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Integrative River Basin Management- Synergies and target areas in the Ilmenau catchment area

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SAWA Ilmenau

Objectives of the SAWA-Ilmenau project

The sub-project SAWA-Ilmenau was run by the working group on Sustainable Land Development at the Leuphana University of Lüneburg under the leadership of Prof. Dr.Mariele Evers, supported by Julia Mußbach and Philipp Arndt (both MSc Environmental Science), Aklilu Teklesadik (Hydroinformatics) and Monika Tischbierek (MSc Engineering).
The project work concentrated on the field of integrative river basin management (IRBM; German: IFGM); the River Ilmenau was chosen for the case study.
The principal goals of the project were

  1. to identify the flood risk characteristics of the Ilmenau and its catchment
     2. To bring together and analyse various usage rights and developments, technical planning measures and institutions (e.g. management plans for the WFD, the Habitats Directive (FFH), land use plans) in order to identify and visualise synergies and potential conflicts
     3. Analysis of target areas for river catchment management measures using cascade GIS methods.
    Details of the various use requirements, planning projects (e.g. WFD, FFH, spatial or construction planning aspects) in the catchment were compiled and visualised so as to be able to show where synergies are possible.

Together with the regional stakeholders a concept for management measures was developed which prioritises measures in the project area and enables tools and resources to be purposefully employed. To this end, a landscape analysis method and a catalogue of adaptive methods was developed which took into account information on the various relevant planning areas as well as potential implementation tools. The focus of the analysis was to interlink and draw together the different data from widespread sources so as to highlight the synergies and show how the issues can be meaningfully consolidated.
In this way, we are able to support and optimise the manifold coordination, agreement and implementation processes required in integrated river basin management.

Steps taken

The SAWA-Ilmenau project comprised the following stages:

• GIS-based spatial analysis to identify areas in the catchment relevant to flood protection measures (e.g. flood source areas, potential risk areas)
• GIS-based spatial analysis to identify target areas for the implementation of measures to reduce flood risk and improve water quality
• Development of a catalogue of measures for planning areas relevant to preventive flood risk management
• Participation process involving regional partners and the stakeholders (discussions with experts, workshops)
ProjektansatzSAWA.JPG

Cooperation partners - the stakeholders

Rivers know no borders – neither do floods. It is thus particularly important that all the planning parties involved should act in concert and cooperate to the best possible degree. Ongoing and regular communication and close cooperation are important prerequisites in river basin management.
For this reason all the relevant water management, nature protection, spatial planning, forestry and agriculture authorities in the Ilmenau basin were included in the project work:
IMG1669.JPG
Federal State Government Regional Office Lüneburg
Town of Lüneburg
District of Lüneburg
District of Uelzen
District of Harburg
Chamber of Agriculture, Lower Saxony, District Office Uelzen
Forestry Office Lüneburg
Lower Saxony Water Management, Coastal Defence and Nature Conservation Agency (NLWKN), District Office Lüneburg
Water and Rural Conservation Association (GLV) for the middle and upper Ilmenau

Basic principles of flood risk management

The project area

The Ilmenau catchment

The Ilmenau catchment in northern Germany (Lower Saxony) is 2984km2 in area and lies within the Elbe catchment area. The Ilmenau is a direct tributary of the tidally influenced lower Elbe. It is formed south of Uelzen by the confluence of the two headstreams, the Gerdau and Stederau. Because of the semi-natural nature of parts of the upper and middle Ilmenau and the occurrence of protected species and habitats, large areas of the water system have been designated protected areas within the European NATURA 2000 network. Parts of the watercourse are designated reference water bodies for the Water Framework Directive (water type 17: primarily gravel, lowland rivers).
The catchment area of the Ilmenau is dominated by land used for agricultural (55%) and forestry (33%) purposes. The largest town in the catchment is Lüneburg with a population of around 82,000. The town lies directly on the Ilmenau and faces flood risks. Other towns are Uelzen, Bad Bevensen and Bienenbüttel. Downstream of Lüneburg, the Ilmenau is influenced by the tidal cycle of the Elbe (EC-WFD Report 2005).
The Ilmenau is 109 km long and traverses an altitude difference of 67m. Along its route it is joined by the Wipperau, Neetze, Luhe and Vierenbach rivers and itself flows into the Elbe at Hoopte. As a largely semi-natural river, the Ilmenau is the most important water body in the Lüneburg Heath. Numerous endangered species have been found to occur in the running waters of the Ilmenau, meaning that parts of the river are of European significance. 

Characteristics of floods in the Ilmenau catchment

Flooding has been known along the Ilmenau for centuries. Historical photographs confirm the flood problem and the associated risk of damage. Historical sources describing flood events go back as far as the 15th century; the earliest recorded flood occurred in 1408. 

"On 3 February 1408 the Ilmenau rose so high that the waters stood in the middle of Bardowick, flowed through the houses and caused great damage. There followed three whole months of severe cold, much snow fell, so that the people were unable to save themselves from the frost and hunger, and many cattle died."

Further flood events in the years:
1432  1579   1677
1439  1602   1709
1440  1611   1795
1514  1658   1830
1517  1674   1841
1572  1676   1926/27  etc.

"In 1579 the great waters were the cause of much damage, especially in the Lösegraben and Mühlenhofe, for the repairs to which the City treasury was obliged to spend over 3000 Marks."

Impressions of historical flood events in and around Lüneburg

Impressions of the January 2011 Ilmenau and Luhe floods

Snowmelt and additional rainfall caused a considerable rise in the water levels of many
German rivers in January of this year. Along the Elbe, such high levels were reached that a state of emergency was announced in the district of Lüneburg.
The effects were also felt on the Ilmenau and Luhe.
IlmenaubeiFahrenholzJan.2011.png  HochwasserIlmenauJan.2011.JPG

Results and products

Catalogue of measures and tools for preventive flood risk management

The catalogue of measures and tools for preventive flood risk management is a collection of management measures and tools which can be employed to reduce the risk of flooding. It is primarily directed at stakeholders and institutions who are responsible for, or involved in, the development of the flood risk plans required by the FD.

Target area analysis

The analyses of the natural landscapes in the Ilmenau catchment and the comprehensive
spatial data collection provide a detailed view of the flood-relevant elements in the catchment.
The target area analyses represent a major step in the development of an integrative
river catchment management plan.
Methodologyforidentificationoftargetareas.bmp

By combining several topical maps in the Geo
Information System, a target area analysis aims to focus on
areas which are particularly relevant for a given analysis and
which are thus potential areas for the implementation of
management measures, such as restoration of a water body.
The cascade analysis approach narrows down the areas step
by step until the target areas are eventually identified.

The digital 'Ilmenau Atlas'

The Ilmenau Atlas map collection is a compilation of spatial information which is used as the basis for the development of an integrative river basin management plan. The basic geo-data,specialised data and maps are divided into the following categories:
■ Basic maps: These provide, amongst other things, general information on topography,
land use and on preparing these data for the Ilmenau catchment.
■ Evaluation maps: These present various evaluations made by the SAWA Ilmenau project,
e.g. changes in land use in potential flood plains, retention capacity, target area analyses.
■ Maps of target areas: These link the natural landscape analyses for the catchment with the catalogue of measures for preventive flood risk management. They present the various target areas in which certain measures have been prioritised; here, it is necessary to distinguish between the general target areas, such as the designated flood plain area, and the target areas which have been identified in the course of the SAWA project, the target area analyses.

Particular emphasis is placed on the use of
freely available geodata and on data already
available from the regional project partners.
This means that the methodology can
also be more readily applied to other river
catchments.

Target area maps

The target area maps show identified areas with high priority targets or focused measures and target area analysis in the Ilmenau catchment area.
By means of the SAWA catalogue of measures and tools for preventive flood risk management a targeted presentation format was chosen. That means, target areas of these maps are predestinated for implementation of measures:
● for securing retention areas
● for expending and reclaiming of retention areas
● for water retention on land
● for minimizing the damage potential

Cooperation with the regional stakeholders

Floods know no borders. It is obstructive to think in terms of administrative borders when dealing with flood risk management. Thus, an integrative approach is increasingly being followed which aims to involve all stakeholder concerns in flood-relevant planning. Only if everybody pursues the same goals, can these goals be achieved. Cooperation is thus an important step towards successful flood risk management.
There was close contact with the regional cooperation partners throughout the course of
the project. The ideas and results were discussed and refined together with the stakeholders during two workshops held at Leuphana University Lüneburg; practical relevance and practicability were also topics of discussion.
The contents of the target area analysis and the possible measures from the matrix of the catalogue of measures can be included in the development of the flood risk management plans but equally in the management plans and planned measures for the Water Framework Directive, in landscape and regional planning etc. Thus, the agreed measures
become incorporated by means of different tools into planning and management,making implementation more effective and efficient.

Summary

The methods and tools for integrative flood risk management employed in the SAWA-Ilmenau
project can be used to reduce flood risk, but at the same time take ecological, and other, objectives into account.Synergies were identified for the Ilmenau catchment, regional deficits determined, and regionspecific measures for given target areas developed. This was achieved by means of a matrix for measures and tools, a spatial analysis using a cascade GIS approach and the preparation of data in a digital atlas with geo-referenced pdf maps and other relevant information. The project activities were discussed, and consensus reached, with regional stakeholders in the course of numerous one-to-one conversations as well as in workshops. The contents can be used both for the development of the flood risk management plans, which must be completed by 2015, and in other planning and management tools such as landscape plans, regional plans or funding programmes, thus demonstrating that the agreed measures can be
effectively and efficiently implemented.

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