• Energy Research

This chapter describes the status of groundwater resources in France. French geology consists of a large variety of rock types, resulting in very different types of aquifers ranging from sedimentary basins, alluvial plains, limestone rocks, and crystalline rocks. Today, groundwater resources represent about 66% of Frances's domestic water supply, 31% of industrial water supply and 37% of total water use in agriculture. According to the European Water Framework Directive, about 33% of groundwater bodies were considered in good chemical status, and 10% were considered in a bad quantitative status in 2013. The main quality issues for groundwater are related to diffuse contamination by agricultural practices (i.e. fertilizers and pesticides). France has not yet faced the extreme cases of aquifer depletion experienced in many other countries. However, associated groundwater dependant ecosystems can be affected by groundwater abstraction. The long term challenges for groundwater management in France are related to the decrease of recharge due to climate change, sea level rise along the coast, and future change in groundwater use. The identified adaptation strategies are (i) new groundwater management policies, (ii) the development of managed aquifer recharge, and (iii) active groundwater management .

Extreme rainfall on Mediterranean karstic watersheds can lead to flash floods that may cause serious human and material losses. The anticipation of these events and the risk management during flood events are at the core of society and financial stakes. Karstic aquifers should also be considered as valuable groundwater resources. An active management of these aquifers may allow for an optimal use of water resources, while regulating the influence of the karst during flood risk periods. This study was carried out in the framework of the \textquotedblleftMultiple-Use Management of the Mediterranean Karstic Aquifer of the Lez River\textquotedblright project. It aimed at identifying the impact of the anthropic management of the water resource and floods under the present and future climate on the catchment. This project led to building a graphical method (toolbox for flood management presented as an abacus) for (i) a better understanding of the evolution of the water volume of the karstic system, the river discharge and the propagation of floods through constructed infrastructure of the river in urban areas, (ii) real-time flood forecasting, and (iii) analysing the impact of climate projections and active management scenarios with respect to the water in the karstic system as well as with respect to the flooding areas. The use of active management is thus shown to increase the availability of water resources while reducing flood risks.