- Drawdown definition hydrogeology pdf#
- Drawdown definition hydrogeology series#
- Drawdown definition hydrogeology zip#
Safeguards were added to check that the Solver is i nstalled and the workbook is not opened from within a zip file. October 18, 2022-Revisions in version 4 include the following. A tool for removing non-numeric entries from water-level data and reducing water-level data by averaging was added. Equations on hidden CONTROL page were extended so that recovery could be detected after the first 1,000 pairs of observations. September 23, 2022-Revisions in version 3 include the following. An error trap was added to the GROSS FIT button so elapsed times of 0 would be ignored while scaling the X-axis of elapsed time. November 17, 2021-Revisions in version 2 include the following. User will be warned and workbook will be closed if opened from within a zip file. The fitting routine will stop and warn the user if the Solver is not i nstalled. CJ-Drawdown+Recovery-2019.xlsm workbook requires that the Solver is i nstalled and the workbook is not opened from within a zip file. This workbook and other workbook applications are better used on local drives instead of a network drive.
Drawdown definition hydrogeology pdf#
Average hydraulic conductivity is reported if an assumed thickness is specified.įigure 2.- OUTPUT page in CJ-Drawdown+Recovery-2019.xlsm with data from well UE-19fS (2565-4779 ft) from Frus and Halford ( 2018).ĬJ-Drawdown+Recovery-2019.xlsm and explanatory PDF can be downloaded with the following link. Transmissivity is reported with a user defined number of significant digits. Fit between straight line and plotted data can be refined visually to ignore outliers with the “ADJUST LINE” button. A straight line initially is regressed to drawdown and recovery data with the “GROSS FIT” button. Analyzable drawdown and residual drawdowns are plotted on a semi-log plot.
Drawdown definition hydrogeology series#
A continuous series of antecedent, pumping, and recovery water levels in the pumped well are specified as depth to water or water level above the transducer. Simultaneous interpretation of Cooper-Jacob ( 1946) and Theis recovery ( Jacob, 1963) methods has been implemented in the workbook CJ-Drawdown+Recovery-2019.xlsm (Figure 2). This approach is a refinement of previously developed workbooks ( Halford and Kuniansky, 2002 Frus and Halford, 2018). Translation does not affect the slope so drawdown and recovery data can be interpreted simultaneously. Translated recovery data is shifted up on the Y-axis by the difference between averages of drawdowns and residual drawdowns (Figure 2). Translated recovery data is shifted left on the X-axis of Δt-Qstart/Δt-Qstop so that the first recovery observation coincides with the last drawdown observation. Residual drawdowns can be displaced to coincide with drawdowns so that drawdown and recovery could be interpreted simultaneously with a single line (Figure 1). A, Cartesian plot of changes in depth to water relative to drawdown and recovery B, Semi-log plot of translated recovery data combined interpretation of drawdown and recovery. Plotted positions of drawdown and residual drawdown data are largely irrelevant because estimated slopes determine transmissivity estimates.įigure 1.- Examples of pumping test results in well UE-19fS (2565-4779 ft) from August 1965. Increasing time plots to the left with transformed recovery data, where Δt-Qstart/Δt-Qstop have large values when recovery starts and theoretically diminish to 1 after infinite recovery (Figure 1). Residual drawdowns are plotted on a transformed X-axis of time-since-pumping-started divided by time-since-pumping-stopped, Δt-Qstart/Δt-Qstop (Jacob, 1963). This displacement generally is uniform because flow rate should be constant while pumping. Drawdowns are displaced along the Y-axis because well loses increase overall drawdown during pumping. Slopes of drawdowns and residual drawdowns are identical, but plotted data during drawdown and recovery are displaced (Figure 1). Represent aquifer transmissivities despite mismatches between field conditions Estimates from these constant rate tests frequently Practitioners using both methods, regardless of differences between fieldĬonditions and theory.
Drawdowns and residualĭrawdowns in confined and unconfined aquifers have been analyzed by many Proportional to slopes of lines in both methods. Line to drawdowns or residual drawdowns on an arithmetic axis vs. Transmissivity is estimated by fitting a straight Single-well aquifer tests frequently are analyzed withĬooper-Jacob ( 1946) and Theis recovery ( Jacob, 1963) methodsīecause analyses are simple.
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