In an effort commissioned by Waterschap Amstel, Gooi en Vecht (AGV) we at Natursquared took stock of the (economic) advantages and disadvantages that the instalment of nature-friendly banks in the Bovenkerkerpolder, a management area of Waterschap AGV, could have. In order to reach this goal we were requested to make an estimate of the costs and benefits of nature-friendly banks and to investigate how the costs for these banks are distributed.
What are nature-friendly banks?
Nature-friendly banks are landscape features designed with an explicit focus on biodiversity. Unlike conventional banks on agricultural plots, nature-friendly banks provide space for various types of vegetation (flowers, herbs, reeds) and provide habitat for pollinators and other animal species. But nature-friendly banks not only contribute to species diversity on land, water quality and thus aquatic life also benefit from a nature-friendly bank design. Flowering plants and rich reed beds provide a habitat where fish can spawn, grow, and shelter, and where macrofauna can flourish (aquatic species just barerly visible to the naked eye).
Design scenarios for nature-friendly banks
To identify the costs and benefits of nature-friendly banks in the Bovenkerkerpolder, we conducted thorough explorative desk research. For example, we identified the demonstrated effects of nature-friendly banks in contexts similar to the Bovenkerkerpolder. We then drew up two design scenarios based on interviews we conducted with farmers in the management area and experts from the Water Board. The following design scenarios were designed by us:
– Excavating the existing bank for the purpose of creating the nature-friendly variant
– Creation of the nature-friendly bank in the existing watercourse.
After drawing up these design scenarios, we quantified the effects of creating nature-friendly banks in the Bovenkerkerpolder for each design scenario. We did this on the basis of context-related variables such as total linear meters of bank and hectares of grassland.
Costs and benefits of nature-friendly banks
We then identified the costs and benefits for each of the involved parties, the farmers and the water board, and summarized them in a cost-benefit summary. We expressed these costs and benefits in monetary values.
The aformentioned cost-benefit overview included a schematic representation of promising financing scenarios for both the water board and the farmers. We distinguished the costs of construction and maintenance,as well as the possible compensation for loss of income. In doing this we unearthed the various options for cost sharing between farmer and water board.
Because attracting social parties can reduce costs, we also explored the potential for social contributions from public and private actors to finance nature-friendly banks in the Bovenkerkerpolder.
Nature-friendly banks, we concluded, can contribute to water quality and biodiversity, while also contributing positively to the aesthetic value of the landscape. In the final report and public summary that we completed and presented in the penultimate week of 2022, we provided guidance for the design and financing of this intervention in the Bovenkerkerpolder. We further concluded that the results from our research could be tested in a pilot project in the Bovenkerkerpolder. This could provide further insights and lessons regarding the practical opportunities and objections of nature-friendly banks and contribute to the wider rollout of this landscape intervention. For these and more detailed conclusions and recommendations we advise to consult the public summary.