Boulder revetment to save Magħluq wetland from coastal erosion

A 130m-long boulder revetment will have to be built along the Ballut ta’ Marsaxlokk seashore to protect the protected habitat from sea erosion.

The coastal wetland’s shoreline is being impacted by sea erosion, and the revetment will reclaim the land area lost in the past decades due to these coastal changes.

The proposal, first floated three years ago, has been beefed up by detailed studies undertaken by AIS, an environmental consultancy firm.

Without the intervention, further coastal erosion will jeopardise the site’s integrity and lead to the loss of species and habitats, endangering one of Malta’s few inland surface water bodies.

A comparison between two satellite images shows that while the coastal profile in 2002 was straight, it became concave in 2021, an estimated reduction of 1,500sq.m in almost 20 years.

The Environment and Resources Authority (ERA) will be responsible for the overall project with works carried out in conjunction with Infrastructure Malta.

The 130m-long revetment will be constructed along the entire shoreline of the Ballut ta’ Marsaxlokk. The revetment will be mostly located underwater but will rise to 2 to 2.5 metres above the waterline, along an 8-metre width throughout the entire length.

The inner perimeter of the revetment will be lined with a 2m-wide passageway along the entire length, serving both as extended protection to the wetland and as a means of access from the sandy beach to the north of the wetland towards the hardstanding quay to the south.

The Ballut wetland

The Ballut ta’ Marsaxlokk is one of the few remaining coastal wetlands in the Maltese Islands.

In view of its ecological importance, the wetland was designated a Special Area of Conservation, forming part of the Natura 2000 Network included in the EU Habitats Directive. The wetland contains several marshland areas and a large number of trees which also host migrating birds. The site is currently being managed and overseen by Nature Trust Malta, a non-governmental organisation.

The shoreline facing the southwest is prone to wave action originating from the mouth of Marsaxlokk Bay. A salt marsh is recharged from rainwater run-off. Seawater input became significantly restricted when a sand embankment was constructed in the 1980s which segregated the marshland from the southern beach and the sea. Culverts were also laid to connect the marshland directly to the sea.

But debris accumulation within the culverts has blocked this connection. As a result there is very limited water circulation in the area with the area becoming dry in summer.

The marshland is occasionally supplemented by sea water which forces its way through the wave breakers. The likelihood of such occurrences is remote and was only observed once during a 12-month monitoring period between 2021 and 2022.

By limiting erosion the new revetement will enable the reintroduction of lost habitats and foster increased biodiversity within the area.

Moreover, the infrastructural works being proposed by IM will also allow controlled seawater flow into the marshland without causing detrimental erosion effects on the coastline.