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SUSTAINABILITY OF GROUND-WATER RESOURCES IN THE PISCATAQUA RIVER
AND COASTAL WATERSHEDS, SOUTHEASTERN NEW HAMPSHIRE
National Ground Water Association
October 3-4, 2002, Burlington, VT
Thomas J. Mack, U.S. Geological Survey, Pembroke, NH
David R. Wunsch, New Hampshire Geological Survey, Concord, NH
Abstract
NE Conference
Population growth and accompanying development over the past 20 years have led to an increase in ground-water use from surficial and fractured-bedrock aquifers in southeastern New Hampshire. New roads, parking lots, buildings, homes, and other development-related changes have created impervious surfaces that decrease recharge to aquifers. Over this same period, drillers have been drilling progressively deeper wells to meet the increasing domestic needs of modern appliances and landscaping. The combined effects of the recharge losses and increased withdrawals raise serious questions about the sustainability of the ground-water resources in this region.
The New Hampshire Geological Survey (NHGS), New Hampshire Department of Environmental Services (NHDES), the Office of State Planning (NHOSP) Coastal Program, and the U. S. Geological Survey (USGS) are regionally investigating the availability and sustainability of water resources in southeastern New Hampshire. The 830-mi2 study area includes New Hampshire's Piscataqua River watershed and coastal drainage basins.
This investigation consists of several major components including geohydrologic-data collection, compilation, and monitoring; water use data collection and assessment; and regional water-resource analysis. Existing geohydrologic data for wells, surficial deposits, and aquifer systems that have been generated by various Federal, State, and local agencies and the private sector will be compiled, geo-referenced, and incorporated into geographic information system (GIS) databases suitable for computer-based analyses. This investigation will be supported by creation of a seamless digital surficial-geologic-map database. A regional, long-term water-resources monitoring program, consisting of a network of ground-water observation wells and streamflow-gaging stations, is being developed to evaluate climatic and anthropogenic stresses on the hydrologic system. A comprehensive water-use assessment will include the collection and compilation of information on withdrawals, returns, transfers and uses by different types of users in each town. All components of water use will be accurately estimated or measured so that detailed water budgets and water-use projections can be calculated.
A regional ground-water-flow model will be developed and applied on a 100-mi2 subregion in New Hampshire's seacoast area to provide an integrated analysis of geologic information, new and historical hydrologic data, and complex regional water uses. The model will be used to calculate water availability, evaluate the effects of projected water-use development on sustainability, and provide a means to assess alternate water-management scenarios. The model also will provide more accurate estimations of boundary conditions for detailed investigations in the region. The modeling approach will be evaluated to assess its suitability for future application at larger and smaller scales than this investigaion. Communities, regional planning agencies, public-water suppliers, and State and Federal agencies will be provided with critical data and management tools to identify problems and evaluate future water use or availability in the study area.
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