Keywords: L-moment, regional frequency analysis, drought severity, semi-arid regions, evapotranspiration, FAO Penman-Monteith, cumulative precipitation deficit, CPD, maximum precipitation deficit, MPD, rainfall, Iran, water vrequirements, agriculture
Application of L-moment for evaluating drought indices of cumulative precipitation deficit (CPD) and maximum precipitation deficit (MPD) based on regional frequency analysis
Two indices of cumulative precipitation deficit and maximum precipitation deficit are used for assessing the severity of drought of a certain year such that a regional frequency analysis has been carried out by L-moment. In this paper, 11 synoptic stations in Isfahan province, Iran with a semi-arid environment have been used. Hosking homogeneity test is applied for identifying a homogeneous region and Hosking goodness of fit test is performed for selecting the best regional distribution. According to the two tests, generalised logistic (GL) for the two of the drought indices is selected as the best regional distribution. Therefore, severity of drought with various return periods is estimated for CPD and MPD using GL. The results show that, Ardestan, Naeen and Shargh Isfahan stations have the most severe drought. Using the outcome of this study, drought severity is quantitatively evaluated and the required water volume for agriculture can be determined in this province for surviving drought.