Analyzing Drought Based on Annual Total Rainfalls over Tokat Province

Abstract

Numerous indices derived from hydroclimatic data were designed to quantify agricultural, hydrological and meteorological droughts. In this study, we taken into account Standardized Precipitation Index (SPI) and the Rainfall Anomaly Index (RAI) for the identifi cation and the assessment of drought events based on total annual rainfalls over Tokat province. The SPI values belonging to each rainfall station showed that the region experienced extreme wet and severe drought for observation years. Tokat province selected as the study area was grouped two hydrological homogeneous region using L-moment approach to analyze regional drought.Generalized Extreme Values (GEV), 3-parameter Log Normal (LN3) and Pearson Type III (PE3) for fi rst region and Generalized Logistic (GLO) for second region were selected as the regional distributions. The RAI was used whether there is existence of linear trend in the observed data in term of drought. But, the RAI values concerning with two region showed that there was no trend.