GC: n
CT: The groundwater zone is generally composed of aquifers and aquitards, with the aquitards having much lower permeability than the aquifers. Most aquifers used for municipal water supply occur beneath an aquitard that provides some protection from contamination from surface sources. The degree of protection an aquitard provides to a particular pumped aquifer depends on many factors including contaminant type, hydrogeologic setting and dynamics of the groundwater flow system established by the pumping. Many aquifers are protected by surficial aquitards, which are clayey or silty deposits occurring at ground surface; others are protected by aquitards buried beneath other geologic deposits. Aquifers not overlain by aquitards are generally much more prone to contamination. Aquitard integrity refers to the capability of an aquitard to provide protection to an underlying aquifer. Determination of aquitard integrity is an important aspect of groundwater management because without it, predictions of future groundwater quality cannot be reliable.
S: CherrPa – http://www.clu-in.org/download/contaminantfocus/dnapl/Chemistry_and_Behavior/Aquitard_State_of_Science_Reportfor_AWWARF_draft_of1-3-05.pdf (last access: 2 October 2014)
N: 1. Probably from latin aqui-, combining form of aqua “water” + -tardus “slow”. First Known Use: 1965.
2. Geological formation of low hydraulic conductivity which transmits water at a very slow rate.
3. Geological formation of a rather impervious and semi-confining nature which transmits water at a very slow rate compared with an aquifer.
4. It does not readily yield water to wells or springs, but may serve as a storage unit for ground water.
S: 1. MW; EOH – http://goo.gl/TW6SCS (last access: 3 October 2014). 2. GDT. 3 & 4. TERMIUMPLUS.
SYN: semi-confining bed
S: GDT; TERMIUMPLUS
