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Næstved Municipality - Climate lakes established and Ellebækken re-meandered

Næstved Municipality - Climate lakes established and Ellebækken re-meandered

To prevent Ellebækken to dry out in the summer and being flooded in the event of large rain, two large lakes were established and the brook was re-meandered.

Where along Ellebækken is the project site? 

The project site is located east of Næstved.

1 Map Case 280120

Map showing the location of the project site (blue spot).

Why climate lakes and re-meandering?
Climate change will bring about increasingly dryer and hotter summers, and the Ellebækken watercourse will be at great risk of drying out during summer with resulting damage to life in the watercourse. The new climate lakes established near Ellebækken store water from the watercourse in winter and release the water during dry periods in summer and autumn. Draining water from the bottom of the lakes means that life in the watercourse is not harmed by too high water temperatures.

Re-meandering improves variation in the watercourse to benefit fish and other aquatic animals, and the addition of spawning gravel and rocks serving as hiding places improves spawning conditions for trout and other fish.

All in all, the project prevents Ellebækken from drying out in summer, and keeps the watercourse on track to meet the goal of good ecological status set out in the national river basin management plans. At the same time, the establishment of the lakes means that, in the event of large amounts of rain, water will be retained in the lakes, so that flooding downstream can be avoided.

Description of the project
Two large lakes have been established. The lakes are separated by a dyke that is part of the system of paths in the area. Inflow to the lakes is directly from the culverted part of Ellebækken. Outflow from the lakes to the watercourse is through drains at the bottom of the lakes. This is to keep the water temperature down in the summer. In the event of large water flow, water will also be released to the watercourse through a small spillway. The stretch of Ellebækken covered by the project has been relocated and re-meandered, and the physical conditions in the watercourse have been improved by laying out spawning gravel and large rocks.

A small lake has been established in the northern part of the project site. This lake has not been connected with the other lakes in the area, so as to avoid fish migrating to the lake. This ensures good habitats in the lake for tree frogs and great crested newts.

The slopes leading to the lakes are smooth, providing good access to the lakes and making it safe to use the area. There are platforms/boardwalks leading out onto the lakes.

To benefit sand lizards, piles of gravel have been laid out, and vegetation of indigenous trees has been established so as to provide shade in the watercourse and to improve biodiversity. A system of paths has also been established in the area.

The project was carried out in winter 2016/2017.

How did Ellebækken cope in summer 2018?
The lakes coped with the dry spell better than expected. Water could be drained from the lakes throughout the summer, and they have therefore proven their worth. Only during a few days in the summer of 2018 was a dried out stretch observed in Ellenbækken downstream, near the outflow.

Map of the project site
2 Map Case280120
Map of the project site with lakes (turquois and dark blue), re-meandered
watercourses (dark blue) and dykes (green).

3 Meandering 280120
The new, meandered course of Ellebækken.

 

4 Boardwalk Case280120
Boardwalk and dyke between the two lakes.

Pictures taken before and after the project
5 Before Case280120
Before the establishment of the lakes there was field.

6 Newlakes Case280120
View of the new lakes.

 

7 Newsite Case280120Fotos: the Municipality of Næstved