GROUND-WATER RESOURCES PROGRAM http://water.usgs.gov/ogw/gwrp/

IAEA/GEF IW Learn/USGS ExchangeApril 16, 2007

Reston, VA

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

Principal Aquifers

Source: U.S. Geological Survey National Atlas of the United States; http://nationalatlas.gov/atlasftp.html

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.

Ground-Water Resources Program

RegionalGW

Evaluations

FieldMethods &

Models

Data Collection&

Water-LevelMonitoring

TechnicalSupport

Other

PriorityGW Issues

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

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

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

Current Regional Ground-Water

Availability Studies

Plan for National Ground-Water

Availability Assessment

Studies

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

Ground-Water Recharge in the Humid

Areas of the US

Mapping spatial and temporal variability

AmargosaRiver

MojaveRiver

TroutCreek

SandHollow

RillitoCreek

AboArroyo

ArroyoHonda

Southwest Project, Recharge Study Sites

Field Methods and Models

http://pubs.water.usgs.gov/circ1260/

Heat as a Tracer

• 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

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

Time-Lapse DTS Data Lo

w T

ide

Hig

h T

ide

Tem

p., d

eg C

• Intermittent cold region near-shore (0-5 m)

• Tidal influence diminishes with distance offshore

• More stable temperatures beyond 30 or 40 m

• MODFLOW– Unsaturated-zone flow (UZF1)– FARM process– Local-grid refinement (LGR)– GSFLOW

• SEAWAT

• SUTRA

Recent Model Development

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

Farm Process for MODFLOW(Schmid and others, 2006)

Local Grid Refinement(Mehl and Hill, 2006)

Parent grid

Child gridInterface

GSFLOW—A basin-scale model for simulation of coupled Ground-water and Surface-water FLOW

InfiltrationInfiltration

Snow accumulationSnow accumulationsnowmelt and runoffsnowmelt and runoff Stre

amStre

am

Precipitation

SEAWAT

Documentation Biscayne Aquifer Analysis

SUTRA

DocumentationSimulated salinity near Hilton Head Island, South Carolina

Ground Water Model Development-- Applications Software

Web Site http://water.usgs.gov/software/ground_water.html

• 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

Water-level changes in the

High Plains aquifer,

predevelopment to 2003.

Source McGuire, 2004.

No National Network!No National Network!

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-WaterClimate Response Network

• 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

Current Climate Response Network

For More Information

http://water.usgs.gov/ogw/gwrp/

THE END

Contact Info:Kevin Dennehy

Program Coordinator, Ground-Water Resources703-648-5018

kdennehy@usgs.gov

Ground-Water Resources Program Studies2006