Flood protection

Coastal flooding can be driven by storm surges and sea level rise. Between 1951 and 2023, the mean sea level in Ostend increased by more than 20 cm. The annual rate of rise has not remained constant over this period but appears to be accelerating despite natural variations. Since 2015, sea levels have been rising by more than 5 mm per year (VMM), a rate slightly higher than the global average between 2014 and 2023 (+4.8 mm per year) (WMO 2024).

The low-lying nature of the Belgian-Dutch coastal region (up to 10 km inland) makes it vulnerable to flooding from the sea. More than 85% of this area lies below +5.0 m TAW and is thus lower than the level of an annual storm surge (+5.5 m TAW) (EEA 2013, EEA 2017). Additionally, around 15% of Flanders lies less than 5.0 m above mean sea level. Moreover, Belgium’s coastline is the most built-up in Europe, with space shared by significant economic activities such as seaports and tourism infrastructure. As a result, in the event of flooding, loss of life and material damage could be severe (Kellens 2011, EEA 2017, Rubbrecht et al. 2022).

To protect the coast from the effects of storm surges and sea level rise, the Government of Flanders is implementing the Master Plan Coastal Safety (2011). This plan outlines the necessary measures to provide adequate protection for the coastline and the adjacent low-lying polders against a storm surge with a 1,000-year return period, using 2050 as a time horizon. The plan considers a sea level rise of +0.3 m compared to the year 2000. Since its approval by the Government of Flanders on 10 June 2011, the plan has been gradually implemented and is already well advanced.

In addition to the Master Plan Coastal Safety, the Coastal Vision strategy has been developed. This long-term strategy aims to protect the Belgian coast against the effects of rising sea levels well into the future. Coastal Vision considers a potential sea level rise of up to +3 m. Both plans apply location-specific measures, with innovative concepts such as nature-based solutions gaining increasing importance.

For more information, see the thematic chapter ‘Safety against flooding’ in the Compendium for Coast and Sea, the publication KustINzicht 2025, and the Klimaatportaal website.