The arid and extremely arid areas of the Middle East are outlined, and the past and present climatic regimes within these areas considered and related to the existing rock and soil conditions.
A system of classification of the ground into four simple zones based on their desert characteristics and the natural processes operating within the zone is described. The general engineering character of each zone is discussed and particular problems highlighted. Zone I is the mountainous areas, zone II the large gravel fans bounding mountains, zone III the alluvial plains beyond the fans, and zone IV the central base level plains between mountains or adjacent to coasts.
The great majority of desert soils are granular and their engineering behaviour is directly related to their grading characteristics. Flooding is an important hazard in the fans and alluvial plains, while in the base level plains high water tables are of major importance. Ground conditions of significance in deserts, which do not generally occur elsewhere include aggressive salty ground, wind blown sands and silts, and hard and soft duricrusts. These and certain other ground conditions are described.