Abstract
The Elbe River basin covers different geographical regions from middle mountain ranges in the west and south to large flatlands and lowlands in the central, north and eastern part of the basin. From its 1394 m high origin in the Czech Bohemian mountains to its mouth in the German City of Cuxhaven at the North Sea, the Elbe River has a length of 1165 km (700 km in Germany) and a drainage basin of 148,268 km² (two-third in Germany) (BfG, 2002, p1). The Elbe region is the driest of the five largest German river basins, resulting in frequent water stress and water deficiencies. The summer of 2003 brought a severe drought and water deficit only one year after the great floods.
Starting on 6 August, 2002, a complex weather situation over central Europe led to heavy and widespread precipitation in Hungary, Austria, southern-western parts of Czech Republic, as well as eastern and southern Germany. Coming from England, the low pressure system Ilse passed along the southern part of the Alps and then headed for Saxony in a so-called Vb track. In a ten-day period from August 1 to 10, precipitation of about 60 mm fell widely in the Elbe River drainage basin area, followed by strong rainfall on August 11 through 13 (BfG, 2002, p9). During this period, many areas in eastern Germany had rainfalls of 100-200mm/day, some even more than 300 mm/day: a precipitation in three days that was two to four times as much as the usual monthly average (LfUG, 2004).
The unusual intensity of rain exceeded the soil’s capacity to retain water and generated two types of floods in the Elbe river basin: flash floods at the tributaries of mountainous catchments (e.g., Weißeritz River, Upper Mulde River) with high discharge dynamic and flow velocity, and slow swell floods of the Elbe River and the lower reach of its main tributaries (e.g., Vltava River, Joint Mulde River). In the Saxon capital of Dresden, the Elbe River rose from a normal summer level of about 2 m, surpassing the historical flood mark of 8.77 m seen in March 1845, to reach a water level of 9.40 m – the highest level ever been recorded.
