For a hiker, there are words that carry meaning! A meaning that anyone who is not a nature walker cannot understand…
“Elevation” belongs to this category of essential words as it is so important in the eyes of those preparing their hike.
But it’s a word that also tends to arouse the headaches of the most recalcitrant to mathematics.
Strict aspirin!
So, we take out, at your choice, the abacus, the calculator or the laptop, without forgetting the IGN map or the GPS and I will explain everything you need to know about the positive, negative, global or cumulative elevation gain!
In short, here is the elevation for dummies…
What exactly is elevation?
Before trudging up the mountain, let’s take a short detour to the Petit Larousse, which tells us that the term “descent” means “difference in altitude, level between two points”.
At first glance, nothing very complicated.
Let’s move on to concrete cases.
You start your hike from a car park located 220 m above sea level and, after 5 hours of walking, you arrive at the top of a pretty wooded hill which is 580 m above sea level.
The difference in height is therefore 580 m – 220 m = +360 m.
Easy!
Another landscape, another atmosphere: a hike in the volcanoes of Auvergne. You start at 890 m altitude and arrive at 1170 m altitude.
Elevation: 1170 m – 890 m = +280 m.
On paper, it’s OK, but your legs tell you that you’re understated. Quite simply because you have climbed and descended 3 Puys, each steeper than the other.
This is also the case if you make a circuit in a loop (that is to say that you return to your starting point): in this case, the difference in altitude is zero.
So the method of calculating the elevation requires some clarification…
What is the elevation gain for hiking?
Details are essential because the difference in altitude influences the difficulty of a hike or even a simple Sunday walk!
When you’re hiking in the plains, on perfectly flat land, more than the drop, it’s the distance that matters.
On the other hand, when you tackle any hilly terrain, it is no longer really the distance that counts, but the slopes that you will swallow, without forgetting the descents, which are sometimes difficult due to the nature of the terrain.
Simply because walking 10 km on the flat is much less exhausting than climbing for 10 km.
Not to mention the time you will spend covering these 10 km….
Depending on the type of terrain or your fitness level, 10 km on the flat takes 2 to 3 hours.
On the other hand, if, during these same 10 km, you climb 500 m, descend 300, then go up another 200 m before descending towards the finish of about 400 m, the time spent walking will be very long for the same distance.
So, to manage your effort and your time, it is essential to know the cumulative difference in altitude (Prepare yourself, I will explain it to you later).
What impact does the elevation change have on my hike?
We have seen that the difference in altitude greatly influences the difficulty of the hike.
And that’s where it comes in the concept of kilometre-effort.
Because, when it comes to walking, not all kilometres are created equal!
Thus, 10 km of hiking is logically worth 10 kilometres-effort.
So, on the flat, you save 10-kilometre of effort. But you will “ride” much more uphill and downhill. Concretely, about a 1-kilometre effort for a 100 m ascent and a 1-kilometre effort for a 300 m descent.
Finally, depending on the elevation, your hike will quickly display twice the number of kilometres-effort of the real kilometres travelled.
Thus, this (positive) drop is taken into account in the hiking rating system, which ranges from 1 to 5.
Before embarking on a course, check this figure which is a guarantee of security.
Finally, you will not apprehend the difference in altitude, in the same way, depending on your state of form and mind, notions that have a significant impact on your walking speed.
What is the difference between positive and negative elevation?
The terms positive and negative elevation is ultimately quite simple to understand:
- The elevation gain is the distance travelled uphill.
- Downhill is the distance travelled downhill.
Did you get it? Nope?
Some examples to understand :
A beautiful sunny day in the Alpilles. On the program for the day, start from an altitude of about 450 m to climb a pass located at 720 m, and descend at the next stage at an altitude of 630 m.
The elevation gain is calculated as follows: 720 m – 450 m = +270 m ascent
The negative elevation: 630 – 720 m = -90 m.
So you will go up more than down!
What is the difference between overall elevation and cumulative elevation?
This is where we get to the heart of the matter.
Still there?
We will immediately leave aside the overall difference in altitude which has no real interest for the hiker since it is simply the difference between the highest point and the lowest point.
On the other hand, the cumulative elevation (positive or negative) is VERY interesting.
Why? Quite simply because a hike is never made only of an ascent and a descent.
Therefore, the cumulative (positive) elevation corresponds to the addition of the elevations of the various climbs that mark out your route. And the cumulative elevation (negative) to the sum of the elevations of the descents, but the figure may seem less important.
Although!…
Let’s return to the volcanoes of Auvergne for a short 4.1 km hike with the Puys de Lassolas and the Vache on the program, one at 1179 m and the other at 1145 m. The start is at 986 m and the finish at 1145 m.
The overall elevation (positive and negative): +159m (1145 m – 986 m)
On the other hand, the cumulative difference in altitude (positive and negative) is totally different since it takes into account all the ascents and descents of the route. :
- First climb: 1179 m – 986 m = +193 m
- Descent: 970m – 1179m = – 209m
- Second climb: 1145 m – 970 m = +175 m
i.e. a total of 193 m + 175 m = 368 m of cumulative positive elevation gain and -209 m of negative elevation gain.
And in the calves, these +368m and -209m of cumulative vertical drop are very different from the +159m of overall vertical drop!
Note: you will notice that +368-209=159, the count is good!
How to calculate the elevation?
To calculate all these elevations, several tools are at your disposal, from the most traditional to the most technological:
- The IGN map thanks to the level curves (calculator required!)
- The GPS watch or a GPS application on your laptop allows you to see, in real-time, the distances travelled, and the cumulative elevations travelled. But you will not be able to anticipate them….
- Online sites or applications to prepare and calculate your route: Openrunner, Geoportal, Map-planner, Sitytrail or Outdooractive.
