Within the Chattahoochee River Watershed study area (313 km2), analysis of historic aerial photography from 1950-2010 revealed the number of reservoirs increased seventeen-fold while the area inundated by water increased nearly six-fold (19 reservoirs covering 0.16% of the study area in 1950 to 329 reservoirs covering 0.95% of the study area by 2010). During the sixty-year period, 33-53% of reservoirs were located on-streams, causing between 10-109 stream fragmentations at any given time.
This work was funded by a National Science Foundation Doctoral Dissertation Research Improvement grant and U.S. Geological Survey Pathways Internship.
Land cover modification adjacent to a small reservoir. Adjacent land cover changes from agricultural to forested to developed.
Small reservoir dam failure and subsequent reforestation.
Small reservoir surrounding land cover change from agricultural to developed to demolished (filled and paved over).
Number of small reservoirs in the largest study area watershed, 1950-2010. The dominant land cover adjacent to small reservoirs transitioned from agriculture to developed during the 1980s.
SWAT was used to model evaporation from small reservoirs in the 1,937 km2 Upper Oconee Watershed. The inclusion of small reservoirs did not increase the predictive ability of the SWAT streamflow simulation. However, additional evaporation caused by artificially created open water was substantial, averaging 14 million gallons/day (a substantial quantity compared to the 14-23 million gallons/day used for consumptive use from the region's largest water supply source, Bear Creek regional reservoir).
This work was funded by a National Science Foundation Doctoral Dissertation Research Improvement grant and U.S. Geological Survey Pathways Internship.
(A) Upper Oconee Watershed above the Penfield USGS stream gauge station and locations of Climate Forecast System Reanalysis (CFSR) cell centroids and National Climatic Data Center (NCDC) meteorological stations (B) The location of the Upper Oconee Watershed in Georgia, USA (C) NLCD open water features with rivers removed (2.24 km2 total) (D) Water bodies digitized using aerial imagery (21.13 km2 total) within the Upper Oconee Watershed.
Comparison of average summer (June, July, August) temperature (°C) and total annual reservoir evaporation (m3) in the Upper Oconee Watershed using SWAT and Penman-Monteith, Priestly-Taylor, and Hargreaves evapotranspiration equations.
Average daily evaporation (m3) for years 2003-2013 from reservoirs in the Upper Oconee Watershed using Penman-Monteith, Priestly-Taylor, and Hargreaves potential evapotranspiration methods.
Comparison of total monthly precipitation with stacked monthly streamflow at the Oconee River Penfield gauge, evapotranspiration, and reservoir evaporation (m3) for the Upper Oconee Watershed, 2003-2013.
Reservoirs cause significant hydrologic change including habitat loss, stream fragmentation, altered net evaporation, and modified sediment and nutrient distribution. The Apalachicola-Chattahoochee-Flint (ACF) River Basin in Georgia, Alabama, and Florida is recognized internationally for freshwater biodiversity, includes one of the fastest growing metropolitan areas in the country, and contains numerous artificial reservoirs. To assess the potential impact of small reservoirs in the ACF, a previously unavailable GIS database of reservoirs was constructed. The reservoirs database was generated through synthesis of data from several agencies and analysis of topographic maps, land cover data, and high-resolution aerial photography from 2005-2008. In total, over 24,500 small reservoirs appeared man-made or man-managed and covered over 230 square kilometers of surface area (25 percent of the basin's total reservoir surface area), cause over 11,000 stream fragmentations, and converted over 1,900 kilometers of linear stream distance from riverine habitat to lacustrine reservoirs habitat, nearly 50 percent of the basin's total converted stream distance.
Map showing 25,000+ reservoirs in the Apalachicola, Chattahoochee, Flint River Basin.
Physicochemical water quality parameters were monitored upstream and along the reaches downstream from nine small reservoirs. Small reservoirs decreased downstream nitrate values and top-release dam structures elevated downstream dissolved oxygen, temperature, and pH. Elevated temperatures and decreased dissolved oxygen values were reduced but still observable 250 m downstream.
This work was funded by a National Science Foundation Doctoral Dissertation Research Improvement grant.
Study site location maps; State of Georgia within the United States (A), Altamaha and Savannah River watersheds and Southeastern Piedmont and Coastal Plain physiographic provinces (B), and nine small reservoirs on NLCD land-cover (C) and topographic (D) maps.