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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2005-5067

Simulated Changes in Water Levels Caused by
Potential Changes in Pumping from Shallow Aquifers
of Virginia Beach, Virginia

By Barry S. Smith

ABSTRACT

A steady-state ground-water flow model of the southern watersheds of Virginia Beach, Virginia, was refined and used to simulate changes in aquifer water levels caused by potential changes in pumping in the Transition Area of Virginia Beach, Va., a 20-square mile planning zone that runs through the middle of the city. Cessation of dewatering at borrow pits, pumping to irrigate a golf course, pumping to irrigate lawns of a hypothetical neighborhood, and pumping to irrigate both the golf course and lawns of the hypothetical neighborhood were simulated.

Simulated recoveries from cessation of dewatering of borrow pits were generally restricted to the immediate area of the pits. The simulated recoveries averaged about 20 feet (ft) near the center of the cells representing the active areas of the pits and 2 ft at the cells representing the extent of the pits.

At a golf course, 4 hypothetical wells pumping 300,000 gallons per day (gal/d) from the Yorktown sand aquifer resulted in drawdowns averaging 10 ft in the pumping cells and 1 ft at a distance of 1.2 miles (mi) from the center of the pumping cells. The extent of the 1-ft drawdown was virtually the same as that simulated previously and reported in a permit application for the golf course.

Simulated pumping of 150,000 gal/d from 4 cells in the confined sand aquifer representing a 40-acre neighborhood resulted in drawdowns averaging 7 ft in the pumping cells and 1 ft at a distance of 0.8 mi from the center of the cells. Simulated pumping of 300,000 gal/d from the same 4 cells resulted in drawdowns averaging 15 ft in the pumping cells and 1 ft at a distance of 1.4 mi from the center of the cells.

Simulated pumping of 150,000 gal/d at the golf course and another 150,000 gal/d in the hypothetical neighborhood resulted in drawdowns that averaged 5 ft around the cells representing the golf course wells spaced 1,300 ft apart and 7 ft around the contiguous cells representing the 40-acre neighborhood. A drawdown of 1 ft encompassed most of the eastern half of the Transition Area.

Download the report (PDF, 3.5 MB)

CONTENTS

Abstract
Introduction
    
Purpose and Scope
     Study Area
     Previous Studies
Shallow Aquifer System
     Conceptual Hydrogeologic Framework
     Changes in Ground-Water Levels
Simulation of Ground-Water Flow
     Model Layers
     Refined Grid
     Ground-Water Flow
Simulated Changes in Water Levels
     Cessation of Dewatering at Borrow Pits
     Pumping to Irrigate a Golf Course
     Pumping to Irrigate Lawns of a Hypothetical Neighborhood
     Pumping to Irrigate the Golf Course and the Hypothetical Neighborhood
     during a Summer Drought

Summary and Conclusions
Acknowledgments
References Cited

This report is available online in Portable Document Format (PDF). If you do not have the Adobe Acrobat PDF Reader, it is available for free download from Adobe Systems Incorporated.

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Send questions or comments about this report to the Virginia District Office (804) 261-2600.

For more information about USGS activities in Virginia, visit the USGS Virginia District home page.

 

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