Are you planning a hiking trip to the backcountry or full-blown wilderness? One of the most useful skills you can have is knowing how to read a topographic map. Having map-reading skills and knowing how to use a compass can literally save your life.
In this article, we offer a lesson in map reading. We’ll guide you through all steps and skills needed to navigate in the wilderness.
WHAT IS A TOPOGRAPHIC MAP?
Topographic maps are different from other types of maps because of their high level of detail. Also known as topo maps, these maps are so-called planimetric maps. They show the world from a bird’s eye view, perpendicular to the ground.
Common road maps are planimetric maps as well, but they contain much less information. Topographic maps are extremely useful because they include natural and man-made features as well as the land’s topography.
Contour lines represent the topography. These lines connect spots with the same elevation and allow you to visualize what a landscape looks like. Like How Stuff Works says, topographic maps show the 3D world on a 2D surface.
Photo by istockphoto.com/portfolio/jahmaica
HOW TO READ A TOPOGRAPHIC MAP: 5 STEPS
STEP 1. UNDERSTAND THE CONTOUR LINES
Contour lines are the most important characteristic of topographic maps. If you don’t know how to read these lines, a topo map might seem overwhelming. If you do know, however, these maps are a godsend on wilderness hikes. Their wealth of information is also a great help when planning a backpacking trip.
Thin brown lines snaking their way across the map, contour lines connect places with the same elevation. In practical terms: a line marked “2,500 feet” means that it represents all points on the map located 2,500 feet above sea level. Contour lines are always closed loops (sometimes continuing outside your map).
They are categorized in intervals. Common intervals are 5, 10, 20, 40, 80 or 100 feet. The intervals depend on the scale of the map and sometimes on the represented landscape. If contour lines lie close to each other, that indicates a steep slope. Contour lines with a lot of space between them indicate flat or gently sloped landscapes.
It is also important to realize that, because contour lines come in intervals, there might be elevation change between them. For instance, as Backpacker.com points out, between 40-foot contour lines, there might be a 20-foot cliff or 30-foot ravine. Sometimes, this “problem” is solved by adding interval lines between the contour lines. These lines aren’t marked, but indicate smaller intervals between the main contour lines’ intervals.
There’s hardly ever a smooth transition between contour lines. That said, these lines help greatly when picturing what the landscape looks like.
5 THINGS TO REMEMBER ABOUT CONTOUR LINES
Section Hiker lists a number of basic things to know about contour lines. They’re critical with regards to how to read a topographic map.
1. All points on a contour line have the same elevation (above sea level).
2. Contour lines form closed loops. Typically, the area inside the loop is higher than the contour line.
3. Contour lines are indicated by intervals. One side of the line is higher, the other side is lower.
4. If contour lines lie close together, the landscape is steep. Lines located further apart mean a flatter landscape.
5. Contour lines crossing a stream or river will form a V-shaped pattern on the map. The tip of the V always points upstream. So, the V’s opening points downstream, or downhill.
STEP 2. KNOW THE FEATURES
Besides contour lines, you’ll find many other features on a topographic map. This is arguably the most realistic type of map available.
Features on a topographic map include the following. They are all indicated by different symbols and/or colors.
CULTURAL: roads, buildings, power lines, railroads, urban spaces and boundaries.
NATURAL: woods, orchards, vineyards and parks.
AQUATIC: rivers and streams, lakes, seas, swamps and waterfalls.
RELIEF: mountains, canyons, depressions, plateaus, slopes and valleys.
TOPONYMICAL: names of places, water features and highways.
STEP 3. LEARN WHAT THE COLORS REPRESENT
Color designations make topographic maps much easier to read. Large spaces have their own color. Woods, parks and other heavily vegetated areas are green while blue colors and lines represent water features, including rivers, lakes, ponds, wetlands and snowfields.
Grey or red indicates urban, built-up and man-made areas. Houses are small black rectangles. Larger buildings such as shopping malls and factories are shown as their actual shapes. Red lines represent major roads. Thin black lines are trails.
As mentioned above, the contour lines are brown-colored, as are their respective elevation numbers.
STEP 4. KNOW THE SCALE OF THE MAP
When learning how to read a topographic map, it’s important to be aware of the scale of your map. Obviously, there are no life-sized maps. Instead, to represent a large area, cartographers make maps on a ratio scale.
This means that one unit of measurement on the map correlates with a larger unit in the real world. The first number on any scale legend is one. This is your map’s unit of measurement—in the United States, it is generally an inch. The second number on the scale is the distance in real life, in the same unit of measurement.
For example, a scale of 1:20,000 means that one inch on your map correlates to 20,000 inches in the real world. You can find the scale legend at the bottom of your map.
STEP 5. FIND NORTH
In order to be able to use your topographic map on the trail, together with your compass, you must know where north is. Fortunately, this couldn’t be any easier. North is always, without exception, the top of your map.
VIDEO: HOW TO READ A TOPOGRAPHIC MAP
This twelve-minute video by Reality Survival shows you clearly how to read contour lines, the most important feature of topographic maps.