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How to read a topographic map when hiking

 

When we go hiking we go through valleys, mountains, ravines and endless landscapes in direct contact with nature. A sport that every day is becoming more and more a tourist activity, with thousands of followers eager to enjoy all that hiking and trekking has to offer.

How to read a topographic map when hiking

Undoubtedly an experience not without risk, which requires us to follow some guidelines for preparation and implementation of the route. It also requires us, as simple as the route may seem, to have basic equipment and adequate training, both physical and technical.

Within the equipment that should always accompany us are topographic maps. Something fundamental when preparing the route and also when carrying it out.

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What are topographic maps?

Nowadays the GPS has almost displaced the traditional map to oblivion, surely we will not be many of us who still carry in our car the typical road map bought at a gas station.

And in the world of hiking and mountaineering something similar happens, we must rely on new technologies but we must also know how to read a topographic map when hiking.

Topographic maps have detailed information about the terrain, including the morphology of the terrain, its characteristics and even man-made modifications to the terrain.

These maps translate the natural environment they represent, with its mountains, rivers, valleys... onto paper, thanks in part to techniques such as contour lines.

 

 How to read a topographic map when hiking

Topographical map / Image: IGN

 

Why learn to read a topographic map?

Learning to read a topographic map is fundamental, we must not forget that this type of maps are not only found on paper, they are also used by our GPS. A map will allow us to know the terrain, to know where we are and to decide if necessary the best route to follow.

 

Characteristics of a topographic map

In general, all topographic maps are composed of a series of parts, layouts and data that we have to know how to recognize and interpret.

 

The scale of the topographic map

A map represents a large area of the earth, and it must also be accurate to allow us to know, for example, the real distance at ground level that separates two points on the map.

This is achieved thanks to the scale of the map; it is nothing more than a numerical figure that tells us what 1 cm of the map is equivalent to on the real terrain, it is usually represented as follows 1:25000 or 1:50000... among others.

The smaller the scale, the more detail we will be able to represent of the terrain, since they cover less amount of the same. In hiking, trekking or mountain the maps that are used usually have a scale of 1:25000 which means that each cm of the map means 25000 cm on the terrain, that is to say 250 m.

On the other hand, topographic maps also have a graphic scale that facilitates the estimation of distances from the map.

 

Topographic map scale

Legend Topographical map / Image: IGN

 

Legend of the topographic map

When we open a map we immediately realize that it is full of symbols, colors and lines. Valuable information that helps us to interpret the map.

We can find the meaning of all these symbols, colors and lines in the map legend. For example, a line with red and white stripes represents the route followed by a GR, a blue line marks the course of a river, an area painted with green tones refers to a denser vegetation.

Legend topographic map

Legend topographic map

Legend Topographical map / Image: IGN

 

Level curves

Level curves or contour lines connect points on the map that have the same elevation or altitude. These level curves allow us to know the slope or unevenness of the terrain. The closer the level curves are to each other, the steeper the slope of that area of the terrain; on the other hand, if they are increasingly separated, they indicate that the slope is becoming gentler.

Also by means of contour lines we can see, among other things, the shape of a particular peak or mountain, through the circles that draw the level curves.

In order to be able to interpret these level curves better and to know at what altitude we are, we will find different lines marked with their corresponding elevation, for example 1800 m. This means that all the points that join that line are at the same altitude and that from that line to the next one we will be going up or down meters depending on their altitude.

Depending on the scale of the map, the equidistance of the level curves or difference in altitude between each curve can be 5 m, 10 m, 20 m, 40 m, 80 m or 100 m.

 

Level curves topographic map

Capture Topographic Map / Image: IGN

 

Index curves or master curves

Although there are maps that have more lines marked with their corresponding altitude, it is a common practice, to facilitate its reading, to find every 5 contour lines an "index or master" curve, a thicker line. This line does detail its exact elevation at some point along it, allowing us to easily read the elevation of the terrain in that area.

 

Equidistance between contour lines

Earlier we talked about the equidistance between contour lines, but would you know how to define in a map with which equidistance it works?

It is very easy, you can know it in two different ways, the first one looking at the map legend. The second by checking the level curves on the map, as you know every 5 curves there is a thicker one that serves as an index, you just have to compare the difference in altitude between one and another to know what is the equidistance between the contour lines.

Knowing this data is important because you have to extrapolate this difference to the real world. If we have for example 40 m of equidistance it means that the difference in vertical from one curve to another is 40 m.

 

Mountains, valleys, depressions... how are they represented?

The shape and layout of the contour line as we have already said also shows us the type of terrain we are on.

For example, a valley such as the Ordesa valley is represented by level curves in the shape of a V, or a U depending on how closed it is, which gain elevation as they approach the head of the valley, the vertex of the V.

On the other hand the mountains are indicated with circles, which in turn have other circles within them until you reach the smallest circle inside which is the top of the mountain, provided that these circles of course increase in elevation as we approach the smallest. Although usually if it is a depression is usually accompanied by characteristic marks within it.

 

Level curves / Image: Pastranec (via Wikimedia Commons).

Level curves / Image: Pastranec (via Wikimedia Commons).

 

The grid system of topographic maps

In addition to getting an idea of the terrain it represents, the map also helps us to know our exact location or that of a specific point, in short, to carry out precise navigation.

All topographic maps have a superimposed grid and its upper part is oriented to the North. Each line represents a projection of a meridian or a parallel depending on whether it is vertical or horizontal. At its end we will see coordinates, usually in UTM format that allow us to obtain the exact location of a point on the map.

Other important data that we must know and that the map gives us is the magnetic declination that it has, that is to say the difference that there is between the magnetic north and the geographic north. Necessary data to navigate with the map and the compass and to orient the map in the correct direction.

 

Grid topographic map

Capture Topographic Map / Image: IGN

 

Recapping....

There are many types of maps, oriented to different activities, with more or less detailed information, specific to a particular area... Therefore the first thing to do is to know which map we need: tourist, cultural, aquatic, natural, relief, toponymic.

There are many publishers that nowadays develop topographic maps for hiking, many of them very complete and updated. But a map is useless if we do not know how to read it, if we do not know how to use it and if we do not take it with us in our activities.

 

Links of interest...

Buy maps here

Orienteering course with map and compass, here

 

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