GROUNDWATER GROUNDWATER GROUNDWATER Aquifer Geologic unit that can

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GROUNDWATER § Aquifer “Geologic unit that can store and transmit enough water to be a significant water resource” 1. Large volume (in relation to the amounts being removed annually) 2. Moderately high porosity 3. Facilitate easy movement of water toward a well § aquiclude

GROUNDWATER § Confined versus unconfined

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GROUNDWATER § Elevation energy and pressure energy

GROUNDWATER § Elevation energy and pressure energy

GROUNDWATER § Potentiometric surface § Equipotential lines § Potentiometric contours

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GROUNDWATER §Vx = Q/A §Water potential (hydraulic) gradient: §Q = h/ d

GROUNDWATER §Q = A h/ d §Q = K A ( h/ d) §Hydraulic conductivity (K) §“Permeability” §T = Kb §where b = aquifer thickness

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GROUNDWATER § Storage properties of aquifers § In GW flow, S = 1 and volume stored/unit volume =

GROUNDWATER § The volume of water a unit volume of aquifer releases in response to h = Specific storage, Ss Volume water released [L 3] Ss = Volume of aquifer [L 3] x h [L] Storage coefficient or storativity, S Volume water released [L 3] S= Surface area of aquifer [L 2] x h [L]

GROUNDWATER S and Ss are related as S = b. Ss

GROUNDWATER Unconfined aquifer: Specific yield (Sy) = sy = volume of stored GW released per unit surface area per unit decline of S = sy = b. Ss and Ss = sy b

GROUNDWATER = Sy + Sr Fc

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