Groundwater Resources Program (Dennehy)
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Presentation given during the USGS/IAEA/IW:LEARN groundwater learning exchange in the US April 14-26, 2007. IAEA/GEF IW Learn/USGS Exchange April 16, 2007 Reston, VA Kevin Dennehy GROUND-WATER RESOURCES PROGRAM http://water.usgs.gov/ogw/gwrp/
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Groundwater Resources Program (Dennehy)
- 1. GROUND-WATER RESOURCES PROGRAM http://water.usgs.gov/ogw/gwrp/ IAEA/GEF IW Learn/USGS Exchange April 16, 2007 Reston, VA
- 2. Ground Water in US • Ground water is the source of drinking water for about 50% of the US population, about 96% of water used for rural domestic supplies, and 40% of water used for public supplies • Provides 42% of irrigation for Nation’s agriculture • Sustains flow of most streams and rivers • Maintains a variety of aquatic ecosystems
- 3. Principal Aquifers Source: U.S. Geological Survey National Atlas of the United States; http://nationalatlas.gov/atlasftp.html
- 4. GROUND-WATER RESOURCES PROGRAM Mission To provide objective scientific information and develop interdisciplinary understanding to help assess and assure the availability of the Nation’s ground-water resources.
- 5. Ground-Water Resources Program Regional GW Evaluations Field Methods & Models Data Collection & Water-Level Monitoring Technical Support Other Priority GW Issues
- 6. Goal To provide the Nation with an overview of the status and trends in water availability and improve ability to forecast availability for future uses. •How much water do we have? •How is water availability changing? •How does the availability of ground-water relate to demand, recharge, and geographic location? Regional Ground-Water Evaluations
- 7. Products • Water budgets of major systems • Current estimates and historic trends in ground-water storage, recharge, and discharge • Ground-water models that provide – Regional context for more local studies – Tool to make future projections of water availability
- 8. Products (Cont.) • Region-wide estimates of key hydrologic variables (e.g. aquifer properties, recharge, and withdrawals) for major aquifers. • Evaluation of the existing network for monitoring ground-water availability • Testing and evaluation of new approaches for analysis of regional aquifers
- 9. Current Regional Ground-Water Availability Studies Plan for National Ground-Water Availability Assessment Studies
- 10. Priority Ground-Water Issues • Aquifer Management • Aquifer Storage and Recovery • Ground-Water Recharge • GW/SW Interaction • Characterization of subsurface heterogeneity • Flow and transport in karst and fractured aquifers
- 11. Ground-Water Recharge in the Humid Areas of the US Mapping spatial and temporal variability
- 12. Amargosa River Mojave River Trout Creek Sand Hollow Rillito Creek Abo Arroyo Arroyo Honda Southwest Project, Recharge Study Sites
- 13. Field Methods and Models
- 15. • Continuous measurement over kilometers • Temporal resolution = ~1 min • Meter-scale spatial resolution • ~0.1 °C thermal resolution • 25 yr sensor life (in-place) Fiber Optic Sensing Technology
- 16. Fiber-Optic Grid Boat house & control unit •Additional temperature sensors (Hobos) attached for ground truth; seepage measurements; pore-fluid salinity measurements. Waquoit Bay Study Area
- 17. Time-Lapse DTS DataLowTideHighTide Temp.,degC • Intermittent cold region near-shore (0-5 m) • Tidal influence diminishes with distance offshore • More stable temperatures beyond 30 or 40 m
- 18. • MODFLOW – Unsaturated-zone flow (UZF1) – FARM process – Local-grid refinement (LGR) – GSFLOW • SEAWAT • SUTRA Recent Model Development
- 19. Unsaturated-Zone Flow (UZF1) Package (Niswonger, Prudic, and Regan 2006) • Simulates flow, storage, and ET in the unsaturated zone and recharge to the water table in response to infiltration at land surface
- 20. Farm Process for MODFLOW (Schmid and others, 2006)
- 21. Local Grid Refinement (Mehl and Hill, 2006) Parent grid Child gridInterface
- 22. GSFLOW—A basin-scale model for simulation of coupled Ground-water and Surface-water FLOW InfiltrationInfiltration Snow accumulationSnow accumulation snowmelt and runoffsnowmelt and runoff Stream Stream Precipitation
- 23. SEAWAT Documentation Biscayne Aquifer Analysis
- 24. SUTRA Documentation Simulated salinity near Hilton Head Island, South Carolina
- 25. Ground Water Model Development-- Applications Software Web Site http:// water.usgs.gov/software/ground_water.html
- 26. • USGS database (GWSI) contains more than 850,000 ground-water records. • Annually about 20,000 wells are measured— periodic and continuous. • Real-time data are available on about 1,000 wells during the most recent year. Data Collection and Ground-Water Level Monitoring Networks
- 27. Water-level changes in the High Plains aquifer, predevelopment to 2003. Source McGuire, 2004. No National Network!No National Network!
- 28. Goal: Monitor effects of drought and other climate variability on ground- water levels. Well selection criteria: • Open to a single, known hydrogeologic unit • Known well construction • Located in unconfined aquifers or near-surface confined aquifers that respond to climatic fluctuations • Minimally affected by pumpage • Essentially unaffected by irrigation • Long-term accessibility • Well has never gone dry USGS Ground-Water Climate Response Network
- 29. • In 2006, CRN consists of 554 wells (286 RT, 213 tape-down wells and 55 continuous recorders). • About 140 wells are totally supported with Federal funds (GWRP) and the remainder from cooperative arrangements. • In 2006, 51% of wells in network are instrumented for real-time data. • Each of the 50 States and Puerto Rico have at least one well in the network. USGS Climate Response Network
- 30. Current Climate Response Network
- 32. THE END Contact Info: Kevin Dennehy Program Coordinator, Ground-Water Resources 703-648-5018 kdennehy@usgs.gov
- 33. Ground-Water Resources Program Studies 2006
Editor's Notes
- 62 Principal Aquifers
- Presentation Outline Regional/National GW Evaluations —gw availability Priority GW Issues —Improve scientific understanding of gw resources Field Methods —develop new tools and methods for ground-water studies Data Collection —collect and disseminate basic gw data Technical Support --provide scientific leadership for gw studies
- Studies involve computer-based ground-water flow models as a tool for hydrologic evaluation of the Nation’s most important regional aquifers. Information about these aquifers is critically needed to better manage the ground-water resources in these areas that are experiencing escalating demands. The evaluations will document the effects of human activities (depletions) on ground-water levels, ground-water storage and other sw bodies.
- Range in size from 20,000 mi2 (52,000 km2) Central Valley to 70,000 mi2 (181,000 km2) for the Mississippi Embayment
- Objective—To develop a better understanding of recharge processes at the local scale and to evaluate techniques to scale up site-specific recharge estimates to regional aquifers CONCLUSIONS --Comparison of multiple methods is recommended --High quality, long-term continuous hydrologic and climate records are important. --Local-scale estimates of recharge are highly variable and may be difficult to regionalize or transfer from one location to another. --Temporal variability must be considered. --Regionalized recharge estimates should be used with caution. --Difference in the positions of sw and gw divide can make a large differnece in average annual baseflow values averaged over an entire basin.
- Individual Sites --Suite of methods applied at each site Regionalization --Look at spatial distribution recharge --Identify mechanisms of recharge across region --Provide regional context for detailed studies Methods Geophysical Tech -- Temperature—seem to favor quantitative estimates --Gravity --Electrical Channel-loss methods --gaging --Streambed temp. Environ. Tracers --Chloride --Stable isotopes
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- <number> GSFLOW-- coupling MODFLOW with the Precipitation Runoff Modeling System (PRMS) watershed model
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- Expands the capability of MODFLOW to better simulate ground-water and surface-water interactions at the basin scale by coupling MODFLOW with the Precipitation Runoff Modeling System PRMS) watershed model.
- <number> SEAWAT was developed as an extension of MODFLOW. It was first applied in an analysis of ground-water discharge to Biscayne Bay, Florida. The figure on the left is the cover of the model documentation report. The figure on the right shows simulated values of ground-water salinity at the base of the Biscayne aquifer. Red and tan denote the highest and lowest simulated salinities, respectively, and the solid black line indicates the position of the saltwater-freshwater interface in 1995.
- <number> SUTRA has been applied in an analysis of saltwater intrusion into the ground water supply in the vicinity of Hilton Head Island, South Carolina. The figure on the left is the cover of the model documentation report. The figure on the right shows simulated values of ground-water salinity in the Upper Floridan aquifer in 1997. Purple shading denotes areas in which the simulated chloride concentration exceeds the potable water limit of 250 milligrams per liter.
- <number> USGS is the primary Federal science agency for water-resource information. USGS monitors the quantity and quality of water in the Nation’s aquifers and rivers and provides long-term data and scientific analyses to support water management decisions. USGS monitors--- GWSI—850,000 records of well, springs, test holes, tunnels, drains, and excavations in the US. Includes site descriptive information on well location, well depth, and aquifer. USGS annually monitors ground-water levels in about 20,000 wells. GW data collected and stored as either periodic measurements (17K) or as continuous records (3K). About 1000 of the continuous measurements are real-time. Data from real-time sites are relayed to USGS offices nationwide through telephone lines or by satellite transmissions providing access to real-time ground-water data. Daily summary data are generated and made available online.
- 174,000 mi2 (451,000 km2)
- <number> The USGS maintains a network of wells to monitor the effects of droughts and other climate variability on ground-water levels. The network consists of a national network of about 140 wells monitored as part of the Ground-Water Resources Program (began in 2001), supplemented by wells in some States monitored as part of the Cooperative Water Program
- <number> The CRN is designed to show long term trends and display statistics that are not available from the National Water Information System's web service, NWISWeb. Many of the sites in the CRN have real-time data reporting capability, which is integrated with the site's long term record to provide a current picture of ground water conditions framed in a historical perspective. There are three levels of detail available—NATIONAL, STATE, AND WELL LIMITATIONS: Inconsistent coverage of our Nation’s aquifers and recharge areas—about 60 percent of the Nation’s principal aquifers are now being covered. Limits of Federal funding and changing funding priorities by cooperators. Especially out west, extensive gw use or large depth to water table is difficult to identify climate signal.
- <number> Background --Looking to better inform everyone about the Program—Fact Sheet & Website --GWRP principal USGS Program for assessing the availability of ground-water resources at regional/national scales.