The occurrence of floods in Brandenburg is determined by the two river basins, the Oder and the Elbe. Both rivers cross Brandenburg territory in the middle of its course in one case and in both middle and lower course in the other. On the Elbe, including its tributaries, 26,000 people are affected on around 26,300 hectares of state land. On the Oder, which forms the border with the Republic of Poland in Brandenburg's territory, and its tributaries, around 34,400 people and 87,000 hectares of state land directly affected. Of particular consequence is the low-lying Oderbruch, where if the flood defences were to fail, 20,000 people would be endangered as a result.
High waters do not always have to automatically mean large amounts of damage due to flooding. In potentially endangered areas of the State of Brandenburg a clearly improved level of protection was able to be achieved in recent years though technical flood prevention measures (dikes, dams, detention reservoirs and other defences), as well as through targeted flood management.
The protection of low-lying areas and areas close to rivers against flooding due to high water is ensured primarily through technical measures, such as dams, detention reservoirs and in particular dikes. Therefore, large amounts of funds have been used and continue to be used in order to bring the dikes on the sections of river potentially subject to flooding up to the current technical standards. The dike building measures and the proper upkeep of flood defences are incumbent upon the State Environment Office (LUGV).
Besides the technical flood defence measure, the retention and recovery of flood plains, as well as adapted land usage in areas in danger of flooding are increasing in importance.
High water events do not respect country borders. The relationships in the upper catchment area of a river a have a significant effect on the high water situation downstream. The high water situation in Oder and Elber sections in Brandenburg is characterised by the source areas in the Polish and Czech uplands, as well as by the measures affecting the flow on the upper and middle courses. In the River Basin Commissions, high water management for flows which cross countries or borders is therefore agreed at the national and international level. Action plans relating to river basins are produced in which all high water defence measures from the building of dikes to retention measure and flood warning to joint flood information services are considered.
|River basin||Established flood areas / hectare||Dikes, dams / km|
|* of which 161 kilometres are main or winter dikes, as well as 154 kilometres of polder, cross, canal and summer dikes|
The Elbe flows through the State of Brandenburg from river kilometre 120.5 to 135.0 (Elbe-Elster district) and from 431.5 to 502.0 and at the same time in these sections it forms the border to the Free State of Saxony and the States of Saxony-Anhalt and Lower Saxony. Of particular importance for flood defence is the section of the Elbe in the district of Prignitz with the confluence of the Havel, Stepnitz, Löcknitz and the Karthane. In this area there are 141.2 kilometres of dikes to protect inhabitants who are potentially in danger. Of this, 76.2 kilometres is directly on the Elbe. Up until the end of 2008, 68 kilometres of dike were improved on this section of the Elbe, so that almost 90 per cent of these dikes had safeguards against flood danger and which corresponded to the regulations.
In the district of Elbe-Elster the section of the Elbe in the area of Mühlberg represents a further area of focus for flood defences. Here, 15 kilometres of dikes protect residential areas and industrial sites.
The improvement works on the Elbe dikes in Brandenburg are due to be completed by 2015. The necessary increase in the height of the Elbe dikes will take approximately a further 10 years.
The improvement works to the dikes mainly take place on the old layout. The Elbe dike between Lenzen and Wustrow (Böser Ort) is being moved back from the river by up to 500 metres as part of a large nature conservation project.
From the confluence with the Elbe, the “wild” Stepenitz is worth paying particular attention to. Over a course of 86.4 kilometres in length it overcomes a height difference of 84 metres. With its high flow gradient this central watercourse in Prignitz displays the characteristics of a mountain stream which quickly swells when it rains. Most recently in June 1993 unusual, regional heavy rain led to flooding, above all in the town of Perleberg, because the flow rate of up to 65 cubic metres per second was not able to be harmlessly led away. In order to avoid damage in the future, the relief of the Perleberg urban area was undertaken with a complex of river engineering measures. In 2006 the pilot project “Scientific and Methodical Research for the Efficient Development of a Flood Defence Plan (HWSP) / Flood Risk Management Plan (HWRP) Including Strategic Environmental Testing for the State of Brandenburg, as well as Data Management and the Trial Example of the Stepenitz” was begun. The draft of the HWRP for Stepenitz is due to be completed in 2011.
In the Havel river basin, the Lower Havel from Berlin until the confluence with the Elbe is most important for flood defences. The numerous tributaries below Rathenow, which are influenced by backwaters, are kept in with dikes around the area of the confluence. In this area there are polder areas which can be flooded to relieve the Elbe (peak capping) in times of extreme high water flows, in agreement with Lower Saxony, Mecklenburg-Vorpommern and Saxony-Anhalt. To ensure the inclusion of the states of Mecklenburg-Vorpommern, Lower Saxony Saxony-Anhalt and Brandenburg and cost sharing, a corresponding state agreement was made in 2008. The Havel is a typical flatland river and high water events are predominantly flood waves which continue for a long time, but are not significant. It is only below Rathenow that the high water situation is also dependent upon the water level of the Elbe.
The flow regime in the Oder is characterised by high water flow when the snow melts in the uplands and by low flow rates in the summer months. Heavy rainfall generally leads to flooding, above all in the upper course of the river. Unusually heavy rainfall which continues for a long time has also led to devastating high water events in the summer season, the last time being in 1997. A particular danger is posed by ice jamming on the Oder when the confluence is frozen over and the start of the thaw in the upper course leads to building up of a wave of high water. Since the summer high water in 1997, great efforts to maintain and improve the dikes along the Oder in Brandenburg according to modern technical standards have been undertaken. The Oder dikes have been expanded with a 1 metre freeboard to meet a water level which occurs once every 200 years. Of the 163 kilometres of dikes on the Oder almost 90 per cent have now been improved with support from the EU. The focus of dike construction is on the area of the Lower Oder Valley.
The Brandenburg section of the Lausitzer Neiße is largely lined with dikes. The improvement work has been completed, apart from residual work in the Guben area. The dikes have been expanded with 50 centimetre freeboard for a one in every 100 years flood. In the backwater areas of the Oder the expansion took place along the lines of the expansion of the Oder dikes, with a 1 metre freeboard for a one in every 200 years flood.
The sections of the Oder and the Lausitzer Neiße in Brandenburg form the border with Poland. The fundamental questions on improvement of the dikes and further flood-related measures in the high water flow profile are therefore mutually agreed within the German-Polish Border Water Commission.
The Schwarze Elster flows through the Federal State of Brandenburg with a length of 86.6 kilometres and is completely lined with dikes for this section. The development of a high water risk management plan is currently being started. Assuming an overwhelming need for the improvement of the existing dikes, the preliminary planning is aimed at guaranteeing the flood protection of housing and infrastructure through the strengthening of existing dikes and the construction of new dike wings and the building of walls. Through the extensive use of natural retention areas, a reduction in the total length of the dike of up to 50 per cent is envisaged.
The high water flows in the Spree are decisively influenced by the retention at the Bautzen and Quitzdorf dams (Saxony), as well as the Spremberg dam (Brandenburg) and the relatively large retention areas. At the Spemberg dam the use of a flood protection area of approx. 19m cubic metres means a flattening of flood peaks can be achieved. Through the improvement of dikes along the Spree in the 90's, primarily in the urban area of Cottbus, and further river engineering measures, the protection offered to inhabitants in the Spree area has been considerably increased. The development of a high water risk management plan for the entire Spree area and the Dahme is currently being prepared.
International Flood Protection Conference 2011 (in german, polish, czech)
Regional Flood Protection Conference 2011 (in german)
Elbe high water 2006 (in german)
Elbe high water 2002 - information from LUGV on the situation in the Havel (in german)
Oder high water 1997 (in german)
Fact files on the rivers mentioned: Elbe, Havel, Oder, Lausitzer Neiße, Schwarze Elster, Spree (in german)
Ministerium für Umwelt, Gesundheit und Verbraucherschutz, Abteilung Wasser- und Bodenschutz, Referat 64, E-Mail: Ref.64@MUGV.Brandenburg.de