United Weißeritz Flood Vulnerable Area

The flood-prone area presented in map form is based on Section 75(1)(1) and (2) SächsWG. It is an area that is only flooded when a flood event is exceeded, as is statistically expected once every 100 years. Pursuant to the second sentence of Section 75(2) SächsWG, the extreme event was classified in accordance with the hazard map of the flood protection concept for the Weißeritz (responsibility: Free State of Saxony (Landestalsperrveraltung). It corresponds to the floodplain of the Weißeritz floodplain of 12-13 August 2002. The recurrence interval of this event was determined by the LfULG at the age of 500 years (Sächsisches Landesamt für Umwelt und Geologie; Event analysis Floods 2002 in the Osterz mountain rivers; July 2004), the outflow volume was stated to be about 450 m3/s. It was the largest flood of the Weißeritz ever observed. The outflow amounted to about 1.5 times the largest flood of 30 July 1897. In June 2013, the fourth largest Weisseritz flood occurred since the beginning of the observation. The discharge volume was between 150 and 170 m3/s, the final evaluation by the competent authorities of the Free State is still pending. By 2020, the Vereinigte Weißeritz in Dresden is expected to be expanded in such a way that a flood like in August 2002 can be discharged in the river bed without extensive outflows. The efficiency of the waterbed is currently around HQ100 (flow rate 234 m3/s). Until then, large-scale flooding is still to be expected in the event of extreme events and, as a result, dangers and impairments to the well-being of the general public and public security and order (endangerment of life or significant damage to health and property). In accordance with § 75(5) SächsWG, planning and construction measures adapted to the risk must be taken in the flood-prone area described in order to prevent damage caused by ingress of water as far as possible. In particular, structural measures must be taken to prevent the entry of substances hazardous to water in the event of flooding.