Qormi, Birkirkara face highest flooding risk, study shows

Qormi is the locality where most people face the highest risk of flooding, followed by Birkirkara, a draft policy document shows.

There are 563 Qormi residents and 491 people in Birkirkara who live in zones at the highest risk of flooding.

The document drawn up by the Energy and Water Agency addresses flooding issues in Malta and makes several proposals to mitigate the impact.

The policy suggests the inclusion of rainwater harvesting infrastructure in new developments approved by the Planning Authority. It argues that these measures could save approximately 70,000 cubic metres of water annually.

The document identifies the areas most prone to flooding in Malta and Gozo and assigns a risk factor (RF), ranging from four (RF4), which may entail significant human, natural, economic, historical, and cultural losses, to one (RF1), representing very low risk.

Localities with lower risk are mostly affected during rainfall events with a probability of occurrence once every 50 or 200 years.

The areas with higher risk factors are those where flooding occurs frequently throughout the year, posing a significant danger to assets of natural, economic, historical, and cultural significance.

The proposed plan suggests prioritising RF4 areas when implementing flood mitigation measures.

The document also identifies the number of households and residents exposed to each type of risk in various localities.

All the localities in this mapping exercise fall within Malta’s water catchment areas - where water passes through valleys.

Populous catchment areas

The most populous catchment areas are the Birkirkara catchment, which includes Msida, parts of Attard, Lija, Balzan, and Birkirkara; and the Qormi catchment, which includes Qormi, part of Attard, Zebbug, Siggiewi, and Rabat.

In the Birkirkara catchment, 4,345 people are exposed to some degree of flood risk - 3,502 people in Birkirkara and 359 in Msida.

Among those living in the highest risk zones, there are 491 residing in Birkirkara and 300 in Msida.

In the Qormi catchment, 1,717 residents are exposed to some degree of risk - 1,172 in Qormi and 249 in Attard. Qormi is the locality with the largest number of people in Malta facing the highest risk – 563 residents living in six streets, including Triq il-Wied, Triq San Bastjan, and Triq San Frangisk.

Other areas with a significant number of residents at high risk of flooding include Fontana (176), St Paul’s Bay (194), and Marsaskala (257).

In Marsaskala, the streets exposed to the highest risk of flooding is found in Triq San Gwakkin, Triq La Sengle, and Triq Buzbiez, which are in the old village core.

Qormi’s particular exposure

In the Qormi catchment, flood hazard areas are primarily located along natural valleys, especially those that have seen urban sprawl.

The document says these areas in Qormi include many commercial properties and floods could also lead to significant transport disruptions.

In the Birkirkara catchment the greatest risk is found along Valley Road and Triq Dun Gaetano Mannarino both of which form part of a valley.

In the Marsaskala catchment, flood risk areas are mainly located in the lower portion of the catchment area, where urbanization obstructs the natural flow of stormwater runoff.

The risk is highest during once-in-every-200-year storm events.

The urban areas most at risk are found along Triq La Sengle and Triq San Gwakkin.

Water saving measures

The draft policy suggests the inclusion of rainwater harvesting infrastructures in new developments, indicating these could result in an annual water savings of approximately 70,000 cubic meters.

To put this into perspective, 70,000 cubic meters of water is equivalent to the amount of water contained in 28 Olympic-sized swimming pools. It would also provide enough water to irrigate 10 football fields for a year and roughly match the annual water usage of over 200 households.

The proposed plan also includes a revision of the existing regulatory framework for the construction of rainwater harvesting cisterns in new developments.

This measure is among several others being contemplated in the new plan, which has been issued for public consultation.

The report is a requirement of the European Floods Directive, which obliges Member States to create a Flood Risk Management Plan, identifying areas facing significant flood risk.

Why flooding occurs in Malta

The factors contributing to flooding, according to the document, include sprawling urbanization and deficiencies in stormwater infrastructure in valleys.

Unlike mainland Europe, where the major cause of flooding is overflowing rivers, Malta’s main problem is the location of most urban development in low-lying areas.

These low-lying areas often consist of dry valleys, which have been integrated into the urban fabric over time and now serve as main thoroughfares. When a storm event occurs, these paved dry valley beds act as conveyance channels for stormwater, which flows for only a short time before reaching the sea.

More wells, less floods

The plan also addresses the flow of water from rooftops to roads. According to the latest Census, the percentage of dwellings with wells has decreased significantly, from 35.9% in 2011 to just 25.6% in 2022.

This suggests that many dwellings approved since 2011 lack wells.

Prior to 2012, a law dating back to 1818 required all buildings to have a cistern in good condition, but this law was widely ignored despite flooding and water scarcity issues.

Regulations on the minimum energy performance of buildings require new buildings to incorporate in their design a reservoir of adequate size for the storage and re-use of rainwater runoff. In the case of apartment blocks, the well has to be used by at least one of the flats.

The new measure being contemplated seeks to strengthen these regulations by establishing an administrative framework for their effective implementation, with the Buildings and Construction Authority (BCA) responsible for this task.

The plan also envisions a support scheme for the restoration of rainwater harvesting facilities in existing houses, which is expected to save an additional 42,000 cubic meters of water. This measure will result in the reinstatement of damaged or unused wells to provide households with a second-class water system.

The most cost-effective measure, according to the plan, will be the addition of 7,300 square meters of green areas in urban environments, including the planting of 1,800 trees.

While the volume saved from being lost to the sea is not quantified, the implementation of a Valley Management Master Plan is considered the most effective measure.