Analysis of groundwater level historical data to detect climate change impact in France
Résumé
The level of groundwater bodies depends for many of them on the infiltration of meteoric water and willthereforebenecessarilyimpacted by climate change if it causes a change in the infiltration system (intensity, period). To assess and monitor the impact of this change, a dedicatedgroundwater monitoring network isnecessary. As this impact iscurrentlyunclear, the implementation of such a network involves an analysis of existinggroundwaterlevel data series. The studywasbased on modifiedMann-Kendall and Pettitt tests fromgroundwaterlevel data and a comparison of trends betweengroundwaterlevel data and climate data (precipitation, temperature, potentialevapotranspiration). Trend detection tests werecarried out on 377 piezometers of the french national groundwater quantitative monitoring network for whichwehad a data series of at least 25 years. In the end, 70 have a significant trend, 44 down and 26 up. Piezometersshowingsignificant trend mostlyconcernaquiferswithpredominantannualhydrologic cycle. But most of aquifers in France have longer hydrologic cycles and statistical tests do not permit to distinguishbetweenclimatic and anthropogenic influence. The conclusion of thisstudyisthatwecannotdemonstrate a significant impact of climate change on groundwaterlevels but itreinforces the need to set up a monitoring network dedicated to the impact of climate change on groundwater. In order to set up that network, about 40 aquiferswereselectedwithfollowingcreteria : unconfinedaquifer, recharge likely to beimpacted by climate change, aquiferweaklyimpacted by withdrawals.For each selectedaquifer,a monitoringwell or a springwasselected, based ona number ofcriteria andin particular the factthat the wellis inside an unconfined aquifer which is not influencedbypumping. They will constitute a new groundwater monitoring metanetworkto cover monitoring of climate change
Domaines
Hydrologie
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