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Published byEllen Wilkins Modified over 9 years ago
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Groundwater Recharge and Groundwater Quality Issues Vincent W. Uhl, PH, PG Vincent Uhl Associates, Inc. Lambertville, NJ Slides 1 to 10
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Presentation Summary Assess Groundwater Resources from a Growth – Management Perspective Look at Limitations and Opportunities Local Planning to Protect Water Resources Tools needed to accomplish this planning
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Hunterdon Aquifers Piedmont (Brunswick, Lockatong, Stockton) Highlands (PreCambrian and Limestone) Sourlands and Cushetunk Mountain (diabase)
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Water Budget Overview P = R + I + ET P = Precipitation R = Runoff I = Infiltration (Recharge) ET = Evapo- transpiration Annual Averages usually used
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Infiltration ≈ Baseflow Recharge to ground water eventually flows to streams unless taken out through wells
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GW Recharge Soils, precipitation, land cover Part moves “quickly” to streams Part moves to aquifers and then “slowly” to streams or wells
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Groundwater Recharge – Ways to Estimate Sophisticated Water Balance (See Van Abs Slide 4) NJGS Method Recharge as a fixed percentage of precipitation Baseflow Analysis Very Conservative – e.g. 7day 10 year low flow Average Baseflow DRBC Approach in SE PA Watersheds which is 75% of the 25-year recurrence baseflow.
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Recharge Estimates – The Math Recharge is often expressed as gallons per day per square mile (gpd/mi 2 ) Examples for the Highlands Precambrian Rock aquifers: 7 day 10 year low flow – 85,000gpd/mi 2 Average annual base flow – 525,000 gpd/mi 2 75% of 25-year baseflow recurrence interval – 225,000 gpd/mi 2
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Translating Recharge to: Gallons per day per acre 640 acres in a square mile. 85,000 gpd/mi 2 525,000 gpd/mi 2 225,000 gpd/mi 2 130 gpd/acre 820 gpd/acre 350 gpd/acre
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Translating Gallons per day per acre of recharge to lot sizes Using 400 gpd/household 130 gpd/acre 820 gpd/acre 315 gpd/acre 3 acre lots 0.5 acre lots 1.25 acre lots Go to Slides 11 to 23
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