Section 3: Hazard Identification and Risk Assessment. Description - Wildfire

Transcription

1 3.3.12: Wildfire Description - Wildfire Wildfires are uncontrolled fires often occurring in wildland areas, which can consume houses or agricultural resources if not contained. Common causes include lightning, human carelessness, and arson. Wildfires are fueled by naturally occurring or non-native species of trees, brush, and grasses. Topography, fuel, and weather are the three principal factors that impact wildfire hazards and behavior. The areas of highest risk to life and property are the Wildland Urban Interface (WUI). The United States Forest Service (USFS) defines the WUI as the area where houses meet or intermingle with undeveloped wildland vegetation. This makes the WUI a focal area for human-environment conflicts such as wildland fires, habitat fragmentation, invasive species, and biodiversity decline. For additional information about wildfires visit the State of New Jersey Forest Fire Service website at Location - Wildfire The potential for wildfires exists over the entire region, although the probability is relatively low particularly in the urban areas due to the detection and suppression capabilities that exist. The rural and forested areas of the region are at a greater vulnerability than the urban areas. Figure RP below identifies the wildfire fuel hazard risk for the NJ4 HMP region. Fuel hazard refers to the risks associated with the amount of biomass that will burn under a given set of conditions. Moisture content and fuel size are the primary determinants of availability. Arrangement and compactness of fuel may also determine availability. 1 The map was developed based on GIS data obtained from the New Jersey Forest Fire Service (NJFFS) a division of the New Jersey Department of Environmental Protection (NJDEP) website. The NJFFS developed the Wildfire Fuel Hazard data based upon NJDEP's 2002 Land Use/Land Cover (LU/LC) datasets and NJDEP's meter Digital Elevation Grid datasets (considering both land use and slope to determine rankings). The wildfire fuel hazard data was released for the State of New Jersey in May The map shows that the fuel hazard risk is greatest in central and eastern Cumberland County as well as eastern Camden and Gloucester Counties. 1 National Park Service. Fire and Fuel Management: Definitions, ambiguous terminology and references. Page RP.3-239

2 Figure RP.3-101: Wildfire Fuel Hazard Risk in the NJ4 HMP Region (Source: NJDEP (GIS), New Jersey Forest Fire Service) Page RP.3-240

3 The NJFFS also produced wildfire risk maps in 2010 for New Jersey. The following series of maps (Figures RP RP.3-105) below identify the wildfire risk for each of the four counties within the region. Similar to what is presented in the regional Wildfire Fuel Hazard Risk map above, the maps show the risk is higher in portions of the eastern and southern part of region. Figure RP.3-102: Camden County Wildfire Risk (Source: New Jersey Forest Fire Service, 2010) Page RP.3-241

4 Figure RP.3-103: Gloucester County Wildfire Risk (Source: New Jersey Forest Fire Service, 2010) Figure RP.3-104: Salem County Wildfire Risk (Source: New Jersey Forest Fire Service, 2010) Page RP.3-242

5 Figure RP.3-105: Cumberland County Wildfire Risk (Source: New Jersey Forest Fire Service, 2010) The eastern portions of Camden, Gloucester and Cumberland County are located within the Pinelands National Reserve (PNR). The PNR was created by Congress under the National Parks and Recreation Act of The PNR covers approximately 1.1 million acres in New Jersey (22% of the State s land area) and includes portions of seven counties and all or parts of 56 municipalities. 2 The draft State of New Jersey 2014 Hazard Mitigation Plan describes the PNR as a fire-adapted forest ecosystem that depends on wildfire for reproduction and the control of fuel buildup. This forest community is one of the most hazardous wildland fuel types in the nation. Pinelands fires burn extremely hot and spread rapidly. New Jersey has a high population density and more people are moving from urban areas to build homes in rural wildland areas. With more people living in and enjoying the State s wildlands for various forms of recreation, the number of potential fire starts and the seriousness of their consequences increases. A potentially explosive combination is created when hazardous wildland fuels, home development, and an increased risk of human-caused ignition come together under extreme fire weather conditions. 2 New Jersey Pinelands Commission Page RP.3-243

6 Figure RP identifies the Pinelands Management Areas that are divided into nine land-use management areas. The Management Areas within the NJ4 HMP regional region are described below: 3 " The Agricultural Production Area covers 68,500 acres and is dedicated to active agricultural use. Farm-related housing on 10 acres and non-farm housing on 40 acres are allowed. Permitted nonresidential uses are agricultural commercial and roadside retail within 300 feet of pre-existing commercial uses. " The Forest Area of the Pinelands covers 245,500 acres. It is a largely undeveloped area and contains high-quality water resources and wetlands that provides suitable habitat for many threatened and endangered species. Permitted residential densities average one home for every 28 acres. " Pinelands Villages include 24,200 acres and 47 small, existing, spatially discrete settlements that are appropriate for infill residential, commercial and industrial development compatible with their existing character. Residential development is permitted on minimum 1-acre lots if not sewered. " The Preservation Area District is 288,300 acres in the heart of the Pinelands environment and is the most critical ecological region. It is a large, contiguous wilderness-like area of forest that supports diverse plant and animal communities, including many threatened and endangered species. There is no residential development except for one 1-acre lot in an infill area (2,072 acres in size) and special cultural housing exceptions on minimum 3.2-acre lots for properties owned prior to " The Regional Growth Area covers 77,200 acres and is an area of existing growth. The adjacent undeveloped lands are capable of accommodating regional growth influences while protecting the essential character and environment of the Pinelands. Residential development is approximately three homes per acre with sewers. Commercial and industrial uses are also permitted. " The Rural Development Area covers 112,500 acres and is a transitional area that balances environmental and development values between conservation and growth areas. Limited, lowdensity development and roadside retail is permitted. Residential densities average one home per every 5 acres. 3 New Jersey Pinelands Commission Page RP.3-244

7 Figure RP.3-106: Pinelands Management Areas (Sources: New Jersey Pinelands Commission) Page RP.3-245

8 Severity and Extent - Wildfire The frequency and severity of wildfires is dependent on weather and on human activity. In the region, severity has historically been very low, and duration a matter of hours to a day. The risk is increased and compounded by increasing development within the zone commonly referred to as the wildland-urban interface or WUI. Within this zone of natural landscape, buildings become additional fuel for fires when fires do occur. Most wildland fires are human-caused and occur in the interface of developed lands with forest and rangelands. In particular, the dry conditions, high temperatures, and low humidity that characterize drought periods set the stage for wildfires. Occurrence and Probability - Wildfire The NJFFS indicates there are approximately 1,500 wildfires that destroy 7,000 acres of forest land in New Jersey each year. A variety of sources were reviewed to identify past wildfire events in New Jersey including the NJFFS, the NCDC, the SHELDUS database, and other open sources of data. The NCDC database indicates there have been 26 wildfires in the NJ4 HMP region since These events are listed in Table RP Table RP.3-114: Wildfire Events in the NJ4 HMP Region, June (Source: NOAA/NCDC) The 2002 and 2005 wildfire events both occurred within the Wharton State Forest. This state forest totals 115,000 acres and is the largest single tract of land within the New Jersey State Park System. The first event in June of 2002 consumed about 750 acres and forced the shutdown of an electrical transmission line. Approximately 100 homes were evacuated, but the fire was contained before causing any injuries or property damages. The second event occurred in April of 2005 and started as a small fire in Waterford Township. The fire was fanned by strong winds of up to 25 mph and eventually burned 325 acres before being contained. No injuries or damages were reported. In the past, numerous wildfire events have occurred in parts of the region. The NCDC database records indicate these events have been relatively small and resulted in no injuries, deaths, or property damage. 4 Note to Draft Regional Hazard Mitigation Plan Reviewers: Table RP and related text entries will be inserted and/or confirmed in the Final RHMP. Page RP.3-246

9 Figure RP below shows the history of major wildfire events (events greater than 100 acres) in New Jersey between 1924 and 2011 as reported by the NJFFS. The map shows that with the exception of eastern Camden County, the major wildfires in the region have occurred from the 1920 s to 1970 s. Figure RP.3-107: New Jersey Wildfire History (Source: New Jersey Forest Fire Service) With a total of [insert number] past wildfire events in the region between 1950 and 2013, the region experiences a wildfire event on average roughly once every [insert number] years. With one event roughly every [insert number] years, there is a [insert number]% annual probability of a future wildfire event occurring in the region. The past wildfire data indicates that the probability of future wildfires occurring in is fairly high, with a moderate impact on property and life in the region. Page RP.3-247

10 Risk Assessment - Wildfire There are no records of deaths or injuries and no recorded loss of property from wildfires in the region. Although there have been no reported injuries or property damage from wildfires the areas of highest risk to life and property in the region can be identified by examining the WUI. The WUI is where wildfire poses the biggest risk to human lives and structures. The regional risk assessment included analyzing data from the New Jersey Forest Fire Service (NJFFS) and the United States Forest Service (USFS). The risk assessment was completed by identifying areas in the region with a combination of the extreme fuel hazard and high and medium interface/intermix (WUI). Wildfire hazard data from these two sources was considered the best available data to determine the wildfire risk to life and property in the region. The risk assessment determined the number of acres in the region (and square miles) where these two wildfire risk categories intersect. The results were then used to rank municipalities based on the total amount of intersecting land area in each jurisdiction. The intersection analysis rankings were then compared to the Municipal Working Group rankings. Finally, municipalities with significant differences between the two were identified. Using a Geographical Information System (GIS), the USFS integrated U.S. Census and USGS National Land Cover Data, to map the risk areas related to the WUI. Figure RP identifies the WUI areas for the region. The map shows the highest risk areas are the high density interface/intermix (shades of red) and the medium density interface/intermix (shades of light brown). The map shows there are small pockets of high density interface/intermix scattered throughout the region. The map also shows the high density areas with no vegetation are predominately located in western Camden County and northwestern Gloucester. The map also shows the majority of Cumberland and Salem Counties include very low and low density vegetation (and no vegetation) areas as well as uninhabited areas (particularly Cumberland). The WUI for the High and Medium Density Interface/Intermix (the highest risk areas) within the region are summarized in Table RP below. The table shows the number of housing units and population within these areas as well as percentage comparisons to the region. The table shows that 20.3% of the housing units and 21.4% of the population in the region lives within the High or Medium Density Interface/Intermix areas. Table RP.3-115: High Density Interface and Medium Density Intermix (WUI), Population and Housing Units Within the NJ4 HMP Region (Sources: USDA Forest Service Northern Research, 2010 US Census) WUI Category Housing Units % of Total Housing Units in Region Population % of Total Population in Region High Density Interface 19, % 49, % High Density Intermix 1, % 3, % Medium Density Interface 33, % 90, % Medium Density Intermix 28, % 76, % Total 83, % 219, % Page RP.3-248

11 Figure RP.3-108: Wildland Urban Interface (WUI) in the NJ4 HMP Region (Sources: USDA Forest Service Northern Research, NJDEP (GIS)) Page RP.3-249

12 County Table RP summarizes by county the number of housing units and population for the WUI High and Medium Density Interface/Intermix. The table shows that Gloucester County has the highest number of housing units and population located with the High and Medium Density Interface/Intermix. Table RP.3-116: High Density Interface and Medium Density Intermix (WUI), Population and Housing Units (Sources: USDA Forest Service Northern Research, 2010 US Census) High Density Interface Housing Units Pop. High Density Intermix Housing Units Pop. Medium Density Interface Housing Units Pop. Medium Density Intermix Housing Units Pop. Total Housing Units Total Population Camden 3,234 8, ,592 28,727 9,550 25,521 23,537 62,758 Gloucester 4,423 10,937 1,434 2,630 10,298 29,858 11,310 30,442 27,466 73,867 Salem 3,268 7, ,364 12,577 1,398 3,389 10,252 23,809 Cumberland 8,458 22, ,440 19,042 6,681 17,217 22,667 59,098 Grand Total 19,383 49,191 1,905 3,567 33,694 90,204 28,939 76,569 83, ,531 In addition to the WUI data, the fuel hazard data was also analyzed. Table RP below identifies the land area per wildfire fuel hazard risk category in the region. The moderate fuel hazard risk category has the highest land area, covering a total of square miles (or 17.9% of the region). The table also shows that square miles (or 7.87% of the region) is categorized as extreme. Table RP.3-117: Wildfire Fuel Hazard Risk (Land Area) in the NJ4 HMP Region by Fire Description Category (Source: NJDEP (GIS), New Jersey Forest Fire Service) Fuel Hazard Risk Square Miles % of Regional Land Area (Square Miles) Extreme % Very High % High % Moderate % Low % Total acres % Table RP summarizes by county the number of square miles for each wildfire fuel hazard category. The table shows that with the exception of the Very High category, Cumberland County has the highest number of square miles for all categories. Table RP.3-118: Wildfire Fuel Hazard Risk (Land Area in acres) by County (Source: NJDEP (GIS), New Jersey Forest Fire Service) Very Grand County Extreme High Moderate Low High Total Camden Gloucester Salem Cumberland Total acres Page RP.3-250

13 Data from both the wildfire fuel hazard and the WUI included as part of the hazard profile can be combined to compare areas of wildfire concern. Figure RP identifies the extreme wildfire hazard areas and the high and medium density (interface/intermix) WUI areas within the region. The map shows the highest risk WUI areas are the high density interface (shaded red) and the medium density interface/intermix (shaded dark brown and light brown). In the region, these areas are predominately located in central to eastern Camden, Gloucester, and Cumberland counties. Figure RP.3-109: Extreme Wildfire Fuel Hazard and Wildland Urban Interface (WUI) in the NJ4 HMP Region (Sources: New Jersey Forest Fire Service, USDA Forest Service Northern Research, NJDEP (GIS)) Page RP.3-251

14 These two risk categories (High/Medium WUI and Extreme Fuel Hazard) can be further analyzed by using GIS analysis tools to determine the areas where the extreme fuel hazard intersects with the medium and high interface/intermix areas of the WUI. Figure RP identifies one of the main areas where these two areas overlap, the northeastern part of the region. Figure RP.3-110: High and Medium Density Wildland Urban Interface (WUI) Intersecting Extreme Wildfire Fuel Hazard (Sources: New Jersey Forest Fire Service, USDA Forest Service Northern Research, NJDEP (GIS)) Page RP.3-252

15 Table RP identifies the number of square miles in each county where the Extreme Wildfire Fuel Hazard intersects with the High/Medium Interface. The table shows that Camden County has the highest number of square miles (3.71 square miles) where these two risk areas intersect. Table RP.3-119: Intersection (Square Miles) of Extreme Wildfire Fuel Hazard Risk and High/Medium Interface (WUI), by County (Source: NJDEP (GIS), New Jersey Forest Fire Service) County Square Miles # of Parcels Camden ,272 Gloucester ,700 Salem Cumberland ,103 Grand Total ,430 The results of the analysis show that 53 of 90 municipalities in the region had areas where the extreme fuel hazard intersects with the High/Medium Interface. Of this total, 47 municipalities had more than one acre of land where these two categories intersect. The 47 municipalities are identified below in Table RP The table includes both the number of acres and square miles that intersect in each municipality. The table shows that Winslow Township in Camden County has the greatest number of square miles (1.86 square miles) where these two categories intersect. Table RP.3-120: Municipalities With More Than One Acre Intersecting Extreme Wildfire Fuel Hazard Risk and High/Medium Interface (WUI), ordered by Square Miles/Acres (Source: NJDEP (GIS), New Jersey Forest Fire Service) Municipality County Acres Square Miles Winslow Township Camden 1, Millville City Cumberland Franklin Township Gloucester Monroe Township Gloucester Waterford Township Camden Vineland City Cumberland Fairfield Township Cumberland Voorhees Township Camden Lawrence Township Cumberland Gloucester Township Camden Commercial Township Cumberland Deerfield Township Cumberland Berlin Township Camden Berlin Borough Camden Maurice River Township Cumberland Washington Township Gloucester Upper Pittsgrove Township Salem Bridgeton City Cumberland Pittsgrove Township Salem Gibbsboro Borough Camden Chesilhurst Borough Camden Alloway Township Salem Quinton Township Salem Page RP.3-253

16 Municipality County Acres Square Miles Upper Deerfield Township Cumberland Elk Township Gloucester Clayton Borough Gloucester Pine Hill Borough Camden Deptford Township Gloucester Glassboro Borough Gloucester Lindenwold Borough Camden Newfield Borough Gloucester Lawnside Borough Camden Mantua Township Gloucester Pine Valley Borough Camden Greenwich Township Cumberland Stratford Borough Camden Pilesgrove Township Salem Woodbury Heights Borough Gloucester South Harrison Township Gloucester Pennsville Township Salem Harrison Township Gloucester East Greenwich Township Gloucester Barrington Borough Camden Hopewell Township Cumberland Greenwich Township Gloucester Lower Alloways Creek Township Salem Downe Township Cumberland Woodbury City Gloucester Grand Total , Hazard Rankings Wildfire The results of the analysis of the two land categories (WUI and extreme fuel hazard category) was then used to rank municipalities as low, medium, or high based on the amount of land area intersecting the extreme fuel hazard and the High/Medium Interface (WUI). Municipalities with greater than 80 acres were ranked high, those with acres were ranked medium, and less than 10 acres was considered low. Figure RP displays the wildfire hazard ranking by municipality based on the intersection of the extreme wildfire fuel hazard risk and high/medium interface (WUI). Page RP.3-254

17 Figure RP.3-111: Wildfire Hazard Ranking by Municipality Based on The Intersection of the Extreme Fuel Hazard and High and Medium Interface/Intermix (WUI) Page RP.3-255

18 As part of the risk assessment each jurisdiction ranked the 12 hazards as high, medium, low, or not applicable. Figure RP identifies the Wildfire hazard rankings per the Municipal Working Groups. The map shows the Municipal Working Group rankings match up well with the areas of risk identified by the USFFS (Fuel hazard and risk maps), the WUI and the data analysis comparing the areas where the extreme fuel hazard intersects with the medium and high interface/intermix areas of the WUI. The map shows the high risk areas (shown in red) are located in the eastern and southeastern areas of the region. Figure RP.3-112: Wildfire Hazard Ranking by Municipal Working Groups Page RP.3-256

19 The subjective Municipal Working Group hazard rankings were then compared with the objective rankings completed based on the land area intersecting the extreme wildfire fuel hazard risk and medium and high interface/intermix areas of the WUI in each municipality (Figure RP.3-111). Although many of the municipalities had a similar hazard ranking when compared with the population and building permits, there were some differences in the results. A number of municipalities ranked the Wildfire hazard much lower when compared to the data analyzed. Table RP below identifies the municipalities where the hazard was ranked low by the municipality, but ranked high based on the intersection of the two categories. Table RP.3-121: Significantly Different Hazard Rankings - Wildfire Municipality County Municipal Working Group Hazard Ranking Hazard Ranking Based on Intersection of the Extreme Fuel Hazard and High/Medium Interface/Intermix (WUI) No. of Acres Intersecting Two Risk Categories Berlin Borough Camden Low High Gloucester Township Camden Low High Voorhees Camden Low High Bridgeton City Cumberland NA Medium Deerfield Township Cumberland Low High Millville City Cumberland Low High East Greenwich Township Gloucester NA Low 3.47 Harrison Township Gloucester NA Low 3.56 Woodbury City Gloucester NA Low 1.17 Washington Township Gloucester Low High Pilesgrove Township Salem NA Low 4.43 Comments 5 5 Note to Draft Regional Hazard Mitigation Plan Reviewers: The Comments entries in Table RP will be added and the contents of the table potentially revised as a result of the on-going review of the Municipal Appendices by the Municipal Working Groups. Page RP.3-257

20 Critical Facilities Hazard Exposure Assessment - Wildfire 6 The wildfire risk assessment also included identifying critical facilities that may be at risk from wildfire. To identify critical facilities potentially exposed to the wildfire hazard, land areas within the extreme wildfire fuel hazard risk or the High and Medium WUI were identified for the region. Figure RP identifies the critical facilities located within these areas. In the region there are a total of [insert number] critical facilities. Of this total, [insert number] are located within the extreme wildfire fuel hazard risk or the High and Medium WUI. A summary of the critical facilities by county is shown in Table RP The detailed results of this assessment for each participating municipality are indicated in the Appendices. 7 Table RP.3-122: Critical Facilities within Extreme Wildfire Fuel Hazard or High or Medium WUI by County County Camden Gloucester Salem Cumberland # of Critical Facilities Figure RP.3-112: Critical Facilities within the Extreme Wildfire Fuel Hazard Risk or the High and Medium WUI 6 Note to Draft Regional Hazard Mitigation Plan Reviewers: Results that will be cited in subsection text, depicted in Figure RP and shown in Table RP.3-122, is subject to change based on work-in-progress iterations and will be completed after the on-going review of the Municipal Appendices. 7 See Part 3.4: Critical Facilities Inventory and Hazard Exposure Assessment in the Appendices. Page RP.3-258

21 Data Limitations - Wildfire The current risk assessment analyzes a combination of wildfire hazard data to identify the amount of land area and number of parcels at risk within various wildfire hazard zones. However, the parcel data doesn t provide an indication as the potential risk within each parcel. The most significant data limitation of the wildfire hazard analysis is uncertainties about the specific location of structures and other assets within parcels. The risk assessment could be significantly improved and refined by incorporating building footprint data. This data could be used to go beyond using the number of parcels as an indication of risk by identifying the exact number of structures within different wildfire hazard zones. The building footprint data would most likely include some basic information about the structure including building replacement value, square footage, and type (commercial, residential, etc.) that could be used to determine the value of structures within areas potentially at risk from wildfires. Page RP.3-259

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