New & Noteworthy

Press Release: Study Explores Groundwater and Geothermal Energy in Drought-Stricken Eastern Oregon and Neighboring States

Technical Announcement: USGS Issues Revised Framework for Hydrogeology of Floridan Aquifer

Press Release: High Plains Aquifer Groundwater Levels Continue to Decline

Regional Groundwater Availability Study Geospatial Data

Press Release: USGS Assesses Current Groundwater-Quality Conditions in the Williston Basin Oil Production Area

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USGS Groundwater Watch

USGS maintains a network of active wells to provide basic statistics about groundwater levels.

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Recession-Curve Displacement Method for Estimating Groundwater Recharge In Humid Regions

Effect of Sensitivity to Recession Index (K)

"The use of the Rorabaugh Method requires the designation of a recession index. When this variable is determined from streamflow data, the data analyzed should come from parts of the year when groundwater evapotranspiration (GWET) is small because GWET can affect the rate of recession." -- Rutledge (2000)

From analysis of streamflow data, Rutledge (2000) showed that RORA is relatively insensitive to the value of K. He states that…"if the recession index is decreased by 50 percent the recharge estimate will increase by generally 4-9 percent. If the recession index is increased by 50 percent the recharge estimate will decrease by generally 2-4 percent. Even when the recession index is increased by 10 times, most estimates of recharge change by less than 10 percent. Most of these changes are less than 1 in/yr."