The goal of this project is to significantly advance the capability to accurately predict sediment transport and seabed morphology in three-dimensional coastal and estuarine environments. To achieve this goal, state-of-the-art algorithms for fully coupled wave, current, sediment transport and bed morphology will be developed, analyzed, and implemented. The development of this system will require a better mathematical and physical understanding of the tightly coupled nature of the various processes involved. In addition, it will require computational strategies which address the accurate and efficient coupling of interdependent processes that exhibit a wide range of spatial and temporal scales?both within the fluid motion itself and between the fluid and bed motion. Robust and highly parallelizable algorithms for the various processes will be developed based on discontinuous Galerkin finite element methods, and the coupling of these algorithms will be carefully investigated in order to maintain numerical accuracy, efficiency, and local mass conservation of sediment and fluid phases.
Studying and predicting the morphodynamics of the coastal zone requires a detailed knowledge of winds, waves, currents, sediment transport and, ultimately, the resulting morphological changes of the seabed that occur as a result of these processes. The erosion and deposition of bed sediment can have a major detrimental impact on the coastal population, infrastructure and environment. For example, during Hurricane Katrina, four major levee breeches that occurred during the storm were a result of foundation-induced failures caused by scour. The transport of sediment is closely tied to a number of other issues in the coastal zone, including water quality and related ecological concerns, beach and shoreline erosion, and the maintenance of navigation channels and harbors through dredging activities. Accurate estimates of expected sediment transport and bed morphological changes can aid greatly in the long-range planning and management of coastal and estuarine environments. In this project, the investigators will develop a fully coupled wave, current, sediment transport and bed morphology model system. Such a system will significantly advance the capability to accurately predict sediment transport and seabed morphology in coastal and estuarine environments. From this research, a better scientific understanding of the complex interrelations among hydrodynamic, transport and morphodynamic processes in the coastal zone will emerge, which can lead to more informed decision-making that will help protect the coastal population and infrastructure. The developed software of the project will also provide a computational infrastructure that can be used in many other applications within the area of computational modeling. Furthermore, the technology developed under this project will be disseminated to government agencies such as NOAA and the US Army Corps of Engineers.
Intellectual Merit: The primary objective of this project was to advance the capability to accurately predict sediment transport and related processes in coastal and estuarine environments through the development, implementation, and analysis of a computational modeling system that accurately and efficiently couples the flow and transport processes, that incorporates all the relevant physics, and that accurately and robustly solves the resulting mathematical equations. Two central modeling tools were developed under this project in support of this objective: (i) DG-SWEM, a Shallow Water Equation Model with modeling components for simulating currents and waves (hydrodynamics), as well sediment transport and the resulting morphological changes of the sea bed (morphodynamics). The DG-SWEM software has been designed to take advantage of high-performance computing (HPC) environments and makes use of a number of efficient numerical methods and supporting concepts developed under this project in order to make its application to large-scale spatial domains (e.g., entire ocean basins) possible. (ii) ADMESH, an ADvanced MESH generation tool for automatically generating digital maps (or meshes) that characterize the complicated geometry of the sea bed and the shorelines associated with these types of problems. The creation of such a mesh is typically a very time-consuming and user-intensive process. ADMESH was created to address this issue and can be used to quickly and automatically generate high-quality computational meshes for performing simulations. The mesh generation tool allows the user to directly extract coastline and bathymetric data via the National Oceanic and Atmospheric Administration’s web-based extraction tools. ADMESH has been used to automatically generate a number of meshes along the along the East Coast of the U.S. and Europe. Broader impacts: The software and computational tools developed under this project have been, and continue to be, applied to a number of coastal issues of national interest, including simulation of hurricane storm surge and circulation and wave activity in the Great Lakes. These models help provide a better scientific understanding of the complex interrelations among hydrodynamic, transport and morphodynamic processes in coastal areas, which can ultimately lead to more informed decision-making that will help protect the coastal population and infrastructure. The research conducted under this project also provides a computational infrastructure and supporting numerical tools that can be used in many other applications within the general field of computational modeling. This project supported graduate students in computational and applied mathematics and engineering at the University of Texas at Austin and the Ohio State University.
