In this week's module, we analyzed LiDAR elevation data to explore erosion from coastal flooding. We also identified areas likely to be most affected by storm surges during a tropical event.
In the first map above, we can analyze which areas in this part of coastal New Jersey were most affected by erosion due to storm surge from Hurricane Sandy in 2012. The image is the result of the Raster Calculator tool. With the red to blue color ramp applied, red is showing the lowest elevation and blue is displaying the highest points. I can see a lot of red area where ocean waves swept through the neighborhoods and wiped out the beach. There is a bridge and main entrance road at the south end of the map, and it is surrounded in red color, telling me that the ocean pushed through this area quite strongly. Alternatively, the inlet on the north end of the map has minimal red around it and seems to have fared well.
There are also large swaths of land on the intracoastal side that seem to be heavily eroded in areas where it looks like a small island was destroyed and new sand bars were exposed. I feel like the red area on the western edges of the map can’t be reliable because it is inconsistent with the basemap imagery. On the basemap, I can still see areas that were wiped out.
The higher blue points show me where there is debris build-up, and this build-up is concentrated most along the roads. The highest concentrations of debris buildup are on the west side of the map in the neighborhood peninsulas on intracoastal. The debris build-up and erosion are widespread, but the worst of it seems to be closest to the bridge in the southern part of the map.
In the second map, we compared LiDAR and USGS elevation data to identify flood zones where the elevation was less than 1 meter. We then identified which buildings were within each respective flood zone. We used the Region Group tool to exclude areas that were not connected to open water. I think that the LiDAR elevation data used here returned realistic results and identified buildings that are most at risk of storm surge flooding. In addition to identifying at-risk buildings near open water, we could also analyze wetlands, coastal estuaries, and inland waterbodies that could cause flooding during a Tropical Event.
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