Review of The Major Water Resources in France

Underground tablecloths, streams, lakes... are natural resources. These potential sources of supply have the role of satisfying domestic or economic water needs. A source created by man will be considered artificial. This is the case with water bodies or canals. Coastal waters may also constitute a water resource, particularly in some coastal areas, for example, for household use after desalination or for feeding marine aquaculture basins. On the other hand, it should be emphasized that a cistern or a well are not resources but storage devices.

Important water resources:

On average, there are 480 billion m³ of precipitation for the French territory each year. We can also count 270 000 kilometers of permanent streams and groundwater, estimated at 2 trillion m³. On the basis of these figures, France can be considered to have considerable water resources.

• 61% Evaporation
• 23 % Groundwater
• 16% Rivers, laks.

A very dense hydrographic network

All the waterways in France represent a total length of 270 000 km. The watersheds of the four main French rivers, Garonne, Loire, Rhône, Seine, dray 63% of the waters of the territory. The remainder is ensured by numerous coastal basins, Adour, Somme, Charente, var, or tributaries of rivers of neighboring countries, Rhine, Scheldt. Beyond the quite satisfactory level of precipitation and total flow, France also enjoys very good natural storage capacities, thanks to mountain ranges and to large underground aquifers.

Bring a nuance to these reassuring averages. Indeed, all the French regions are not housed in the same sign. Consideration should also be given to the level and regularity of rainfall (which varies from 0.5 to 2 meters/year depending on the region), the presence or not of large underground aquifers, the levels of flow (from 1 to 10) and that of the sampling. For example, Brittany is known for its low wealth of underground resources, due to its granitic soil. It is therefore necessary for this region to resort to superficial resources for the bulk of its production of drinking water.

A contrary, on the Mediterranean rim, the climate is drier and prone to violent variations in rainfall. In a large Southwest quarter of the country, the strong need for increased irrigated areas causes drought. Hence, sometimes, the need to restrict uses by prefectural decrees or to provide equipment (dams, reservoirs, other boreholes).

Last, the current global warming, if confirmed, could increase exceptional hydrological events (floods, intense rains, storms, droughts) that may lead to long-term constraints on water resources and their uses in particular in the summer.