General National Id Germany_01 Site name Stretch of the Elbe river near Lenzen Summary In the framework of the large-scale nature conservation project "Lenzener Elbtalaue", a dyke along the river Elbe (in Germany) has been relocated. This created a new retention area with a diverse floodplain, including alluvial forests, half-open pasture landscapes and other typical habitats of lowland floodplains. With 420 ha it is the biggest application of this type of measure in Germany so far. The project successfully combines flood protection and nature conservation objectives. Since the cutting of the old dyke in 2009, the measure could proof its effectiveness during several high water events. Light or indepth? In-depth The in-depth description of the case study cs-de-01-elbe-final_version.pdf Location description The measures are applied on a stretch of the Elbe river in Germany, next to Lenzen, between the Elbe kilometers 473.5 and 489.5. NUTS Code Brandenburg RBD code DE5000 Transboundary 0 Data provider Verena Mattheiss, ACTeon Source(s) Auenschutz - Hochwasserschutz - Wasserkraftnutzung. Beispiele für eine ökologisch vorbildliche Praxis Die Deichrückverlegung bei Lenzen an der Elbe Naturschutzgroßprojekt Lenzener Elbtalaue Hochwasser: Rückverlegung des Deichs bewährt sich Die Deichrückverlegung bei Lenzen an der Elbe Landwirtschaftliche und touristische Nutzungsänderungen im Naturschutzgroßprojekt "Lenzener Elbtalaue" (2005 - 2009) Sozio-ökonomische Evaluierung (I) Sozio-ökonomische Betroffenheit der Landwirtschaft durch Deichrückverlegung im Bereich der brandenburgischen Mittelelbe unter Berücksichtigung betrieblicher Anpassungsmöglichkeiten Floodplains in Germany "Synergies with nature conservation, WFD and flood protection" NWRM(s) implemented in the case study Floodplain restoration and management Forest riparian buffers Meadows and pastures Channels and rills Longitude 11.478521 Latitude 53.097326 Site information Climate zone cool temperate dry Mean annual rainfall 300 - 600 mm Mean rainfall unit mm/year Average temperature 9 Mean runoff 704 Mean runoff unit 600 - 750 mm Type Case Study Info Average slope range 0-1% Vegetation class Prior to the project implementation, the area was subject to agricultural use. After implementation it was converted to alluvial forests and half-open pasture landscapes. Monitoring maintenance Monitoring impacts effects 1 Monitoring location Catchment outlet Administrative annual cost information no information Monitoring parameters The following aspects are monitored (Damm et al. 2011): - Hydrology: 12 groundwater gauges are supervised by the association carrying the project - Hydraulics: Construction of 4 dyke gauges through the large-scale nature conservation project, steady reading of the meter by the state office, analysis through the Federal Waterways Engineering and Research Institute - Soils: Two permanent observation plots of the Land Brandenburg, complemented by an evaluation at the end of the project - Forestry: Examination of the planted alluvial forests in 2009 (evaluation) - Fishes: Examination of the flood channels in 2009 and 2010, in time intervals further observations in cooperation with research institutes - Birds: Examination in the framework of the evaluation of the project continuously 2007-2010, continued by the state of Brandenburg - Vegetation: surveys through cooperation between the project management association, the state of Brandenburg and different research institutes Performance Performance impact estimation method Catchment outlet Performance impact estimation information Substantial modeling exercises and numerical calculations had been undertaken to predict the effect on flood peaks. A two-dimensional, hydro-dynamic numerical model has been used (it compares the previous situation without dyke relocation with the one with dyke relocation). The impact of the measures with regards to flood protection could be directly observed during the extreme flood event in January 2011. Design & implementations Application scale River Basin Installation date 2011 Age 3 Performance timescale Immediate Area (ha) 1031 Area subject to Land use change or Management/Practice change (ha) 420 Size 420 Size unit ha Design capacity description The newly created retention area of 420 ha between the old dyke and the new one can comprise up to 16 million m3. In times of extreme flood events the measure allows lowering the water level of up to 40 cm in the area. Max water retention capacity 16 Max water retention capacity unit mio m3/month Basis of design Through the NWRM, 36% of a 20-25 years flood flow (3250 m3/sec) would take place in the newly created floodplain. Constraints no information on physical / biophysical constraints Favourable preconditions Preconditions which led to the implementation of the measure were not natural, but mainly due to the fact that the old dyke had been constructed very close to the river bed. Management change from Agricultural land use. Management change to Landscape conservation measures. Inflow volume 2300 Inflow volume unit m3/sec Outflow volume 1667,5 Outflow volume unit m3/sec Peak flow rate 3250 Public consultation 1 Design contractual arrangement Arrangement type Responsibility Role Comments Name Design consultation activity Activity stage Key issues Name Comments Implementation phase Guided tours Guided tours take place in the project area. Implementation phase Visitor centre A visitor centre informs about the project. Design land use change Land use change type Design authority Authority type Role Responsibility Name Comments NGO Implementation Trägerverbund Burg Lenzen e.V. Other Initiation of the measure Biosphere Reserve "River Landscape Elbe-Brandenburg" Management of the biosphere reserve. Other Implementation Brandenburg State Office of Environment, Health and Consumer Protection Regional authority with different responsibilities (nature conservation, water management, etc.). Responsible for the construction of the new dyke. Farmers Initiation of the measure Large-scale farmer Manager of a large-scale farm (about 3600 ha) situated in the area. Interested by promoting regional development activities. Monitoring Federal Waterways Engineering and Research Institute (BAW) Research institute accompanying the project. Lessons, risks, implications... Key lessons The project shows a successful combination of nature conservation, flood protection and other objectives (agricultural, regional development, and others). It is said that public communication activities should have been made in a more intensive way, in particular at the beginning of the project. From an ecological perspective, an earlier / deeper connection to the Elbe would have been better to improve the lateral connectivity and morphological dynamic of the river. The latter would have also helped to minimize sedimentation processes in the new floodplain area, which can be expected in the middle and long term. The highest effect of the measure can be stated next to the first opening of the dyke (on the "evil place") and it decreases towards the downstream part of the dyke relocation. Further downstream from the dyke relocation, the measure does not have any effect anymore on the water level. Upstream, the positive effect diminishes with an increasing distance. This shows that the measure has a very clear, but mainly regionally working impact. In order to solve the important flood problems of the Elbe river, it is indispensible to carry out other dyke relocation measures. The measures are suitable to be applied also elsewhere. However, areas free of settlement are needed. The continuous persuasion works from a few - and over several years - is highlighted as one key factor for the successful implementation of the project. The prior implementation of research projects ensured the effectiveness of the measure design, but was also very useful for providing support for public discussion. Financing difficulties 1 Financing difficulties information The large costs of the project led to important financing problems. Thanks to the multifunctionality of the measures applied (nature conservation, flood protection), financing from different sources was possible. However, none of them was sufficient on itself. financing funding solutions Different financing sources had been combined to collect sufficient funds. Furthermore, to benefit from all financing sources, a private body was needed as applicant, and an association has been created with different stakeholders for this purpose. Transferability The preconditions in terms of stakeholder engagement were quite particular - going back to changes in the framework of the political turnover in Germany. However, from a technical point of view, dyke relocations can be implemented in any other area were sufficient settlement free areas exist. Success factor(s) Success factor type Success factor role Comments Attitude of relevant stakeholders Financing possibilities Successful coordination between authorities Communication activities Conducted assessments (incl. economic) Legal obligations Existing institutional framework Financing Financing type Comments National funds Sub-national funds Funds from the State of Brandenburg. Other The association managing the project brought in money in alliance with different nature conservation NGOs. Barrier Barrier type Barrier role Comments Other secondary barrier No major barriers to implementation are reported, apart from the need for substantial funding, but which could be resolved. Driver Driver type Driver role Comments Organisation committed to it main driver It was only due to the continued commitment of local stakeholders that the project could be implemented. Past flooding events main driver Reducing the local flood risk was a main driver for the implementation of the measures. Legal obligations main driver There had been legal obligations to adjust the old dyke to current requirements - which temporarily coincided with the development of the project idea. Financing share Financing share type Share Comments National funds 93 75% From the German government and 18% from the state of Brandenburg. View Private funds 7 From the project management association. View Policy, general governance and design targets Policy description The project was implemented mainly to reduce the flood risk, but also to restore alluvial forests in the area. Policy target Target purpose Peak-flow reduction Runoff control Improved Biodiversity Pollutants Removal Policy pressure Pressure directive Relevant pressure Policy area Policy area type Policy area focus Name Comments Policy impact Impact directive Relevant impact Policy wider plan Wider plan type Wider plan focus Name Comments Policy requirement directive Requirement directive Specification Socio-economic Direct benefits information Increased flood protection and biodiversity benefits. Ancillary benefits information Benefits for the regional development: The project area got quickly established as a regional attraction on the international Elbe bike trail. In connection with a centre for environmental education and a visitor centre for the area a sustainable increase of the number of visitors occurred. Furthermore, during the construction period, there had been some socio-economic effects in terms of employment and local consumption. Costs investment 13000000 Costs investment information 11.5 million euros for the construction of the new dyke (include 0.71 million euros for planning). 1.5 million euros for opening the old dyke (include 240 000 euros for planning). Costs operation maintenance n/a Costs maintenance information Maintenance costs exist for maintaining the dyke. Costs total 13000000 Costs total information 11.5 million euros for the construction of the new dyke (include 0.71 million euros for planning). 1.5 million euros for opening the old dyke (include 240 000 euros for planning). Compensations annual information no information Compensations basis information no information Compensations nr beneficiaries information Land in the newly created floodplain only belonged to two farmers. Compensations scheme information Compensation payments have been made for the abandonment of agricultural areas, for the herewith induced operating adaptations of the farming activity, the dissolution of current land tenures and the land use difficulties of furthermore cultivated areas. Information on Economic costs - income loss Agricultural activities have been abandoned, but which were (after the German reunification) anyway not very adapted to the new market situation. Ecosystem improved biodiversity 1 Information on Ecosystem improved biodiversity Alluvial forests have been initiated by planting respective tree species. Furthermore, an half-open pasture landscape is maintained. An impact has been stated amongst others with regards to the development of a diverse avifauna. Ecosystem provisioning services 1 Information on Ecosystem provisioning services Agricultural activities have been abandoned. No information on other potential provisioning services. Information on Economic costs other annual Hunting rights have been limited in the area. Ecosystem impact climate regulation No information available Biophysical impacts Retained water 16 Retained water unit mio m3/month Information on retained water 16 million m3 of water can be retained by the new floodplain area in case of flood events. Increased water storage 38095 Increased water storage unit m3/ha Information on increased water storage In terms of flood events, up to 16 million m3 can be retained in the 420 ha of the newly created floodplain area. Peak flow rate reduction 36 Peak flow rate reduction unit % Information on Peak flow rate reduction In times of extreme flood events (ocurring every 20-25 years), 36% of the flood flow is taking place in the floodplain. Information on Increased groundwater level Problems with upward seed are mentioned in the area next to the relocated dyke. Information on Ecosystem flood control volume The created floodplain is limited by a (relocated) dyke - no separation of the effects is possible. Information on Ecosystem flood control return periods Effects with regards to the following flood events have been calculated: a) Flood events recurring every 1-2 years = 1500 m3/s b) Flood events recurring every 3-5 years = 2300 m3/s c) Flood events recurring every 20-25 years = 3250 m3/s Water quality overall improvements N/A info Information on Water quality overall improvements An effect on water quality is assumed through the retention of nitrogen and phophorous in the floodplain. Information on Water quality Improvements (P) Retention of P is assumed, no measurements took place. Information on Water quality Improvements (N) Retention of N is assumed, no measurements took place. Soil quality overall soil improvements Not relevant for this application Information on Soil quality overall soil improvements With regards to the impact of the measure, it is not about the quality of the soil, but its change back to its alluvial character. Reducing flood risks quantity change Depending on the importance of the flood event, the effect of the measure has been calculated as being the following (compared to the previous status, prior to the dyke relocation): a) Flood events recurring every 1-2 years = 1500 m3/s b) Flood events recurring every 3-5 years = 2300 m3/s c) Flood events recurring every 20-25 years = 3250 m3/s Share of the flow taking place in the newly created floodplain: a) 8.6 %, b) 27.5 %, c) 36 % Difference of the water level: a) 9.2 cm, b) 28 cm, c) 38.9 cm Full Context Pathway(aka Context) Default view Area(aka Level or Site) ALL