Linear Moments Application in Drought Prediction (Case Study: Central Catchment of Iran)

Knowledge of drought phenomenon occurrence is useful in water resources management. Drought study is done based on some measured parameters. On the other hand، regional analysis is recommended where there is uncertain data (or data lacking) at some stations. In this research، the mentioned theory and the linear moment method were used for the Central basin of Iran. The precipitation data of 47 stations of the region were used. In order to determine homogeneous areas، we used some effective parameters of stations such as elevation، average annual precipitation، maximum 24 hours precipitation، seasonal drought index and standardized precipitation index. The study area was divided into homogeneous regions by using R software according to the mentioned parameters. Then، discordant stations were detected using the discordancy measure. The homogeneity of stations was tested using the H statistic. The best probability distribution was determined in each homogeneous area، and by using the selected distribution، drought severity maps representing 40%، 60% and 80% of mean annual precipitation were drawn. The results show that northern and western parts of the central catchment of Iran are more likely tobe at risk of moderate and severe droughts.