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National Water Census

Dept. of Interior WaterSMART activities

Dept. of Interior WaterSMART activities

Apalachicola-Chattahoochee-Flint River Basin Focus Area — Studies

The Apalachicola-Chattahoochee-Flint (ACF) River Basin spans Georgia, southeastern Alabama, and northwestern Florida, covering 19,800 square miles. The basin includes the drainages of the Chattahoochee River and the Flint River, which meet to form the Apalachicola River. The Apalachicola River flows into the Gulf of Mexico at Apalachicola Bay.

For over two decades, there have been periodic conflicts over water resources in the ACF River Basin among Alabama, Florida, and Georgia and other stakeholders that depend on the river system for public supply, industry, power generation, and agriculture. As the region has grown and developed over the past 50 years, competition among all water users has become more pronounced, particularly during drought conditions. The debate over water availability has focused on the management of water in reservoirs that are operated by the U.S. Army Corps of Engineers. Although the Corps manages these reservoirs using their own hydrologic model of the ACF mainstem, there are many other uncertainties about water availability across the river system that no existing models address adequately. The USGS WaterSMART studies will focus on the most critical of these uncertainties, including the influence of water withdrawals and wastewater returns on instream flows, the indirect effects of groundwater pumping (for irrigation) on surface water, interbasin transfers, storage in unmanaged reservoirs, and effects of increases in impervious surface and climate variability.

The WaterSMART Geographic Focus Area Study in the Apalachicola-Chattahoochee-Flint River Basin - click to enlargeThe WaterSMART Geographic Focus Area Study in the Apalachicola-Chattahoochee-Flint River Basin will build on existing USGS data collection and modeling capabilities to enhance estimates of water use, develop linked surface-water and groundwater models, and develop relations between streamflow and ecological conditions.
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The ACF Basin Focus Area Study has three major components:

  1. Estimating water use. The water-use component is developing a site-specific database of water use for the ACF Basin, developing improved methods for estimating agricultural withdrawals, and compiling available water-use projections. Calculations of net water use will be improved by obtaining information on interbasin transfers, determining irrigation and septic-tank return flows, and estimating consumptive use by thermoelectric power plants.
  2. Modeling surface-water and groundwater flow. The hydrologic modeling component will consist of a surface-water model for the entire ACF Basin and a groundwater model for the lower ACF Basin. These models will be linked where agricultural pumpage of groundwater is greatest. This will fill a gap in understanding about the extent to which surface water availability in the lower reaches of the basin, particularly in the lower parts of the basin, vary due to groundwater pumping. By providing an improved method of simulating groundwater/surface-water interactions, the model will improve understanding of the basin's water budget.
  3. Developing a better understanding of the ecological effects of hydrologic alterations. The ACF River Basin's physical and biological diversity, and its importance to diverse water users, provide an ideal context for developing tools that will allow stakeholders to better estimate streamflow requirements for ecological purposes. Ecological water science activities in the ACF combine basin-wide streamflow models with on-the-ground measurements of changes in the occurrence or abundance of different kinds of fish and mussel species. These biological measurements are being conducted seasonally in six ACF sub-basins. Data from the field research will allow scientists to calibrate simulation models that evaluate how changes in species occurrences relate to changes in streamflow patterns.

As with the studies in other Focus Area basins, the work being conducted in the ACF Focus Area under WaterSMART is enabling USGS to build expertise in integrating water availability and use studies at a regional scale. In addition to the studies being conducted under WaterSMART, the ACF basin and the surrounding region has served as a pilot study for developing several other Water Census methods that should be broadly transferable to other river systems. This includes research on:

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