KLEVER - Climate-optimized drainage management in the district of Emden

Background and Goals

The anthropogenically controlled drainage of the diked lowland areas along the North Sea coast has for centuries formed a central prerequisite for the use of the coastal region as a cultural landscape and settlement area. Over time, a complex drainage infrastructure has evolved, operated and maintained by drainage associations and slaughterhouses.
The drainage situation in the area of the I. Drainage Association Emden (I. EVE), where about one third of terrain surface is below zero altitude, is particularly challenging. Due to the topography of the area, it is only possible to dewater in a natural gradient into the outer waters during short tidal low-water phases (Siel operation). In the remaining periods – at higher tidewater levels – on the other hand, drainage is only possible by using the pump (scooping operation). Without proper drainage, large-scale floods would regularly occur in the association area.
Despite the state of completion of the drainage system, internal drainage in the association area of the I. EVE is already reaching its capacity limits in extreme weather conditions such as storm surges and prolonged continuous rain periods. Due to the consequences of climate change (changes in precipitation, sea-level rise) as well as progressive surface sealing, the burden on the system will increase further in the future.
Against this background, the objectives of the KLEVER project were in particular:
1) using model-based scenario analyzes to investigate the expected effects of the changing factors influencing domestic drainage in the I. EVE
2) to identify possible measures to adapt the drainage system and management as part of a project-accompanying participation process and to subject these to a multi-criteria evaluation,
3) to quantify selected policy options in terms of their potential effectiveness.

Content time

to

Research area/region

Country
  • Germany
Region of implementation (all German federal states)
  • Lower Saxony
Natural spatial classification
  • coasts: North Sea-/Baltic Sea coasts
Spatial resolution 

area of the I. Drainage Association Emden (I.EVE)

Steps in the process of adaptation to climate change

Step 1: Understand and describe climate change

Approach and results 

In order to transfer global climate changes to the different regions of the world, regional climate models are used, which take into account local topographic conditions in the calculation. The three regional climate models used in this project were developed specifically for climate projections in Central Europe. The regional climate models used for KLEVER have been calculated using the scenarios RCP8.5, RCP4.5, A2, A1B and B1. The analyzes are based on a model ensemble of three regional climate models (REMO, WETTREG and XDS) and five different scenarios.
In the context of KLEVER, the changes in the two climatic variables of temperature and precipitation were considered, which have the greatest effect on runoff formation and thus on the requirements of domestic drainage.
Global sea-level rise varies regionally due to ocean currents and coastal morphology. The regional model calculations of the IPCC scenarios RCP4.5 and RCP8.5 were evaluated for the analyzes regarding the future development in the area of the association area of the I. EVE. Each scenario is quantified by a variety of climate models. KLEVER considered both the mean values of all models (ensemble average) and the 95% percentiles (value exceeded by 5% of the models) for the scenarios. The projections considered show for the North Sea coast an expected sea-level rise between 50 and 110 cm by the end of the century.

Parameter (climate signals)
  • Altered rainfall patterns
  • Higher average temperatures
  • Sea level rise und storm surges
  • Extreme precipitation (incl. hail, snow)
Further times 

Presence until 2100

Step 2a: Identify and assess risks - climate effects and impact

Approach and results 

To estimate the potential impact of the scenarios on the water balance, hydrological models can be used. In order to estimate the hydrological changes associated with the climate and land use scenarios in the I. EVE association area, the SIMULAT water balance model was used after previous calibration and validation.
The resulting estimates for mean and seasonal changes as well as for extreme events clearly show that in the future climate-induced drainage conditions in the area of the I. EVE are to be assumed.

Step 3: Develop and compare measures

Measures and/or strategies 

In order to best adapt the drainage system and management to future changes and developments, it is essential to involve all relevant institutions in a brainstorming process to develop suitable adaptation options. For this reason, a project-accompanying participation process was carried out for the development of measures within the framework of KLEVER, in which representatives of various institutions from the fields of action water management, nature conservation, agriculture, inland fisheries, tourism / leisure, spatial planning and civil protection were involved.
The participation process in the context of KLEVER took place in three phases. The most important building blocks were individual and small group discussions with the stakeholders, discussions in the stakeholder forums and working group meetings held at the end of the project to concretize the results from the forums.
As a result of the cross-sectoral composition of the actors involved, a broad range of proposed measures emerged, which were grouped into further categories of measures and areas (drainage infrastructure, retention capacities, water retention, flood prevention, communication and cooperation).
In order to assess which measures best meet the different requirements of the drainage system and management, a multi-criteria evaluation process was used in the course of the project-accompanying participation process, with the help of defined criteria on the part of the involved actors. The three main criteria are: water management relevance, effects on other requirement areas as well as probability of implementation, each with three further subcategories.
The project results can serve as starting points for more in-depth conceptual considerations and concrete planning for the adaptation of the drainage system and management in the I. EVE region and comparable coastal areas.

Participants

Funding / Financing 

Federal Ministry for the Environment, Nature Conservation and Nuclear Safety

Project management 

Carl von Ossietzky University of Oldenburg
Jade University
Küste und Raum

Cooperation/Partners 

I. Drainage Association Emden
Lower Saxony State Office for Water Management, Coastal Defense and Nature Conservation Agency (NLWKN)
County of Aurich
City of Emden

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Fields of action:
 water regime and water management