Ground investigations in hot deserts require an approach that takes account of the special environmental and ground conditions, as well as recognizing the scale, nature, cost and extent of the project in question. For example, the objective of a rapid reconnaissance of a wide area of terrain is to provide coverage at relatively low cost, using techniques such as normal observation, field mapping, geophysics or trial pitting. Whereas, by contrast, the requirements of a design-stage investigation are much more specific and detailed, focusing on individual structures or potential geotechnical hazards. To be cost-effective, the design of such an investigation needs to be based on a good feasibility/reconnaissance study.

The individual stages of the site investigation process are described in Chapter 6. The ground investigation methods described in this chapter represent the second stage, usually using intrusive techniques, but a flexible approach is required to ensure that the maximum benefit is derived from the results. The desk study is used to provide an initial design of the second-stage ground investigation. During the intrusive phase there should be a continuous review of the data, with modifications being made to the scope and programme based on results obtained in the field.

Sections 7.1–7.3 of this chapter address the technical and practical considerations that must be taken into account when planning ground investigations in desert conditions. Existing desert ground models have been described in Chapter 4 and an Earth systems model is proposed. The table presented in Section