GE 4150 Natural Hazards, Fall 2007

Lab 2: Analyze Societal Vulnerability to Natural Hazards (Data taken from Solving Disaster Management Problems Using ArcGIS 8 by Glenn Johnson)

Synopsis: During an emergency a portion of the population will require additional assistance that they cannot provide themselves. These are usually people with fixed income, mobility issues, or limited education. By conducting a vulnerability analysis we can see what communities will need extra assistance and plan for this in the future. In this exercise we are calculating vulnerability for Wilmington, North Carolina which is plagued by many natural disasters such as hurricanes, wind damage, and ice storms.

Beginning Setup: 1. Create a folder on your h: for your lab work. 2. Copy the SocietalVulnerability.mdb from the class files to your h:. Be sure to do this in ArcCatalog

Exercise Steps: 1. Open Societal.mxd from the class drive. You will see New Hanover county with Wilmington represented in pink.

2. Examine the demographic data; turn on and off each layer. This data was created from Census block data. These demographic attributes were chosen to help identify areas that will potentially rely on public assistance during an emergency. Red indicates an area of high vulnerability.

3. Right click on any of the demographic layers and choose Open Attribute Table. Each field coincides with one of the demographic layers. Each field is a value that represents the percentage of each block group with those characteristics. For example, a value of 55 under PCT_RENT indicates that 55 percent of the households in that block group rent their home. Uncheck and Collapse the Demographics folder.

4. We will be using another feature class which has all of the demographic information in one place. Add the SocietalAnalysis feature class to your Map. This is located under the SocietalVulnerability.mdb (geodatabase). Open the attribute table for this layer. You can see the same information is present from the Demographics layers. In addition we have rankings for each of the demographic layers. These were calculated by classifying the percentages into quantiles. A rank of 1 is the lowest vulnerability concern, while a rank of 4 is the highest vulnerability concern.

5. The RiskSummary layer was created by using hazard information from hurricane storm surge, coastal erosion, wind, earthquake, flood, wildfire, and tornadoes all of which affect the area. The data was compiled to create the RiskSummary layer which analyzes risk from all of the hazards combined. 6. We want to calculate a societal vulnerability score for the region using the rank data we already have. Open the table for SocietalAnalysis. We are going to create a new field. Go to options and choose add field. Name it SocVulScore, leave everything else the same and press ok. Right click on the column heading in the table. Choose calculate values, say yes when asked if you want to calculate outside of an edit section. Type the following expression, you can double click on each of these attribute to put the data in the query:

[NoDiplomaRank] + [NonWhiteRank] + [NoVehicleRank] + [Over65Rank] + [PvertyRank] + [PublicAssistRank] + [RentalRank] + [SingleParentsRank] Click OK. Close the attribute table.

7. Right click on SocietalAnalysis and choose properties ( as a shortcut you can just double-click on the layer). Go to the symbology tab, on the left choose quantities, then graduated colors. For Value: SocVulScore. In the color ramp, right click on the drop down window and uncheck graphics. If you want to see the names of the color bars, instead of the actual colors you can uncheck and check this. Choose slope as the color ramp. For the classification, change the classes from 5 to 4. Underneath label, edit labels as shown below.

Range Label 8-13 Low (8-13) 14-19 Moderate (14-19) 20-25 Moderate-High (20-25) 26-32 High (26-32) Click OK to close the layer properties.

8. Now that we have identified vulnerable areas we want to identify properties which are in the high vulnerability zone. Turn on the Residential Parcels layer. Right click on the layer and Zoom to Layer. You can see much of the residential parcels are located within the city of Wilmington.

9. We want to choose the parcels with a high Societal Vulnerability Score (SocVulScore). From the selection menu, choose select by attributes. Make sure the SocietalAnalysis layer is in the layer tab. Type the query: [SocVulScore] >=26 Click apply then close.

10. Go back to the selection menu and this time choose select by location. Select features from Residential Parcels that intersect the SocietalAnalysis layer. Make sure use selected features is checked. Click apply then close.

11. Right-click on Residential Parcels and choose Data>Export Data. Export the selected features within the SocietalVulnerability database on your h: and save the file as AtRiskParcels. Click Ok, click yes to add the selected features to the map. Turn off the residential parcels layer. 12. Next we want to identify the at risk parcels that are within the natural hazard risk zones. Turn off the SocietalAnalysis layer. From the selection menu, choose select by attributes. Choose RiskSummary as the layer and type the following expression: [RISK_SUM] >=12 Click apply then close.

13. Next use the select by location tool. Select AtRiskParcels that intersect RiskSummary, make sure the use selected features tab is checked. Click apply and close.

14. Right click on the AtRiskParcels>Data>Data export. Save as HazardRiskParcels in the SocietalVulnerability geodatabase on your h:.

15. From the file menu choose Save As. Save the map document on your h: as final_Societal.

Lab Questions 1. Is there a similar pattern for all of the layers under demographics? (Red means an area of high concern). In what region are the red areas found and what are the possible reasons for this?

2. What is the percentage of people over the age 65 living in tract 0111 and block 3?

3. How many blocks have a SocVulScore above 23?

4. Is block 1 in tract 0106 located in a high hazard zone?

5. What is the highest social vulnerability score? What track and block is these region found? What is the percentage of renters in the area? What is the percentage of people with no diploma?

6. How many parcels are located in the HazardRiskParcels layer?

7. What is the name of the lake in Wilmington in the Moderate-High vulnerability zone (shown in orange)?

8. Zoom to layer by right clicking on HazardRiskParcels. Find the two parcels located in the upper right corner, on the outskirts of the city. What do you think is the main hazard which might affect this site?

9. How many residential parcels intersect the stream Mineral Springs Branch?

10. If you were an emergency manager for the city of Wilmington what are 3 things you would do to help the vulnerable population during a hazard situation? Think back on Hurricane Katrina and what could have been done there.