Document Type



Virginia Institute of Marine Science

Publication Date



Oceans '12 IEEE/MTS proceedings


Chesapeake Bay


Sub-grid modeling is a novel method by which water level elevations on the sub-grid level can be obtained through the combination of water levels and velocities efficiently calculated at the coarse computational grid, the discretized bathymetric depths, and local friction parameters without resorting to solve the full set of equations. Sub-grid technology essentially allows velocity to be determined rationally and efficiently at the sub-grid level. This salient feature enables coastal flooding to be addressed in a single cross-scale model from the ocean to the upstream river channel without overly refining the grid resolution. To this end, high-resolution DEMs will be developed using GIS from Lidar-derived topography for incorporation into a sub-grid model, for research into two case studies related to inundation: (1) The Great Flood of 1936 was utilized as a test for sub-grid modeling in Washington, DC. It demonstrated that the sub-grid model can achieve accurate results upon comparison with NOAA observation data and replicate the results of a likewise-resolution true grid model, indicating that there is minimal loss of quantitative accuracy in the sub-grid approach (R 2 = 99.98). (2) Spatial comparison of GPS wrack line data with model results for 2011 Hurricane Irene demonstrated that sub-grid model results accurately predicted the water level observed at Langley Research Center.



coastal flooding, storm surge, modeling, estuaries, Lidar data, river discharge