• Research

• Longleaf Pine Research
• Aquatics Research
• Wetlands
• Streams/Rivers
• Groundwater
• Preliminary Aquatic Assessment of the Chickasawhatchee Swamp
• Baseline Hydrology of the Chickasawhatchee Swamp
• Effects of the Chickasawhatchee Swamp on Surface-Water Quality
• Nitrogen and Carbon Transformations in the Chickasawhatchee Swamp
• Biogeochemical Studies of the Upper Floridan Aquifer
• Evaluation of Groundwater and Surface-Water Exchanges in the Lower Flint River Basin, Georgia
• Land-Use Impacts
• Wildlife Research
• Research Publications
• Graduate Projects

Evaluation of Groundwater and Surface-Water Exchanges in the Lower Flint River Basin, Georgia

Research Team: David W. Hicks (Scientist), Dr. Stephen P. Opsahl (Assistant Scientist), Christopher Wheeler (Research Technician III), and Brian Clayton (Monitoring Technician)

The importance of the Flint River to the southwestern Georgia area, in terms of economics, human health, recreation, and aquatic habitat, is incalculable. Large withdrawals of groundwater and surface water for agricultural use during the summer months, coupled with reduced seasonal rainfall generally results in greatly diminished streamflow by late summer and fall. During this base-flow period, as much as 50% of the Flint River flow is groundwater inflow from the Upper Floridan aquifer. Regional streamflow is augmented by a significant volume of groundwater from numerous springs that emerge in or near the river between Albany and Bainbridge. Synoptic streamflow measurements made during base-flow conditions showed that during the late 1980's as much as 650 cubic feet per second of flow was contributed by the Upper Floridan aquifer in this river reach.

Although the connection between the Upper Floridan aquifer and the Flint River is well documented, the processes that control the rate of groundwater discharge to the streams are poorly understood. It is hypothesized that hydrologic factors other than site-specific groundwater levels in the western part of the Flint River Basin and the stream-aquifer head relation have a pronounced bearing on the rate of groundwater discharge to the lower Flint River. The hydraulic gradient from recharge areas to the streams has a pronounced effect on the rate of groundwater flow toward the streams. Even during times of severe drought the head relation at the stream-aquifer boundary changes very little. Thus, it is believed that the variably changing water table, resulting from pumping, has reduced the hydraulic gradient in some parts of the lower Flint River Basin and has resulted in reduced groundwater discharge to the streams.

Following are specific elements of the study:

1. Evaluate long-term changes in groundwater levels in wells tapping the Upper Floridan aquifer.
2. Develop maps showing the changes in hydraulic gradients over time.
3. Quantify seasonal groundwater contribution to the lower Flint River basin.
4. Measure the age of groundwater discharging from selected springs in the basin, and compare the age of groundwater among the springs in terms of relative distances from source/recharge areas.
5. Identify the hydrologic factors affecting the rate of groundwater discharge to the Flint River

Research in progress, publications forthcoming.

Funded by: Department of Natural Resources