Nature-based solutions

Application ID	The Netherlands_01
Application Name	Wetland International – European Association
Application Location	Country	Germany	Country 2 (in case of transboundary applications)
	NUTS2 code
	River Basin District Code		River Kyll, Middle Rhine Catchment
	WFD Water Body Code
	Description		Kyll river, upstream of Steinebrück, tributary of the Mosel.
Application Site Coordinates (in ETRS89 or WGS84 coordinate system)	Latitude (WGS84): 50.37		Longitude (WGS84): 6.42
Target Sector(s)	Primary:		Nature
	Secondary:		Agriculture
Implemented NWRM(s)	Measure #1:		Social Cost – benefit analyses for rewetting upstream catchment areas in the German Middle Mountains and upscaling them to the Rhine Basin. Rewetting by removing humanly enlarged drainage channels and extended river segments in upstream catchment areas to preserve water near the source and lower peak flows downstream.
	Measure #2:
	Measure #3:
	Measure #4:
Application short description	Restoration of the natural sponge function of upstream micro-catchments has the potential to let the whole catchment downstream benefit.

Brief description of the problem to be tackled	Micro-catchments of big rivers changed dramatically in the last centuries. Marshy, upstream valley parts used to function as “natural sponges”, temporarily storing water from heavy rainfall, before gradually releasing it as small and steady streams. It is important to know that not only rainfall and snow falling in the valley itself was buffered but also precipitation of the much wider, uphill surroundings. Because of this a relatively small patch of wetland on the valley floor had a disproportionally large, regulatory effect. By now, all across Europe these crucially important wetland areas have been drained. The steady flows of water emerging from them changed into strongly pulsating streams, responding almost immediately to changes in rainfall with higher occurrences of both flooding and droughts, on local, regional and (inter)national scale. This already causes problems and without action these will increase because climate change results in more erratic precipitation patterns and thus even more fluctuations in river discharge.
What were the primary & secondary targets when designing this application?	Primary target #1:		Self-regulation of water by filtration / storage / accumulation by ecosystems
	Primary target #2:		Flood control and flood risk mitigation
	Secondary target #1:		Regulation of hydrological cycle and water flow
	Secondary target #2:		Natural assimilation (purification) of effluents through dilution, dispersion, and physic-chemical processes
	Remarks:		Carbon storage is another very important target!
Which specific types of pressures did you aim at mitigating?	Pressure #1:	Floods Directive identified pressure
	Pressure #2:	WFD identified pressure
	Pressure #3:	Other EU-Directive's identified pressure
	Pressure #4:
	Remarks:
Which specific types of adverse impacts did you aim at mitigating?	Impact #1:	Floods Directive identified impact	Flood risk mitigation (and drought prevention) with NBS by delaying and preserving water in upstream catchment areas before in enters the mainstream
	Impact #2:	WFD identified impact
	Impact #3:	Other EU-Directive's identified impact
	Impact #4:
	Remarks:
Which EU requirements and EU Directives were aimed at being addressed?	Requirement #1:	Floods Directive-mitigating Flood Risk	Flood risk mitigation (and drought prevention) with NBS by delaying and preserving water in upstream catchment areas before in enters the mainstream
	Requirement #2:	WFD-achievement of good chemical status	Retention of nutrients in upstream catchment areas
	Requirement #3:	Other EU-Directive requirements	Green Deal climate mitigation by sequestration of carbon
	Requirement #4:
	Remarks:
Which national and/or regional policy challenges and/or requirements aimed to be addressed?	Building a physical, social, Institutional and economic landscape in upstream catchment areas where land use is in balance with its water and soil system

Dominant Land Use type(s)	Dominant land use	3.1.2
	Secondary land use	2.3.1
	Other important land use	1.1.2
	Remarks: Most of the forested areas are drained
Climate zone	cool temperate moist
Soil type (from the list with the FAO classes)	L5704_B321, L5504_B321
Average Slope	sloping (5-10%)
Mean Annual Rainfall	1200 - 1500 mm
Mean Annual Runoff	450 - 600 mm
Average Runoff coefficient (or % imperviousness on site)	> 0.8
	Remarks: Precipitation 1207 Potential evapotranspiration 598 Actual evapotranspiration 549 Streamflow 500 Overland flow 403 Lateral flow 13 Percolation to groundwater 280
Characterization of water quality status (prior to the implementation of the NWRMs)	Concentrations of 0.01 mg l^-1 total P and 3.9 mg l^-1 total N were measured at Steinebrück station on January 26, 2009 (Rheinland-Pfalz, 2020).
Comment on any specific site characteristic that influences the effectiveness of the applied NWRM(s) in a positive or negative way	Positive way: Removal of drainage in forested areas besides the removal of drainage in pasture areas can influence the effectiveness of the NWRM. Upstream areas are important to retain rainfall and delay it to leave the catchment further downstream
	Negative way: The effectiveness can be less positive if land owners are not willing or able to cooperate. There are many landowners in the upstream areas.

Project scale	Large (e.g. watershed, city, entire water system)	It focusses on small upstream catchment areas, the effect though has influences downstream on the river itself and eventually on the Rhine scale
Time frame	Date of installation/construction (MM.YYYY)	No pilot is started, research project
	Expected average lifespan (life expectancy) of the application in years	Decades
Responsible authority and other stakeholders involved	Name of responsible authority/ stakeholder	Role, responsibilities
	European Union	Green Deal, WFD, Flood directive
	River commissions	Wetland restoration is an opportunity for better water quality, flood prevention and WFD implementation in the Rhine and the Mosel.
	Nature organizations and environmental NGO’s	The Sponge Project partners set up studies about wetland restoration. The natural park in the research area would benefit from a lift in biodiversity, water quality and a more regular water flow. (Biodiversity (main), water quality, hydrological cycle)
	Districts and Municipalities	Related to wetland restoration is the municipal responsibility of administering land-use planning. Furthermore, wetland restoration is of interest to the municipalities, since they are responsible for e.g. attenuating natural disasters like floods, clean drinking water, water abstraction, water legislation, land cultivation and in general for implementing (environmental) laws (Auge, 2020; Haschke, 1998; Vidaurre et al, 2016) (hazard regulation (flood/drought), water quality, hydrological cycle, food and fibre provision)
	Farmers/landowners	Wetland restoration requires land that is still mostly in the hands of private owners. This is where a competing interest is identified. However, wetland restoration also brings advantages for this stakeholder, through ESs such as tourism, flood prevention. Also financial land compensation can benefit them. (Food and fibre production (main), tourism, flood prevention)
The application was initiated and financed by	Initiated by Wetland International Europe, Financed by the JRC
What were specific principles that were followed in the design of this application?	Nature-based solution, technically simple with low costs for implementation, restore natural processes in the upstream catchment areas for the beneficial of the upstream residence and downstream residence
Area (ha)	Number of hectares treated by the NWRM(s)	47,6 km²
	Text to specify	The catchment of Steinebrück is 47.6 km², the NWRM has a direct effect upstream of Steinebrück. There are significant effects downstream when the NWRM could be upscaled.
Design capacity	Design capacity is delaying 20 – 30% of the peak discharge in Steinebrück when 38% of the available sponge sites in the catchment are restored.
Reference to existing engineering standards, guidelines and manuals that have been used during the design phase	Reference	URL
	1	https://europe.wetlands.org/publications/sponge-restoration/
	2	https://europe.wetlands.org/publications/wetland-restoration-impact-on-streamflow-rhine-basin/
	3
	4
	5
Main factors and/or constraints that influenced the selection and design of the NWRM(s) in this application?	Size of the catchment, location of the catchment, land use

Impact category	Impact description The response of streamflow to extreme rainfall events was attenuated, as peaks were lower but broader after wetland restoration. In this way, the maximum annual peak discharge decreased by an average of 12 – 24% in the three micro-catchments of the Rohrbach and Lewertbach streams. At the larger scale of the Kylldal catchment, with its outlet at Steinebrück, however, maximum annual winter peak flows were 10% lower after wetland restoration at 38% of the available sites. The delay in flow after extreme precipitation events also causes a higher baseflow recession after wet periods. The change to lower peak discharges and higher water availability in drier periods can be viewed as a positive impact on the hydrological regime of these areas. Nutrient exports from the Kylldal catchment were low for the reference scenario, which can be due to the limited area of pasture in the catchment, the use of filter strips to reduce stream nutrient loading and the relatively low amounts of manure applied on pasture. Wetland restoration did have a positive impact on the nutrient exports from the project areas and the Kylldal catchment as a whole. Nitrogen and phosphorous loads and concentrations were reduced by up to 67% in the project areas. The effect at catchment scale was somewhat lower, but still substantial, with simulated reductions in the order of 20%. Based on this study, wetland restoration can be viewed as a viable ecosystem-based solution to improve the hydrological services of catchments. The largest gains for both streamflow and nutrient exports can be expected in agricultural areas that now experience considerable fast runoff into the drainage and main channels.	Impact quantification
		Parameter value; units and/or	% change in parameter value as compared to the state prior to the implementation of the NWRM(s)
Runoff attenuation / control
Peak flow rate reduction		10 – 30% reduction with 38% of the area with sponge restoration
Impact on groundwater
Impact on soil moisture and soil storage capacity
Restoring hydraulic connection
Water quality Improvements		20% reduction of N peak discharge
WFD Ecological Status and objectives
Reducing flood risks (Floods Directive)		10 – 30% reduction with 38% of the area with sponge restoration
Mitigation of other biophysical impacts in relation to other EU Directives (e.g. Habitats, UWWT, etc.)		EU Habitats Directive priority habitat. Wetland restoration also contributes to the goals of the EU Birds Directive (such as Breeding and feeding grounds for songbirds, waders and waterfowl), the goals of greening the Common Agricultural Policy and the Trans-European Network for Green Infrastructure TEN-G.
Soil Quality Improvements
Other

What are the benefits and co-benefits of NWRMs in this application?
Financial costs (estimation) Value in € (Total + possible breakdown)	Total	Value in €
	Capital:	546.000,00 €	Per hectare / per decade
	Land acquisition and value:	180.000,00 €	Per hectare / per decade
	Operational:	25.000,00 €	Per hectare / per decade
	Maintenance:	91.000,00 €	Per hectare / per decade
	Other: monitoring	125.000,00 €	Per hectare / per decade
Were financial compensations required? What amount?	Was financial compensation required: -
	Total amount of money paid (in €): -
	Compensation schema: -
	Comments / Remarks: Research project, not yet implemented
Economic costs	Actual income loss: -
	Additional costs: -
	Other opportunity costs: -
	Comments / Remarks: Research project, not yet implemented
Which link can be made to the ecosystem services approach?

Monitoring requirements		Research project, not yet implemented
Maintenance requirements		Research project, not yet implemented
What are the administrative costs?		Research project, not yet implemented

Which assessment methods and practices are used for assessing the biophysical impacts?		Pre vs post, business as usual vs NWRM
Which methods are used to assess costs, benefits and cost-effectiveness of measures?		Teeb methodology
How cost-effective are NWRM's compared to "traditional / structural" measures?		enefit / cost ratio is estimated on 2.4. Every 1 euro spend provides 2.4 Euro’s benefits
How do (if applicable) specific basin characteristics influence the effectiveness of measures?		They influence them enormously. NWRM in this case can be implemented in upstream river catchments in middle mountain areas in the whole of Europe with low sloping areas https://media.stroming.nl/sponges/
What is the standard time delay for measuring the effects of the measures?		Hydrological effect are immediate, ecological effects takes 3 – 5 years

What were the main implementation barriers?		Lack of vision and governance in upstream catchment areas at local, regional, national and European governments; The lack of perspective for landowners in upstream areas.
What were the main enabling and success factors?		The benefits from investing in upstream catchment areas for reducing peak flows, increasing low flows and carbon sequestration.
Financing		Research project, not yet implemented
Flexibility & Adaptability		Research project, not yet implemented
Transferability		Research project, not yet implemented

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Natural retention for flood risks, drought control, biodiversity restoration and climate challenges: the Kyll river case

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