Unsurprisingly, the abundant rainfall recorded in recent months has a direct effect on the level of water recharge in our territories. Reading the monthly hydrological situation bulletin for October 2024 in New Aquitaine is enlightening regarding the level of groundwater: “With 96% of piezometers with a level higher than their average, including 75% with a very high level, we are at the forefront of the most favorable situations of the last twenty-one years for the month of October”indicate the editors of the Nouvelle-Aquitaine regional biodiversity agency (ARB-NA).
The risk of flooding could be amplified due to high levels of water tables, rivers and humidity
Regional Biodiversity Agency
The same goes for the level of watercourses, with 98% of stations having a flow rate above average, including a large majority (93%) with a very high flow rate for the month of October. Or the filling rate of reservoir dams of 81%, significantly above average “and the most ever recorded at the beginning of November over the last sixteen years”. A situation described as “very satisfactory” after several years of drought, but the territories could suffer this winter, warns the ARB-NA: “The risk of flooding could be amplified due to the high levels of water tables, watercourses and soil humidity currently observed. »
Rain in October: + 77% in Poitiers
At the level of the Vienne department, the weather data for the month of October confirm that we did not lack water. According to data from the Météo France station in Poitiers Biard compiled by the Infoclimat site, the rain gauge recorded 127.9 mm over the month, or +77% difference from the 1991-2020 normal (72.4 mm). And despite average temperatures above normal 1991-2020 (+2.2°C for minimums; +0.3°C for maximums), signs of the effects of global warming linked to human activities, we have still suffered. lack of sunshine. After -29% deviation from normal in September, it was -36% in October!
The groundwater is full
This significant precipitation had an immediate effect on the watercourses in the Vienne in October, with all measuring stations (nine) noted with a very high flow, according to the ARB-NA. And the underground water tables followed the movement with the twenty-seven piezometers indicating a level from high to very high. The agency considers that 94% of the piezometers present in the Jurassic limestone of Poitou display a very high water table level. This is also the case in the captive infratoarcian of Poitou (13% high, 88% very high). Two years ago, in mid-November 2022, 77% of piezometers noted a level below average and the Clain was just coming out of its crisis flow (2 cubic meters per second).
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