Présentations Colloques

Poster
7.02
Session 7.02: Urban Hydrogeology
Parmentier (orateur)
The impact of urbanization on groundwater quantity and quality – model predictions for urban planning of the city of Lille
At less than 10km south of the urban core of the city of Lille (North of France), the chalk aquifer is a shallow and productive groundwater resource. Around 40% of the water supply of the city of Lille comes from wellfields located in this area. Due to its location, this area is becoming more attractive for economic and residential development. Urbanization inevitably causes soil sealing and runoff collecting, leading to the decrease of groundwater recharge, and then to the risk of a non-sustainable drinking water resource.**In this study, the impacts of urbanization on groundwater systems are analyzed using a previously developed hydrogeological model [1]. Predictive simulations over the next 30 years are built taking into account surface sealing of soil due to future urban development projects. The modeling results suggest that urbanization in south of Lille should increase the supply by rivers and waterways and should decrease the groundwater level in the chalk aquifer. No modification of the size of the feeding area could have been identified.**These changes of amount and origin of water should likely impact the water resource quality because (1) the water and sediments of rivers and waterways are of poor quality, (2) the decrease of groundwater levels can alter the wetland purification system, and (3) the decrease of groundwater levels near a Chalk-Clay interface can modify the geochemical behavior of undesirable substances (see [2] for details).**The impacts of urbanization on groundwater systems can be predictable and should be considered in urban planning. The impacts of soil sealing have been analyzed in the area around the city of Lille. Urbanization also leads to a more intense anthropic activity that increases the risk of accidental pollution. With the aim of defining a territorial development consistent with the sustainability of water resource, hydrogeological study should be associated with economic and or social studies.**References- [1] Bessiere et al. (2015) BRGM RP-63689-FR. [2] Cary et al. (2014) Applied Geochemistry 48-70-82.
FRANCE