Training On Demand

1
Topo Map Familiarization

• Training On Demand

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What is a Topographic Map

• A topographical map is a representation of the
  Earth, or part of it.
• The distinctive characteristic of a topographic
  map is that the shape of the Earth's surface is
  shown by contour lines.  
• Contours are imaginary lines that join points of
  equal elevation on the surface of the land above
  or below a reference surface such as mean sea
  level. 
• Contours make it possible to measure the height
  of mountains, depths of the ocean bottom, and
  steepness of slopes.

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What is a Topographic Map cont.

• A topographic map shows more than contours.  
• Maps includes symbols that represent such
  features as streets, buildings, streams, and
  woods. 
• These symbols are constantly refined to better
  relate to the features they represent.
• A topographic map tells you where things are and
  how to get to them.
• In our case, they assist with the location and
  verification of wildland fires.
• They show the distance between any two places,
  and they also show the direction from one point
  to another.

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Distances How far is that?

• Maps are made to scale that is, there is a
  direct relationship, between a unit of
  measurement on the map and the actual distance on
  the ground.
• If 1 inch on the map represents 1 mile (which
  converts to 63,360 inches) on the ground, the
  map's scale is 163,360.
• A convenient way of representing map distance is
  by the use of a graphic scale bar. 
• Most USGS topographic maps have scale bars in the
  map margin that represents distances on the map
  in miles, feet, and kilometers. 

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Map Legend Info

• Scale indicates 124ooo
• Map is complete with scale bar to measure
  distance
• Contour interval as indicated is 40 ft.

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Contour How High is that?

• Contour lines are a method of depicting the
  3-dimensional character of the terrain on a
  2-dimensional map.
• Contour are lines drawn on the map represent
  equal points of height above sea level.
• On multi-colored maps, contour lines are
  generally represented in brown.
• The map legend will indicate the contour
  intervalthe distance in feet (meters, etc.)
  between each contour line.
• There will be heavier contour lines every 4thgt or
  5th contour line that are labeled with the
  elevation

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Contour How High is that cont.

• Contour maps give us the grounds topography by
  the way the lines interact with each other as
  seen here.

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Other General Map References

• Black - man-made items
• Blue - water
• Brown - contour lines
• Green - substantial vegetation
• White - little or no vegetation
• Red - major highways
• Purple - features added to the map since the
  original survey.

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Practical Map Usage

• Topo maps are used for two main purposes in the
  fire service
• Triangulate the location/ boundaries of a fire
• Or
• Identify the location of fire resources in the
  field
• Both operations require the use a way to gauge
  location
• Latitude/Longitude or the Public Land Survey
  System defines locations on a map
• Both require useful knowledge of compass
  operation.

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Know Your Compass
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What Is Public Land Survey System?

• The Public Land Survey System (PLSS) is a way of
  subdividing and describing land in the United
  States.
• All lands in the public domain are subject to
  subdivision by this rectangular system of
  surveys, which is regulated by the U.S.
  Department of the Interior
• The PLSS is used to divide public domain lands,
  which are lands owned by the Federal government
  for the benefit of the citizens of the United
  States.
• The original public domain included the land
  ceded to the Federal Government by the thirteen
  original States,
• It encompasses major portions of the land area of
  30 southern and western States.
• Since the original PLSS surveys were completed,
  much of the land that was originally part of the
  public domain has been transferred to private
  ownership. 

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Public Land States

• Alabama
• Alaska
• Arizona
• Arkansas
• California
• Colorado
• Florida
• Idaho
• Illinois
• Indiana
• Iowa
• Kansas
• Louisiana

• Michigan
• Minnesota
• Mississippi
• Missouri
• Montana
• Nebraska
• Nevada
• New Mexico
• North Dakota
• Oklahoma
• Ohio
• Oregon
• South Dakota

• Utah
• Washington
• Wisconsin
• Wyoming

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How PLSS works

• Land is divided into 6-mile-square townships,
  which is the level of information included in the
  National Atlas.
• Townships are subdivided into 36 one-mile- square
  sections. Sections can be further subdivided into
  quarter sections, quarter-quarter sections, or
  irregular government lots.
• Most PLSS surveys begin at an initial point, and
  townships are surveyed north, south, east, and
  west from that point.
• This line is perpendicular to the Principal
  Meridian.

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Township and Ranges

• Township N S
• Range E W
• Each 6 miles squares
• Fire in T3N R2E

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Sections

• 1 mile square
• 640 acres
• Numbered within
• Township/Range

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Section 10
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Section Subdivisions

• ½ Sections, ¼ Sections divide the section number
  further
• Identified by cardinal direction location
• Ie. SW ¼ of Section 10.

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How does this Apply to me?

• Fires are now most often located by Latitudinal
  and Longitudinal coordinates
• Devices utilizing satellites easily gather
  coordinates for easy reference
• Devices must be set to DATUM NAD83 to provide to
  correct information
• PLSS acts as a secondary way of indicating the
  location of a wildland fire.
• PLSS will make conversion to Latitude and
  Longitude easy
• By identifying a fires location it can be
  determined who must be notified

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Triangulating a Fire

• Triangulation has become a generic term for the
  process of measuring to two or more known points
  to determine - using geometry - the location of
  an unknown point.

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Compass Triangulation

• To map a fire, firefighters should always
  triangulate to insure the most accurate possible
  idea.
• Align the base plate with an imaginary line
  between two points on the map.
• Turn the compass dial until the north lines align
  with the north lines on the map.
• Read the bearing set on the compass dial.

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Transfer Your findings to the map
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Taking a bearing to an object

• Hold the compass flat.
• Sight from an object you can identify on the map
• Move the dial to match north
• Remember to account for magnetic declination
• Read and document the bearing
• Move to your next landmark

23
Magnetic Declination

• Grid North
• Where the grid on your map is pointing. Since
  grid lines on the map are all parallel, they
  never meet in one point.
• Magnetic North
• Where the magnetic needle points. These wavy
  lines depend on iron magma in the earth that
  changes each year
• According to the NOAA Frisco CO has a 9 E
  Magnetic Declination in 2012
•  9E means we rotate the base plate's orienting
  arrow 9 E of 0/N to compensate for the 9
  declination
• Not a big deal when we are close, but over
  distance it can lead to significant inaccuracies.
• Topo maps should indicate a declination chart on
  them

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Plotting bearings on a map

• Set the bearing on the compass dial.
• Lay the long edge of the compass on the known
  point (where the bearing was taken from).
• Turn the compass plate so that the north lines
  align with the north lines on the map.

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Taking bearings off a map

• Align the base plate with an imaginary line
  between two points on the map.
• Turn the compass dial until the north lines align
  with the north lines on the map.
• Read the bearing set on the compass dial.
• Be aware then of magnetic declination and whether
  your compass is measuring magnetic north or has
  been adjusted to grid north.

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Conclusion

• Topo maps and navigation for the purpose of
  locating wildland fires is not difficult.
• However, it is a skill that needs to be practiced
  on a frequent basis to remain proficient
• Utilize what you have learned and practice your
  skills
• Once you are re-familiarized with finding
  bearings on a map, you will remember how
  triangulation works
• Practice these skills as a company