Fine Spatial Resolution Simulation of Two-Dimensional Modeling of Flow Pulses Discharge into Wetlands: Case Study of Loxahatchee Impoundment Landscape Assessment, the Everglades

Abstract

Wetland ecosystems are controlled by their hydrology. Recent experimental and numerical investigations have suggested that flow pulses are needed to preserve sediment redistribution in some wetlands. In this study, the authors investigate the effect of pulsed-flow conditions on the hydrologic regime of low-gradient densely vegetated wetlands using a fine-resolution, two-dimensional depth-averaged numerical flow model. The model was applied to simulate flow depth and velocity within the Loxahatchee Impoundment Landscape Assessment (LILA) wetland located in Boynton Beach, Florida. Two pulsed-flow conditions with low-pulse and high-pulse flow magnitude were considered. The simulation results of low-pulse flow conditions reveal the areas within deep sloughs where flow velocities and directions change continuously, creating enhanced mixing areas within the deep slough. These mixing areas may have the potential to affect processes such as sediment redistribution and nutrient transport. Simulation of high-pulse flow magnitude, however, results in more uniform flow velocity inside deep slough. It also indicates that a pulse can only be detected when inflow discharge is at least 3.0 m3/s. Lower inflow discharge values are too weak in magnitude to generate substantial changes in water surface elevation and velocity and they may not exhibit a flow wave propagation into the study area.