation parameter estimates “a” range from 260 to 821 mm/h for return periods of 2 to 100 years, while the parameter estimates “b” fall between 0.49 and 0.89. The cross-validation approach was performed to ensure reliability and accuracy. The results showed that R² values are very close to 1 (0.9925 for a (T = 2yrs), 0.9998 for a (T = 5yrs), 0.9979 for a (T = 10yrs), 0.9958 for a (T = 20yrs), 0.9934 for a (T = 50yrs), 0.9920 for a (T = 100yrs), 0.9934 for b) which confirm the precision of the outputs.