Type of Document Thesis Author Ignatius, Amber R. Author's Email Address email@example.com URN etd-07132009-113438 Title Big Water, Little Water: Identification Of Small And Medium-Sized Reservoirs In The Apalachicola-Chattahoochee-Flint River Basin With A Discussion Of Their Ecological And Hydrological Impacts Degree Master of Science Department Geography, Department of Advisory Committee
Advisor Name Title J. Anthony Stallins Committee Chair Helen Light Committee Member Lisa Jordan Committee Member Tingting Zhao Committee Member Keywords
- Stream Fragmentation
- Habitat Conversion
Date of Defense 2009-07-10 Availability unrestricted AbstractDams and reservoirs in the Apalachicola-Chattahoochee-Flint (ACF) Rivers have been associated with significant hydrologic change including water quality decline, habitat loss through stream fragmentation and habitat conversion, temperature alteration, disrupted riparian zone function, modified sediment distribution, and loss of water through evaporation. As this river basin is both an international hotspot of biodiversity and one of the fastest growing areas of the country, the implications of these alterations are of great importance both economically and environmentally.
While the basinís few large government and public utility owned reservoirs have been examined extensively, the cumulative impact of the tens of thousands of small reservoirs is less well known. To assess the impact of these small reservoirs, a geographic database of reservoirs was constructed for the ACF basin for a range of reservoir sizes. The initial framework for this reservoir database was generated through inspection, standardization, and synthesis of data from several agencies. The database was edited using high-quality aerial photography from 2005 through 2008, topographic maps, and landcover data and then assessed for accuracy. The creation of this dataset confirmed over 24,500 small reservoirs throughout the basin.
Trends for a variety of reservoir characteristics were observed within reservoir size categories (small, medium, and large based on reservoir volume). Small and medium reservoirs were unevenly distributed throughout the basin with fewer found in the flat and more southerly regions of Florida. More small and medium reservoirs were found in the agricultural belt of southern Georgia, but the highest densities were found in the steeper and more populated region between the northern Georgia cities of Columbus and Atlanta. Examination of purpose and ownership trends confirmed that larger reservoirs are owned by federal and state governments and public utilities and provide recreation, hydropower, water supply, navigation, and flood control. Smaller reservoirs are local or privately owned and are typically recreation, farm, irrigation, or stormwater retention ponds.
Only 5% of the total volume of reservoirs in the ACF basin is contained in small reservoirs because water depths in small reservoirs are relatively shallow compared to depths in medium and large reservoirs. In terms of surface area, however, small reservoirs contribute 25% of the total surface area of all reservoirs in the basin. Surface area is an important measure with regard to impacts on downstream flow because of the potential for evaporative losses from reservoir surfaces. In addition, small reservoirs have clearly had a major impact on stream integrity through fragmentation and conversion of riverine habitat to lacustrine-type habitat. Based on an analysis of the intersection of reservoirs with flowlines, over 11,000 small reservoirs intersect streams, with the result being conversion and fragmentation of extensive riverine habitat throughout the basin. Of the 6 percent (3,900 kilometers) of the total linear stream distance in the ACF basin covered by reservoirs, approximately half (1,900 kilometers) is covered by small reservoirs. In summary, small reservoirs have had multiple impacts throughout the Apalachicola-Chattahoochee-Flint river basin, and based on the results of this research, habitat conversion, stream fragmentation, and the potential for decreasing downstream flows through evaporative losses appear to be the most important of those impacts.
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