Lahars Are Frightening (GIS 4048- Applications in GIS)

Kicking off Applications in GIS we start with an introduction to lahars. What is a lahar? It is a mud flow composed of water, debris, and pyroclastic material. They have the viscosity of wet concrete and have the potential to flow at speeds up to 60 mph and distances of more than 190 miles.

Our lab focused on Mt. Hood, located in Oregon, just east of Portland. The goal was to identify potential hazard areas from lahar-prone valleys that exist on the volcano's flanks. We began with two DEM's which needed to become merged. The fill tool was then used which helped fill in sinks in the surface raster. Next, the flow directional tool was used to assign each pixel a value so that the direction of water flow across the cell could be represented. The flow accumulation tool could then be utilized to calculate the number of cells that flow into one another. Other tools utilized were the Int tool which converted the raster, which contained floating point numbers, to integer numbers. Finally, the Con Tool, which allowed us to define a stream by creating a threshold for the flow accumulation values.

Once these steps were completed, a buffer was placed around the new feature class created from the stream. From here, all the block groups that intersected the buffer could be obtained. This was also applied to the local schools as well. The culmination of all this can be seen in the map provided.

This was a tough assignment in wrapping my head around the new tools and remembering how to use tools I have utilized previously. Work has been hectic so finding the time for school wasn't easy. Now that things are leveling out, the road ahead should be a bit easier.

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