GIS 5990 Module 9: Biscayne Shipwrecks, Analyze Week

Five shipwrecks in Biscayne NP with 300 meter buffers showing benthic zones.

Reclassified layers showing benthic zone and bathymetric data; these layers were used in the weighted overly below.

The output of the Weighted Overlay tool using the reclassified benthic zone and bathymetry layers.

This was the second week of our three-week project focusing on GIS use in analyzing shipwrecks in Biscayne National Park. This module was similar to our previous work in creating predictive models, only this time we processed data relating to the sea floor. As seen above, the variables included in our weighted overlay were benthic zones and bathymetry. Interestingly, the bathymetric data seemed to contradict the actual locations of known shipwrecks; most shipwrecks were not located in the shallowest waters. To account for this, the weighting of the bathymetric data was lowered to 30%; the benthic zone data comprised the majority 70% weighting.

For the most part, this was an enjoyable assignment to complete. I did run into a frustrating difficulty at the end as I attempted to run the Weighted Overlay tool. Many, many attempts either ran into errors or resulted in a raster output that was not classified correctly. Eventually, I checked the properties of my input data, the reclassified benthic zone and bathymetry rasters. I discovered the latter raster was lacking a defined coordinate system; fixing this allowed the tool to run quickly and correctly. The experience reinforced the lesson that I must always check my data to ensure everything is in order.