Groundwater Recharge and Groundwater Quality Issues

1
Groundwater Recharge and Groundwater Quality
Issues

• Vincent W. Uhl, PH, PG
• Vincent Uhl Associates, Inc.
• Lambertville, NJ
• Slides 1 to 10

2
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

3
Hunterdon Aquifers

• Piedmont (Brunswick, Lockatong, Stockton)
• Highlands (PreCambrian and Limestone)
• Sourlands and Cushetunk Mountain (diabase)

4
Water Budget Overview

• P R I ET
• P Precipitation
• R Runoff
• I Infiltration (Recharge)
• ET Evapo-transpiration
• Annual Averages usually used

5
Infiltration Baseflow

• Recharge to ground water eventually flows to
  streams unless taken out through wells

6
GW Recharge

• Soils, precipitation, land cover
• Part moves quickly to streams
• Part moves to aquifers and then slowly to
  streams or wells

7
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.

8
Recharge Estimates The Math

• Recharge is often expressed as gallons per day
  per square mile (gpd/mi2)
• Examples for the Highlands Precambrian Rock
  aquifers
• 7 day 10 year low flow 85,000gpd/mi2
• Average annual base flow 525,000 gpd/mi2
• 75 of 25-year baseflow recurrence interval
  225,000 gpd/mi2

9
Translating Recharge toGallons per day per acre

• 640 acres in a square mile.
• 85,000 gpd/mi2
• 525,000 gpd/mi2
• 225,000 gpd/mi2

• 130 gpd/acre
• 820 gpd/acre
• 350 gpd/acre

10
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