Glossaire de A à Z


Unconfined aquifer

Updated on 19/06/2018
Définition
Sens technique
Aquifer with a free surface and unsaturated zone.
Source
According to Poitou-Charentes Regional Council

Unconfined groundwater

Updated on 19/06/2018
Définition
Sens technique

Volume of groundwater whose surface is free, i.e. at atmospheric pressure. The surface of an unconfined groundwater fluctuates freely without any constraint. These aquifers are often shallow.

Source
According to BRGM

Underground dam

Updated on 06/09/2018
Définition
Sens technique
A groundwater impoundment structure built across underground water channels. The underground dams are built in the sub-soil. They store water in geological formations, retain groundwater and require pumping facilities to make water usable.
Source
according to the Japanese Ministry of the Environment

Underground disposal

Updated on 06/09/2018
Définition
Sens commun
Discharge of effluents or pollutants on the ground or infiltration into the subsoil.
Source
according to the Ministry of the Environment and BRGM

Underground river

Updated on 06/09/2018
Définition
Sens commun
Stream passing through a very large cavity (e.g. a cave or a cavern) or a set of large communicating cavities.
Source
according to UNESCO

Unsaturated zone

Updated on 25/02/2019
Définition
Sens commun
Subsurface zone not completely saturated with water (coexistence of water and air in the interstices of the rock) above the surface of an unconfined aquifer and where flows are vertical.
Source
according to BRGM and AFB

Untreated wastewater/sewage

Updated on 19/06/2018
Définition
Sens commun
Wastewater discharged into the natural environment without any treatment.
Source
According to Eurostat

Untreated water

Updated on 19/06/2018
Définition
Sens commun

Surface or ground waters as they occur in the natural environment before being treated for use. These are untreated wastewaters.

Source
According to Poitou-Charentes Regional Council

Up-dating/up-grading

Updated on 13/07/2018
Définition
Sens technique
A mathematical operation that compares economic values spreading over time by adjusting the future value of a property to the current value. The update allows the analysis to take into account the costs or benefits that will materialize in the future. Note: The choice of an up-date rate (coefficient used to bring a future value back to a present value) has an influence on the result. In 2005, the General Planning Commission proposed revising the up-dating rate of public investments.
Source
According to the Ministry for the Environment and IOWater

Upstream

Updated on 04/07/2018
Définition
Sens commun
Part of a watercourse which, with respect to a given point, is located between this latter point and the watercourse hearwaters.
Source
According to Adour-Garonne Water Agency

Urban Waste Water Treatment Directive

Updated on 13/07/2018
Définition
Sens technique

Directive 91/271/EEC of 21 May 1991 concerning urban waste water treatment. It concerns the collection, treatment and discharge of urban waste water and the treatment and discharge of waste water from certain industrial sectors. Its purpose is to protect the environment against the adverse effects of the above-mentioned wastewater discharges. For this purpose, it defines the obligations of local authorities regarding the collecting and treatment of urban waste water and the terms and procedures for agglomerations with more than 2,000 population equivalents. The municipalities involved must, in particular,:…

Source
According to the Ministry for the Environment and AFB

Urban wastewater collecting system

Updated on 13/07/2018
Définition
Sens commun

All facilities for the collecting and treatment of urban wastewater. These systems are often managed by public authorities or semi-public associations.

Source
According to Eurostat

Usable Agricultural Area

Updated on 13/07/2018
Définition
Sens commun
Surface including field crops, permanent grassland areas, permanent crops (vineyards, orchards, etc), fallow lands, family gardens and orchards. The usable agricultural area does not include the grounds of buildings and yards, moors and unproductive wastelands, poplar plantations, thickets, woods and forests of the farm, as well as non-agricultural areas.
Source
According to Poitou-Charentes Regional Council

Use restriction

Updated on 06/09/2018
Définition
Sens réglementaire
Exceeded limits lead to restrictions of use and water withdrawal, to cope with a shortage of water resources during low water periods. Restriction measures are defined locally by the prefects. Generally, measures to limit withdrawals are progressive (depending on the thresholds defined for vigilance, alert, quick reaction alert or crisis) and adapted to different uses (domestic, agricultural, industrial).
Source
according to the Ministry of the Environment

Useful flood flow

Updated on 13/07/2018
Définition
Sens technique
Flood flows essential to the life of the watercourse and its water dependent areas, and having no unacceptable effects (especially on living settlements). Small floods have a fundamental role in the dynamics of environmental recovery, they should not be removed nor the environments be protected from them.
Source
According to the Ministry for the Environment and AFB

Utilization value

Updated on 13/07/2018
Définition
Sens technique
Value assigned to a good or service by an agent on the basis of the usefulness he derives from it. The utilization value involves two components: the actual utilization value and the option value attached to a possible use later on.
Source
According to Rhone-Mediterranean and Corsica Water Agency