Temporal and spatial behaviour of drought in south Germany

The temporal and spatial variability of drought behaviour in southern Germany has been investigated applying the theory of runs. With this approach drought duration and the deficit volume (severity) were described using Q90, the 90 percentile exceedance discharge as a threshold. The number of drought events within a year revealed a dryness index indicating the years 1962-1964, 1971-1973, 1976 and 1991 as dry years. Pronounced winter drought events (October-March) were found regularly in the Alpine regions resulting in small coefficient of variations (between 90 and 130%) of the annual variability of drought severity. The Pre-Alps and the River Rhine regions show in particular summer droughts with high coefficients of variations (between 170 and 220). The high value for the Rhine region indicates the irregular temporal occurrence. The study revealed the benefits of the method to detect the regional pattern of drought behaviour.