LAUSR

The determination of the drought characteristics of a basin that feeds a reservoir and provides water for agricultural irrigation or energy production is important for the sustainable management of reservoirs. In the present study, the meteorological and hydrological droughts of the upper basins feeding the Demirköprü Reservoir in the Gediz River Basin of Turkey are examined over one, three, six and 12 month timescales. The methods used include the standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) for defining meteorological droughts, and the standardized runoff index (SRI) method for defining hydrological droughts. The results show that the wet periods are dominant in the water years before 1984, and the dry periods occurred more frequently and were longer after this year in the basin. Owing to a temperature increase, it is determined that the effect of potential evapotranspiration losses on drought events has increased in the years after 2000, and the droughts that occurred after this year have happened more intensively in the basin. The results also show that both the meteorological and hydrological drought trends of the basin are prone to dry conditions and no that change is expected in these trends in the near future. Considering the predicted global climate changes, the results provide a source for describing the characteristics of the meteorological and hydrological droughts observed in the basins for the sustainable management of reservoirs which have a large irrigation area or energy production.