ABSTRACT
Hydrological drought is usually an expression of deficiencies in the supply of surface and subsurface water supplies (Hisdal & Tallaksen 2000). This phenomenon is the last stage in the drought process, which includes three successive phases: atmospheric, soil moisture and hydrological drought. Summer droughts are caused by low precipitation and often accompanied by high evapotranspiration losses. By contrast, winter droughts occurring when temperature is below the freezing point and water in the catchment is stored as snow and ice (Fleig et al. 2005).
