Surface-Water and Groundwater Interaction Science in Oklahoma and Texas - Overview

Streams interact with groundwater in all types of landscapes. The interaction takes place in three basic ways:

• streams gain water from inflow of groundwater through the streambed (gaining stream),
• streams lose water to groundwater by outflow through the streambed (losing stream), or
• they do both, gaining in some reaches and losing in other reaches.

For groundwater to discharge into a stream channel, the altitude of the water table in the vicinity of the stream must be higher than the altitude of the stream-water surface. Conversely, for surface water to seep to groundwater, the altitude of the water table in the vicinity of the stream must be lower than the altitude of the stream-water surface. Surface-water depletion is directly associated with chronic lowering of groundwater levels. The amount of water that is gained by a stream from groundwater is called baseflow.  Several different methods of analyzing hydrographs have been used by hydrologists to determine the baseflow component of streamflow.

The movement of water between groundwater and surface water provides a major pathway for chemical transfer between terrestrial and aquatic systems. As chemicals are transferred between groundwater and surface water, the supply of carbon, oxygen, nutrients such as nitrogen and phosphorus, and other chemical constituents that enhance biogeochemical processes on both sides of the interface can be affected. This transfer can affect the biological and chemical characteristics of aquatic systems downstream.

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SURFACE-WATER AND GROUNDWATER INTERACTION SCIENCE CAPABILITIES

OTWSC has expertise in surface-water and groundwater interaction science applications, including, but not limited to: 

• Using passive near-surface and frequency-domain electromagnetic induction methods profiling to identify where surface water and groundwater exchange occurs
• Using time-domain electromagnetic sounding (TDEM) and seismic refraction tomography (SRT) geophysical methods for mapping the contact between aquifers
• Providing qualitative information regarding surface-water and groundwater exchanges
• Characterizing the connection between surface water and groundwater
• Estimating surface-water/groundwater exchange as part of the water budget
• Numerical modeling of the integrated surface and groundwater system
• Estimating contributions of runoff and baseflow and evaluate trends in streamflow and baseflow over time
• Quantifying recharge rates to groundwater

Find out more about OTWSC surface-water science and groundwater science expertise in these printable information sheets.

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CURRENT SURFACE-WATER AND GROUNDWATER INTERACTION SCIENCE

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Coastal Lowlands Regional Groundwater Availability Study

Estimating Potential Effects on Streamflow from Nearby Wells in the Lower San Antonio River Basin

Hydrologic Monitoring of Medina and Diversion Lakes, San Antonio Area

Red River Focus Area Study

Streamflow and Springflow at Comal and San Marcos River

Transboundary Aquifer Assessment Program

Upper Rio Grande Basin Focus Area Study

Using Geophysics to Study Surface-Water/Groundwater Interaction

Seismic and Geoelectric Characterization of the Precambrian Granite Gravel Aquifer

Investigation of Preferential Groundwater Seepage in the Ellenburger – San Saba Aquifer Using Geoelectric Measurements

Water Quality

Edwards Aquifer Recharge Zone Monitoring Network

Edwards Aquifer Recharge Zone Surface-water and Groundwater Interaction

Salado Creek Bacteria Source Tracking

Pecos River Basin Salinity Assessment

National Water-Quality Assessment Project in Texas - Groundwater Activities

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More information about how surface-water and groundwater interact is available in USGS Circular 1139: Ground Water And Surface Water A Single Resource