EXPLORING BEAVER HABITAT IN EUROPE:

BEAVERS AS THREAT TO DIKES IN THE NETHERLANDS

Beavers have been reintroduced in many counties in Europe , including the Netherlands. The beaver population is gradually growing and with that comes the conflict with the important diking system protecting the low lying areas in Holland from flooding. In 2007 ALTERRA WAGENINGEN UR published an interesting report: Graverij van bevers in de rivierdijken in de Gelderse Poort (Beavers digging in the riverdikes of de Gelderse Poort- the area of the Waal river just upstream of the Nijmegen Bridge). Alterra- rapport 1604. ISSN 1566-7197. Author: F.Niewold)

  • After 150 years of absence beaver were reintroduced in the Netherlands in 1988 in de Biesbosch and between 1995-2000, 54 beavers (Castor fiber) were introduced in the Gelderse Poort
  • In march of 2007 the total population in the Netherlands was 315 individuals, with about 80 in the Gelderse Poort.
  • In two places beaver dug holes in the riverdikes as lodges: Although these holes did not endanger the structural safety of the dikes, future population expansion could create a real problem.
  • In this study Freek Niewold looked at potential risk areas and possible strategies to reinforce sensitive areas at risk.
  • The photographs below give an overview of this issue

Figure 1: Locations in de GeldersePoort with dike stretches sensitive to digging beavers and requiring priority protective actions.

 

Figures 2. Oblique overview of the area. The Nijmegen bridge is just on the left side. The Arnhem Bridge (A bridge to far) is just 20 minutes by car to the north.

The area with the orange arrow was holed by beaver and re-engineered to protect it from future damage. See also figure 3. The light blue area highlights one of areas sensitive to beaver holing- Wz3

 

Figure 3 This collage shows a combination of images, starting with beaver holes , the re enforcement of the toe of the dike after the damage was repaired. Another sensitive area was identified as well ( blue arrows)

More information of course in the Alterra report referred to earlier (PDF, but need to be able to read Dutch)