The question that now arises is what would happen if the state decided to constrain urbanization even more. The question leads to two other possible urban expansion programs and which includes a concentration and densification of urban areas in concentrated dwelling areas.“These theories were not just plucked out of thin air”, explains Arnaud Beckers. “They are in accordance with the current political thinking of the ministry responsible for urban planning. These areas of concentrated housing vary according to the density of the population, services such as schools or businesses, distance to main emploment centers and are the result of a rationale which covers considerations other than flood-prevention.” These theories aim to bring about a more rational use of territory such as limiting journeys by concentrating the population into areas that are already populated and where services are altready developed, for example. These scenarios are prospective therefore, but are connected to concrete discussions currently taking place in Wallonia. 

The first of these two scenarios of urban densification was estimated at a regional level, where there is a concentration of households near the main centres of employment, that is to say, Brussels, Charleroi and Liege. The second would involve a densification at a more local level, no longer taking account of an exodous from the countryside or from smaller towns. These possible scenarios will depend mainly on limits to future political decisions. They will become a reality following the occurrence of many factors external to public authorities, such as the availability of work, the cost of living in the big cities or the fluidity of public transport.

Each of these three urbanization scenarios (continuation of the current situation, densification at a regional level, densification at local level) was confronted by three degrees of restriction. The highest degree of restriction was a ban on building in areas with average to high flood-risk, the lowest consisted of an absence of restriction. The middle degree of restriction only banned urbanization in zones with a high flood-risk level.  By combining these results with the two climatic scenarios, the researchers were able to establish flood-related damage estimates due to flooding of the river Meuse over the next 100 years.



Ultimately, according to the optimistic “dry climate ” scenario, and following nine possible town-planning scenarios, damage caused by flooding would reach a range calculated to be somewhere between 334 and 462 million Euros, representing a growth of between 1 to 40% in relation to an estimate based on 2009 data. On the other hand, according to the less optimistic scenario, predicting an increase in flood-risk of 30% between now and the year 2100, damage would reach a range estimated to be between 2,124 and 2,408 million Euros, which represents a growth of between 540 to 630%.

The figures speak for themselves, a restriction in the areas of risk causes a marked decrease in costs related to flood-damage and this applies to all possible scenarios. Although far from being sufficient, such a restriction would allow for a reduction in catastrophic damage along with other measures such as the building of dams or dykes to avoid catastrophic damage. These figures only concern flooding of the Meuse but provide some indication of general trends. For their part, the researchers have just launched a new four-year study which will take into account new factors such as disruption to transport, economic activity, interaction with underground water, or the effects of flow into the river basin in more precise urban and climate scenarios. While waiting for their results, a first prudent measure to be taken by public authorities would be to cease building in areas prone to flooding.