Linking streamflow drought to the occurrence of atmospheric circulation patterns

The growing use of surface water resources calls for more intense research on low flow causes and characteristics. This paper presents an investigatio n linking regional streamflow drought to the occurrence of atmospheric circ ulation patterns (CPs). Streamflow drought events of 74 basins in southern Germany were determined using the threshold level approach. The regional cl assification of the basins through a cluster analysis of the drought series provided the basis for the definition of a regional drought index and the following investigation of the influence of CP occurrence on drought. Frequ ency cross-tabulation showed several high-pressure and anticyclonic CP type s to be strongly associated with streamflow drought in southern Germany. Th e influence of these CPs on streamflow drought was quantified using a logis tic regression model, The model results revealed important regional differe nces concerning the time lag of the drought response and the relevant CPs.