Establishing regional intensity-duration-frequency (IDF) relationships by using the L-moment approach and genetically based techniques for the Euphrates-Tigris basin

Regional intensity-duration-frequency (IDF) relationships for the Euphrates-Tigris basin were established using genetic programming (GP) and multi-gene genetic programming (MGGP). The regional homogeneity of the study area was provided with two sub-regions (SRI and SRII) using the L-moment method. Estimated intensity values for various recurrence periods from selected regional distributions, new IDF relationships were established through GP and MGGP approaches, and the successful results were compared with the results obtained from the distributions. In addition, the parameters of 11 empirical equations commonly used in the literature for rainfall intensities were determined according to particle swarm optimization (PSO), artificial bee colony (ABC), genetic algorithm (GA), and flow direction algorithm (FDA) optimization methods. The rainfall intensity results of both the new IDF equations established with GP and MGGP techniques and the highest-performing empirical equations showed that the closest findings to the data set from regional distributions were obtained with MGGP for SRI and GP for SRII. Graphical Abstract