Tuesday, 24 January 2012: 2:00 PM
An Inundation Forecast System for Scituate, MA
Room 337 (New Orleans Convention Center )
Strong extratropical cyclones (e.g., Nor'easters) can cause significant coastal flooding in New England each year, with major damage to property and infrastructure and some loss of life. The FVCOM-based Northeast Coastal Ocean Forecast System (NECOFS) presently provides 3-day forecasts of total water level, currents, and waves along the coast (treated as a vertical wall) on the regional (GOM3) grid. In collaboration with the NWS Taunton (MA) Weather Forecast Office, we have set up an inundation model forecast system for Scituate (MA) as a pilot study to test the capability of NECOFS for “end-to-end” inundation forecasting. This system includes a fully 3-D current-wave interaction FVCOM model with flooding/drying and seawall/dike capabilities, and features an unstructured grid based on high-resolution LIDAR, USGS, and state bathymetry and land elevation data that nests with the regional GOM3 grid. An inundation forecast is made in two steps: the NECOFS regional forecast is first made and then its 3-day output is used to drive the Scituate forecast model system. This two-step approach simplifies inundation model system setup, providing for a stable regional model grid while facilitating easy modification/refinement of the local land topography (and water bathymetry) model grid and the addition of new areas into the inundation forecast system. The Scituate inundation forecast system has been used to hindcast three major Nor'easters (May 25, 2005; April 18, 2007 (Patriots' Day storm); Dec. 27, 2010). Comparisons with limited in situ data indicate that storm-driven waves play an important role in increasing inundation. The model-predicted inundation occurring within Scituate harbor was well-resolved and realistic, while inundation caused by the wind-wave-current-driven overtopping of the exposed northern seawall was not. This “splash-over” process is not included in the Scituate inundation forecast system at present but work has started on including this in the future.