Application of Flow and Sediment Transport Simulation: A Case Study of Loxahatchee Impoundment Landscape Assessment (LILA)

Wetlands around the world have been historically drained for land development, recreational, and agricultural purposes.  Often these extensive usages result in degradation of wetland features, which impact wetland ecology, biology, and biodiversity.  An example of such degradation is seen as loss of the ridge and slough features and their connectivity in the highly controlled Everglades of South Florida.  Understanding hydrologic conditions and sediment transport, involved in ridge and slough landscape formation, stability, and maintenance is crucial in restoration efforts. 

A physically based numerical model of sediment transport has been developed as an extension to FLO – 2D integrated surface water/groundwater model.  The developed model has been used to simulate the effect of sediment transport and surface water/groundwater interactions on spatial and temporal variation of bed elevation in the ridge and slough landscape, and to explore how these processes may affect the formation, maintenance and stability of the ridge and slough landscape patterns observed in wetlands.  Sensitivity analysis was performed to assess how the model responds to changes in flow conditions and groundwater head elevation.  Water samples were taken from several locations within a flowing macrocosm of Loxahatchee Impoundment Landscape Assessment (LILA) before, and after extreme rainfalls, and during a series of manually generated pulse flow.  Suspended sediment concentration was measured in the lab.  These data along with other data such as water depth and velocity, and groundwater head, were collected to support and validate the developed model.  Bed elevation is been measured using site topography from available LiDAR data.

Results from the model development and numerical simulations from this research will provide an improved understanding of how wetland features such as ridges may have formed and degraded by changes in water management that resulted from increasing human activity in wetlands such as The Florida Everglades, over the past decades