Hazard Warning Map Saxony (Atlas of Flood Hazard in Saxony)

The hazard warning map shows flood areas and intensities (water depth or specific runoff) in extreme floods for the Elbe river and the I. Ordnung waters in Saxony on an overview scale (1:100,000) with a data level of 2004. Extreme flooding (EHQ) is an event that is significantly larger than HQ(100), at least the highest observed event, but generally HQ(300). Flood areas were calculated without taking into account the effect of existing flood protection systems, such as dams, dikes or polders. The illustrated intensities and extensions represent an enveloping of all possible flood scenarios, i.e. not all illustrated areas are affected by a single event. This also applies in the event of a failure of protective devices. In addition, the limits of the flooded areas at HQ(20) and HQ(100) are shown, also without taking into account the effect of flood protection devices. Due to the different flooding and thus damage processes, a distinction was made between shallow valley areas (slide-free, mostly non-run-changing flooding) and steep areas (dynamic flooding with boulder transport, erosion and expected run-change). Since the flood depth at the steep water sections can only indirectly give a statement about the intensity and thus about the hazard, the flow velocity on the forelands was additionally determined. The product of flood depth and flow velocity is represented as a specific runoff (runoff per metre water width) for EHQ.