Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | home
INTRODUCTION
This methodological study of the Wildland\Urban Interface identified, mapped and quantified risk and hazards facing rural populations from natural disasters such as wildland fires. For the purpose of this study the term 'risk' is defined as the probability of loss and the term 'hazard' is defined as an object or condition which influences risk.
Nationwide, there is growing concern over threats to rural populations posed by natural disasters including tornadoes, ice storms, earthquakes and wildland fire. Wildland fire is the most common and prolific of the natural disasters in Arkansas. In nature, wildland fires are beneficial toward maintaining forest health, minimizing fuel loads, and ordering plant communities. Plant communities regularly exposed to fire developed species which tolerated or even required fire for propagation and regeneration.
Wildfire is a natural phenomenon initially finding its origin in lightning but also with anthropogenic roots. Humans have spread fire to virtually every ecosystem on the Earth. In addition to using and controlling fire, humans are the primary ignition source vectors for the propagation of fire, and modifiers of fuel sources. Wildland fires are defined as those fires which burn vegetative cover: grass, grain, brush, timber, or slash (Clayton 1985).
First among concerns about wildland fires are the rapidly growing population pressures seen in many rural areas of the country, these same rural population pressures are evident in northwest Arkansas. In the past rural typified an agricultural community, today, rural is also characterized as residential. During the settlement of the country, rural residences reduced forest fuels as a form of rural fire protection practice. As the populations moved to urbanized areas near cities rural fire protection practices became urban fire practices. Today, rural communities are becoming increasingly popular, however, their behavior patterns have reversed, forest fuel loads are often left undisturbed or even increased because of aesthetic or scenic reasons. In areas of dense rural residential settlement homes can actually add to the fuel load available to a wildfire increasing the size and magnitude of the fire. Early settlers relied on fire practices to reduce risk or fire proof their properties, the new rural settlers rely on urban fire organizations such as the volunteer fire departments for fire protection.
This study develops the following spatial models: threat matrix, suppression matrix, and risk matrix. When combined, these matrixes will produce a predictive model of wildfire risk to rural residences in northwest Arkansas. The technologies required already exist and most of the data sets are readily available. Unique to Arkansas but common to others states such as California is the issue of urban dwellers unknowingly moving into 'hostile' natural environments where the infrastructure, especially fire protection, has historically been geared toward protection of natural resources. Because of a lack of education about these hazards most rural home owners are unaware of potential risk from wildfire to their life, property, and the natural resources. Because they can obtain homeowner fire insurance, belong to a local rural fire department, or because of lack of recent fire events many rural homeowners believe that they are not at risk from wildfire.
Fire organizations found their roots in rural America and evolved into wildland and urban fire organizations (Payne, 82). Fires within or threating the Wildland\Urban Interface have elements of both wildland and urban fires. For this reason both organizations become involved in protection and suppression of wildfires. There is no one single fire organization yet to evolve for the Interface. Rural Volunteer Fire Departments (RFD) increasingly find themselves protecting life and property without adequate knowledge of forest fuel hazards and without effective wildfire tools and training to combat these fires.
Four of the interim models developed in this study: access potential, ignition potential, fuel potential, and response potential, would be useful to local volunteer firefighters and natural resource managers. These models will help them better assess the risks and hazards threatening rural landowner's property. Computer models can be quickly updated as more detailed and timely information becomes available.
Increasing growth of rural populations, increasing urban sprawl, increasing usage of wildlands for recreation, and increasing forest fuel loads all pose an immediate and direct threats to the contact zone between wildlands and people. This contact zone is termed as the Wildland Urban Interface. The Wildland/Urban Interface is defined as the line, area, or zone where structures and other human developments meet or intermingle with undeveloped wildland or vegetative fuels (United States Department of the Interior, 1995). The Wildland/Urban Interface has become the site of a potential major fire problem that will continue to escalate as the nation moves into the 21st century. When people and wildlands come into contact conflict arises, either directly from the threat of wildfire or from an inadequate emergency service infrastructure necessary to protect the Interface.
In 1994, $450 million of Federal wildland fire suppression dollars were provided by Congress as 'emergency appropriations' spent on protecting the wildland/urban interface (Williams, 1995). Recent reports such as the National Commission on Wildfire Disasters Report (1993) and Fire In Rural America (1992) document the continued expansion of urban areas into rural United States Department of the Interior; United States Department of Agriculture, 1995). Arkansas Forestry Commission (AFC) state foresters are responsible for wildfire education, protection, and suppression in Arkansas. These protected lands include all forest and pasture lands exclusive of areas within incorporated town and city boundaries, agriculture lands (row crop), and federally owned land (Kluender et al., 1988).
The National Fire Protection Association (NFPA) estimates that since 1985 wildfire has destroyed more than 9,000 homes and resulted in the deaths of many firefighters and private citizens. In Arkansas, one study by Kluender et al. (1988) for the period, January 1983 to December 1988, reported a total of 16,047 (2,675 annually) wildfires. Ninety-eight percent of the fires were under 40 Ha (100 acres), three fires were over 300 Ha (740 acres), and the largest fire, caused by arson, was a 875 Ha (2162 acres) wildfire.
Forest fuels are increasing in Arkansas for a number of reasons. Vegetation growth related to Arkansas' mild climate. Warm summers with an average annual temperature of 62.4 degrees F and wet growing seasons with an average annual 49.6 inches of rainfall extends the growing season for vegetation (Smith 1980). This, coupled with an aggressive wildfire suppression response, is contributing to the wildland fuel load buildup. During normal years, existing suppression forces are able to cope with wildland fires keeping the average size of a wildfire in Northwest Arkansas to around 15 acres (6 Ha).
It is during periods of severe 'cyclical' drought that firefightning forces are placed under considerable strain and potential wildfire disasters are most likely. Wildfires played a major role in shaping the existing fuels in AFC's Fire District 6. Stahle et al. (1985) found that historical evidence indicated regular periods of drought over a 450 year period making the areas woody vegetation susceptible to periodic wildfire. Phillips' (1987) analysis of the Palmer Drought Severity Index (PDSI) from 1891 to 1980 found, periodicity, cycles of 14.3 years and 14.8 years, at a 90% confidence level, and peaks at 14.8 and 15 years with cross-spectral analysis. Phillips' (1987) found evidence in the literature that supports nationwide drought cycles of 16 to 21 years. There exist a correlation between the PDSI data and the number of wildfires in Arkansas from 1992 to 1996. This demonstrates the impact of drought upon increased frequency of wildfires. During the interim, when there are years of mild wildfires, it becomes increasingly difficult to justify maintaining an expensive suppression organization.
There exists a dichotomy in fire suppression techniques with respect to wildland fires in the Interface. The two most likely agencies, in Arkansas, to respond to wildland fires are the local volunteer fire department and the Arkansas Forestry Commission. Rural fire department's effectiveness are limited because of several issues. Rural Fire Department's operationally are restricted to well maintained roads, adequate water sources must be nearby, and all their training focuses on structure fires. When a fire is more than 300 feet away from the nearest road it essentially becomes 'out-of-reach' of the local volunteer fire department. As a consequence the volunteer fire crew becomes less effective, and valuable natural resources are destroyed, and state forestry fire crews must respond (McFarland, Deputy State Forester, Arkansas Forestry Commission, oral communication). On the other hand, the AFC operates 'off-road' and uses fire and plow to combat wildfire, but the AFC fire crews receive no training in fighting structure fires. The AFC's mandate to protect natural resources is compromised when life and property are at risk from a wildfire. In the past years low rural population levels plus adequate suppression forces, working together, have kept loss of life and property low. Today, with ever increasing rural population growth and increasing fuel loads the Interface is becoming a more 'hostile' environment.
New technologies such as satellite imagery, global positioning systems, and geographic information systems can be used to identify, inventory, and map the potential risk posed by wildfire to residences in the wildland urban interface.
The study area encompasses Arkansas Forestry Commission Fire District 6 (Benton, Carroll, Crawford, Madison, and Washington counties) located in Northwest Arkansas. District 6 is located in the Ozark Highlands geographic region (see Figure 1) which is characterized by flat-topped mountains and narrow ridges with steep-sided valleys. This area is furthered subdivided into the Salem Plateau, Springfield Plateau, and the Boston Mountains (Smith 1989). Soil types are predominately Ultisol, characterized as deep, weathered, strongly leached soils found in warm, humid climates (Smith 1989).
The study area was located in Northwest Arkansas in the AFC's District
6. The close proximity to the university allowed for extensive field work
when developing the fuel map. This area contains many midsize cities (less
than 50,000) that are characterized as being in the scenic Ozark Mountains,
a major reason why individuals choose to locate in rural areas. The study
area does not contain all 13 Fuel Models developed by Anderson (1982) but
enough do occur that a valid Wildland/Urban Fire Hazard Model can be developed.
Several counties in AFC District 6 contain many expensive homes located
in the Wildland/Urban Interface. Washington County and Benton County are
the second and third most populated counties in Arkansas. By the year 200
northwest Arkansas is expected to receive 32% of the projected population
growth.
Figure 1. Arkansas Forestry Commission Fire District 6 in Northwest Arkansas
AFC Fire District 6 contains 2,283,088 acres (923,953 Ha) of total land cover; 61% is forested and 39% is in urban/agriculture (Dzur et.al, 1995). District 6 ranks 8th in total area among the 11 AFC Fire Districts. District 6 ownership is characterized as private 89.94%, US Forest Service - Ozark National Forest 7.12%, Arkansas State Parks 0.67%, Arkansas Game and Fish Commission 0.53%, US National Parks Service - Buffalo National Park 0.19%, Military Reservations 0.03%, Arkansas Natural Heritage Commission Natural Areas 0.02%, and 1.4% in surface water represented by various local lakes (Table 1).
Table 1. Ownership Categories by Area.
Ownership |
Area in Acres |
Area in Hecatres |
Percent |
| Private | 2,053,489 | 831,035 | 89.94% |
| USFS National Forest | 162,597 | 65,802 | 7.12% |
| Arkansas State Parks | 15,264 | 6,177 | 0.67% |
| Arkansas Game and Fish | 13,292 | 5,379 | 0.58% |
| Buffalo National Park | 4,304 | 1,742 | 0.19% |
| Military Reservations | 788 | 319 | 0.03% |
| Natural Areas | 541 | 220 | 0.02% |
| Water | 32,812 | 13,279 | 1.4% |
| TOTAL | 2,283,088 | 923,953 | 100.00% |
The major forest types in the Ozark Highlands consist of: white oaks-red oaks-black oaks, post oak-black oak, blackjack oak-hickory, river birch-sycamore, and shortleaf pine-oak; grasses, legumes, forbs, and woody plants make up the understory . Tucker (1990) examined early Government Land Office (GLO) survey records and other historical evidence and concluded that pre-settlement vegetation was not dissimilar to that now present. Sargent (1884) mapped extensive grassland prairies in northwest Arkansas with major concentrations occurring in Washington and Benton counties.
Wildland fires, whatever their source, influenced the spread and maintenance of open grasslands in the regions forest. Over the years the ecotonal zone between the forested Ozarks and the prairie moved back and forth under the influence of these spatial and temporal changes in the landscape and climate. Today, fire or its absence has allowed many open grasslands areas to be invaded by sugar maple associations and cedars along with the development of an understory component, all part of a natural successional process. Foti and Glenn (1990) using General Land Office (GLO) records indicated that the openness of the Ouachita Mountain landscape was often ascribed to frequent fires.
Arkansas' climate is humid subtropical with warm, sultry summers with at least eight months of growing season. Average annual rainfall in Northwest Arkansas is 49 inches (124 cm), average January temperature is 35 degrees F. (7 degrees C.), and the average July temperatures is 80 degrees F (25 degrees C). The winters in Arkansas are colder and dryer. Westerly winds influence Arkansas weather patterns, bringing wave cyclone systems into contact with warm, humid tropical air masses (Smith, 89). Generally, there are two fire seasons in south Arkansas, spring and fall, and one fire season in north Arkansas, fall. Spring winds and cured fuels causes spring fires to spread faster, causing more damage, and costing more to suppress (Kluender, et al, 1989).
Chapter 1 | Chapter 2 | Chapter 3 | Chapter 4 | Chapter 5 | home