Models

Tidal Models | VDatum | Storm Surge Forecast Models

Tidal Models

The NOAA Office of Coast Survey will develop a calibrated hydrodynamic tidal model for the greater Pensacola region. Model simulations will be made with a computational finite element model that uses an unstructured grid of triangular elements in order to provide high resolution of complex coastline and bathymetric features while minimizing cost elsewhere. Tidal boundary condition and body forcing will be used to simulate a time series from which tidal datums can be computed (e.g. Mean High Water, Mean Lower Low Water). Model output will be verified against CO-OPS tidal datums at stations throughout the model domain.

VDatum

VDatum is a vertical datum transformation tool jointly developed by the National Ocean Services' Coast Survey Development Laboratory and the National Geodetic Survey that is able to transform disparate bathymetry and topography data to a common vertical datum. Combination of elevation measurements that are referenced to inconsistent vertical datums causes artificial discontinuities in the elevation field, particularly in coastal areas where bathymetry and topography meet. Vertical datum transformations are required to combine and compare coastal geospatial data collected from diverse sources. Once these incompatibilities are addressed, the data can be combined into a seamless data set that extends from seafloor to land.

The accuracy of VDatum results depends on the quality of the data controls used in the project. Therefore, the quality and utility of the available tidal datums and benchmarks will be evaluated prior to incorporation into VDatum. Tidal datums are used to validate the predicted tidal datum fields computed from the tidal model simulations. The tidal benchmarks provide a surveyed reference point of known position and elevation that is used to relate tidal datums to orthometric datums. Once the VDatum tool is developed and quality controlled, it will be used to merge the newly collected topography and bathymetry (topo-bathy) data into a seamless surface. This merged topo-bathy data set will be made available in the most widely used formats within the user community. The final VDatum product will also be made available in both software and web-based conversion tools.

Storm Surge Forecast Models

Storm surge forecast models predict surge height based on numerous criteria, including bathy/topo, tidal, atmospheric, and wave conditions. The model can simulate historical, hypothetical, or predicted hurricanes depending upon the model application scenario. These models require atmospheric conditions including pressure and wind fields which are a function of the track, size, forward speed, and strength of the given storm. Calculations of surge are then made for a specific region, incorporating the unique shoreline, bay, and river configuration and other physical features.

The National Ocean Service's Coast Survey Development Laboratory is developing a demonstration storm surge model that will incorporate high resolution of coastal and inland regions and continuous bathy/topo elevation data referenced to a common datum. The storm surge model will be based upon the tidal model with the addition of land areas up to the 10 meter topographic contour for the area from west of Mobile Bay, AL, to east of Pensacola Bay, FL. This will allow for accurate modeling of hurricane-driven inundation throughout the region. Model forcing will include atmospheric wind and pressure effects as well as tidal forcing and freshwater inflow; surface wave conditions will be examined as feasible. For more information on how storm surge forecast models will be used in this project, view the Forecasting and Predictions section.

Return to top