Files
Abstract
Water in the Everglades of central and southern Florida originally flowed from north to south as sheetflow. However, a network of canals, levees, and structures was created to drain the Everglades for agriculture and urban development. These changes altered the natural flow regime, allowing canals to shunt large volumes of water with high phosphorus (P) loads downstream. To remediate this, the Everglades is undergoing a multibillion-dollar hydrologic restoration. One of the restoration goals is to obtain the right water quality and quantity, that is, to provide a more “natural” flow of clean water. This dissertation sought to address this goal by focusing on canals: discharge releases, water quality, and sediment characteristics. The first study characterized and compared the flow regimes of a canal, river, and wetland slough and quantified the effect of flow on water quality constituent behavior using concentration-discharge (C-Q) relationships. The next study developed high-resolution estimates for suspended sediments and P to better assess how rapid changes in canal discharges could impact exports. The final study delineated the dynamics between discharge, water quality, and sediments in canals across the Lower Everglades. The results showed that characteristics of the canal, such as high flow variability and lack of a floodplain, led to an increase in water quality constituent concentrations, especially at high flows. The proximity and discharge volume from a canal inflow structure increased the concentrations of the high-resolution estimates by mobilization and resuspension processes. The suspended sediments closest to the inflow structure had low P contents that increased with increasing distance. Similarly, surficial bed sediments closest to the inflow structure had high bulk density and low P content, while those farther away had the opposite. This indicated that discharges from the structure transported organic P-rich sediments further downstream and left behind heavier P-poor sediments. Thus, canal transport processes are crucial for evaluating restoration goals. I propose that the discharge threshold from C-Q relationships, which segments water quality constituent behavior at low and high flow, be used as a management tool to determine the range of canal discharges that will maximize freshwater delivery and minimize P export.