With a view to improving the management of rainwater resources in its territory, Brest Métropole, which has been doing this for several years, will be launching a vast campaign to measure shallow groundwater in partnership with the Brittany Regional Division of the French Geological Survey (BRGM).
23 September 2020

This so-called piezometric campaign will take place from 24 September to 7 October 2020, for the purpose of mapping the depth of the superficial aquifers in the eight communes of Brest Métropole. 

To produce this map, five BRGM technicians and hydrogeologists will conduct a field measurement campaign using piezometric probes; these are simple devices of electrodes placed at the end of a coil of wire marked in metres, that trigger a ringing sound or light up a light when they come into contact with water. 

BRGM teams will be looking for nearly 300 public and private wells and boreholes, spread throughout the Greater Brest area, in order to measure the level of the aquifer under the ground. In urban areas, it is sometimes difficult to access these measurement points. This means that BRGM will also need the collaboration of the inhabitants of the Greater Brest area, in order to gain access to wells and boreholes that are on private property. 

The success of the operation will depend greatly on the number of points measured. 

This map of the level of the aquifers during low water periods at all the measuring points in the territory will be useful in various fields, in particular spatial planning. 

It will enable better prevention of flood and pollution risks, by facilitating analysis of the regulation of rainwater flowing over sealed surfaces and into the natural environment during heavy rainfall events. It could also improve the management of drinking water and sanitation networks. The data could also be used for drilling new boreholes or installing underground structures. 

The results of the measurement campaign and the groundwater level map will be available from the end of 2020; the map and the data collected will be available on the following websites: