Program in GIS

Relief Zones and Candidate Relief Sites
Overview

Figure 1: Relief priority zones and candidate relief locations.

Source:  Brenton White ArcMap Project 3 screen capture.

Figure 1 provides an overview of the results of analyzing the tornado activity and determining the relief priority and candidate relief locations, illustrating the areas most likely to have the greatest need for emergency relief and identifying the public facilities near the affected areas.

Relief priority ranged from 1 (the highest) to 5 (the lowest) and there were 33 candidate relief facilities identified.

The analysis included:

• Determining the width of each tornado

• Establishing a 1 mile buffer zone around each tornado path

• Calculating the population density for each buffer zone to establish a relief priority

• Finding all the churches, hospitals, and schools in the buffer zones (see Figure 2)

• Optional: Using U.S. Census tracks to identify relief priority zones

Attribute Table for Candidate Relief Sites

Figure 2: Name and type of candidate relief locations.

Source:  Brenton White ArcMap Project 3 screen capture.

Figure 2 shows the 33 candidate relief sites that are located in the relief zones.

Close Up of the Highest Priority Areas

Figure 3: Candidate relief locations in highest priority zones (close up).

Source:  Brenton White ArcMap Project 3 screen capture.

Where the most intense tornado hit the most densely populated area, there were quite a few facilities to serve as candidate relief sites (12 out of the 33 identified).  Note that the area between the tornado path and the relief priority zone is the tornado's width and, generally speaking, it's damage path.

Limitations of this Analysis for "Real World" Emergency Planning and Relief

The biggest limitation to this analysis is using the density for the entire county as representative of the density in the path of a tornado.  Also, there could be a public facility very close to the 1 mile buffer that could be used if the analysis where to contain "secondary" candidate locations (by, say, having another buffer extending 1 additional mile  beyond the first mile buffer).  Notice that many tornados have no relief sites nearby (see figure 1), which the "secondary" buffer may uncover.  Another limitation of this analysis is limiting (no pun intended!) the facilities to schools, churches, and hospitals as there are other facilities that could accommodate injured or displaced individuals. Finally, assuming that the damage is limited to the width of the tornado probably underestimates the impact the tornado made and it is possible that some of the candidate relief sites are damaged as well.

Optional:  Use Census Track Data

Relief Zones and Candidate Relief Sites Using Census Track Data
Overview

Figure 4: Relief priority zones and candidate relief locations using U.S. Census Tracks.

Source:  Brenton White ArcMap Project 3 screen capture.

Figure 4 shows the changes to the analysis by using the more detailed U.S. Census Track data than from using county data.  We get a much more detailed picture of the relief priority zones.

Close Up of Some High Priority Areas Using Census Track Data

Figure 5: Candidate relief locations in some of the highest priority zones using U.S. Census Tracks.

Source:  Brenton White ArcMap Project 3 screen capture.

Figure 5 shows the variation of relief priority when using Census Track data when compared to Figure 3.  Note that not all the candidate locations are in the highest relief priority zones, unlike the ones in Figure 3 using county data.

Close Up of Other Priority Areas Using Census Track Data

Figure 6: Candidate relief locations in some of the highest priority zones using U.S. Census Tracks.

Source:  Brenton White ArcMap Project 3 screen capture.

Figure 6 shows some high relief priority areas that were not identified on the overview image (see Figure 1) using just county data.  With the additional detail of the Census Tract data, we see that there are areas with relief priority at its highest.  Our county analysis would have overlooked this important area.

GEOG 5222: Project 3: Locating Tornado Relief Sites. May 2004.

Lesson 3 tables.  http://www.e-education.psu.edu/courses/geog5222/zips/lesson3_tables.zip.  Accessed 3 May 2004.