US Army Corps of Engineers

Coastal Inlets Research Program

Estuarine and Coastal Modeling 16
Part of the CERF 2021 26th Biennial Conference

Feedback Between Basin Morphology and Sediment Transport at Tidal Inlets

Authors: Douglas Krafft, Richard Styles, Mitchell Brown
Presenter: Douglas Krafft

Increasing societal pressures are driving changes to coastal land use practices. These changes could potentially alter hydrodynamics and sediment transport patterns and exacerbate navigation channel shoaling conditions. Established theory suggests that basin morphology determines the net sediment transport characteristics in tide-dominated coastal embayments. The long-term evolution of an idealized lagoonal-type barrier island inlet was numerically modeled under five different morphological conditions that transitioned from net sediment import to export to investigate the potential impact of coastal development. Simulations were designed to address the potential effect of elevation distribution in wetland restoration and island construction on sediment transport and resulting deposition/erosion patterns. Estuaries without tidal flats tended to promote sediment import. Simulations with extensive wetlands showed net export, but some sediment from the tidal flats was deposited in the channels. Alternatively, the case with extensive rarely submerged areas also showed net export, but sediment from the inter-tidal zone tended to bypass the deeper sections. Additional simulations varied the horizontal sediment distribution, adding large volumes of sediment to intermediate simulation results at different distances from the inlet. Comparisons between results demonstrate the impact of horizontal and vertical sediment distributions on long-term simulations of sediment import and export from lagoonal-type barrier island systems.