It's where topography and terrain features all come together and is useful when you're trying to figure out where you are or when you're trying to confirm your location on a map. It's also a good way to describe your location to someone else.
Here are 4 steps to learn how to use terrain association.
1. Orient your body, your map and your compass to North.
This will give all of your tools the same frame of reference and reduce the amount of stress on your brain.
2. Describe what you see around you in each direction.
- Is the ground sloping up or down as you look north?
- What does the ground look like as you look to the east, south and west?
- Can you see any prominent hilltops or valleys?
- Are there any bodies of water within your line of sight?
Describing the terrain around you will help you actively think about the shape of the terrain and start to draw out what that shape means to you as you're walking around.
If you're struggling to describe the terrain, try describing it out loud. It forces you to focus and really think about what you are seeing. In return, it prompts the brain to more actively process the terrain. It prompts the brain to more actively process the information.
3. Draw the logical conclusions.
For example, if you see one lake directly to your south it means that you must be somewhere on the map where there is a lake to the south and you can rule out those parts of the map where there is no lake to the south.
If you don't know where you are on a map you can then determine that you are standing to the north of the lake and then focus your attention to the section of the map that is to the north of the lake to really zero in on the terrain and find your location.
The end of this step is when you confidently point to a place on the map and say "I think I am here."
4. When you think you know where you are on the map, look for things on the ground that would prove you wrong.
This is a similar analysis to what you did at step 3, but now that you have taken a position it's time to make sure you're right. Review your observations from step 2. If the ground is sloping down to the north in front of you make sure it does so on the map too. Check that for every observation and as soon as you find one that doesn't match, go back to step 3.
Looking for things that will prove you wrong is important because you aren't trying to find the place on the map that is pretty similar to where you are on the ground, you are trying to find the place on the map that is exactly where you are on the ground.
All the confirming information in the world can be undone by one piece of disconfirming information. So, looking for those disconfirming pieces of information is more efficient.
As a final note, it's important to understand that navigation takes a careful balance of confidence and humility. You have to be open to your potential mistakes or you'll never correct them and will end up lost. But at the same time, you can't allow yourself to be frozen in fear, afraid to make a decision. Either extreme will get you in a lot of trouble.
One thing that can help is practice. Once you can quickly match what you see around you with what you see on your map, navigation becomes almost second nature.