Travelers and the nature of deserts:
- For those travelers staying in well regulated accommodation in good hotels, the realities of the desert can be disguised for as long as electricity and pure water supplies are sustained. Much of the information in the following section can thus be ignored, though not with total impunity. Trips into the desert even by the most careful of tour operators carry some of the hazards and a knowledge of good practice might be as helpful on the beach or tourist bus as for the full-blooded desert voyager. There is a contemporary belief that the problems of living and traveling in deserts have been solved. Much improved technology in transport together with apparent ease of access to desert areas has encouraged these comfortable ideas. The very simplicity of the problems of deserts, lack of water and high temperatures, make them easy to underestimate. In reality, deserts have not changed and problems still arise when traveling in them, albeit with less regularity than twenty or so years ago. One aspect of the desert remains unchanged - mistakes and misfortune can to easily be fatal. Desert topography is varied. Excellent books such as Allan JA & Warren A (1993) Deserts: a conservation atlas, Mitchell Beazley, show the origins and constant development of desert scenery. Desert and semi-desert is the largest single surface area and so has an importance for travelers rarely met with elsewhere. Its principal features and their effects on transport are best understood before they are met on the ground. The great ergs or sandseas compromise mobile dunes and shifting surface sands over vast areas. Small mobile barkhams, which are crescent shaped, can often be driven round on firm terrain but the larger transverse and longitudinal dunes can form large surfaces with thick ridges of soft sand. They constantly change their shape as the wind works across them. While not impossible, they can be crossed only slowly and with difficulty. The major sand seas such as those a Calanscio, Murzuq, and Brak should be treated as no-go areas for all but fully equipped and locally supported expeditions. Similar conclusions apply to the extensive outcrops of rocky desert as exemplified by the Jabal As-Sawda in Libya. The wadi beds which penetrate much of the Sahara, serirs and gravel plains provide good access for all-terrain vehicles. The main characteristic of the desert is its.
Aridity
- Aridity is calculable and those navigating deserts are advised to understand the term so that the element of risk can be appraised and managed with safety. CW Thornthwaite's aridity index shows water deficiency relative to water need for a given area. There is a gradient from N to S throughout the region, of rising temperatures, diminishing rainfall, and worsening aridity. Aridity of the desert is thus very variable, ranging from the Mediterranean sub-tropical fringe to a semi-arid belt to the S and a fully arid desert interior. In basic terms, the further S you are the more dangerous the environment. Do not assume that conditions on the coast properly prepare you for the deep S. The Sahara is also very varied in its topography, climate and natural difficulties posed for the traveler. Rapid transition from rough stone terrain to sand sea to salt flat has to be expected and catered for. For practical purposes, aridity here means lack of moisture and.
Very high temperatures.
- The world's highest temperatures are experienced in the Sahara, over 55^C. Averages in the southern desert run in summer at more than 50^C in the shade at midday. In full sun very much higher figures are reached. High temperatures are not the only difficulty. Each day has a large range of temperature, often of more than 20^C, with nights being intensely cold, sometimes below freezing. In winter, air temperatures can be very low despite the heat of the sun and temperatures drop very rapidly either when the sun goes down or when there is movement from sunlight to shade, say in a deep gorge or a cave. Increasing aridity means greater
Difficulty in water availability.
- Scientists define the problem in terms of water deficits. The region as a whole and the deep Sahara in particular are very serious water deficit areas. Surface waters are lacking almost everywhere except in the case of the Nile in Egypt and Sudan. Underground water is scarce and often available only at great depths. Occasional natural seepage of water give rise to oases and/or palmeries. They are, however, rare. Since water is the key to sustaining life in deserts, travelers have always to assume that they must be self-sufficient or navigate from one known water source to another. Isolation is another feature of the Sahara. Travelers' tales tend to make light of the matter, hinting that Bedouin Arabs will emerge from the dunes even in the most obscure corner of the desert. This is probably true of the semi-desert and some inland wadi basins but not a correct assumption on which to build a journey in the greater part of the Sahara. Population numbers in the desert are very low, only one person per 20 km sq. in Al-Kufrah in SE Libya, for example, and most of these are concentrated in small oasis centers. Black top road systems are gradually being extended into and through the Sahara but they represent a few straggling lines across areas for the most part without fixed and maintained highways. The very fact that oil exploration has been so intense in the Sahara has meant that the surface of the desert is criss-crossed with innumerable tracks, making identification of all routes other than black top roads extremely difficult. Once off the main roads, travelers can part from their escorts and find no fixed topography to get them back on course. Vanishing individuals and vehicles in the Sahara are too frequent to be a joke. To offset this problem read on. The most acute difficulty with off-road emergencies is finding the means of raising assistance because of isolation. Normal preventative action is to ensure that your travel program is known in advance by some individual or an institution to whom regular check-in is made from points on the route. Failure to contact should automatically raise the alarm. Two vehicles are essential and often obviate the worst problems of break-down and the matter of isolation. Radio communication from your vehicle is an expensive but useful aid if things go wrong. Bear in mind the enormous distances involved in bringing help even where the location of an incident in the desert is known. Heavy rescue equipment and/or paramedical assistance will probably be 500km or more distant. Specialist transport for the rescuers is often not instantly available, assuming that local telecommunication systems work and local administrators see fit to help.
Living with the climate
- Living with desert environments is not difficult but it does take discipline and adherence to sensible routines at all times. It is an observed fact that health problems in hot and isolated locations take on a greater seriousness for those involved than they would in temperate climates. It is still common practice with Western oil companies and other commercial organizations regularly engaged at desert sites to fly ill or injured persons home as a first measure in the knowledge that most will recover more rapidly without the psychological and environmental pressures of a desert site. Most health risks in the desert are avoidable. The rules, evolved over many years, are simple and easy to follow:
- 1. Allow time to acclimatize
- 2. Stay out of direct sunlight
- 3. Wear clothes to protect your skin
- 4. Drink good quality water
- 5. Be prepared for cold nights
- 6. Stay in your quarters or vehicle if there is a sand storm.
- 7. Refrain from eating dubious foods.
- 8. Sleep off the ground if you can.
0 comments:
Post a Comment