Drought Streamflow Reduction

A groundwater model for estimating streamflow reductions due to pumping from nearby wells was developed. The model can be used to evaluate well permit applications for groundwater withdrawals. The computer program is based upon an analytical solution of a two-dimensional planimetric representation of a stream/aquifer system in a semi-infinite domain.

Principal Investigator: John F. Dowd (University of Georgia)
Principal Investigator: Kathryn J. Hatcher (University of Georgia)
Principal Investigator: Phillip J. Smith (University of Georgia)
Principal Investigator: John F. Dowd (University of Georgia)

Sponsor: GWRI
Start Date: 1987-07-01; Completion Date: 1987-07-01;
Keywords: surface-groundwater relationships, groundwater, water management, conjunctive use, wells, regulation, streamflow, groundwater models


Description:
A groundwater model for estimating streamflow reductions due to pumping from nearby wells was developed. The model can be used to evaluate well permit applications for groundwater withdrawals. The computer program is based upon an analytical solution of a two-dimensional planimetric representation of a stream/aquifer system in a semi-infinite domain. The variables required are transmissivity, pumping rate, well location, and aquifer storativity. The program calculates drawdown in the aquifer, drawdown adjacent to the stream, amount of flow induced from the stream into the aquifer, and total contribution from the stream into the well for four time steps per simulation. The program runs interactively on IBM-PC-compatible microcomputers. Results are presented through a summary table and high-resolution graphics when hardware graphics support is available. Output options include line graphs of drawdown along the stream, flow from the stream into the aquifer, and a contour plot of water table drawdown.
The completion report also includes a sensitivity analysis of the computer program for ranges of data likely to be encountered in the southeastern coastal plain is presented. The results illustrate the relative influence of each input parameter and highlight critical data needs for permit evaluation. The results indicate that for many combinations of field conditions and sustained pumping, 90% or more of the total well withdrawal is derived from nearby streams.