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How To....Walk Across A Desert

How-toJames HipkissComment

For most people the word desert conjures up the images of endless sand dunes stretching to the horizon. This is rarely the case.Roughly speaking, a desert is defined by lack of rainfall, less than 100mm per annum; making Antarctica the largest desert in the world and the Kalahari only a semi desert or merely hyper arid.

Dunes are in fact a geological rarity, as most deserts are gravel plains or low lying sand and scrub, known as Hamada in Arabic. But...deserts by comparison to say, arctic environments are considerably easier for us to endure as our ancestors evolved on the sun blasted savannas of Africa. The advantage with this is the amount of specialist equipment needed to survive is minimal, specialist knowledge however is paramount. Spending time with and learning as much from the locals is the very best way to gain an understanding of desert travel. I was lucky enough to have spent time with the San of the Kalahari and am still learning from the Bedu after five years. Exposure Ultimately this is the greatest threat to life (not snakes and scorpions) and the two most important things to consider are shade and water - the more shade you have the less water you drink. Not so much of a problem if you are in a vehicle, but on foot it becomes a constant worry.

The mornings walk is the most important as you have to find shade before it gets too hot at midday, the availability of shade may mean that you cannot walk directly to your objective but have to detour. The afternoons walk is easier as you can camp anywhere for night. How much water should you be drinking a day? This is a question I am endlessly asked and the answer is that there are many variables; body mass, fitness, temperature, exertion and most importantly acclimatisation. During the 2002 Namibia crossing I drank only three litres a day, the medical opinion was that I would die if I didn't drink five, but I had been living full time in Namibia for eight years. On the other hand for our young peoples expeditions in the cooler months, we budget for five litres a day per person, but that includes tea and cooking. Salt intake is just as important as water, without salt the body cannot absorb water. Thirst is a poor indication of how hydrated you are, check the colour of your urine. It should look like lager, if it looks like Guinness you're in trouble.

Also be aware that drinking too much water (Hyper-Hydration) is potentially fatal. If you run out of water under no circumstances drink your own urine (or anybody else's for that matter). Madonna may allegedly do it every morning, but it will just put more stress on an overly stressed renal system and speed up your inevitable demise. Navigation It is difficult to get good detailed maps of most desert regions and obviously an OS map is out of the question. GPS is a big help but they have been known to run out of batteries and even break down and should never be used as your primary navigational instrument. Finding your way is made easier by the normally clear skies and this enables us to use the sun, moon and stars to get our bearings. During the day the sun can provide a rough idea of North or South, made more accurate by using your watch as a sundial in reverse, or very accurate using a sun compass. These were used extensively by the Long Range Desert Group in WWII and a cruder form was thought to have first been used by the Vikings.

But basically at noon in the northern hemisphere the sun will give you south and in the southern hemisphere north. A moon enables travel at night and gives us direction, on a moonless you can use the stars, but the chance of injury due to standing on, falling over or into something is high due to absolute lack of light. When dunes do form, they form in different types. Where there are large volumes of sand, linear or multi cyclic dunes form at ninety degrees to the prevailing wind. Barcan dunes on the other hand form when there is a smaller volume of sand and are crescent shaped with the horns pointing away from the prevailing wind. Both these can be of use in navigation if you know where the prevailing wind comes from. In the Namibia for example the prevailing wind is from the SWW, so the linear dunes run pretty much north south. Weather I once read somewhere that more people drown in deserts than die of thirst.

This may or may not be the case, but flash floods are a very real danger. There may be a cloudburst 100km away that you are unaware of, the rain runs off the sun baked earth down the ephemeral riverbeds picking up a wall of debris in front of it. If you are camping in that riverbed you have no chance. Deserts can get extremely cold at night; this is due to the sand, which is a poor insulator, quickly radiating the heat it gained during the day as soon as the sun goes down. I have experienced minus ten in the Sinai and minus five in the Kalahari, but as soon as the sun comes up its back into shorts. The Bottom Line Ultimately, as with any expedition it all comes down to; planning, preparation, stamina and guts. How far can you walk, how little can you drink and how long can you keep it up for.

Good luck.

Written by Sam McConnell FRGS, Desert Expedition Leader The content of the website is for information only and the views expressed do not reflect those of Explorers Connect. These 'How To...' guides are for information only and do not replace rigorous preparation for any expedition.