Chapter 3 Processes and landforms in deserts

Abstract

The ground conditions relevant to construction in deserts are controlled to a great extent by geomorphological processes of landscape development acting on the extant geology and topography. Thus, examining the geomorphological ‘process–response’ system forms the basis for understanding the desert landscape and natural hazards to safe and economic construction (Chapter 4). Within the geomorphological systems, the balance between erosion, transportation and deposition caused by wind, water and gravity, linked to soil moisture deficit and the prevalence of salt compounds, is instrumental in creating distinctive morphological forms. In addition to contemporary geomorphological processes, the extent and location of desert areas have fluctuated throughout the Cenozoic, and in particular during the Quaternary. Thus, all existing deserts contain landforms created under different climatic regimes that remain as relict features that might or might not be stable under prevailing conditions. In this chapter the processes that create desert landforms are presented under four categories: This is not a typical format for presenting desert geomorphology but is suitable for highlighting the features and processes that have engineering geological significance. For a classical treatment of desert geomorphology, reference should be made to Cooke et al. (1993) and Thomas (1997), which currently remain the definitive books on the subject. ### 3.1.1. Weathering processes Desert weathering is pervasive, selective and frequently superficial (Cooke et al. 1993). This results from extreme variations of microclimate and, because the proportion of exposed rock is higher than in most other climatic zones, the properties of rocks impose a strong differentiation on the effectiveness of weathering. Flaking, spalling, splitting, pitting, granular disintegration and bizarre morphological forms abound. Weathering also prepares bedrock for the subsequent operation of erosion, thereby providing the means for landform evolution (Viles & Goudie 2007 …