This project will compare numerical and empirical model predictions of coastal flooding at representative military facilities, with the goal of identifying the best practice for any facility. Unlike previous efforts, this project will consider a suite of open-source numerical models, which include all of the relevant physics that contribute to total water levels, such as sea level rise, tides, wind-induced surge, wave runup, and infragravity motions. Total water levels will be predicted for selected tropical cyclones and storm events with varying tracks and intensities, to represent the full range of possible forcings at each location. Locations include facilities on the U.S. Gulf and Atlantic coasts and in the Pacific Ocean to represent the full range of coastal geographies. Model performance will be compared with respect to inundation depths, timing and duration of flooding at each installation, as well as computational costs. This comparative assessment will inform the use of the most appropriate model in terms of resolved physics and computational effort for predictions of total water levels at any facility, thus enhancing military installation readiness and resilience, in direct support of Department of Defense and ESTCP priorities.
Total water level (TWL) projections will be made at three installations using historical extreme events and a range of Sea Level Rise (SLR) scenarios. Simulations will be performed using empirical and numerical models that account for different physical processes whose importance may vary depending on the installations’ hydrodynamic and geomorphological regimes. The simulation tools are all open-source, have been validated through numerous test cases, have been published in the peer-reviewed literature, and many have been adopted by federal agencies. The project team will use these simulation tools to quantify the importance of storm surge, waves, runup, and morphological change on installation flooding and identify model predictive skill through degradation procedures consisting of 1) forcing and bathymetry resolution and availability, and 2) model physics.
The project team will work closely with installation planners, facilities managers, and engineering to understand the challenges they face for future coastal flooding and their needs regarding predictions and easy to understand tabulated and graphical results. At the project culmination the project team will have: 1) Tested a range of model approaches from low-cost/low-effort empirical to high-fidelity, nested, global to regional scale, three-dimensional simulations for predicting TWLs; 2) Quantified the importance of wave effects (relative to storm surge and tides) for altering TWLs for different morphologies; 3) Quantified the effect of model simulations with and without incorporating morphological change; 4) Determined model predictive degradation by a) sequentially reducing model physics and b) sequentially reducing model input (analogous to a real world scenario where data are often coarse or lacking) 5) Developed simple, web-based, graphics-driven tools for the demonstration sites enabling stakeholders and managers to easily identify water level risks associated with different predicted SLR scenarios, characteristic storm events, and modeling approaches; 6) Provided an assessment of the cost (computational and budgetary) vs. model skill at each site; 7) Proposed a potential modeling framework for a small range of forcing/geomorphology scenarios that exist at other military installations.