ABSTRACT
Saturated soil mechanics was originally developed in northern Europe and the north eastern United States, both regions with water surplus climates, high rainfall, low evaporation and, consequently, shallow water tables. As a result, in the countries of these regions, soil mechanics started as a study of saturated soil and, to a large extent, has continued along these lines, even though, as Fig. 1.1a (after Tricart & Cailleux, 1965) shows, the area of the Earth’s land-surface where arid to semi-arid climates prevail (areas 8 to 11) probably exceeds that where annual water surpluses occur. Arid to semi-arid climates include: deserts and degraded steppes with or without severe winters, semi-arid steppes and grasslands with or without severe winters and savannas. Much of the area indicated as azonal mountainous regions (13) is also semi-arid to desert. For example, the whole of the Atacama Desert, reputedly the driest in the world, falls in this area.
