APRONA

Responsible entity

The association for the protection of the groundwater of the Alsace plain (APRONA) is in charge of managing the regional observation networks related to the quantity and quality of groundwater in Alsace and of making information available to the various water stakeholders. APRONA gathers representatives of the Rhine-Meuse Basin Committee, local authorities as well as users, private companies, farmers or nature protection associations. Competent personalities are also associated, in particular a representative of the Ministry of the Environment of Baden-Württemberg (Germany).

Institutional setting

APRONA was created on March 28, 1995 and its founding members are: the French State, the Regional Council of Alsace, the General Council of the Lower Rhine, the General Council of the Upper Rhine, the Rhine-Meuse Water Agency. APRONA is composed of: a board of directors, an office, active members, associate members and honorary members. Active members must be approved by the board of directors and have a deliberative vote at the General Assembly. Associate members participate in the work of the association, but do not have the right to vote. Finally, honorary members can be appointed by the general assembly on the proposal of the executive committee and the board of directors.

Geographical setting

The Rhine water table (water mass CG001 – Pliocene of Haguenau and Alsace water table) is one of the most important underground water reserves in Europe. It extends, in Alsace, on 3200 km² of which 400 for the pliocene of Haguenau. The quantity of water stored, for this part of Alsace alone, is estimated at 35 billion m3. The supply of the water table is ensured:

• directly from precipitation on the plain (effective rainfall);
• by infiltration of the Vosges rivers whose flow is also dependent on precipitation;
• by infiltration of water from the Rhine, depending on the section and the development;
• by lateral contributions at the edge of the Vosges or the Black Forest, by the water tables of the Doller, Thur, Lauch and Fecht rivers in particular.

The water withdrawals from the aquifer are mainly due to:

• exchanges with the rivers and the Rhine which can drain the water table;
• withdrawals by pumping for domestic, industrial or agricultural uses.

The fluctuations of the water level are not without consequences on the natural environment and the human activities: drying up of the wetlands, water rising in the individual houses or the public buildings, incidences on the importance and the propagation of the pollution (appearance of the new vectors of water pollution from the ground or the surface water poorly protected by permeable soils and located at a low depth), the water table is subject to degradation due to multiple pollution, diffuse and/or punctual, of industrial, agricultural, domestic origin or pollution of surface water which infiltrates into the water table.
The Sundgau is the part of the Haut-Rhin department located south of Mulhouse. From a geographical point of view, it is a landscape of gentle hills continuing towards the west with the hills of Belfortain. The region is bordered to the north by the Doller valley and the Alsace plain, and to the east by the Rhine plain, known as the “Sierentz ditch” between Basel and Mulhouse. In the south it stops on the Swiss Jura chains, of which the Ferrette limestone massif represents the first buttress.

Detailed explanation

Measuring network
APRONA manages a piezometric network of 170 points on the Alsace water table, which can be used to: (i) carry out a global statistical analysis and characterize the functioning of the water table, (ii) carry out hydrodynamic and transfer modelling at the scale of the water table or more locally, (iii) establish reference conditions and analyze the representativeness of the monitoring networks, (iv) defining and monitoring vulnerable sectors within the framework of drought decrees, (v) mapping areas at risk of flooding by rising water table or preferential infiltration, and (vi) evaluating water table-river exchanges and monitoring remarkable wetlands.

Live monitoring
Live monitoring of the water table is possible for 27 reference points of the network. For each station, graphs established with updated data (refreshed every 12 hours) present the evolution of the water table over the last 15 days and over the 12 months and the measurements are automatically put online on the APRONA website. The monthly situations are represented with the help of the standardized piezometric indicator (SPI) which allows to qualify the water table levels in relation to the whole chronicle and the evolution of the levels in relation to the previous months.

State of the the art
The state of the art is frequently published to act in favor of the recovery of the quality of groundwater. These assessments are carried out every 6 years. Through a follow-up of historical pollution and the search for emerging molecules, these assessments help to anticipate, redirect and/or size the actions to be implemented to recover and preserve the quality of the water resource. This work also contributes to the transboundary declination of periodic inventories of the most important aquifer in Europe by associating the German and Swiss partners on their territories concerned.