Hydrological droughts in the Juzna Morava river basin (Serbia)

Spatial and temporal analysis of hydrological droughts, defined by two variables: deficit and duration of drought, is presented in this paper. Time series of deficits and drought durations are derived using threshold level method for 15 hydrological stations in basin of Juzna Morava (Serbia). Since Q90 was used as threshold level for drought definition, these time series are ready for frequency analysis of extreme droughts. The longest average duration of drought is observed on Visocica River at Bracevci, then on Vlasina River at Vlasotince, and shortest droughts on upstream stations of Juzna Morava, Vladicin Han and Grdelica. There is a direct relationship between absolute values of drought deficits and catchment area or mean annual water discharge, while standardize deficits have similar spatial distribution as drought duration. Regional deficit index (RDI) was calculated, which enabled insight in spatial-temporal drought characteristics in defined regions, like seasons when droughts most often occur, and derivation of largest droughts, both in terms of their duration, and covered area.