Effects of Flooding and Drought on Water Quality in Gulf Coastal Plain Streams in Georgia

Research Team: Dr. Stephen W. Golladay (Associate Scientist) and Juliann M. Battle (Research Technician III)

Since 1994, water-quality constituents have been measured monthly in three adjacent Coastal Plain watersheds in Southwest Georgia. The study included both average and extreme hydrologic conditions. During 1994, rainfall was 65 cm above annual average and the highest flows on record were observed. From November 1998 through November 2000, 19 months had below average rainfall. Lowest flows of record were observed during the summer of 2000. The watersheds are human-dominated with row-crop agriculture and managed forestlands being the major land uses. However one watershed (Chickasawhatchee Creek) had 10-13% less agriculture and greater wetland area, especially along the stream. Regional hydrologic conditions had a strong influence on water quality. Suspended particles, dissolved organic carbon, NH4-N, and soluble reactive phosphorus concentrations were greater during wet and flood periods compared to dry and drought periods for each stream. Regional hydrologic conditions had little effect on NO3-N or dissolved inorganic carbon. Chickasawhatchee Creek had significantly lower suspended sediment and NO3-N concentrations and greater organic and inorganic carbon concentrations than the other streams. Differences reflect greater wetland area and stronger connection to the regional aquifer system in Chickasawhatchee Creek. Even though substantial human land use occurred within all watersheds, water quality was generally good. Good water quality can be attributed to low stream drainage density and relatively intact floodplain forests. Low drainage density minimizes surface runoff into streams. Floodplain forests reduce non-point source pollutants through biological and physical absorption. In addition to their role in preserving water quality, floodplain forests provide important ecological functions through the export of biological important materials (nutrients and organic carbon) to streams. Extreme low flows may be disruptive to aquatic life due to both the lack of water and to the scarcity of biologically important materials originating from floodplain forests.

Additional Information:

Golladay, S.W. and J. Battle. 2001. Does the Chickasawhatchee Swamp influence water quality? pages 337-340 in Proceedings of the 2001 Georgia Water Resources Conference. Kathryn J. Hatcher (ed.). Institute of Ecology, The University of Georgia, Athens. pdf version

Golladay, S.W. and J. Battle. 2002. Effects of flooding and drought on water quality in Gulf Coastal Plain streams in Georgia. Journal of Environmental Quality 31: 1266-1272.

Funded by: The Joseph W. Jones Ecological Research Center