Aspects of seasonality and flood generating circulation patterns in a mountainous catchment in south-eastern Germany

Abstract

Abstract. Analyses of discharge series, precipitation fields and flood producing atmospheric circulation patterns reveal that two governing flood regimes exist in the Mulde catchment in south-eastern Germany: frequent floods during the winter and less frequent but sometimes extreme floods during the summer. Differences in the statistical parameters of the discharge data can be found within the catchment from west to east. The discharges are compared to a number of landscape parameters that influence the discharge in the subcatchments. Triggering circulation patterns were assigned to all events of the annual maximum discharge series in order to evaluate which circulation patterns are likely to produce large floods. It can be shown that the cyclone Vb-weather regime (TM, TRM) generates the most extreme flood events in the Mulde catchment, whereas westerly winds produce frequently small floods. The Vb-weather pattern is a very slowly moving low pressure field over the Gulf of Genoa, which can bring large amounts of rainfall to the study area. It could also be shown that even with the two flood regimes estimates with the annual maximum series provide a safer flood protection with a larger safety margin than using summer maximum discharge series for extreme summer floods only. In view of climate change it is necessary to integrate knowledge about catchment characteristics, the prevailing flood regime or the trends of weather patterns in the estimation of extreme events.

A consistent set of trans-basin floods in Germany between 1952–2002

“…This finding is in line with other studies that have detected a shift towards increased winter precipitation and the responsible circulation patterns in Central Europe (e.g. Caspary, 1995Caspary, , 2000Jacobeit et al, 2003Jacobeit et al, , 2006Belz et al, 2007;Pauling and Paeth, 2007;Petrow et al, 2007). …”

“…Depending on the catchment size, various studies have used a time lag of one (catchments between 500-5000 km 2 ) to three days (catchments >20 000 km 2 ) to link the flood triggering circulation pattern with discharges (Duckstein et al, 1993;Frei et al, 2000;Bárdossy and Filiz, 2005;Petrow et al, 2007). We choose a pre-POT interval of 3 days.…”

Rain Microstructure Parameters Vary with Large-Scale Weather Conditions in Lausanne, Switzerland

“…The relationship between large-scale weather types and local weather phenomena has been verified previously, e.g., some weather types have a major influence on the generation of extremely hot days [41]. Moreover, GWLs influence stream flows [42], floods [43,44], forest fires [45], and even debris-flow events [46]. More directly, GWLs have a substantial influence on precipitation totals, particularly on their extreme values [47][48][49] and even seasonal extremes [50].…”

Association between anomalies of moisture flux and extreme runoff events in the south-eastern Alps

“…In comparison, major central-European floods are characterised by non-convective, Correspondence to: M. Müller (muller@ufa.cas.cz) regional rains that occur in the cold, rearward sector of a cyclone. Cyclones are frequently of Mediterranean origin and affect central Europe as they move to the north-east along the so-called "Vb track" (Seibert et al, 2007;Petrow et al, 2007). This generalized cyclone track runs along the Alps into eastern Europe.…”