Case studies: Skodbjerge Denmark

Skodbjerge: the narrow sand barrier in Denmark

Skodbjerge is a narrow sand barrier in Denmark. The natural active profile retreat here is 1-2 m/year. The barrier is part of a common agreement in which a 110 km long stretch of coast is protected by the state and the 4 municipalities. The aim is to have a safety level corresponding to a 1/100 year event, and to reduce the profile retreat to 0.75 m/year. This is achieved by sand nourishment, primarily at the outer bar.

The area is a combination of natural open dunes and areas with holiday houses in the dunes. The turnover in coastal tourism is the highest in Denmark. The beach is wide and the sediment is mainly sand and includes gravel

Method

The method was to design a shoreface nourishment to provide safety, and to analyse the effects of aeolian transport on added safety and nature.

The effect of the nourishment was assessed using surveys perpendicular to the coast. The aeolian transport was assessed using airborne Lidar and small drone footage.

Results

The main result is that shoreface nourishment stabilised the beach. The shoreface nourishment diffused downstream and strengthened the bar.

Another main result is that aeolian transport of sand from the beach to the dunes contributes to preserving the safety by preventing erosion and flooding.

The analysis also shows that using building with nature measures, such as sandnourishment, wave and wind sediment transport, also preserves habitats and a natural coast which is a foundation for the local coastal tourist economy. This economy has the highest turnover in Denmark.

The analysis shows it is essential to know the natural variability in order to assess the effect. At least 4 yearly surveys for at least 5 years must be conducted before human impact is made.

Local context

The dominant wind direction is shorewards and the climate is windy. This provides an opportunity to use aeolian transport as an approach.

Future research directions

Further research is needed on quantifying the natural variability and the impact of shoreface nourishment on that. It requires a lot of surveys that are difficult to do because of the severe waveclimate prompting for new survey techniques.

Documents

All documents of the BwN project can be found at publications, below you find the documents belonging to this specific case study:

• Report on beach nourishment at Fredericia Denmark (pdf, 14 MB)
• Denmark Coast Policy Brief (pdf, 3.1 MB)
• System description of Skodbjerge, Denmark (pdf, 1.3 MB)
• Shoreface nourishment effects, An analysis of the 2011 nourishment performed at Skodbjerge (pdf, 3.4 MB)
• Report on aeolian sediment transport at Skodbjerge (pdf, 5.3 MB)
• White paper - Economic rationale for scaling up BwN along the Danish Coast (pdf, 1 MB)