Updated: Coastal defence at Marsalforn

Updated - adds reaction by Mepa.

The tamarisk-lined fishing harbour beach at Marsalforn looks set for extension as Gozo's first artificial beach.

It is hard to believe it will all be worth it merely for the benefit of a few- Anne Zammit

Yet, a report from the Marine and Storm Water Control Unit at the Ministry for Resources and Rural Affairs shows that the proposal is rather more complex than a straightforward beach re-nourishment as was done at St George's Bay.

Works, which can only take place in calm seas over the dry tourist season, include upgrading of the storm water channel, building of a protective groyne, and the construction of a submerged breakwater in the middle of the bay. The emphasis is on improving coastal defence with an extended beach area as an add-on tourist attraction.

Once every 50 years a storm blows up that is forceful enough to send two-metre-high waves directly into the north-facing bay. On approaching the inner part of the bay, storm waves can rise up to a height of four metres, crashing over the sea wall.

Owners of summer houses barricade their doorsteps with iron-clad screens in winter and shop shutters have been known to suffer damages.

In January 2010, storm waves lifted parts of the newly-laid promenade, throwing debris into the street and damaging shutters and house entrances. Some blamed the event on poor workmanship. Small boulders from the sea bed were also swept into the street.

Damage to the Marsalforn seafront is said to have become more frequent and intense after the 1960s breakwater on the Żebbuġ side of the bay was destroyed in a storm some years back. Erosion of the existing beach, next to the tiny fishing harbour, appears to have increased as a result.

A decision against repairing the old breakwater was taken when a study found it would have to be extended to a length of 160 metres to be effective.

The visual intrusion of a large breakwater of the type at Mġarr Harbour was decidedly unacceptable. There were also fears that this would cause water in the bay to become stagnant and that the arm might provide an excuse for another yacht marina.

The benefits of reducing storm damage through beach nourishment will have to be weighed against many considerations. Creating a wide beach can reduce storm damage to coastal structures by dissipating energy across the surf zone and beach instead of having an impact on land-based infrastructure.

An artificial reef placed in sections, such as a submerged breakwater reaching across the bay from the fishing harbour, would break up the force of the waves entering the bay.

At the same time a strong offshore flow may be anticipated in the gaps between sections as water flows back out to sea compensating for the mass of water that has crested over the 'reef'. It is quite possible that longshore drift, set off by new currents in the bay, could produce a higher rate of erosion of the artificial beach.

A groyne, or physical barrier to stop beach sediment being washed away, appears to be an option, although careful design is important to avoid erosion along the shore.

Artificially nourished beaches tend to erode faster than natural beaches unless nourishment is successfully complemented by measures to reduce erosion rates.

It is generally recognised that beach nourishment has a finite lifetime of between one and 10 years, and 're-nourishment' is almost always required.

This bodes well for whoever supplies the beach nourishing material since such a self-perpetuating contract may present an attractive prospect. In Gozo the present plan appears to be for the beach nourishment material to be sourced from a local limestone quarry.

Despite the use of a silt curtain, as proposed in the project description statement, the effect this project may have on the clear blue waters of Marsalforn does not seem to have been examined thoroughly.

Dredging of an underwater cradle for the submerged breakwater to rest will turn the crystal waters from clear to cloudy. The more long-term impacts have not been made clear.

According to the projected timescale in the MRRA report work on the submerged breakwater would begin in the summer of 2013. The report says dredging to excavate a shallow trench and fill the submerged breakwater with gravel would take at least 30 days to complete.

It is hard to believe it will all be worth it merely for the benefit of a few at the expense of an existing balanced landscape of the harbours and beach with their unique character.

Depositing of quarry sand by five tipper trucks, a crane and a mechanical shovel, which is to spread the material along the entire seawall length will coincide with the peak summer period between May and August 2012.

Selection of suitable material for beach re-nourishment is an essential stage in the process. Ideally a sand survey presenting geophysical profiles with surface and core samples should be carried out.

What is especially important is the sediment's grain size, which must closely match the native material of the existing beach.

The ability to predict the performance of a beach nourishment project is highest when the project is constructed on a long, straight shoreline without the complications of inlets or other engineered structures.

Studies on the different coastal defence options for Marsalforn Bay were carried out for the MRRA by Sogreah Consultants, an independent consulting group.

The name Sogreah is also associated with the Artelia Group and a patent for Accropode, which evolved from the original Dolos, A-Jack, and Tetrapod breakwater blocks designed to be resistant to wave action.

The planning authority is currently assessing the application submitted under architect Angelo Portelli from the Ministry for Gozo's Department of Projects and Development. A new target date for the permit has been assigned following changes to the original proposal.

In the absence of a full environmental impact assessment there is a strong risk of permanent alteration of the natural environment at Marsalforn Bay.

MEPA REACTION

The Malta Environnment and Planning Authority (MEPA) in a reaction, said it denies the concluding statement made by Anne Zammit that MEPA is currently assessing the application for the construction of coastal defences against wave incidence on shore at Marsalforn Bay, in the absence of a full environmental impact assessment that may result in a strong risk of permanent alteration of the natural environment at Marsalforn Bay.

"The Authority can confirm that following the submission of a project description statement by the applicant (Ministry for Gozo) earlier in this year, MEPA screened the proposal and last July, informed the applicant that both an Environment Impact Statement (EIS) and an Appropriate Assessment (AA) need to be carried out for the application to be processed.

"Both the EIS and the AA will assist the Authority to predict, analyse, interpret and prevent significant environmental and ecological impacts of the proposed project.

"The EIA process for the drawing up of a full Environment Impact Statement commenced on the 16th August with a 3 week public consultation period whereby the public was given the opportunity to suggest what key issues should addressed in the compilation of the Environmental Statement (ES) and the framework of approach that has to be taken. These Terms of Reference will be sent to the applicant and published on the Mepa website in the coming days. Following this the applicant, through the appointed consultants can start working on the Environment Impact Statement (EIS) -which will once again include a public consultation phase together with a public meeting," Mepa said.