Exploring the Relationship Between Reservoir Management and Riverine Ecosystems from Space

Abstract

Rivers serve as the habitat for aquatic organisms and a source of resources to meet societal needs through river regulation. Despite its societal benefits, river regulation disrupts the river environment in diverse ways, including changes to river water temperature and consequently, aquatic organisms. However, historically, considerations for effective river regulation tend to focus more on the impacts on flow (quantity) than the impacts on water temperature (quality). Such a bias toward water quantity considerations distorts the overall effectiveness of reservoir management efforts for better riverine ecosystem outcomes. Therefore, the goal of this dissertation is to explore the relationship between reservoir operations and riverine ecosystems using an enhanced approach to estimating riverine water temperature through satellite remote sensing. Central to the study is the development of the Thermal History of Regulated Rivers (THORR) framework, which integrates satellite remote sensing and data-driven techniques to estimate river water temperature in the continuum of space and time. This framework enhances traditional in-situ measurements by providing estimates in areas without direct monitoring. Temperature estimates from THORR are applied to further examine how river regulation’s impact on water temperature can potentially influence the dynamics of fish abundance in regulated rivers. The findings indicate a likely connection between the rate of fish retention in a river reach and the water temperature of the reach, which is influenced by my upstream river regulation. Finally, in an effort to extend THORR’s application, the study investigates the feasibility of solely using satellite remote sensing to identify harmful algal blooms in regulated rivers. A successful identification of harmful algal blooms can open up the possible link between river regulation, water temperature, and algal blooms as another component of riverine ecosystems. Overall, this dissertation encapsulates the feasibility and need to incorporate water quality considerations in river regulation for better riverine ecosystem outcomes. The principal mode of investigation relies on satellite remote sensing, specifically Landsat and Sentinel-2 products. However, this study sets a foundation for promising explorations using recent satellite products such as the Surface Water and Ocean Topography (SWOT) for water quantity considerations and Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) for further water quality considerations.