A topographic map shows you the shape of the land, not just the tracks on it. Once you can read one, you can look at any piece of terrain and have a reasonable idea of what walking through it will involve before you get there. It is one of the more useful skills you can develop for outdoor activities and it genuinely does not take long to learn.
Contour Lines
Contour lines are the concentric lines that show elevation. Each line represents a fixed height difference from the one next to it, usually 10m or 20m on standard topographic maps. Where lines are close together, the terrain is steep. Where they are widely spaced, the slope is gentle. A series of concentric circles indicates a hill or a depression. Understanding contour lines is essentially all of topo map reading.
Index Contours and Scale
Every fifth contour line is usually printed darker and labelled with its elevation. These are index contours. They let you work out the height of any point on the map by counting contour lines up or down from the nearest labelled one. The map scale, usually shown at the bottom, tells you the relationship between distance on the map and distance on the ground. A 1:25000 map means 1cm on the map equals 250m on the ground.
Reading Ridges and Valleys
Contour lines form a V shape when they cross a valley, with the V pointing uphill. On a ridge, the same V shape points downhill. Water flows away from ridges and toward valleys, which means valleys often have water sources and ridges typically do not. Being able to identify these features on a map before you get to them helps significantly with navigation.
Practical Tips
- Orient the map so it matches the terrain around you before trying to navigate from it
- Find a known feature, your starting car park, a lookout, a junction, and confirm it on the map before you move
- Count contour lines to estimate the climbing ahead
- Use a ruler or your finger to estimate walking distances against the scale bar
Getting the Right Map
NSW LPI produces 1:25000 topo maps covering the entire state. They are available as printed copies from map shops and as digital downloads through the LPI website. The digital versions can be loaded into Avenza Maps on your phone for offline navigation. For most day walks in national parks, the free AllTrails maps are sufficient, but for anything remote a proper topo is worth having.
