WTAQ: A Computer Program for Calculating Drawdowns and Estimating Hydraulic Properties for Confined and Water-Table Aquifers
Water-Resources Investigations Report
99-4225
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Abstract
The computer program WTAQ calculates hydraulic-head drawdowns in a confined or water-table aquifer that result from pumping at a well of finite or infinitesimal diameter. The program is based on an analytical model of axial-symmetric ground-water flow in a homogeneous and anisotropic aquifer. The program allows for well-bore storage and well-bore skin at the pumped well and for delayed drawdown response at an observation well; by including these factors, it is possible to accurately evaluate the specific storage of a water-table aquifer from early-time drawdown data in observation wells and piezometers. For water-table aquifers, the program allows for either delayed or instantaneous drainage from the unsaturated zone. WTAQ calculates dimensionless or dimensional theoretical drawdowns that can be used with measured drawdowns at observation points to estimate the hydraulic properties of confined and water-table aquifers. Three sample problems illustrate use of WTAQ for estimating horizontal and vertical hydraulic conductivity, specific storage, and specific yield of a water-table aquifer by type-curve methods and by an automatic parameter-estimation method.
Suggested Citation
Barlow, P.M., and Moench, A.F., 1999, WTAQ: A Computer Program for Calculating Drawdowns and Estimating Hydraulic Properties for Confined and Water-Table Aquifers: U.S. Geological Survey Water-Resources Investigations Report 99-4225, viii, 74 p. :ill. ; 28 cm., https://doi.org/10.3133/wri994225.
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | WTAQ: A Computer Program for Calculating Drawdowns and Estimating Hydraulic Properties for Confined and Water-Table Aquifers |
| Series title | Water-Resources Investigations Report |
| Series number | 99-4225 |
| DOI | 10.3133/wri994225 |
| Year Published | 1999 |
| Language | ENGLISH |
| Publisher | U.S. Geological Survey |
| Contributing office(s) | Groundwater Resources Program |
| Description | viii, 74 p. :ill. ; 28 cm. |