DROUGHT ANALYSIS WITH STANDARDIZED SOIL MOISTURE INDEX USING HYDRO-METEOROLOGICAL DATA

Abstract: The drought, which directly affects the agriculture of a region and the living standards of the indigenous people, is an important climate event. In this study, it was aimed to interpret the drought periods in the headwater of the Çarşamba Subbasin of Konya Closed Basin by using the Hydrologiska Byråns Vattenbalansavdelning (HBV) model, which is a conceptual rainfall-runoff model. For this purpose, the standardized soil moisture index (SSI), which is a simple drought index, was used depending on daily soil moisture. Firstly, the HBV model to solve optimization problems was calibrated using the Generalized Reduced Gradient (GRG) code. The success of the HBV model for a region with data scarcity is sufficiently accurate with the percentage bias (Pbias) = 11.454% and the coefficient of determination (R2) = 0.518. In this study, based on daily soil moisture data, years were divided into drought periods to better understand and interpret region drought. As a result, almost the same number of dry days was obtained in all years.