While torrential rains and floods hit several European countries, including Germany, on Thursday, hydrologist Emma Haziza, guest of Europe 1, spoke of different causes that could lead to these climatic events, which are always more violent and recurring.
Among them, an urbanization not adapted to the evolution of the flood zones.
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The departments of Bas-Rhin and Haut-Rhin are placed on orange vigilance for the risk of flooding, and thunderstorms have caused flooding in Germany, killing dozens of people.
Guest from Europe 1 on Thursday, hydrologist Emma Haziza, reviewed the different causes leading to such flooding episodes.
Among them, urbanization bears a large share of the responsibility for the damage caused.
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"Calibrate these torrential rains as soon as concrete is placed"
"It is due to a sum of elements", concedes Emma Haziza, who however dwells more on the problem of urbanization in urbanized areas and "to the fact that we do not know how to calibrate these torrential rains from when placing concrete ".
Even today, explains the hydrologist, "there is hardly any place in France where you build a house while integrating the risk of flooding".
Indeed, she said, this is a very recent problem.
Because if we already know which areas are liable to flooding, climate change means that these areas are no longer at the same water heights.
"We have double the precipitation coming, with these cold drops and this extremely hot air around", develops the hydrologist.
"June 2021 is the third hottest month on the planet in 142 years of data," she continues, citing a mass of hot air and more precipitation, more violent and more dangerous.
"Unmapped risks of runoff"
While a million French people currently live in a flood zone, Emma Haziza insists: "We need to think deeply" about integrating new reflexes into town planning. Reflexes which are "absolutely not taken into account, neither by the town planner, nor by the architects", except in the zones concerned by the plans of prevention of the risks of flood, where the town planning is rather well controlled, specifies she does. In all cases, "the risks of runoff are not taken into account, are not mapped", deplores the hydrologist. As for the manholes, "they are absolutely not suited to rainfall levels of this magnitude," she continues. "So there really is some deep thinking that needs to be done extremely quickly."