Streams/Rivers

Aerial view of Ichawaynochaway Creek.The Flint River basin is one of 14 watersheds found within the state of Georgia. Beginning in the Georgia Piedmont, the Flint River watershed drains 8,460 square miles before it merges with the Chattahoochee River in the Coastal Plain of southwest Georgia. The lower Flint River basin offers numerous opportunities to study the unique biology, hydrology, and biogeochemistry of aquatic systems that are characteristic of the southeast Coastal Plain.

Rivers and creeks of Southwest Georgia, like many in the Coastal Plain, are low-gradient with broad floodplains. Floodplains occupy about 5-10% of watershed area and sometimes exceed 1 km in width. In undisturbed areas, the floodplains or riparian zones are dominated by cypress and flood tolerant hardwoods including gum, red maple, and oaks. Because of abundant rainfall (average 130 cm per year), riparian areas may be inundated for long periods of time. This creates a large intermittently flooded habitat where much material exchange can potentially occur between uplands, floodplains, and streams. It has been suggested that aquatic biota take advantage of seasonal riparian flooding as a foraging area. Alternating wetting and drying may also stimulate decomposition and nutrient cycling in riparian soils, enhancing floodplain forest productivity. Flood-pulses may also be sources of high quality detrital and dissolved organic matter, supporting seasonal peaks in stream metabolism. Most of these relationships have not been quantified, nor have they been incorporated into conceptual models of Coastal Plain systems.

In the Dougherty Plain, the lower Flint River and many of the creeks flow through the limestone formation of the Upper Floridan aquifer. The Upper Floridan aquifer contributes substantially to base-level flows of the lower Flint River directly through natural spring conduits. With a near constant temperature of 21 ºC, natural springs provide a thermal refuge for the gulf striped bass during the hot summer months. Some of the bigger springs open up into large underwater caverns where a variety of dark adapted vertebrate and invertebrate species have evolved. Natural springs in the lower Flint increase river discharge by as much as 50% during droughts. Natural springs also substantially change the water chemistry of the River by increasing nitrogen concentrations and reducing phosphorous concentrations. Although natural springs are a prominent feature of the lower Flint River, many questions remain regarding groundwater/surface water hydrologic linkages, and to what extent regional groundwater use is altering the biology and chemistry of the river.

While extensive human development has occurred in the region, large stretches of the Flint River and major creeks remain largely unregulated, floodplain forests are often intact, natural floods still occur, and groundwater quality in the aquifer remains good. This represents a rare opportunity to couple hydrologic, biologic and biogeochemical studies and to contribute to its preservation. Research projects on creeks and rivers are focusing on: