GIS 4048 Module 3: Natural Hazards - Tsunamis

Figure 1: Map showing radiation and runup evacuation zones surrounding the Fukushima II plant and along the coastline.

Module 3 of Applications in GIS continues the theme of natural hazards with a focus on the 2011 tsunami that struck Japan and created a radiation hazard from the Fukushima II nuclear power plant. This necessitated incorporating two hazard zones in the analysis and final map: the multiple perimeters of radiation exposure surrounding the plant and the runup from the tsunami along the coastline. An additional component of the module involved the proper organization of multiple datasets within geodatabases. This organization becomes crucial as the number of datasets and complexity of analyses increase, especially if projects will be worked on my multiple people and returned to over time. Finally, we utilized Modelbuilder to create a workflow that produced the needed datasets and that could be shared and modified.

The simplest step of the analysis depicted in the map above was the creation of the five radiation hazard zones using the Multiple Ring Buffer tool. This created a powerful visual of the potential radiation hazard facing populations and infrastructure at various distances. The tsunami runup hazard zones required more steps to create. In simplified terms, it is the result of combining layers depicting the lands affected by the tsunami with a DEM and categorizing the result into three zones based on elevation (0-10 meters, 11-40 meters, and 41-78 meters).

While the analysis portion of the assignment was a challenge, the requirements for the final map were just as challenging. The need to efficiently display two different hazard zones on the same map created many opportunities for symbologies to clash. After some experimentation, I decided to go with a patterned symbology for the radiation zones while keeping a simple color-based symbology for the runup zones. Each were given moderate transparency. This created a layout that communicated the information while not becoming cluttered. Major Japanese cities were added to the locator data frame to give context for the location of the Fukushima plant and tsunami damage.

GIS 4048 Module 2: Natural Hazards - Lahars

Figure 1: Lahar hazard assessment surrounding Mt. Hood, Oregon.

Having been away from GIS coursework for a few months, the first assignment of Applications in GIS was a welcome return to learning new GIS tools and skills. Specifically, this module focuses on the manipulation of raster data with a focus on tools used for hydrology as well as tools to perform mathematical functions on raster data. The purpose of using these tools was to produce a map depicting potential hazardous areas that would arise from lahars triggered by an eruption of Oregon's Mt. Hood.

Lahars are mixtures of material, generally mud and rock combined with water and volcanic material, that flow down the slopes of a volcano into surrounding valleys. The above map uses digital elevation model (DEM) data to predict the areas most likely to be affected by lahars originating at Mt. Hood. We proceeded through multiple steps to arrive at the final data product. First, two DEMs were mosaicked into one, then the Fill tool was used to "smooth" the raster data to diminish the potential for errors in the data affecting the subsequent analysis. The output of the Fill tool was the input for the Flow Direction tool, the result of which was a colorful raster wherein cells were categorized based on the direction water would flow over the surface. This output, in turn, was used with the Flow Accumulation tool. The output raster shows streams and rivers based on the previous calculations. The Int, Con, and Stream to Feature tools were then used, resulting in a line vector shapefile. The final step of the assignment was to create a buffer of 0.5 miles around this shapefile to catch the schools, cities and overall population (as represented by census block groups) that would most likely be at risk from lahars from Mt. Hood.

Although I do not know how often I will utilize the hydrology tools in my career, I am glad to have been introduced to them should the need arise.