After ten days without a drop, the rain made its big comeback on Monday in part of the country. From this Tuesday evening, the precipitation will become widespread, with stormy and abundant showers in places.
If the return of the rain could be likened to good news in view of the unprecedented episode of drought that Belgium has just experienced on its territory, it will in reality not allow any real improvement for the soil and could even lead to major floods.
Indeed, the weather of the last few days has completely dried up the land and groundwater, allowing a kind of “crust” on the surface of the soil. This natural barrier prevents water from penetrating the land and will, on the contrary, cause runoff.
“At the moment, the earth is like concrete, it is so dry. Locally, if between 10 and 20 liters of water falls per m² in 30 minutes or in an hour, this could create problems in the fields in particular” , explains Stephan van Bellinghen on RTL Info.
A video posted on the Twitter account of the University of Reading, West London, perfectly illustrates this phenomenon. In the sequence, three cups filled with water are used and spilled on three different grounds: wet grass, “classic” summer grass and grass completely scorched by a heat wave.
On the wet lawn, it only takes a few seconds for the water to seep into the ground. On the grass of a “classic” summer, the content takes about a minute to completely pour out. On the other hand, on the dry lawn, the water is absolutely not delivered.
“Experience illustrates how dangerous heavy rainfall after a dry spell can be by causing flash floods“, comments the University of Reading.
To help dry soils, the real solution would be to have fine, soft and lasting rains. A phenomenon unfortunately very rare in summer.