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Adaptation option

Rehabilitation and restoration of rivers (2015)

River rehabilitation and restoration embraces a great variety of measures having in common the emphasis on natural functions of rivers, which may have been lost or degraded by human intervention. Many European rivers have been modified in the past decades to serve only one dominant function (e.g. transportation) or more. However, one-sided use, disregarding of different functions, is no longer optimal and is being replaced by an integrated approach which can have clear benefits in reducing vulnerability to climate change related events such as storms and floods.  River restoration is done to mitigate the negative effects of the modifications, which is not only for ecological functioning of the river but usually other uses as well. Achieving river restoration implies that apart from the technical and ecological considerations, raising support and creating public awareness are just as essential to obtain results. An integrated approach is prerequisite for success.

The development of floodplains and wetlands helps to retain and slowly release water discharge from water bodies, facilitates groundwater recharge, provides seasonal aquatic habitats, supports corridors of native riparian forests and creates shaded riverine and terrestrial habitats. Tidal wetlands as buffers help maintain the functioning of estuarine ecosystems and create natural land features that act as storm buffers, protecting people and property from flood damages related to sea level rise and storm surges. Reversal of delta island subsidence sediment and soil accretion is a cost effective natural process that can help sustain the delta ecosystem and protect delta communities from inundation.

Another measure is storing water in the floodplain, on farmland in the soil, in watercourses, lakes and ponds or on the soil surface. The land remains property of the farmer and is used for temporary water storage. Retention areas are meant to receive the peak discharge of rivers to prevent flooding elsewhere. Emergency retention areas located along the major rivers to receive large quantities of water in extreme conditions to prevent life-threatening situations and large damage elsewhere in e.g. urban or agricultural areas. Relocation of water-sensitive land use types and activities to areas with the lower flood risk is another option, which may facilitate more natural hydrological regimes to return back to high risk areas. The costs can be high in case of need for expropriation, demolishing and re-building of economic activities.

Measures may also focus on the adaptation of dredging practices to changes in water depth, navigability, erosion and siltation in rivers. If the decision to deepen navigation channels is considered inevitable, dredging should be implemented with minimisation of impacts and/or by ensuring that adequate ecological conditions are maintained in adjacent areas, e.g. creation of buffer strips and reed beds in a parallel river arm. Applying rehabilitation of the river and its floodplains simultaneously to the deepening of the navigation channel would ensure that habitats and their capacities are maintained. Significant synergies with flood protection and environmental protection are also possible.

There has been increasing interest in Europe in rehabilitation of watercourses and river valley ecosystems, for example the spatial planning project “Room for the River” in The Netherlands, which included a number of measures leading to rehabilitation of stream morphology and floodplain restoration to create more room for the river and reduce high water levels, such as lowering the floodplains, relocating dikes further inland, lowering groynes in the rivers and deepening the summer beds.

Further, various river restoration projects to mitigate the impacts of hydromorphological modifications are part of the Anglican River Basin Management Plan in the United Kingdom. The level of the projects varies from catchment to landscape level. Floodplain restoration is being driven by the Water Framework Directive, with early projects taking place in the Rheinvorland-Süd on the Upper Rhine, the Bourret on the Garonne, and the Long Eau River project in England. Germany's largest restoration area, Anklamer Stadtbruch, consists of ca. 2000 ha of fen and bog woodlands, former fen grasslands, and the Peene River. The EU-funded REFRESH project was tasked with developing adaptation strategies to mitigate the impacts of climate change on European freshwater ecosystems, including relevant restoration measures.

Additional Details
Reference information

Adaptation Details

Category
Green

Stakeholder participation

The implementation of this adaptation option requires the involvement of various actors (river managers, farmers, inhabitants of villages, etc.) who should be involved to make the adoption of the adaptation option feasible.

Success and Limiting Factors

Implementation of river restoration measures can have a negative effect on navigation, and varying effects (+/-) on tourism, agriculture and drainage, and in general it is intended to have positive effects on biodiversity. However, it is not always feasible to implement because sometimes the river margins don’t allow to restore the river. Success factors generally include strong cooperation among public administrations and other stakeholders, raising support and creating public awareness. Since the specific measures are very much case specific it is impossible to say something about the efficiency or the effectiveness of the measure.

Costs and Benefits

Benefits of this adaptation option include:

  • increased protection from flood related with high precipitation events due increased flow capacity of the river system during flood events, and/or reduced speed of water flow;
  • increased protection from flood related to sea level rise and storm surges;
  • increased habitat quality and/or diversity;
  • maintenance of functioning of aquatic or estuarine ecosystems;
  • increased groundwater recharge.

Passive river restoration, such as abandoning river maintenance, which is less expensive and easier to apply to longer stretches of river, may lead to the comparable positive environmental impacts on the catchment area as expensive active restoration techniques.

Costs can be of different nature (e.g. investment, maintenance, compensation, etc.) and differ substantially on a case by case basis. For example in the case of the ‘Room for the River’ Project in the Netherlands, in farm water storage can be compensated year by year for the estimated damage to crops or paid once for the decrease of the value of the land. Both types of costs depend on the probability of inundation. Examples for annual compensation for damage to crops range from € 300 per ha for a probability of inundation of once a year to € 3 per ha for a probability of inundation between once every 50 and once every 100 years. The single benefit for the decrease of land value ranges from € 2700/ha for a probability of inundation of once a year, to € 550/ha for probabilities of inundation between once every 10 years and once every 100 years. These amounts are based on a land price of approx. € 20000/ha.

River rehabilitation and restoration is a measure promoted by the Water Framework Directive. It can be funded also under the Rural development Policy of the Common Agricultural Policy (CAP) as well as under Interreg. This adaptation option also contribute to the EU policy objective related to biodiversity and nature protection. Options based upon Agri-Environmental Schemes usually go beyond statutory environmental requirements, defined in the Good Farming Practice codes, which act as a baseline level. Thus farmers are paid for the loss of income (e.g. due to reduced production) or the additional costs derived from the adoption of environmentally-friendly farming techniques. Since the EEC Regulation 2078/1992, all EU member states are obliged to develop agri-environmental schemes as part of their rural development policies. Farmers willing to participate in AES sign a contract with the administration for a five year minimum period, and the payments are co-financed by the EU and the Member States. Combinability is high for a number of EU measures on water, environmental quality, nature and participatory processes, and financial support can come, besides the WFD and the CAP, from EU directives like on Flood Directive, Biodiversity, and Waste Framework directives.

Implementation Time

Variable.

Life Time

It varies from annual interventions (e.g. dredging) to more than 25 yr (e.g. room for the rivers).

Reference information

Websites:
Source:
DG ENV project ClimWatAdapt

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