Buncombe County, North Carolina, Multi-Hazard Risk Tool
April 29, 2010
Summary of the Federal Highway Administration’s Quarterly Webinar: Applications of Geospatial Technologies in Transportation
These notes provide a summary of the PowerPoint presentation discussed during the webinar and detail the question-and-answer session that followed the presentation.
The presentation is available upon request from the webinar speaker, Todd Pierce (firstname.lastname@example.org).
Renaissance Computing Institute (RENCI)
University of North Carolina (UNC)-Asheville
Approximately 40 participants attended the webinar.
Introduction to Presentation
Mark Sarmiento of the Federal Highway Administration (FHWA) thanked participants for joining the webinar. This webinar was the sixth in a quarterly series of webinars that have been sponsored by FHWA. The series deals with the application of geospatial information systems (GIS) and other geospatial technologies to transportation. This webinar focused on the development of the Buncombe County multi-hazard risk tool and its applications in the transportation arena.
Purpose and Background
Buncombe County is located in western North Carolina and includes the city of Asheville. The area encounters many types of natural hazards, including flooding, wildfires, landslides, and winter storms. In 2004, Asheville experienced severe flooding and a weeklong drinking water shortage following Hurricanes Ivan and Francis. To help support recovery efforts, the state provided additional emergency management funding. A portion of the funds supported local hazard mitigation efforts through assistance from the RENCI Engagement Site at UNC-Asheville.
The Federal Emergency Management Agency (FEMA) requires the Buncombe County Emergency Operations Center (EOC) to submit a mitigation plan every five years. The EOC determined that a GIS tool would streamline the mitigation plan update process by allowing town and county planners to generate maps and reports without needing to first contact GIS specialists.
The tool was designed with input from planners and the EOC Deputy Director, who expressed needs to determine the spatial extent of hazards and their impacts on infrastructure and property. In 2009, the tool was released to the county and its six towns, which now use the tool to update their mitigation plans. The tool was also released to the Asheville Fire Department, which had expressed interest in using it to identify potential new fire station locations.
System Design and Data
The multi-hazard risk tool runs in Microsoft Internet Explorer and Mozilla Firefox. It displays a map in a GIS-like interface but does not require desktop GIS software. The tool includes almost 140 GIS layers, including infrastructure, land use, topography, and hydrography, as well as data for five hazards: floods, wildfires, dams, winter storms, and landslides. These data were obtained from several sources, including the North Carolina Floodplain Mapping Program, the North Carolina State Geologist's Office, and the Southern Group of State Foresters. Access to the system is currently password protected due to the sensitive nature of some of the data; however, a public version of the tool is available at http://buncombe-risk-tool.nemac.org/
The tool was created using Adobe Flex Builder 3 and ESRI's ArcGIS API for Flex to ensure that it could operate with a Flash application. The tool also uses Adobe ColdFusion to update property value reports and ESRI's ModelBuilder with Python to automatically identify intersections and county parcels. All GIS data are stored in ESRI's ArcSDE databases and made available online through an ESRI ArcGIS Server.
Applications in the Transportation Arena
Although the tool is currently being used primarily for emergency response activities, it has several potential applications for transportation. For example, it can allow transportation planners to evaluate how hazards might affect roads and other transportation infrastructure, such as railroads that fall within a 100-year floodplain or highways that might be affected by a landslide debris flow. In addition, the tool could help planners locate communities that might be cut off from resources and evacuation routes during an emergency. Buncombe County has many communities that are built on hills and are only accessible via bridges located in adjacent valleys. By identifying bridges that lie in a floodplain or potential debris field, planners can locate these at-risk communities and communicate information to emergency management officials to help them prepare appropriate emergency response plans. Tool users must now visually inspect maps for intersections between hazards and transportation infrastructure, but the tool will eventually be able to automatically generate reports that list sections of affected infrastructure.
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User Interface and Demonstration
During the webinar, Mr. Pierce provided a live demonstration of the tool and explained the various features, layers, and data that are currently available. Information about some of the hazard layers and other features is provided below:
- Floods - Flood data includes the floodway and 100-year and 500-year floodplains.
- Landslides - The landslide data consists of stability index and debris pathway layers. The stability index highlights areas of instability, which generally correspond to steep gradients. The debris pathway layer depicts both historical landslide paths and expected paths of future landslides.
- Wildfires - The wildfire data is coarser than the landslide data because they were gathered at a regional level. Parcels are ranked for wildfire risk based on fuel availability, distance from responding agencies, and level of development. An area with high fuel availability but no development might be ranked lower than a developed area with less available fuel.
- Winter Storms - The winter storm layer highlights areas that are above 3,000 feet in elevation, since they are more likely to experience icing.
- Dams - The dam model indicates the projected flow of water from Buncombe County's two large dams if they were to break. The model also includes projections for the county's smaller dams based on floodplain and contour data.
- Reports - The tool can generate reports that list the number and value of tax parcels affected by each hazard. A multiplier value is used to adjust property values. Reports can be exported to Excel.
- Other Features - The tool is linked to Google Street View and allows users to locate tax parcels by address or identification number. The tool also includes ESRI's drive time feature, which could further lead to the tool's future use in transportation.
RENCI hopes to continuously update and improve the hazard models based on new data. The flood model will be refined with building footprint data from the entire county to account for the effect of new development on floodwater flows. In the future, the team expects to update the landslide model to consider the frequency of rain events and the dam model with better engineering studies and hydrological models. In addition to refining its current uses, the team would like to expand the tool to consider other hazards including tornados, earthquakes, and drought events. Other potential improvements might include the use of future development scenarios to identify how growth would affect or be affected by hazards. The tool might also be expanded to additional audiences and geographic areas.
The Buncombe County multi-hazard risk tool demonstrates an important use of an online GIS. The tool has allowed hazard mitigation plans to be updated more quickly and efficiently than in the past. The tool also helps provide information to planners in small towns that do not have extensive GIS resources, facilitating reporting and retrieval of geospatial information.
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Question and Answer Session
Have you shown the tool to the NC Department of Transportation (NCDOT)? What was their impression?
We showed the tool to NCDOT during a Climate Change Adaption workshop in Raleigh, NC, in early March 2010. We also demonstrated the tool to the North Carolina Division of Emergency Management and the State Hazard Mitigation Officer. Both expressed interest and are currently trying to obtain funding from FEMA to expand this system to other counties. We are also working with the Land-of-Sky Regional Council, a local government planning and development organization for the four counties around Asheville. The council is using the tool to develop a transportation plan for its four-county region.
Do you have bridges in the system?
Yes, we have a layer from the North Carolina GIS Clearinghouse for bridges. The bridges appear as points on the map when the layer is selected.
How long have you been working on this application?
It took about six months to meet with stakeholders and gather input and then another three to six months of iterative development to build the application. The tool had to be ready by March 2009 so work started the previous fall. Since then, we have introduced additional layers and converted the interface from Java Script to Flash. We are hoping to expand the tool to other counties because most of the data layers are available for all of North Carolina. No additional coding work would be necessary so it would not take much effort to deploy in another county. The only exception would be the need to integrate hurricane and coastal erosion data for use in the eastern counties.
Since RENCI had conducted similar projects in the past, a foundation was already in place to build this tool. For the most part, we focused on entering the necessary data and creating the ability to generate reports.
How many people worked on this application?
One person performed most of the coding but students and other staff provided assistance to process the GIS data and set up the servers. Others were involved in meeting with stakeholders to determine system requirements. Four people in total were involved in developing the tool.
Are there processes in place for updating data or are data updated as they are needed or available?
We update the parcel data every other week. The Buncombe County website updates parcel data daily so we could conceivably update it in our system every day. The hazard data does not change much but we are trying to update infrastructure information as the EOC requests it.
Has anyone expressed interest in using this tool for creating new data and portraying mitigation measures?
We discussed this with stakeholders and some expressed interest in creating mitigation scenarios. For example, there are many businesses located along the Swannanoa River that have been flooded repeatedly so the county is buying them. We might be able to use this tool to see how removing those buildings will affect flooding downstream. As another example, a bridge in Biltmore Village was recently replaced because its river passage was too narrow. There was some interest in being able to create models to determine how different mitigation actions would affect the transportation network and river flow. However, we have not gone this far yet due to our focus on meeting EOC's needs as well as funding availability.
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To conclude the webinar, Mr. Sarmiento presented some other information and resources related to applications of GIS in transportation:
- The spring issue of FHWA's GIS in Transportation newsletter is now available at www.gis.fhwa.dot.gov/newsletters.asp.
- Upcoming events are listed on the FHWA GIS in Transportation webpage at www.gis.fhwa.dot.gov.
- FHWA's GIS in Transportation website also highlights innovative uses of GIS for transportation and offers related information, opportunities, and resources for sharing uses and applications of GIS.
The next webinar in the FHWA-sponsored GIS in Transportation webinar series will occur in approximately three months. Details for the future event and other upcoming webinars will be publicized on the GIS-T Yahoo group distribution list, in emails to state DOT GIS managers, and on FHWA's GIS in Transportation website.
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