Belgian cities are some of the rainiest in Europe: what's up with water?

By Wini Pannier & Mathilde Abnet 

Climate change is accelerating long-term changes in global temperatures and weather patterns. Melting ice sheets, rising sea levels, disturbed rainfalls, increasing rates of floods and droughts: water is the crux of global warming (United Nations, sd).

 

Images of worldwide devastating wildfires linked to drier seasons seem to be multiplying over the years (United Nations, sd). Especially in the last 5 years we have also experienced it in Belgium: water scarcity, water quality, water salinization... Even though we are also experiencing drier summers in Belgian cities, as visible in the browning grass of park lawns, our rainy Belgian climate could mislead us to think confidently that water scarcity will never be a problem here. However, the opposite is true. (VRP, 2022)

 

Belgium is one of the European countries most at risk for water shortage. On a global scale, Belgium is ranked 23rd out of 164 countries suffering from water scarcity and is the third highest in Europe, as testified by a report by the World Resources Institute (WRI). This scarcity, referred to as “water stress”, is the highest in the territory of Flanders. (aqueduct, sd).

 

Figure 1: Water risk atlas in which Belgium stands out with a high level of water stress (aqueduct, sd)

 

How can the country with the highest number of rainy days in Europe be one of the most water-stressed of continental Europe?

 

Marijke Huysmans, professor of groundwater hydrology at the University of Antwerp, provides us an explanation. Of all the water flowing in our faucets, half is sourced from surface water or “streams” and the other half from groundwaters or “pumped wells”. The groundwater layers or “aquifers” are composed of 10-meter-deep shallow waters and deeper waters, as can be seen on figure 2.

 

Figure 2: groundwater flow systems (wikipedia , sd)

In Flanders, the rain either infiltrates streams and sewers (7%), infiltrates groundwater (30%) or evaporates (63%). Streams are quick to refill, but groundwater aquifers aren’t.

 

The deeper the aquifer, the slower it takes to fill in, cause of the poorly permeable layers. This is related to the geological structure of Flanders, where (except in the coastal area) the subsoil consists largely of clay (VRP, 2022). In the summer, the groundwater aquifers don’t get filled in as much as rain is absorbed by plants and heat. The level is at its lowest at the end of September and highest at the end of March. Given the high demand for groundwater in Flanders and the scarcity of this raw material in general, it is not surprising that groundwater extraction often exceeds the carrying capacity of the groundwater layer. On the other hand, the induced droughts due to climate change, also prevent the aquifers to get refilled in the usual span of one winter.  These droughts are expected to become longer, more intense and recurrent with the increase in the average earth temperature.

 

So, when looking out the window on yet another rainy day, one can be cheered up by the thought of plants being watered. However, heavier rain falls might help the plants in our garden, but they don’t contribute to groundwaters being refilled faster. In fact, the more the deepest reserves dry up, the more time it takes to fill them up again, sometime as long as decades.

 

 

Here's where the counter-intuitive evolution comes in… the water scarcity is happening parallel to an increase of floods in Belgium

 

Due to its strong terrain, Belgium is naturally sensitive to flooding in several areas (cfr. Floodings Wallonia 2021 (Romans Stéphanie, De Tijd)). Even a brief period of intense rain can lead the rivers to expand quickly and reach its peak flow. The many human interventions on the water systems also create extra pressure: large parts have been paved or occupied by buildings, the river has been diked and straightened in various places, weirs and locks control the entire system.

 

"Heavy precipitation only penetrates a little or not at all into the ground, and thus does not feed the groundwater, but instead runs off at the surface. Very often we see the "water" - a combination of rain and soil - flowing through streets." (Walker Lauren, The Brussels Times)

Figure 3: urbanization in Europe (earthly mission , sd)

Figure 4: floods in Vesdervalley (De Standaard, 2022)

 

A tip of the solution: steppingstones towards a climate-proof Flanders

The Government of Flanders recently reached an agreement on an integral Flemish climate adaptation plan 2030, with a view to a climate-proof Flanders by 2050. With this plan, they want to arm Flanders against the impact of climate change and ensure concrete implementation of measures in the field. Within adaptation policy, creating space for water is essential, both in terms of water safety (prevention of and protection against flooding) and extreme drought. In this plan solutions come forward like wetland restoration and afforestation strategies, which are extremely suitable for arming us against drought and flooding. Also, city-adaptations like urban greening, green roofs and green facades, wetter crops… are proposed. The transformation into sponge cities can turn the negative impact of cities and villages on ecosystems into a collective collaborative ecosystem.

 

Conclusion

 

All our extensive water facilities could not prevent us from being confronted with water scarcity, sudden flooding, and limited navigability. The way it is used now, the soil almost everywhere loses its sponging effect, which means that the discharge rate in watercourses can suddenly rise sharply shortly after a heavy rain shower. Fortunately, there are several government initiatives to bring water volumes in Flanders back into balance. Governments, residents, designers and engineers, landscape designers and urban planners will have to work together intensively to form a spatial blueprint for Belgian cities and tackle the issues of flooding, water availability and water shortages. One important conclusion came out of our research, whether it concerns pollution, overuse, drought, or flooding - is a task for all of us together to focus on the care values of natural water cities, citizens, and governments.  

 

Bibliography

 

aqueduct. (sd). water risk atlas. Opgehaald van https://www.wri.org/applications/aqueduct/water-risk-atlas/#/?advanced=false&basemap=hydro&indicator=bws_cat&lat=49.33228198473771&lng=5.394287109375&mapMode=view&month=1&opacity=0.5&ponderation=DEF&predefined=false&projection=absolute&scenario=optimistic

De Standaard. (2022). ‘Onze kaarten tonen de gebieden die niet kúnnen, maar zúllen overstromen’. De Standaard .

earthly mission . (sd). european cities urbanization map. Opgehaald van https://earthlymission.com/european-cities-urbanization-map/

Romans Stéphanie, De Tijd. (sd). Onzekerheid en frustratie regeren jaar na overstromingen. De Tijd.

United Nations. (sd). Water – at the center of the climate crisis. Opgehaald van https://www.un.org/en/climatechange/science/climate-issues/water

United Nations. (sd). What is Climate Change? Opgehaald van http://https//www.un.org/en/climatechange/what-is-climate-change#:~:text=Climate%20change%20refers%20to%20long,activity%20or%20large%20volcanic%20eruptions

VRP. (2022). water. Ruimte , p. 87.

Walker Lauren, The Brussels Times. (sd). Water scarcity as floods rage: Belgium's climate change contradiction. The Brussels Times.

wikipedia . (sd). Groundwater. Opgehaald van wikipedia : https://en.wikipedia.org/wiki/Groundwater#/media/File:Groundwater_flow.svg