Nourishment

The project combined beach nourishment with testing measures to benefit dune formation.

A beach nourishment was done in Ystad Sandskog in April 2020. An experienced organization with specialized ships and essential equipment to extract sand from a marine sand source and pump it onto the beach was hired. 56 760 m3 of sand was extracted from Sandhammar marine sand source at a depth of about 20 meters, then covering the entire backshore area and widening the beach in the foreshore area. The beach widens 20-50 meters, depending on how wide it was from the beginning. 

The beach nourishment was the first of a two-stage process of testing a method to ensure long-term results of it. The next step was to test different measures to benefit dune formation and create a dynamic and natural beach area. A wide beach creates a buffer that can withstand a storm or a high tide better than a narrow beach. However, a naturally formed beach consists of several rows of dunes in different stages of formation. The nourishment creates perfect conditions for dune formation, since dunes form when sand is transported by wind and a wide, dry backshore area facilitates the process. However, since this area is one of the most visited beaches in Sweden, and due to machines cleaning the beach every day, the formation of dunes is impeded. The actions to benefit dune formation were made for the first time and the expectations were high as well as redeemed. 

Vegetative monitoring of the seafloor, carried out in 2019 and 2020, showed dense and valuable eelgrass meadows outside Fortuna beach in Helsingborg. Between 3 and 6 meters and inwards, the meadow is coherent. At 1-3 meters depth, there are patches of dense meadow. These ecosystems are of high value as they bind carbon dioxide, nurse many fish and invertebrate species, reduce wave energy, and bind the sediment. 

The design of the shore face nourishment takes into account the site-specific biotic and abiotic conditions such as waves, sand transport and risk of over-sanding the vulnerable eelgrass habitats. A nourishment closer to land, well combined with the other ecosystem-based measures, was a likely outcome.

Action C5 was performed at two demonstration sites and was a part of several other ecosystem-based measures at the two sites. Both sites have narrow beaches with different hard structures affecting the dynamics on the beach and in the shallow area. One single row of yellow or gray dunes functions as a barrier between the beach and the infrastructure/buildings inland - a textbook example of coastal squeeze. The demonstration sites differed regarding the marine environment. In Fortuna, a massive eelgrass meadow interacts with the beach making it a little less vulnerable to erosion. In Ystad, however, there were only small patches of eelgrass, highly sensitive to changes in the local environment. The eelgrass plays a significant role when deciding what kind of measures are appropriate in a specific area. A shore face nourishment could destroy a meadow if it were to be done without care and knowledge about the marine environment.

By adding sand to these beaches, the purpose of action C.5 was to create a wider and thereby more natural and dynamic beach. Hard structures that impede sediment movement were removed at the Fortuna site and invasive species removed at both sites, push out native, salt tolerant species. All these measures interact and is a prerequisite for the formation of dunes that improve resilience to flooding and high tide and decrease the vulnerability of the area. Simultaneously, positive synergies were achieved by strengthening coastal biodiversity and ecosystem services.

Without the EU-funding it would not be possible to test all the different measures in the project. Eg, testing different ways to promote dune formation is a way to reach new and innovative methods to ensure long-term results of the beach nourishment. Without the EU-funding, these tests would not have been done.