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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Water-Table Fluctuation (WTF) Method

Master Recession Curve (MRC) Approaches for Estimating Recharge Using the WTF Method

The MRC approach used in the WTF method is an automated or semi-automated procedure for calculating DH(t_j) from water-level data. This approach develops an expression for the MRC that can be used to predict the slope of the hydrograph in the absence of recharge. Once the MRC is established, positive deviations of the hydrograph from the MRC are attributed to recharge, allowing recharge to be quantified even during periods of falling groundwater levels. Because of the need for daily water-level data, the MRC approach can be applied only at sites where water levels were continuously monitored.

Even though multiple steps are required, the MRC approaches are straightforward and easy to apply. The approaches avoid subjectivity after the estimation of the MRC parameters, but there remains the possibility that water-level rises that were not due to recharge may have been improperly included in the calculations. At least three different MRC approaches have been developed:

• Delin and others (2007)
• Heppner and Nimmo (2005)
• Crosbie and others (2005)