Project 5 – Aeolian transport

The focus in project 5, under the national analysis of WP3, is aeolian sediment transport and dune development. The dunes along the Danish Jutlandic west coast serve as a natural barrier against the sea, and protect the lower laying areas behind them from flooding and from storm surges. As it is of national interest to ensure resilient dunes effective enough to withstand a 100 year event, an insight in the natural development and behavior of the dune systems are of great interest. As several summerhouse areas as well as critical infrastructure is situated in the nearby hinterland, the knowledge gained could also be of interest regarding future local planning.

In order to investigate the dune systems, three main areas on the Danish Jutlandic west coast have been chosen for analysis: Skodbjerge, Krogen and Vedersø (figure 1).

Figure 1. Analysis areas of Vedersø, Krogen and Skodbjerge

The areas/stretches of Skodbjerge and Krogen are ideal areas as they are already implemented as living laboratories in the transnational projects of Building with Nature and analyzed in regards to shoreface nourishments. The stretch in Vedersø has been found interesting as it presents highly dynamic and large dune systems. All three areas/stretches lie within the common agreement stretch on the Danish Jutlandic west coast, and are supposed to have the same safety levels, making analysis across areas comparable.

As wind is the primary factor in dune dynamics, knowledge on wind characteristics and the changes over time are investigated as these factors can impact the sediment pathway and dune morphology. Knowledge on aeolian dynamics, sediment transport threshold and criteria are used in order to describe the system dynamics and thereby the pathways that sediment follows from source to deposition.

For the three study sites, the changes in the dune morphology are analyzed over longer stretches using LiDAR mappings (figure 2). Since these are available once a year from 2005 until 2018 (apart from 2014), change detection on yearly basis and over longer periods are possible to investigate in relation to orthophoto analysis and wind data.

Figure 2. Example of a LiDAR scan

Blowout study

It is also a goal to establish a detailed blowout study since these dynamic features can have a significant impact on the safety levels of the dunes (figure 3). It is sought to investigate the behavior, development as well as overall volume changes found in the blowout area. Since detailed site specific features and local changes might drown in the overall analysis of the longer stretches, a separate report will present the blowout study, alongside the study site analysis.

Figure 3. Blowout in a dune. A blowout is a sandy depression in the dune caused by removal of sediments by wind