Using Topographic Maps III

Personnel Required

  • 1 - 2 crew

Equipment Required

  • 1:25000 topographic map
  • Bega Map magnetic compass

Contour Lines

  • Contour lines are a method of depicting the 3-dimensional character of the terrain on a 2-dimensional map. Contour lines drawn on the map represent equal points of height above sea level, ie, the contour interval is the vertical distance between contour lines.The map legend will indicate the contour interval—the distance in metres between each contour line.
  • Contour lines close together show steep slopes
  • Contour lines far apart show gentle slopes
  • Contour lines evenly spaced show uniform slope
  • On topographic maps, contour lines are generally represented in brown.

Advanced Firefighters need to be able to read contour lines on a map and identify the salient features.

Gradients

  1. A method of expressing ground slope

Measuring Distances

  1. There are a number of ways to measure distance accurately on a map. One is to use a piece of string or flexible wire to trace the intended route. After tracing out your route, pull the string straight and measure it against the scale line in the map legend.
  2. Another method is to use a compass (the mathematical kind) set to a narrow distance on the map scale like ½ kilometre and then "walk off" your route.