For my first Geol 340 lab I refreshed my basic GIS skills by recycling a lab I from ENVS 330, in more depth. For instance, this was my first introduction to ArcCatalog. This lab focuses on the Willapa Bay estuary in Washington and uses data on habitats from the area by the Columbia River Estuary Study Taskforce (Crest). I remember from ENVS 330 that Willapa Bay is the second largest estuary in the United States and is home to a variety of shelled mollusks and is a huge oyster farming hub. For this lab I looked through the data and metadata, mapped the areas of the different habitats in Willapa Bay onto GIS and then used the data to analyze the percent area of Willapa Bay each habitat consumes.
Reading the metadata I discovered that CREST collected data on Willapa Bays habitats and topography from a few different sources. The State of Washington Department of Transportation (WDOT) and Oregon State university provided aerial photographs, and Marine Resources Consultants, Inc. and the University of Washington provided videography. They used SCHEME coding for the habitat types (Development of a system for classification of habitats in estuarine and marine environments), which was created by the Gulf of Mexico Program, Florida Fish and Wildlife Conservation Commission, and Florida Marine Research Institute. This study was originally conducted to study seagrass in the area.
After downloading the data onto my computer and uploading it onto ArcGIS, I created a new map, displaying the habitat types at Willapa Bay. My one regret is having a monochromatic color scheme. I was carried away with the purple hues, and now realize they are not easy enough to differentiate from one another. As you can see in the legend of the map I created (fig. 1), there are 6 types of habitat at Willapa Bay documented from this project: tidal marsh, land, unknown benthic habitats, unconsolidated sediments, continuous submersed aquatic vegetation (SAV) and discontinuous SAV. Using the data, I connected the scheme codes (4, 6, 7, 11, 211 and 212) to the habitat type they refer to. I then manually plugged this in to the legend so that the areas would read as habitats and not numbers.
FIG. 1: Willapa Bay Habitat Map
I then set out to determine what percent of Willapa Bays’ area each habitat took up, which can be seen below in Fig. 2. I did this by selected only the data for one scheme code at a time and in ArcGIS and calculating the area of that habitat type by selecting calculate and typing in the area =. I then put this information into a pie chart (fig. 2) to see and visualize the percents of each habitat.
FIG. 2: Pie chart showing percent area of Willapa Bay habitats
Willapa Bay has a lot of mud, at 61% of the land area. Marsh takes up the largest percent of this region at 18% and land takes up the third most at 14%. In comparison, the other habitat types are miniscule, not easily visible on the ArcGIS map. My main findings therefore, are that Willapa Bay is mostly made up of mud. I recall that the native species of shrimp called Ghost Shrimp that live in Willapa Bay break up the sediment in the bay, and I wonder if this is why so much of the estuary is mud. This would make interesting further research.