aquitard


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Related to aquitard: Aquiclude, aquifuge

aq·ui·tard

 (ăk′wə-tärd′, ä′kwə-)
n.
A body of rock or stratum of sediment that retards but does not prevent the flow of groundwater from one aquifer to another.

References in periodicals archive ?
Distribution of nitrate in groundwater affected by the presence of an aquitard at an agricultural area in Chiba, Japan.
Using published values for the hydraulic conductivity of bedrock and overburden, they concluded that the mining does not influence the Selisoo water regime because the hydraulic conductivity of the Oandu aquitard and oligotrophic peat layer is low and usually the annual rainfall is larger than 540 mm [yr.
The sequence above the coal seam can be classified as an aquitard consists of top soil and the clay, and the rest of sequences can be classified as an aquifer that includes fine to coarse sand with silt.
In 2008, the mine was found to be damaging the aquitard, the dense layer of rock that forms a natural protective barrier between the aquifer--the city's water supply--and surface.
Other contributions in this issue include an article by Eileen Van der Flier-Keller describing geoscience outreach activities during the British Columbia Year of Science, Stephen Johnston's Presidential Address from the Ottawa GAC-MAC, a historical article by Ian Brookes on longtime GSC geologist Robert Bell's years at Queen's University, a review of the 'roadside geology'-type book, Okanagan Geology South by Jim Britton, and a report by Sarah Agosta and others on the Aquitard Hydrogeology Symposium held last June in Ottawa.
The terms aquifer, aquiclude, and aquitard are relative in a carbonate sequence because of variability in bedding, jointing, and fracturing.
The Uhaku stage is a relative aquitard in the Lasnamae-Ordovician aquifer system between the Lasnamae-Kunda and Keila-Kukruse water bearing horizon.
However, in the presence of an aquitard in the regolith, the flows were more likely to occur laterally than vertically (Macpherson and Sophocleous 2004; Rasiah et al.
Having conducted a review of the relevant literature, they report on the "state-of-the-science" of aquitard evaluation relevant to understanding and predicting chemical and microbial transport to underlying aquifers.