New in GWRP

• Regional Groundwater Studies
  • Groundwater Availability in the United States
• Water Availability Pilot
  • Consumptive water use coefficients for Great Lakes Basin
• Groundwater & the Environment
  • Groundwater Recharge in Southwestern US
• Methods & Modeling
  • SEAWAT v4--Simulation of 3D variable-density ground--water flow and transport
• Data & Information
  • Water-Level changes in aquifers of the Atlantic Coastal Plain, predevelopment to 2000

USGS in Your State

USGS Water Science Centers are located in each state.

Karst Hydrology Initiative & Fractured-Rock Aquifer Studies

The importance of groundwater in complex geologic environments can no longer be overlooked. Karst and other fractured bedrock settings represent extensive groundwater systems that have unique physical characteristics that govern the movement and access to this hidden resource. For example, karst is a complex geological environment where distinctive physiographic and hydrologic features develop as a result of dissolution of soluble bedrock. Ground-water movement and availability in fractured-rock aquifers is controlled by the distribution, aperture, and connectivity of fractures making it difficult to evaluate the groundwater condition at a specific point in time.

Karst topography occurs over nearly 15 percent of the continental United States, and over about 40 percent of the land area located east of the Mississippi River. Much of the recent development along the eastern seaboard and within western mountain communities has occurred in areas underlain by fractured bedrock that do not have sufficient rivers or reservoirs available for new drinking water sources. As growth in these areas continues, the problems of groundwater availability and vulnerability to contamination will also increase.

In spite of the value of these aquifers for supply, their hydrogeology is not as well understood as other aquifer systems, especially at a regional scale. Better regional characterization and understanding of the hydrogeology of complex aquifers, as well as improved analytical and data management tools are needed. The Ground-Water Resources Program has supported and will continue to support such studies. The following projects were recently completed and are presented here to demonstrate the type of work being supported by the Program:

Karst Hydrology Initiative

The Karst Hydrology Initiative is a regional study of the karst aquifers in Alabama, Illinois, Indiana, Kentucky, and Tennessee. The project is a possible prototype for regional studies of karst aquifers. Learn more about the Karst Hydrology Initiative.

Karst Hydrology Initiative--Study area showing major karst hydrogeologic settings in the Interior Low Plateaus physiographic region. Areas underlain by Lower-Middle Ordovician limestones shown in brown, and areas underlain by Mississippian limestones shown in green. (View Larger Map.)

Shenandoah Valley Fractured-Rock Aquifer Studies

The northern Shenandoah Valley area is experiencing economic and population growth, resulting in increased water supply needs. Much of the domestic water supply comes from ground water, and public utilities are located on the Shenandoah River and its tributaries. As a result, surface-water/groundwater interactions are an important area of study to improve understanding of these complex flow systems. GWRP has supported USGS studies of fractured-rock aquifer of the Shenandoah Valley in Virginia and West Virginia. For examples of activities supported by GWRP, see:

• Geophysics is Fundamental to Shenandoah Valley, Virginia, Investigations

For more information

Learn more about karst.