Georgia Water Science Center

USGS Open-File Report 96-433

GROUND-WATER RESOURCES OF THE TALLAPOOSA RIVER BASIN IN GEORGIA AND ALABAMA—SUBAREA 5 OF THE APALACHICOLA-CHATTAHOOCHEE-FLINT AND ALABAMA-COOSA-TALLAPOOSA RIVER BASINS

This report is available online in pdf format (2.8 MB): USGS OFR 96-433 (Opens the PDF file in a new window. )

Celeste A. Journey and J.B. Atkins

U.S. Geological Survey Open-File Report 96-433, 48 pages (Published 1997)

ABSTRACT

Drought conditions in the 1980’s focused attention on the multiple uses of the surface- and ground-water resources in the Apalachicola-Chattahoochee-Flint (ACF) and Alabama-Coosa-Tallapoosa (ACT) River basins in Georgia, Alabama, and Florida. State and Federal agencies also have proposed projects that would require additional water resources and revise operating practices within the river basins. The existing and proposed water projects create conflicting demands for water by the States and emphasize the problem of water-resource allocation. This study was initiated to describe ground-water availability in the Tallapoosa River basin of Georgia and Alabama, Subarea 5 of the ACF and ACT River basins, and to estimate the possible effects of increased ground-water use within the basin.

Subarea 5 encompasses about 4,675 square miles (mi2) in Georgia and Alabama and contains parts of the Piedmont and Coastal Plain physiographic provinces. The Piedmont Province is underlain by a two-component aquifer system that is composed of a fractured, crystalline-rock aquifer and the overlying porous-media regolith aquifer. The Coastal Plain is underlain by a porous-media aquifer formed from the poorly consolidated deposits of sand, gravel, and clay.

The conceptual model described for this study qualitatively subdivides the ground-water flow system into local (shallow), intermediate, and regional (deep) flow regimes. Ground-water discharge to tributaries mainly is from local and intermediate flow regimes and varies seasonally. The regional flow regime probably approximates steady-state conditions and discharges chiefly to major drains such as the Tallapoosa River, and in upstream areas, also to the Little Tallapoosa River and the Tallapoosa River. Ground-water discharge to major drains originates from all flow regimes. Mean-annual ground-water discharge to streams (baseflow) is considered to approximate the long-term, average recharge to ground water. The mean-annual baseflow was estimated using an automated hydrograph-separation method, and represents discharge from the local, intermediate, and regional flow regimes of the ground-water flow system. Mean-annual baseflow in Georgia was estimated to be 534 cubic feet per second (ft3/s) (from the headwaters to the Georgia-Alabama State line), 3,250 ft3/s in Alabama, and 3,780 ft3/s for all of Subarea 5 (at the Subarea 5-Subarea 8 boundary).

Stream discharge for selected sites on the Tallapoosa River and its tributaries were compiled for the years 1941, 1954, and 1986, during which sustained droughts occurred throughout most of the ACF-ACT area. Stream discharges were assumed to be sustained entirely by baseflow during the latter periods of these droughts. Estimated stream discharges near the end of the 1941, 1954, and 1986 drought years were 48, 15, and 85 ft3/s, respectively, at the Georgia-Alabama State line; and 481, 126, and 448 ft3/s, respectively, at the mouth of the Tallapoosa River. Estimated baseflow near the end of the individual drought years was about 9 percent of the estimated mean-annual baseflow in Subarea 5.

The potential exists for the development of ground-water resources on a regional scale throughout Subarea 5. Estimated ground-water use in 1990 was less than 1 percent of the estimated mean-annual baseflow, and about 6 percent of baseflow during the droughts of 1941, 1954, and 1986. Because ground-water use in Subarea 5 represents a relatively minor percentage of ground-water recharge, even a large increase in ground-water use in Subarea 5 in one State is likely to have little effect on ground-water and surface-water occurrence in the other. Indications of long-term ground-water level declines were not observed; however, the number and distribution of observation wells for which long-term water-level measurements are available in Subarea 5 are insufficient to draw conclusions.


CONTENTS

Abstract

Introduction

Purpose and scope

Physical setting of study area

Physiography

Climate

Ground-water use

Previous investigations

Well and surface-water station numbering systems

Approach and methods of study

Mean-annual baseflow analysis

Drought-flow analysis

Conceptual model of ground-water flow and stream-aquifer relations

Hydrologic setting

Ground-water system

Geology

Aquifers

Ground-water levels

Surface-water system

Ground-water discharge to streams

Mean-annual baseflow

Drought flow for 1941, 1954, and 1986

Ground-water utilization and general development potential

Summary

Suggestions for further study

Selected references

 


REPORT AVAILABILITY

This report is available online in pdf format (2.8 MB): USGS OFR 96-433 (Opens the PDF file in a new window. )
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