Doctoral Dissertation Research: Cumulative Impacts of Small Reservoir Construction on Evaporation and Water Quality in the Piedmont

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Over the last two centuries independent landowners have constructed several thousand small artificial reservoirs across the southeastern United States to provide societal functions such as water supply (livestock, agriculture, golf courses), recreation (fishing, boating), stormwater retention, and aesthetic amenity. Typically located near stream headwaters, these small reservoirs disrupt hydrologic connectivity, fragment habitat, distort water level fluctuations, contribute to evaporative losses, impact sediment distribution, alter water temperature, and modify water chemistry. Despite the recognized impacts of small reservoirs, their effect on hydrological health, evaporative losses, and water quality is poorly understood at both the individual reservoir and cumulative watershed scales. To address these issues, this doctoral dissertation research project examines small reservoir impacts within the Upper and Middle Chattahoochee watersheds of northern Georgia and northeast Alabama. This study specifically addresses the following main objectives: 1) development and assessment of a geographic database of pond construction patterns and distribution over time, 2) prediction of evaporative losses from small reservoirs located within different landuse and simulated climate scenarios, and 3) evaluation of physicochemical water alteration trends upstream and downstream of reservoirs with different trophic conditions. Geographic information systems (GIS) analysis of historic aerial photography and landcover data will be employed to characterize and analyze small reservoir construction over time. Monitoring meteorological characteristics will allow for estimation of local and cumulative evaporative losses from small reservoirs. Modeling evaporative losses from small reservoirs under different climate scenarios will provide predictive statistics to guide reservoir policy and planning. Finally, measurement of physicochemical parameters above and along the reaches downstream from small reservoirs with different trophic conditions will reveal how reservoirs alter water quality. Development and evaluation of historic geographic databases of small reservoirs dating back to the 1950s will enhance our understanding of the changing human impact on landscape and biological systems. Knowledge of reservoir impacts will also inform strategies to manage and better protect freshwater habitats, a crucial need to sustain growing populations and increasingly threatened and endangered aquatic species. In addition, this research will directly inform the work of urban planners, policymakers, and small reservoir owners and allow for improved water allocation strategies both within the U.S. and globally. Small reservoir construction is especially common in developing areas including regions within Africa where several thousand small reservoirs have been constructed over the past 30 years to play an integral role in food production, drought mitigation, and health. Understanding the cumulative impacts of small reservoirs is vitally important for sustaining ecological and societal health and is essential for water management planning at the individual reservoir and basin-wide scales.