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| Figure 1 - NJ Coastal Flooding |
In Part 1 of the lab, I explored how GIS and LiDAR can
be used to analyze natural disasters, focusing on Hurricane Sandy’s impact on
Mantoloking, New Jersey. My goal was to measure erosion caused by the storm
using pre‑ and post‑event LiDAR data. After loading both datasets into a 3D
scene, I compared the pre‑ and post‑storm point clouds to observe visible
differences.
Next, I created DEMs by converting each LAS file to a
TIN and then to a raster. Using Raster Calculator, I subtracted the pre‑storm
DEM from the post‑storm DEM to highlight areas of erosion and deposition. The
red‑to‑blue color ramp helped me visualize where the storm removed sand,
destroyed structures, or deposited debris. I then compared these changes with
building footprints and imagery using bookmarks to answer questions about
rebuilding, damage patterns, and data reliability
In part 2 of the lab, I modeled a
1‑meter storm surge using both the LiDAR DEM and the USGS DEM to see how each
dataset affects flood mapping results. I created flood rasters by selecting all
areas below the surge height, used Region Group to identify connected flood
zones, and kept only the region that was truly connected to open water. I then
converted the flood areas to polygons and performed spatial joins to determine
which buildings were flooded according to each DEM. All in an effort to
determine the accuracy of the DEM’s.
Throughout the process, I had to troubleshoot several
issues, including incorrect data paths, confusion about Region Group values,
verifying that “0” meant not flooded, and fixing queries for omission and
commission errors. I also resolved problems with map layout, such as removing
unwanted basemap labels. After calculating errors, I found that the USGS DEM
produced extremely high commission rates, meaning it greatly overestimated
flooding. Because of this, I used the LiDAR results for my final map since they
were more accurate and realistic.








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