The Role of GIS in natural hazards within the United States

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1 GIS and US Natural Hazards Amanda Buboltz NRO 509, Fall 2004 The Role of GIS in natural hazards within the United States Overview: A natural hazard is defined as any occurrence or event that has the potential to cause a loss of human life, injury, or property damage. In the United States, natural hazards include earthquakes, volcanoes, tsunamis, floods, tornadoes, landslides, snow and ice storms, hurricanes and tropical storms, and thunderstorms, as well as other natural events. The risk associated with a hazard takes into account the probability that the hazard will occur and the expected loss due to the hazard. A hazard becomes a disaster when there are significant impacts to human lives and/or property. Areas in the United States that are associated with the deadliest disasters have high populations, high physical exposure to natural hazards, and low amounts of wealth or income. If the wealth of a region is higher, the cost associated with a disaster increases. There are several ways in which people try to prevent a natural hazard from becoming a disaster. For example, several laws exist in areas susceptible to natural hazards. Building codes and zoning are both used in areas prone to earthquakes, hurricanes, or floods. Man-made constructions have been designed in order to reduce impacts associated with natural hazards. In areas that experience flooding, levees, floodwalls, and dams have been built to try to contain water within surface water bodies and reduce the amount of flooding. In the central United States, houses are constructed to withstand strong winds associated with tornadoes. Storm cellars and safe rooms are also used to protect homeowners in the event of a tornado. Warning systems for storms, hurricanes, tornadoes, volcanoes, and tsunamis all exist so that people will be able to seek shelter when a natural hazard is predicted to take place. GIS is an important technology associated with hazard warning and preparation, as well as mitigation. Damage associated with natural hazards and disasters is often determined using air photographs, surveying, pictures and/or videos, and reports (Yuan and Dickens- Miccozzi, 2002). Ratings on disasters from tornadoes, earthquakes, and hurricanes are used to give an estimate on the strength of the event as well as the amount of damage expected or resulting from it. It is important to determine damage amounts due to hazard insurance and other forms of disaster aid. Studies on damage associated with natural hazards and disasters provide information on how to better prepare for a future event. GIS technology is an important tool now being applied to natural hazard studies. The use of GIS datasets allows the creation of maps, graphs, and other products that are useful in reporting information on natural hazards. Depending on the type of natural hazard, applications of GIS vary. For example, GIS can be used to track hurricanes and tropical storms and predict landfall locations, as well as provide maps showing variations in regions that are vulnerable to storm surge, damaging winds, and flooding (Greenwood and Hatheway, 1996). For events such as earthquakes, tsunamis (Wood and Good, 2004), and landslides (Wachal and Hudak, 2000), GIS can be used to help predict areas that are more susceptible to natural hazards based on soil and bedrock types, vegetation, fault locations, elevation, slope, and other such factors. Maps can be and have been produced showing regions that have high probabilities of experiencing problems related to these hazards, including such processes as liquefaction, flooding, and slope failure. Locations of buildings and other developments that are potential

2 problem areas due to their structures or the type of soil or rock they are located on can also be reported using GIS. In flooding hazards, flood zone maps can be produced in order to provide information on regions that are more susceptible to damage (Esnard et al., 2001). A common use of GIS throughout different types of natural hazards is damage assessment. GIS technology can incorporate satellite imagery, GPS information, survey data, and remote sensing techniques in order to determine where a natural disaster has taken place and the amount of damage associated with the disaster. This information is useful for insurance and disaster aid. It is also important when determining locations for high hazard probability and lower probabilities when delineating zoning boundaries. GIS is a much easier, faster, and more efficient tool to use when looking at widespread destruction from a natural disaster. Despite this process, field investigations and other means are needed in order to confirm the information gathered from GIS analyses and examine damage amounts at a smaller scale (Greenwood and Hatheway, 1996). Products produced using GIS technology can be used to inform government agencies, town councils, and the general public about regions that are most susceptible to natural hazards (for example, coastlines, flood plains, steep slopes or slopes with loosely consolidated soils, etc). This leads to better zoning regulations and methods of land use planning. Analyses of damage assessment products provide information on the types of infrastructure that is most likely to become damaged during specific types of natural hazards (mobile homes in a hurricane versus brick buildings in an earthquake). GIS also can be used to determine areas with high populations or costly properties that are at risk of damage from a natural disaster. All of this information is important in hazard preparation and attempted prevention of damage. An important requirement in the production of GIS products for natural hazards is cooperation and the sharing of datasets. In the United States, several datasets that can be useful in producing maps of areas at risk to damage from a natural hazard can be found on the Internet. These datasets include NED, DEM, SSURGO and STATSGO, and census data, as well as others. Satellite imagery is another important component for producing GIS products regarding natural hazards. By providing datasets and finished products online, it becomes much easier for town, city, county, and state governments as well as different government agencies and the public to access information and learn what they can do to be better prepared in the event of a natural hazard. References: Esnard, A-M., D. Brower, and B. Bortz, Coastal hazards and the built environment on barrier islands: a retrospective view of Nags Head in the late 1990 s. Coastal Management 29: Greenwood, D. J. and D. J. Hatheway, Assessing Opal s impact. Civil Engineering: Wachal, D. J. and P. F. Hudak, Mapping landslide susceptibility in Travis County, Texas, USA. GeoJournal 51,3: Wood, N. J. and J. W. Good, Vulnerability of port and harbor communities to \ earthquake and tsunami hazards: the use of GIS in community hazard planning. Coastal Management 32:

3 Yuan, M., M. Dickens-Micozzi, and M. A. Magsig, Analysis of tornado damage tracks from the 3 May tornado outbreak using multispectral satellite imagery. Weather and Forecasting 17: Annotated Bibliography Boruff, B. J., J. A. Easoz, S. D. Jones, H. R. Landry, J. D. Mitchem, and S. L. Cutter Tornado hazards in the United States. Climate Research 24: In this study, episodes of tornado occurrences in the United States were examined in order to determine any changes in the number and location of tornado hazards (the authors define a tornado hazard as a tornado that results in human death or injury, as well as destruction resulting in economic loss). Based on studies of datasets from the 1950 s up to 1999, the authors concluded that the number of reported tornadoes has increased over the years due to better detecting and reporting abilities. Locations of tornado occurrences, tornado hazards and densities, and population change were mapped using GIS, showing a shift in hazards from the central US to the south and east. These maps are well presented in the paper, showing evidence for the authors conclusions of a shift in tornado hazard locations. The paper is descriptive in how tornado hazard occurrences and the frequency of hazards has changed since the 1950 s, but there is little information on how maps were produced. Although the interaction between GIS and the study were obvious, there was very little information provided on this subject. Esnard, A-M., D. Brower, and B. Bortz Coastal hazards and the built environment on barrier islands: a retrospective view of Nags Head in the late 1990 s. Coastal Management 29: This paper provides information on natural disasters and hazard preparedness of the town of Nags Head, North Carolina. The paper is an excellent source of information on how GIS can be used in the field of natural hazard studies. The authors describe different databases available in Nags Head, such as parcels databases, storm surge inlet information flood zone locations, and storm surge potential. These datasets and others can be combined in order to provide information useful in land use planning, mitigation, land loss estimates. Using GIS, the authors concluded that about 1/5 of the developed land parcels were located in regions susceptible to coastal hazards. The paper also describes the importance of having an up-to-date GIS database and current maps in order to better prepare and respond to natural hazards. Greenwood, D. J. and D. J. Hatheway Assessing Opal s impact. Civil Engineering:

4 In the United States, hurricanes are the most damaging natural hazard. This paper describes how GIS was used by FEMA in the prediction of damage associated with hurricane Opal, including storm surge, flooding, and wind speed information. The applications of GIS for hazard preparation is well described, as GIS was also used to determine evacuation routes as well as forecasting hurricane location, speed, and intensity. Another application of GIS technology discussed is damage assessment. Using GIS and satellite imagery, it is possible to get imagery from before and after the event and determine the amount of damage from the storm. Although GIS is useful in determining amounts of damage, the paper emphasizes the need of field studies for confirmation. The use of other technologies related to GIS, including GPS and remote sensing, was used in field studies and are well described. Lowe, A.S The Federal Emergency Management Agency s multi-hazard flood map modernization and The National Map. Photogrammetric Engineering & Remote Sensing The author of this paper describes the desire of FEMA to produce a series of national seamless flood maps that contain flood data that can be combined with other hazard information. The paper does a great job emphasizing the need for cooperation between government agencies in order to produce complex and informative data sets, as well as the importance of sharing geospatial datasets. FEMA s goal is to produce a multilayered map that will be available to the public via the Internet. The agency also hopes to produce an Internet mapping program for flood hazards. The agency is attempting to accomplish this by working with the USGS and using information from The National Map and accessing information and other datasets through Geospatial One-Stop. This is a very informative paper on how GIS and existing datasets and information can be used to produce a new, useful product that will greatly aid other agencies and the public in the realm of flood hazards. Wachal, D. J. and P. F. Hudak Mapping landslide susceptibility in Travis County, Texas, USA. GeoJournal 51,3: This paper describes the use of GIS technology in creating maps showing landslide potential. In the study, the authors produced a map showing regions where landslides have the greatest probability of occurring. This map is useful for land use development and planning, as well as determining the most vulnerable developed regions. The authors did an excellent job on reporting how to use GIS technology for accessing landslide hazards and describing their methods and results so that others can produce maps for different regions. The paper does a good job in describing how GIS is useful for land use planning and mitigation as well as providing information to the public on the potential causes of landslide development and regions where landslides are likely to occur. Wood, N. J. and J. W. Good Vulnerability of port and harbor communities to earthquake and tsunami hazards: the use of GIS in community hazard planning. Coastal Management 32: In this article, a case study was completed on tsunami and earthquake hazards associated with the Cascadian subduction zone. GIS was used to classify hazardous areas, determine areas that were at risk to hazards, and provide suggestions on preparation and mitigation. The authors did an excellent job describing the approach

5 used in and providing a description on creating GIS layers used in the study. The article describes very well the use of GIS in identifying areas that are more susceptible to destruction related to the effects of tsunamis and/or earthquakes. Several maps were provided showing population values, types of development, and property values, as well as areas that had high, intermediate, low, or no risk to varying types of hazards associated with earthquakes and tsunamis. The authors also argue a great case for the integration of GIS in hazard planning in order to determine vulnerable areas and use effective mitigation and preparation processes. Yuan, M., M. Dickens-Micozzi, and M. A. Magsig Analysis of tornado damage tracks from the 3 May tornado outbreak using multispectral satellite imagery. Weather and Forecasting 17: The authors of this paper conducted a study on whether satellite imagery and overlay techniques could be used to assess damage and characteristics of a tornado outbreak during May of Currently, the majority of tornado damage assessments are completed using aerial photographs and field studies. This paper is an excellent example of an application of GIS technology to natural hazard studies. Descriptions of varying satellite imagery (resolution, area coverage, spectral bands, etc.) and their strengths and weaknesses are provided. Satellite images were studied from before and after the event in order to determine changes in vegetation cover. Satellite images of the tornado tracks are provided, showing how these images can be used to look at change.