Jeff_L_Ground_Water_101

Ground Water Resources in NCGround Water Resources in NC
Jeff Lautier
Ground Water Management Section
NC Division of Water Resources
March 5, 2008
AquifersAquifers
••TwoTwo--layered aquifer system:layered aquifer system:
••1:Underlying bedrock stores 1:Underlying bedrock stores
and transports water through and transports water through
fracturesfractures
••2:Overlying 2:Overlying regolithregolith
••3: Interconnected3: Interconnected
••4: Both are unconfined 4: Both are unconfined
aquifers in which the water aquifers in which the water
table is free to fluctuate in table is free to fluctuate in
elevation. elevation.
••5: Generally not as prolific as 5: Generally not as prolific as
coastal plain aquiferscoastal plain aquifers
Mountains & Piedmont
AquifersAquifers
••MultipleMultiple--layered aquifer layered aquifer
systemsystem
••Alternating layers of Alternating layers of
sand, shell materials, sand, shell materials,
limestone, silt and claylimestone, silt and clay
••Uppermost= unconfined Uppermost= unconfined
or water table aquiferor water table aquifer
••Beneath: multiple Beneath: multiple
confined aquifers some confined aquifers some
of which can yield large of which can yield large
volumes of water. volumes of water.
Coastal Plain
-DWR/USGS 46 well drought monitoring network
-unconfined aquifer (confined aquifers unaffected)
-periodic water level measurements
-effects of changes in rainfall/recharge on ground
water levels across the State
Drought network
well NC-195
Elizabeth City, NC
(below minimum
for 1-2008)
Hydrograph
How most recent water levels in 46
well network compare to historical
monthly water levels
2 Above 50th percentile: Green
9 Below 50th percentile: Brown
18 Below 25th percentile: Gold
13 Below 10th percentile: Yellow
4 Below minimum: Red
Drought network
well NC-195
Elizabeth City, NC
(below minimum
for 1-2008)
Drought Conditions:
Reduced recharge to unconfined aquifer in North
Carolina, thus water levels are lower than normal. Some
wells at historic lows
Reduced recharge= reduced base flow to streams, rivers
and lakes.
Central Coastal Plain
Capacity Use Area
-covers 15 counties in
Coastal Plain
-to protect aquifers from
overpumping
-CUA permit required for
pumping >100,000 gpd
from any aquifer
-registration required for
10,000-100,000 gpd
-reduction requirements
for Black Creek and
deeper aquifers
3 zones established:
Declining water level zone
Dewatering zone
Saltwater encroachment zone
Reductions in 3 phases
1st phase: pumping base
rates established
2nd phase: 10-25% reductions
3rd phase: 20-50% reductions
End of 3rd phase:
30-75% reductions
Phase 1: 6 years from 2002
Phase 2: 2008 to 2013
Phase 3: 2013 to 2018
DWR maintains a 548 well monitoring network including
the drought network
Monitor drought conditions, progress of CUA regulations in
improving wl conditions in coastal plain
Study gw conditions and spot potential problem areas in the State
Ground Water Resources in NCGround Water Resources in NC
Questions?