SLOSH Inundation Analysis

 

The SLOSH Inundation Analysis represents the potential storm surge water level that an area may expect for a category of storm.

 

There are three key databases installed in order to do the SLOSHView Inundation Analysis.

  1. NWS SLOSH Basin Analysis - This data is provided courtesy of the National Weather Service. Will Shaffer of the NWS has been very helpful.  For a separate discussion on how SLOSH was developed, see SLOSH Data Summary.

  2. USGS National Elevation database - This data was procured from the USGS and contains elevation information for all coastal areas on a 1 arc second grid. This equates to a data point about every 100 ' or so.

  3. US mapping Information - This database contains detailed road atlas mapping information (street level).

 

The elevation database is key because of differences in elevation across a SLOSH "polygon".  The SLOSH data analyses flood level in "polygon" segments.  The differences in elevation across these segments are sometimes significant so while one part of the segment is "under water" other parts may not be.  SLOSH alone will indicate the entire area as "flooded". 

 

When the SLOSH data is "combined" with the elevation data, on a details map, the result is the SLOSH Inundation Analysis. The system represents that water level (inundation) value with colors. See the samples below.

 

Example of a Cat 4 SLOSH MOM Analysis showing inundation values as text (EM/Pro)

 

Example of a Cat 4 MOM Inundation Analysis (Advanced & RM/Pro)

 

Example of a Cat 4 MEOW Inundation Analysis (Advanced only)

 

There are a couple of important things to consider when viewing the Inundation data.

 

1.  Do not attempt to analyze at too detailed a chart level.  Using the SLOSHVIEW program you can zoom down to the street level....however neither the slosh data nor the elevation data is resolved to that level of detail.  

 

2.  Depending on your processor, it may take quite a while to render the inundation images.  A status bar gives you some indication of progress and you can stop the process at any time.  Using the smaller charts and running in true color mode (24+ bit color) will provide the best performance.  Large maps and lower color capabilities will take the longest.  You can check your system video color settings on Windows in Control Panel Display Settings.