Hansen, L.B., Källstrøm, M., Jørgensen, S.L. & Hasler, B. 2011. Vådområders omkostningseffektivitet. En erfaringsopsamling og analyse af omkostningerne ved at gennemføre vådområdeprojekter under vandmiljøplanerne VMPI og VMPII. Danmarks Miljøundersøgelser, Aarhus Universitet. 63 s. – Faglig rapport fra DMU nr. 835. http://www.dmu.dk/Pub/FR835.pdf.
Wetland restoration is a measure to removal of nitrogen and is an important part of the Danish Action Plans for the Aquatic Environment (VMPII from 1998 and VMPIII from 2004) and in the Agreement on Green Growth from 2009. The wetlands comprise of lakes, meadows, reed swamps and other areas close to watercourses. With discardment of drainage, termination of maintenance of watercourses and other hydrological changes permanent moist or occasionally moist areas that can reduce the nitrogen loss from agricultural soils are being recreated.
All mentioned plans assume that wetland restoration is a relatively cost-effective means compared to other measures. This report analyses existing data regarding costs and effects on nitrogen losses when re-establishing wetlands with the purpose of gaining insight into which types of wetland projects that are the most cost-effective.
With reference to the Agreement on Green Growth between the Local Government Denmark (LGDK) and the Danish Ministry of Environment about the implementation of wetland and river valley projects the most cost-effective wetlands must be chosen. This means that the reduction effect must be achieved through the lowest possible cost per kg N reduction. In the presentation from the Ministry of Environment on implementation models for the wetland effort in the Agreement on Green Growth, which are being implemented in the so-called Water Catchment Plans, it is assumed that there is a connection between large nitrogen reduction and cost effectiveness. However, the analysis in this report shows that such a clear-cut connection does not exist.
The data for the analysis does not include all types of projects but derives from completed VMPII projects. The VMPII action plan established a subsidy scheme for the establishment/restoring of wetlands administered by the Danish Nature Agency. The agreement allowed the counties to seek subsidies to wetland projects. The projects that were not accomplished when the VMPII agreement expired was passed on to the VMPIII agreement as negotiations on wetland projects can be time consuming. These projects are also included in the analysis.
The analyses outline which types of wetland projects that are the most efficient (largest reduction of nitrogen) and the most cost-effective (largest reductions at the lowest cost measured in DKK per kg N). The wetland projects has been analysed in sub-analyses that clarifies what underlies the ranking of the projects according to cost effectiveness; i.e. whether project type, expected nitrogen reduction, cost types, size and geographical location impact the cost effectiveness.
The projects are analysed as a large pooled group in which differences between the various project initiatives are not taken into account (restoration of lake, fresh meadow and others). The results of this analysis suggest that the cost level of restoring a wetland area has a relatively large impact compared to the (expected) nitrogen reducing effect. I.e. land that has been bought at a high price as well as high construction costs overshadows the effect of an expected high nitrogen reduction.
Furthermore, the projects have been split into three sub-groups in order to specifically take the difference in costs between the project types into consideration. The three groups are: Establishment of lakes, establishment of fresh meadows and establishment of grazing areas/permanent pastures. The analysis shows that the three groups differ. The cheapest project is found in projects with permanent pastures when both DKK pr hectare (ha) and DKK pr kg reduces N are taken into account. Construction costs as well as cost in relation to land transactions amounts to a large share of the total costs for lake projects compared to the other project types. The projects are also analysed within the groups (lake, fresh meadows and pastures) and it is concluded (also in this analysis) that it is the differences in the construction costs, landowner compensations and cost in relation to land transactions that separates the projects in each group from each other. In general, the expectations to the nitrogen reductions are not very important for the ranking or the cost-effectiveness but it should be noted that the expectations to the nitrogen reductions are based on model calculations that does not take the specific conditions of each project into account. If the choices of wetland area are based on nitrogen reduction as the primary variable it will not be possible to achieve the best possible total costs effectiveness.
In the third and last part the projects are analysed collectively and in relation to geographical location. It is concluded that there are large differences between the old counties compared to how cost-effective the established projects were and how many projects has been established so far in each of the old counties.
Conclusively the analysis shows that in order to secure the costs-effectiveness before high nitrogen reductions pr ha the costs should to a much higher degree be reduced rather than increasing the nitrogen reduction pr ha. Thus the results of the conducted analysis suggest that it can be cost effective to establish the cheapest projects independently of the expected nitrogen reduction pr ha. Furthermore the analyses show that especially the landowner compensations seem to play a major role for the cost level – and that projects with low construction costs and few costs regarding land transactions are in fact the ones that are the most cost-effective. Thus the conducted analyses seems to indicate that in order to achieve a high cost effectiveness it is important to consider the type of wetland area and by doing so avoid large construction costs as well as landowner compensations and that this is more important than choosing areas with an expectation of a large capacity for nitrogen reduction.
