GIS User for Countywide Groundwater Assessment, Jefferson County, WV
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Transcript of GIS User for Countywide Groundwater Assessment, Jefferson County, WV
County-wide Groundwater AssessmentJefferson County, West Virginia
ObjectiveAssess availability and quality of
groundwater and provide useful information toward promoting long-term management of the County’s Groundwater Resources
Groundwater Budget Study
Groundwater recharge
Groundwater usage
Maintenance of baseflow in streams
Focused on identifying the extent of the County’s groundwater resources
RechargeGroundwater originates as precipitation
The portion of precipitation that percolates downward through the soil and infiltrates into the bedrock aquifer is called Recharge:
Recharge Calculation
Recharge Area (green)
Discharge Area (red)
Previously published recharge rates were applied to County’s total recharge area to determine Annual Recharge Volume
Recharge Rates
Hydrogeologic Unit Recharge Rate (inches/year)
Recharge Area(acres)
Western 5.9 36,734
Central 5.6 70,684
Eastern 5.5 12,331
*recharge rates are representative of drought conditions
Maintenance of BaseflowUtilized published data from similar hydrogeologic setting
to estimate percentage of annual recharge contributing to baseflow
An estimated 50% of annual recharge is required to maintain baseflow in streams and is unavailable for use
Annual Recharge Estimate
Recharge from precipitation: 18,475,000,000 gallons/year
Vol. needed to maintain baseflow: - 9,237,500,000 gallons
Vol. of groundwater available for use: 9,237,500,000
gallons
Groundwater UsageConsidered the following use categories:
Public Supply
Domestic Supply
Industrial
Irrigation
Commercial
Mining
Groundwater Use Estimate
Sources of water use information:
Data Management Unit of the Engineering Division, Jefferson County Office of Environmental Health
WV Dept. of Environmental Protection, Division of Water and Waste Management
WVU Agricultural Extension Service –
Jefferson County Office 2010 U.S. Census Data
West Virginia Office of Miners’ Health, Safety and Training
Water-Use Estimates for West Virginia, Atkins, 2004 – USGS publication
1,465,250,000 gallons per year
Groundwater Use EstimatePercentage of available groundwater used annually:
1.47 bgy 9.24 bgy
Groundwater use estimate:Groundwater deemed available: 16%
Groundwater Well DatabaseAssistance provided by the
Jefferson County GIS Department
Utilized available well completion reports from Health Department
Database consists of over 1100 wells with georeferenced locations
Internship
• Worked for Jefferson County GIS/Addressing Office
• Water budget study• Analytical Services Inc.
The Effect of Bedrock Geology on Well Yield in Jefferson County, West Virginia
Jeremiah SandersShepherd University
My Study
• Focus on geology• How geology affect well yield• Null Hypothesis: There is no difference in the
distribution of well yield between the bedrock formations
Methods
• Well database• Clean up
database• Create parcel ID
Methods
• Importing to ArcGIS• 1276 parcel match• Quality assessment
Methods
• Create new database• New field entries• Examined well
completion reports• Inconsistent entries
in well completion reports
Methods
• Join new database to parcels/address Points
• 911 well points
Methods
• State well records and USGS study (McCoy et al. 2005)
wells added• Total 1124 well points• Joined bedrock data to
well points• Used SPSS 19(IBM, USA)
to check for normality and K-W test
Results
Єa Єe Єh Єt Єw Єwl OЄc Om Omu Opr Os Zc0
50
100
150
200
250
300
Bedrock Formation
# of
Wel
ls
(Єa)-Antietam Formation
(Єe)- Elbrook Formation
(Єh)-Harpers Formation
(Єt)-Tomstown Formation
(Єw)-Waynesboro Formation
(Єwl)-Weverton and Loudoun Formations undivided
(OЄc)- Conococheague Limestone
(Om)-Martinsburg Formation
(Omu)-Middle Ordivician limestone
(Opr)-Pinesburg Station Dolomite and Rockdale Run Formation
(Os)- Stonehenge Limestone
(Zc)-Catoctin Formation
Results
Єa Єe Єh Єt Єw Єwl OЄc Om Omu Opr Os Zc0
20
40
60
80
100
120
140
160
180
Bedrock Formation
Aver
age
Yiel
d (lp
m)
(Єa)-Antietam Formation
(Єe)- Elbrook Formation
(Єh)-Harpers Formation
(Єt)-Tomstown Formation
(Єw)-Waynesboro Formation
(Єwl)-Weverton and Loudoun Formations undivided
(OЄc)- Conococheague Limestone
(Om)-Martinsburg Formation
(Omu)-Middle Ordivician limestone
(Opr)-Pinesburg Station Dolomite and Rockdale Run Formation
(Os)- Stonehenge Limestone
(Zc)-Catoctin Formation
Hydrogeologic UnitsAreas possessing unique characteristics
Western Fault Dominated
Central Folded Carbonates
Eastern Metamorphics
Table of Mean Values
Review of well database illustrates uniqueness of each Hydrogeologic Unit:
Hydrogeologic Unit
Well Depth(feet)
Yield(gpm)
Depth to Water(feet)
Casing Length
(feet)
Western 281 19 46 57
Central 278 32 66 74
Eastern 355 14 94 83
Groundwater Development PotentialThe Central Unit has the greatest number of high yielding wells
Yield (gpm)
Hydrogeologic Conditions Vary Across County
Site-specific assessment is recommended to understand compatibility of groundwater development with planned use
Water Quality Review
Common Groundwater Contaminants:
Hydrogeologic Unit
Common Contaminants
Western Sulfate, Nitrate, Bacteria, Hardness
Central Nitrate, Bacteria, Hardness
Eastern Iron, Manganese, Radionuclides
Contaminant MigrationInfluenced by geologic conditions and land use
Conduits in Karst areas can facilitate direct groundwater contamination and rapid contaminant transport
RecommendationsTo promote sustainability and long-term protection of the County’s groundwater resources, ASI recommends:
Assessment of High-Yield withdrawals
Incorporating Groundwater Protection into long-term planning