Applications Week 4: Coastal Flooding

 

In this week's lab, we explored using elevation models to assess the effects of storms and coastal flooding. For the first part, we examined the change in elevation after Hurricane Sandy in New Jersey, which outlines where buildings were destroyed, where land was eroded, and where debris piled up. In the map below, the dark red areas are where the elevation decreased the most, and the dark blue areas are where it increased the most.


We also compared a DEM from USGS and a LiDAR-derived DEM of part of the Florida coast to see what areas they would identify as being affected by a 1 meter storm surge. This part of the lab was pretty complicated and introduced me to some new tools, such as Region Group and Extract by Attributes. I struggled with table joins, so I selected by location and calculated fields to add the 1 and 0 values for flooded and not flooded to the buildings table.

I was surprised that the USGS and LiDAR DEMs had such large differences between them. The omission and commission error rates were quite high. Assuming that the LiDAR DEM is indeed accurate, the USGS DEM does not seem to be very useful for predicting storm surges and coastal flooding, since it would predict that many buildings would be safe from a 1 meter storm surge that are actually below 1 meter.


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