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Geographic Information Systems: Providing Informationfor Wildland Fire Planning M i c h a e l P. H a m i l t o n , * L u c y A. Salazar,** a n d K e i t h E. PalmerS"

Abstract Controlling wildfires within the wildland/urban interface has proven to be the most complex challenge facing wildland fire agencies. Although program improvements to increase the efficiency of interface suppression efforts have been suggested, the availability of information about the wildfire environment remains a critical resource for wildland fire planning. Geographic Information Systems (GISs) can provide the technology to store, manipulate, analyze, and display spatially oriented information in a form necessary for efficient fire planning and incident decision making. Complex map and attribute information, including vegetation types, fuels models, weather patterns, topography, fire suppression environment, landuse characteristics, and microenvironmenta] features, can be rapidly summarized and integrated. This integrated information can be used to create unique polygons useful in predicting fire behavior, allocating fire suppression resources, and as an aid in planning land use. Simplified user interfaces and the portability of new hardware systems will allow GISs to be used at every level of wildland fire planning.

Introduction

The U.S. Forest Service considers the urban/wildland interface fire problems to be the major challenge facing wildland fire agencies in the United States today. 1 Various actions and strategies have been suggested to ameliorate this ever-increasing fire problem, including improved training of suppression crews, more effective education of property owners, land developers, and local planners, and increased research *Universityof California, James San Jacinto Mountains Reserve, P.O. Box 1775, Idyllwild, CA 92349. **USDA PSW Forest Fire Laboratory, Riverside, California tUniversity of California, Riverside

Key Words: GIS; fire management planning; wildfire; interactive video.

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F e b r u a r y 1989

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on fire behavior in the wildland/urban interface. One underlying facet of addressing this problem is the availability of information about the wildfire environment. Information on fuels, topography, and weather are necessary for wildland fire behavior modeling and fire suppression planning. In the interface region, where structures are interspersed within the wildland area, other factors become involved in planning, including the availability of water, locations and conditions of access routes, flammability of structures and landscaping around structures, placement of structures within the landscape, and potential for flooding following wildfires. This information needs to be current and it also needs to provide a historical perspective for future improvements on planning strategies. Geographic Information Systems (GISs) can provide the technology to store, manipulate, analyze, and display spatially oriented information in a form necessary for wildland fire planning. This paper will present possibilities that are realizable with the majority of currently operating GISs.

Geographic Information Systems Maps have always been a part of wildland fire planning. Hard-copy map s have been used to portray fire spread, prevailing weather pattern s, transportation routes, existing and proposed fuel breaks and firelines, topographic relief, water sources, vegetation types, and past fire perimeters. On large fires it quickly becomes difficult to integrate all of this information, and once the fire reports are completed, these maps are often not easily accessible. Preattack planning maps were to be an integrated system for displaying fire intelligence data for a given planning unit or preattack block,2 but the difficulty of updating and editing hard-copy maps overrode their usefulness as a planning tool. A computerized system would provide the means to store, aggregate, and manipulate these data to provide information for wildland fire planning. A GIS is comprised of software, hardware, data, and a set of operating principles and procedures where spatially referenced data are prepared, managed, manipulated, and displayed to provide information in support of decision making and trends analysis. System manipulation techniques can include: 1. point and polygon retrieval, overlay and merging of polygons, and analysis of adjacent features; 2. data retrieval for the extraction of tabular information and relational files; 3. map generalization for removing boundaries between polygons with similar characteristics; 4. map sheet manipulations for reconciling scale changes between maps and georeferencing new information from different scales; 5. buffer generalization for establishing zones of influence around a

Geographic Information Systems

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point, line, or polygon; 6. measurement and description of points within polygons, line lengths, and polygon areas; 7. digital terrain analysis of elevation data for three-dimensional displays of terrain, generation of elevation contours, slopes, aspects, and watersheds; and 8. point, line, and polygon linkages to additional electronic information including raster image data and video still and motion images recorded on laser videodisc. Various GISs have already demonstrated their usefulness in wildland planning, 3-~ but their capabilities have not been fully explored for providing information for fire management decision makers. Information on Fire Environment A description of the fire environment includes an assessment of fuels, weather, and topography. The attribute files ofa GIS can describe each of these factors in as detailed or as general a resolution as necessary for the specific decisions to be made. Fuels

Fuels can be described by their loadings (both live and dead fuels), heights, depths, continuity, vegetation species, and location. In many situations it is unrealistic to collect all of these data for every piece of ground, even if data storage is not a problem. Fuel models have been devised to provide stylized values of fuel loadings, surface-area-tovolume ratios, fuel depths, fuel particle density, heat content, and moisture of extinction for fire behavior modeling.7 Two commonly used sets of fuel models are used in wildland areas to describe predicted fire behavior s and fire danger. 9 For large areas, fuel models have been defined from Landsat 4,5,1°,11 and Advanced Very High Resolution Radiometer (AVHRR) data. 5,12Custom fuel models can also be developed from on-site inventories or from relationships derived from past research. TM GISs with raster (i.e., grid) capabilities could store and integrate pixel values from satellite, scanned, and video-derived imagery, whereas GISs with vector (i.e., polygon) capabilities could store and integrate area delineations from aerial photographs or transfers from hard-copy maps. In the urban interface, structures also become part of this fuels complex, with spacing, building material, and roof type being of special significance. In general, county building and tax assessor departments maintain very large-scale parcel maps and descriptive information for each private property. Street name and address, lot size, zoning designation, type of structure, area of structure, and history of improvements are recorded to assist in taxation assessment. Often the age of the structure is indicated; this can generally allow planners to determine

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what firesafety restrictions may have applied to each structure. Vegetation surrounding structures is usually not known from records, but state regulations often require minimum clearances for dead and downed fuels, and some local ordinances may require special landscaping with erosion-controlling and low-growing, low-flammability plants. Recommendations for special landscaping, fuels clearing, and hazard reductions (e.g., propane tank placement) 14 can be made using GIS-derived information on vegetation growing conditions (e.g., slope, aspect, elevation, soils) and fuel loadings. The temporal dynamics of fuels and vegetation types can also be addressed with a GIS. Variations in the fuels due to potential and actual harvesting, wildfires, die-back, windthrow, prescribed burning, fuel succession, or urban development could all be registered in the data base and analyzed for their effects on suppression capabilities.

Weather The major weather factors influencing wildfires are wind, temperature, and precipitation. These values are recorded at weather stations interspersed within wildland areas, providing site-specific readings that can be generalized to surrounding areas. Wind models that require spatially oriented topographic information 15,16could be integrated into a GIS. Patterns of precipitation, integrated with hydrological models and topographic relief, could be used to determine potentials for post-fire flooding and erosion. Water availability within reservoirs, urban water systems, and rivers, calculated from precipitation and hydrology models, could assist in dispatching pumpers to the nearest available water supply for any particular time of year.

Topography Topography significantly affects wildfire behavior in a spatial context. Steep slopes can create preheating of fuels ahead of a wildfire. Southand west-facing slopes are typically drier, producing more combustible fuels. Narrow canyons and saddles are usually associated with erratic wind patterns. Structures built at the top of narrow ridges, without adequate setbacks, can be especially vulnerable to fire. Slope also determines the minimal safety distances between buildings and shrubs, as recommended by insurance companies 14or by state and local regulations. Digital elevation models (DEMs) 17 have been developed for many wildland areas within the United States. These data provide point elevations at a grid spacing of 30 m, with an error factor of less than 15 m. A GIS can interpret these data into contours, slopes, aspects, and three-dimensional surfaces (Figure 1).


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F i r e Suppression Environment Information on the fire environment factors of fuels, weather, and topography have additional uses when considering fire suppression strategies. Fuel/landcover information could be used to determine where to use natural firebreaks as firelines, where backfiring would be most effective, where vegetation changes might re sult in reduced fire severity, where more accurate fire perimeters can be more accurately registered, and where unburned islands might be left in the landscape. The effect of variations in locations for fuels management techniques (e.g., prescribed burning) could also be explored with the GIS data bases. Considering structures as fuels, information about their location, spacing, and type of roofing would be of special interest to suppression personnel. The location, description, and shortest distance to the fire, land ownership, administrative boundaries, and condition of access routes are necessary inputs for planning suppression tactics (Figure 2). Some GISs can determine surface distances as opposed to distances "as the crow flies." Length of fire]ine to be constructed or cross-country travel distances in areas of varied terrain could be more precisely determined with this information (Figure 3). Weather patterns typically follow topographic terrain, and therefore, these two factors are often considered together when evaluating fire suppression strategies. Wildfires burning on narrow ridges, natural saddles, or nat'.row canyons (Figure 4) can create extreme fire problems. The addition of structures in these areas can make the fire problem even more unmanageable. Inversion layers can restrict smoke dispersion above certain elevations. These elevation bands could be overlaid with other data layers within the GIS. Inputs on fuel models, weather, and topography provide the necessary information for fire behavior modeling of rates of spread and fireline intensity. 7 A GIS can integrate these data layers to provide spatial delineations of unique combinations of these environmental factors. These unique combinations can be used as inputs to fire behavior modeling schemes 7 to produce spatial perspectives of rates of spread (Figure 5a) and fireline intensity (Figure 5b). Rankings of hazard could be made based on combinations of specific data layers of interest (Figure 6). Estimates of potential fire spotting ahead of a wildfire can also be made using the combination of fuel type, weather, and topography. TM Modeling can also be done before a wildfire occurs to determine strategies for prefire operations, including prevention and fuel management (Figure 7). Suppression planning also requires locational and descriptive information about point data, including existing and potential helispots, heliports, and fire camps; water sources, lightning strikes, fire starts, and fire stations. A GIS could provide the medium to keep this information current, accessible, and integrative with other related data layers.

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Microenvironment Information Up until this point we have discussed GIS data bases in terms of mapping and modeling wildland resources from a macroenvironmental perspective. A great deal of point information must be generalized, where in fact a highly heterogeneous resource may not follow patterns described by large-scale models. The emerging technology of computerinterfaced laser videodiscs and compact discs make it possible to supplement the GIS data bases with visual information about microenvironments, describing areas that would normally be considered point information. TMThis type of information might include historical photographs, characteristics of sensitive biological and cultural resources, images of ground-level fuel characteristics, profile views of vegetation communities, site-specific road or trail conditions, fire equipment caches (and how to locate them), and similar highly localized information. Video maps of oblique and panoramic imagery at various scales can be linked to threedimensional perspectives generated from the GIS data base to provide a more understandable picture of mapped information. Aerial photography, parcel maps, plan maps, and other images that may not be practical to digitize and integrate as a GIS overlay can be cost effectively stored on videodisc and electronically accessed from within the GIS via the relational data base. In this way, video imagery serves as one form of ground truth data for overlays and classifications used within the GIS (Figure 8). Many GIS systems support image processing modules that allow satellite and aircraft sensor data to be manipulated for classification and enhancement before becoming part ofa GIS data base. Image processing of macroenvironmental video images can provide detailed analysis of surface-to-volume relationships, living-versus-dead ratios within vegetation biomass, cover and stand density, and rates of change in vegetation phenology and ontology (Hamilton, unpublished data). Land-Use Information Many of the fire management and suppression problems common to the wildland/urban interface stem from a lack of information available to local government land-use planners. Land-use decisions such as zoning, residential density, and building codes can be arbitrarily made by planners whose experiences are based on urban situations, and who may be unaware of the unique situations common to the wildland]urban interface. Critical, yet unavailable information may include: 1. fire risk and hazard classification maps relating to vegetation type, fuel loadings, vehicle accessibility, and water availability (Fig. 6); 2. fire behavior models, including rate of spread under varying weather conditions; and 3. fire agency evacuation procedures and response time to residences.


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