Southern Louisiana 1/3 arc-second NAVD 88 Coastal Digital Elevation Model

Modeling and mapping of coastal processes (e.g. tsunamis, hurricane storm-surge, and sea-level rise) requires digital representations of Earth's solid surface, referred to as digital elevation models (DEMs). Some modeling utilizes structured, square-cell DEMs, while others utilize unstructured grids that have no regular cell size or pattern. Usually, these different DEM types are developed independently, even though they are built from the same source bathymetric and topographic datasets. The National Geophysical Data Center (NGDC), an office of the National Oceanic and Atmospheric Administration (NOAA), has developed two bathymetric-topographic square-celled DEMs and one bathymetric-topographic unstructured DEM of southern Louisiana. The DEMs were developed for the Hurricane Forecast Improvement Project (HFIP), with the purpose of developing a new methodology for unstructured grid production from structured square-celled grids. The 1/3 arc-second DEM
referenced to North American Vertical Datum of 1988 (NAVD 88) was carefully developed and evaluated. A NAVD 88 to mean high water (MHW) 1/3 arc-second conversion grid derived from VDatum project areas was created to model the relationship between NAVD 88 and MHW in the southern Louisiana region. NGDC combined the NAVD 88 DEM and the conversion grid to develop a 1/3 arc-second MHW DEM. The NAVD 88 DEM was generated from diverse digital datasets in the region. The DEMs were developed to be used for storm surge inundation and sea level rise modeling. The source bathymetric and topographic datasets used in the development of the NAVD 88 DEM were utilized along with the NAVD 88 DEM and derivative grids to develop the NAVD 88 unstructured DEM.