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

在过去的两个世纪里，独立的土地所有者在美国东南部建造了数千个小型人工水库，以提供社会功能，如供水（牲畜、农业、高尔夫球场）、娱乐（钓鱼、划船）、雨水涵养和审美设施。这些小水库通常位于河流源头附近，破坏了水文连通性，破坏了栖息地，扭曲了水位波动，造成了蒸发损失，影响了沉积物分布，改变了水温，改变了水的化学性质。尽管人们认识到小型水库的影响，但它们对水文健康、蒸发损失和水质的影响在单个水库和累积流域尺度上都知之甚少。为了解决这些问题，本博士论文研究项目研究了乔治亚州北部和阿拉巴马州东北部查塔胡奇流域中上游的小型水库影响。本研究的主要目标是：1)开发和评估池塘建设模式和分布的地理数据库；2)预测不同土地利用和模拟气候情景下小型水库的蒸发损失；3)评估不同营养条件下水库上下游的物理化学水蚀变趋势。地理信息系统（GIS）分析历史航空摄影和土地覆盖数据将被用于描述和分析小型水库建设随时间的变化。监测气象特征将有助于估计小型水库的当地和累积蒸发损失。模拟不同气候情景下小型水库的蒸发损失将为指导水库政策和规划提供预测统计数据。最后，对不同营养条件下的小型水库上下游的理化参数进行测量，揭示水库对水质的影响。开发和评估20世纪50年代以来小型水库的历史地理数据库，将增强我们对人类对景观和生物系统不断变化的影响的理解。了解水库的影响还将为管理和更好地保护淡水生境的战略提供信息，这是维持不断增长的人口和日益受到威胁和濒危的水生物种的关键需要。此外，这项研究将直接为城市规划者、政策制定者和小型水库所有者的工作提供信息，并允许在美国和全球范围内改进水资源分配策略。小型水库建设在包括非洲在内的发展中地区尤其普遍，在过去30年里，这些地区建造了数千座小型水库，在粮食生产、缓解干旱和健康方面发挥了不可或缺的作用。了解小型水库的累积影响对维持生态和社会健康至关重要，对单个水库和整个流域的水管理规划至关重要。

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.