This document covers Unit 2 of a training on topographic influences on wildland fire behavior. It discusses how topography affects fuels, fire spread, and barriers to fire spread. Specific topics include how elevation influences vegetation types; how slope, aspect, and drainages impact fire spread direction and rate; how ridges, canyons, and barriers interact with fire; and methods for determining slope in the field. The objectives are to understand topographic map features, and how topography influences fuels, fire behavior, and barriers.

1. 2-1-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Unit 2

2. 2-2-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Unit 2 Objectives
1. Identify standard features on a
topographic map.
2. Describe how topography affects
fuels and their availability for
combustion.
3. Describe how topography can affect
the direction and rate of spread of
wildland fires.

3. 2-3-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
4. Describe how changes in fuel and
topography can provide full and
partial barriers to the spread of
wildland fires.
5. Describe how slope percent can be
determined or estimated in the field.
Unit 2 Objectives

4. 2-4-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
.A
B.
C.
.D
.E
.F .G
H.
I.
.J
2-4-S290-EP

5. 2-5-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Match these features to
the boxes on map:
Contour Line
Elevation
East Aspect
North Aspect
South Aspect
West Aspect
Canyon
Barrier
Box Canyon
Mountain Peak
Intersecting Drainage
Ridge
Topographic Map Features
2-5-S290-EP

6. 2-6-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Topographic Map Features
2-6-S290-EP

7. 2-7-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
How Topography Affects
Fuels and Their Availability
for Combustion

8. 2-8-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Elevation Above Sea Level
sea level
grass
shrub
timber
tundra
snow 10,000 ft.
2-8-S290-EP

9. 2-9-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Fires on slope reaching 10 acres +
Percentoffires
Level Base of
slope
Middle
of slope
Top of
slope
2-9-S290-EP

10. 2-10-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Fires starting
at base of
slope often
become the
largest fires.
55%
slope
30%
slope
0-5%
slope

11. 2-11-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Cardinal Directions
• North
• South
• East
• West
• Northeast
• Northwest
• Southeast
• Southwest

12. 2-12-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Fire Occurrence by Aspect
Percentoffires
Aspect
2-12-S290-EP

13. 2-13-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Effect of Aspect
on Fuel
Temperature and
Moisture
Highest Fuel Moisture
Lowest Average
Temperature
Lowest Rate of Spread
Later Curing of Fuels
Late Snow Melt
Earlier Heating
Earlier Cooling
Later Heating
Later Cooling
Lowest Fuel Moisture
Highest Average Temperature
Highest Rate of Spread
Earlier Curing of Fuels
Earlier Snow Melt

14. 2-14-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Aspect Affects Fuel Moisture
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
1 3 5 7 9 11 13 15 17 19 21 23
Time (Military)
%MoistureContent
North Slope
South Slope

15. 2-15-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-15-S290-EP

16. 2-16-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
How Topography Can Affect
the Direction and Rate of
Spread of Wildland Fires
2-16-S290-EP

17. 2-17-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Slope affects fire behavior
Fresh air
Burning chunks
Rolling down slope
Faster ignition and spread
draft
preheating
2-17-S290-EP

18. 2-18-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-18-S290-EP

19. 2-19-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Wedge shape fire pattern
2-19-S290-EP

20. 2-20-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Wedge Shape
2-20-S290-EP

21. 2-21-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Slope
Reversal

22. 2-22-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Slope Reversal
2-22-S290-EP

23. 2-23-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-23-S290-EP

24. 2-24-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Slope Reversal
2-24-S290-EP

25. 2-25-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-25-S290-EP

26. 2-26-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Ridges
2-26-S290-EP

27. 2-27-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-27-S290-EP

28. 2-28-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Fires in the bottom of narrow canyons
2-28-S290-EP

29. 2-29-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Bottom
of a
narrow
canyon

30. 2-30-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Stable Air Conditions
Narrow canyons easily allow for
stable air mass, such as an
inversion to form.

31. 2-31-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior 2-31-S290-EP

32. 2-32-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Air flow
Surface winds will usually be
shaped by the canyon, following
the canyon’s direction, forming
eddies and strong upslope
currents at its sharp bends.

33. 2-33-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Intersecting Drainages
2-33-S290-EP

34. 2-34-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Intersecting Drainages
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35. 2-35-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Chimney Effect

36. 2-36-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Chimney Effect Conditions
• Unstable air conditions causing a
convection current through the
canyon.
• Air drawn in at the base to support
convection currents.
• Available fuel to support rapid
burnout.

37. 2-37-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
How Changes in Fuel and
Topography Can Provide Full and
Partial Barriers to the Spread of
Wildland Fires
2-37-S290-EP

38. 2-38-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Barrier Definition
• Barriers are natural or artificial.
• Limit the direction of spread.
• Can provide opportunities for control.
• Barriers may not reduce spotting potential.
A barrier is any obstruction to the
spread of fire. Typically an area or strip
devoid of combustible fuel.

39. 2-39-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Barriers to Fire Spread

40. 2-40-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Partial Barriers
A change in fuel conditions may
offer only a partial barrier by
slowing the spread of fire.

41. 2-41-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Exercise #2

42. 2-42-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier
to fire spread?
2-42-S290-EP

43. 2-43-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier to fire spread?
2-43-S290-EP

44. 2-44-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier to fire spread?
2-44-S290-EP

45. 2-45-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier to fire spread?
2-45-S290-EP

46. 2-46-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier to fire spread?
2-46-S290-EP

47. 2-47-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Is this a good barrier to fire spread?
2-47-S290-EP

48. 2-48-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
How Slope
Percent Can
Be Determined
or Estimated
in the Field
2-48-S290-EP

49. 2-49-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
% Slope vs. Degrees
Percent slope = Rise
Run
1 foot
1foot
45
o
100%
X 100
RUN
RISE

50. 2-50-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Slope Meter

51. 2-51-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Review Unit 2 Objectives
1. Identify standard features on a
topographic map.
2. Describe how topography affects
fuels and their availability for
combustion.
3. Describe how topography can affect
the direction and rate of spread of
wildland fires.

52. 2-52-S290-EPUnit 2 Topographic Influences on Wildland Fire Behavior
Review Unit 2 Objectives
4. Describe how changes in fuel and
topography can provide full and
partial barriers to the spread of
wildland fires.
5. Describe how slope percent can be
determined or estimated in the field.