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

Automated Determination of K

The recession index (K) can also be determined by automated construction and analysis of the master recession curve for a watershed by the use of the RECESS program (Rutledge, 1998). RECESS is an interactive program requiring the hydrologist to pick nearly linear segments of the streamflow hydrograph for automated determination of the master recession curve and recession index. The procedure used by RECESS is shown schematically below, and is outlined in detail in Rutledge (1998).

Schematic representation of the method used to determine the master recession curve: (A) selected recession segments, (B) recession index (K) (time per log cycle of streamflow recession) and best-fit line, and (C) the master recession curve, obtained from coefficients of function in B. (from Rutlidge, 1998, fig 3)

New S-PLUS® Version of RECESS and SCREEN

The RECESS program is being incorporated (2006) into S-PLUS® statistical/graphical package by the USGS Minnesota Water Science Center to allow easier analysis because of an enhanced ability to graphically analyze hydrograph data. S-PLUS provides a consistent user interface and the possibility of developing a graphical user interface. Functions are also being developed to plot the analyses; print a concise listing of the analysis; and extract summary information. These functions produce output that replaces the output files from the original programs and eliminate the need to use a separate program to plot the data.

The enhancements include the programs to:

• examine daily values for missing data. This is a necessary first step for all other programs. The S-PLUS® function is called screenData to avoid a conflict with an S-PLUS® function called SCREEN.
• identify and analyze streamflow recessions. This is necessary for the RORA program and provides other useful information about streamflow. The S-PLUS version is called RECESS2 because it uses a slightly different rule to define a recession, but gives identical results for recessions found in common.