SLR Consulting use sophisticated hydrodynamic modelling to develop sea defences for Malta

SLR Consulting Ltd has recently completed a two year collaboration with Ecospan and AIS Environment in Malta. In partnership SLR undertook the hydrodynamic modelling of Marsaxlokk Bay; a natural port adjacent to a small fishing village on the south-eastern part of Malta, which is traditionally famous for its Sunday fish market and painted boats.  

Modelling was aimed at assessing the impact of a project to develop the infrastructure and coastal sea defences within the bay to provide additional shelter for boats and improve water quality within the harbour. 

The Malta Environment and Planning Authority (MEPA) requested information on what the effects would be from these proposals. The final report showed the results of the hydrodynamic modelling and reviewed the potential differences in impacts of alternate schemes.

(Image 1: saltwater marsh of international significance)

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SLR’s primary role was to assess the potential impacts of options that included:

  • a proposed breakwater on the west side of the Bay
  • a repaired and potentially extended breakwater on the east side of the Bay
  • a breach in the harbour wall to provide for additional flushing and water quality improvements
  • and to identify whether modifications or re-design could have the potential to make improvements to the schemes.  

Of particular concern was the potential impact on a nearby saltwater marsh of international significance that lies adjacent to the shoreline. 

(Image 2: Marsaxlokk Bay and development proposal)

The Il-Ballut saline marshland is designated at an international level as a Special Area of Conservation (SAC) and as such the team had to assess whether development of the sea defences would have the potential to cause harm through increased erosion or accretion of the protective beach in front of the saltmarsh. 

SLR, in partnership with Ecospan, and using information provided by AIS Environment, developed a hydrodynamic model of the Bay and the surrounding area of South East Malta including water depths, current flow, wave conditions and wind factors. The team then used internationally recognised mathematical modelling techniques to consider the effect of the tides, wind driven currents and of waves entering the area from offshore or generated within the bay. 

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SLR was able to identify that certain modifications would ensure that the risk of harm to the saltwater marsh would not be significantly increased. The report demonstrated the individual and combined impacts of proposals and made recommendations for mitigation or control. The project Environmental Impact Assessment, including the results of the modelling along with other key aspects, was ultimately consolidated and submitted by the project managers, AIS Environment.   

(Image 3: example of model data output)

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