Well-filled water tables: a safety mattress for the summer

Well-filled water tables: a safety mattress for the summer
Well-filled water tables: a safety mattress for the summer

“With all this rain, at least this summer we won’t be bothered with stories about groundwater lacking water…” With this rain that never stops falling, that’s the comment a bit sarcastic that we can hear or read on social networks.

We agree, the weather is crap. After experiencing the third wettest winter since 1991 (310.7mm of precipitation for an average of 228.6mm) and 61 days of rain (55.2 on average), spring continued at the same pace.

Between March 1 and May 20, 234.2mm of water fell in Uccle (for a spring normal of 165.6mm) and regional average precipitation throughout Belgium was above normal values ​​everywhere, ranging from 105% to 135% of normal depending on the region.

So, yes, with excess precipitation since October, water reserves are well stocked.

During its last assessment in April, the SPW Drought Expertise Unit noted that the levels “are currently higher than or close to the highest levels encountered at the same period during previous dry years (2017-2020 and 2022-2023). )”.

Some water tables are even at saturation. A rather rare phenomenon in Wallonia having even been observed in Rosières, in Walloon Brabant: the water table releases its excess water through a drilling point.

A comfortable mattress for the summer but not to waste

“The levels of groundwater reserves are indeed very comfortable,” notes Aurore Degré, professor of hydrology at Gembloux-Agro-Bio-Tech. “But this is certainly no reason to waste this precious resource.”

Especially since even if it is still raining a lot, the recharge period is now over and is gradually giving way to lowering levels. A phenomenon linked to evapotranspiration and the capture of water by plants during the development phase. A phenomenon which will increase with the development of crops which are established, late but gradually, in the fields. So much water which therefore no longer supplies water tables which, not being waterproof, begin their natural discharge process.

The situation in May therefore does not absolutely guarantee that there will be no shortage of water until the fall. This is particularly true in areas where aquifers have lower storage capacities, such as in the Ardennes for example. Even if, we repeat, the mattress is comfortable this year to absorb normal summer consumption.

Water shortage in the province of Luxembourg: replenishment of reservoirs continues

“I am not pessimistic for this year,” Aurore Degré continues, however, when talking about crops. “We really need a radical change, with several weeks of drought which would quickly dry out the soil before the plants can develop. This is unlikely. “

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