Stream restoration in Haarby reduces the risk of flooding

The city of Haarby in the Municipality of Assens on Funen experienced occasional flooding due to raised water levels in the local watercourse Haarby Å. As a consequence, the municipality established a new wetland area north of the city. The watercourse was remeandered and two new lakes were established. The new wetland serves as a retention buffer during heavy rainfall and therefore reduces the risk of flooding downstream in the city.

• Wetland serves as a buffer

  A stretch of around 1.2 kilometres of the Haarby Å watercourse was restored to a more naturally meandering course. During periods with heavy rainfall, the watercourse will now overflow its banks to a newly established wetland area, reducing the risk of flooding further downstream.

   

  The new wetland also helps reduce the discharge of nitrogen to Helnæs Bay.

• Background: Flooded basements due to saturated ground and heavy rainfall

  At the turn of the millennium, the discharge of nitrogen from the catchment area via Haarby Å to Helnæs Bay was so extensive that measures were required to protect the aquatic environment. As a positive side-effect, the measures that were taken now also help prevent flooding in Haarby.

  In around 2000, the former County of Funen launched a project to remeander Haarby Å with a view to reducing discharges of nitrogen into Helnæs Bay.
  
  The idea was to restore the watercourse to its former naturally meandering course after the area north of Haarby had been drained for decades to create farmland.
  
  Funds from the Danish Parliament's Action Plan for the Aquatic Environment II made remeandering of the watercourse, creating two new lakes and expanding two existing lakes possible In a wetland area like this, nitrogen is degraded and, at the same time, the area serves as a retention basin for surplus water from the watercourse.
  
  Before the remeandering project, basements in the city of Haarby occasionally flooded during heavy rainfall or during periods when the ground was heavily saturated with water.  Climate protection of the city is a positive side effect of the project, which is becoming ever more topical at the prospect of periods of more powerful rainfall and more frequent cloudbursts as a consequence of climate change.

• The solution: Establishing a 32-hectare wetland

  A 1.2-kilometre stretch of Haarby Å north of Haarby was remeandered. This created a 32-hectare wetland with four lakes, where water from the watercourse is retained during heavy rainfall events.

  The remeandering of the watercourse means that it has less drop and, based on hydraulic calculations, the watercourse will now overflow its banks into the area laid out as wetland .
  
  Furthermore, two existing lakes have been extended and two new lakes have been established.
  
  The pumps previously used to pump the water away from the area so that the land could be used for farming have been shut down.
  
  Therefore, groundwater, water from drainage channels in the catchment area and water from the watercourse now runs to and through the area.
  
  There are 16 land owners in the area and agreements have been established with them to realise the project.
  
  The area has not been dimensioned to cope with a specific size or type of event, and, in principle the project will last for ever.

• Benefits and added value: Recreational area and improved aquatic environment

  The new wetland north of Haarby primarily serves to reduce discharges of nitrogen into Helnæs Bay.

   

  The fact that Haarby now has climate protection and an expected considerably lower risk of flooding is therefore a positive side-effect of the environmental project.
  
  Furthermore, Haarby now has a recreational area where hiking paths are being established and, possibly, also a birdwatching tower.
  
  Another great benefit of the project is the expected greater biodiversity, in the form of richer wildlife and flora, e.g. greater numbers of amphibians, birds, insects and plants.

• Financing: A DKK 3-million project

  Total establishment costs were around DKK 3 million, of which DKK 2 million were provided as state aid under the Action Plan for the Aquatic Environment II. The Municipality of Assens contributed around DKK 1 million.

   

  The area will need to be maintained to keep it a marsh and prevent it from growing into forest. The municipality has decided to do this by having the area grazed by animals. Private land owners are already allowing animals to graze on large parts of the land. The municipality is responsible for maintaining paths and a possible future birdwatching tower.
  
  Annual operating expenses for the municipality are estimated to be around DKK 30,000 for maintenance of paths. Furthermore, the municipality has set aside a one-off amount of DKK 150,000 to fence in the area to be grazed.

• The process and stakeholders: A long process

  You cannot change a landscape from one day to the other. It took 16 years to finally realise the new wetland area near Haarby Å. The project was achieved through dialogue with the landowners and by allowing for plenty of time for reflection along the way.

  In 1998, the County of Funen applied for funds under the Action Plan for the Aquatic Environment II to remeander Haarby Å with a view to reducing discharges of nitrogen into Helnæs Bay.
  
  First, the county obtained funding to carry out preliminary surveys. In the subsequent phase, funding was awarded to realise the project.
  
  After this, dialogue and negotiations with the 16 landowners in the area began. This included a series of collective meetings and individual meetings at which the landowners had their say and at which specific and realistic opportunities for the project and for establishing agreements were identified.
  
  In practice, the Danish AgriFish Agency was responsible for the land consolidation process and for negotiating compensation with landowners. However, the Municipality of Assens was also involved in the dialogue with landowners.
  
  During the process, a local-government reform meant discontinuation of the County of Funen and expansion of the Municipality of Assens. The process to establish the wetland continued alongside these changes.
  
  "We succeeded in reaching agreements with everyone, because we allowed everyone plenty of time for reflection. Sometimes we need time to reflect in negotiation procedures like these, so that opportunities for agreements can mature," said Gunilla Ørbech, project manager and biologist at the department for nature and the environment in the Municipality of Assens.
  
  Landowners were eligible for a one-off compensation payment under the Action Plan for the Aquatic Environment II. Compensation was determined, e.g. on the basis of hydraulic impact studies of the relevant land plots. In simple terms, these studies showed how wet, or not, the land would become.
  
  The changes to the land were recorded in the Land Register.
  
  In 2014, all negotiations were completed and establishment of the new wetland commenced.

• Barriers: Negotiations with landowners take time

  The project encountered no insurmountable obstacles. However, the project illustrates how realising a large project of this kind in collaboration with landowners takes time.

   

  The Danish AgriFish Agency carried out negotiations with the 16 landowners on the size of the compensation they would receive for allowing their land to be turned into wetland.