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Directory: HomeAbout Our Water Committee Projects Publications and Resources About the Committee Kids' Corner |
Aquifer: a zone of earth material capable of supplying groundwater at a useful rate
from a well. On the Eastern Shore, there are four major aquifers that make up one system.
The four major components are the Columbia, Upper Yorktown-Eastover, Middle Yorktown-Eastover
and Lower Yorktown-Eastover,
generally the earth material that bears the water is gravel, sand or shell.
Confining Layer: a layer allowing little water to move through it and made
of earth materials that have few interconnected pores. Confining layers
break our aquifer system up into its several components. It is made up of silts and
clays.
Unconfined Aquifer: an aquifer with no confining layer restricting the upper
surface of the area of groundwater saturation. Only one of our aquifers, the
uppermost one called the Columbia, is an unconfined aquifer. The top of the zone of groundwater
saturation is our water table.
Confined Aquifer: an aquifer that has a confining layer restricting it, this
sometimes causes the water to be under pressure. The Yorktown Aquifers are all confined
aquifers.
Recharge: any process that adds water to the aquifer and can be natural
infiltration from rain or snow or human induced such as a broken water line. Increased
pumping also increases natural infiltration rates. On the Eastern Shore, recharge
comes from rain, snow and leakage from ponds. The current estimates of recharge to
our water table aquifer (the Columbia) varies across the Shore from 0.7 inches/year
to over 13-inches/year. These estimates are based on age dating the water in our
shallow water table aquifer (USGS WSP 2479)
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Accomack-Northampton Planning District Commission Phone 757-787-2936 or toll-free 866-787-3001 Fax 757-787-4221 email anpdc@a-npdc.org 23372 Front Street, PO Box 417, Accomac, VA, 23301 |
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