Paul Ward
GEOG 370
4/19/06
Fire Fuel Mapping/Modeling in a Forested Environment Lab Report
Forest Fire Composite Risk Area Map
PURPOSE
As a technician for Glacier National Park, Montana, you are to utilize GIS tools to
evaluate and map forest fire risk areas. Assess the distribution and levels of several forest
fire contributing factors (attributes) – NDVI/standing biomass levels, forest fuel loads,
land slopes, winds (and their direction), hiking trails, and water (or lack thereof), develop
in ArcGIS risk area maps for each individual attributes; finally, form a composite map
weighing each individual risk area map equally to determine low, medium, and high risk
areas for forest fires.
BACKGROUND and ASSUMPTIONS
The fuel content of forest biomass largely determines the severity of forest fires; they
determine how much energy a fire will have. Some additional contributing factors are
winds, soil water content, humidity and open water, size and surface area of biomass.
High winds, low soil water content/humidity, and small fuel pieces (more burning surface
area) all contribute to more severe forest fires. Another factor is the difference between
live and dead wood - dead wood burns more quickly. High slope areas will spread fires
more quickly than flat land because the fire can move in an upward direction. Finally,
low density fuel resists fire less than high density fuels – because more air can feed a fire
in spread-out fire fuels. All these factors contribute to the degree of severity of forest
fires.
Paul Ward
GEOG 370
4/19/06
Fire Fuel Mapping/Modeling in a Forested Environment Lab Report
PROCEDURE
In ArcGIS, using multiple layers, individually import maps of landcover, NDVI,
elevation, and water bodies, as well as the shapefiles of trails in the park area.
With the landcover map, select and highlight high risk landcover areas (Lodgepole pine,
brush, Engleman spruce/fir, medium density spruce/fir, successional vegetation) by
attributes using the raster calculator. Distinguish high-risk landcover areas from all other
areas on the layer by reclassifying the attributes into only two categories – high risk and
non-high risk. Perform the same procedure for low-risk areas. Then import the NDVI
layer, and using the raster calculator, and select areas with high standing vegegation
(NDVI >= 200); reclassify the attributes of the layer to two categories – those with NDVI
greater than or equal to 200, and those with NDVI less than 200. Using the elevation
map, and the spatial analyst’s slope and aspect tools, form individual layers of slope and
aspect. For the slope layer, use the raster calculator to highlight areas with slope greater
than 35 degrees. For the aspect layer, use the raster calculator to highlight areas with
prevailing southwest winds, as those winds spread fires. For both of these layers,
reclassify the layers to highlight the risk areas – those with slope greater than 35 degrees
or those with prevailing southwest winds, and reclassify the rest as non-risk areas.
Import the shapefile of the roads, and form a 150 meter linear buffer around the road
using the spatial analyst. Similarly, again import the landcover map, and form 500 meter
buffers around areas with free standing water. Then reclassify the layer to the areas
within 500 meters of water and those not within 500 meters of water. Finally, with all of
Paul Ward
GEOG 370
4/19/06
Fire Fuel Mapping/Modeling in a Forested Environment Lab Report
these layers, add them up using the raster calculator. Reclassify the layer to three
attribute categories – low risk, medium risk, and high risk. Form a aesthetically pleasing
and useful map using this map content.
CONCLUSIONS
It should not be doubted that utilizing GIS to produce maps of forest fire risk areas is
useful to help inform Park Rangers and other administrative protection agencies of highrisk areas. But the usefulness of this map would be limited by the preventative steps one
took after making it – including educating park rangers, hikers and other park-goers of
high-risk areas, conditions that lead to high forest fire risk, and the prevalence of these
conditions in the park area. In addition, it would be useful to study historical patterns of
forest fires in accordance with climate and the other attributes studied in forming the
map. Frequently recording new data and forming new composite maps of forest fire risk
areas each new “fire” season would also be a crucial step in helping to reduce the risks of
forest fires. Without using the map for good purposes, it would do little good, but by
using it as an educational tool to locate and identify risk areas, it is definitely very useful.
GIS as a whole is very useful for environmental mapping purposes, but also limited in its
impact unless the information it provides is “put into practice” for real-world uses.
Good job
20/20