Arid Environments

by

David S.G. Thomas

• LAST REVIEWED: 29 September 2014
• LAST MODIFIED: 29 September 2014
• DOI: 10.1093/obo/9780199363445-0002

Introduction

Arid environments cover almost half the earth’s land surface and embrace a considerable range of environmental conditions. Terms such as arid, desert, and dryland are commonly used interchangeably and without strict scientific usage, though “arid” is also used as a formal division of drylands within the widely used classification scheme in UN Environment Programme 1997 (cited under Defining Arid Areas). Arid environments are characterized by an overall moisture deficit, often expressed as annual precipitation being less, often significantly less, than potential evapotranspiration. Consequently, soil moisture levels are low, which has impacts for plant and animal life and for the geomorphic processes that shape arid regions. Systematic scientific study of arid environments grew throughout the 20th century, prompted by the realization of a lack of robust scientific knowledge of these regions, and, from the 1950s and particularly 1970s onward, by concerns surrounding human usage, the occurrence of droughts, and the risks of “desertification.” Atmospheric conditions mean that subtropical locations dominate the regions where drylands occur, but continentality, topographic rain shadows, and the impact of cold ocean currents are other factors that influence dryland occurrence (see Thomas 2011 [Arid Zone Geomorphology: Process, Form and Change in Drylands], cited under General Overviews). Importantly, arid regions and drylands are not necessarily hot year round, with continental deserts, for example the Gobi in Mongolia, experiencing extremely low winter temperatures. This article focuses on geomorphic systems, but with relevant linkages to ecology and issues of human-environment interactions.

General Overviews

The works in this selection provide overviews of the processes that shape arid regions, and many also address, to some degree, ecological characteristics. Cooke and Warren 1973 was the first widely available systematic textbook covering the main geomorphological processes that shape arid environments. This remained the case until the 1980s, when several competing, but differing, texts appeared, some of which have been updated in the early 21st century to capture significant research developments. Thomas 2011 is the most recent comprehensive volume, while Parsons and Abrahams 2009; Laity 2008; and Cooke, et al. 1993 are alternatives.

• Cooke, R. U., and A. Warren. 1973. Geomorphology in deserts. London: Batsford.

  The first comprehensive text on desert geomorphology, which in its day captured the key geomorphic processes and landforms shaped by wind and water, with a particular focus on the driest areas rather than drylands as a whole.

• Cooke, R. U., A. Warren, and A. S. Goudie. 1993. Desert geomorphology. London: UCL Press.

  This text was, in effect, a continuation of Cooke and Warren 1973, with a similar format and level of coverage. Six sections provide a global perspective; analyses of desert surfaces, fluvial systems, aeolian processes, and aeolian landforms; and a section describing different arid regions of the world.

• Laity, J. J. 2008. Deserts and desert environments. Environmental Systems and Global Change. Hoboken, NJ: Wiley-Blackwell.

  Similar coverage to other books in this section, but much more of an introductory text with lesser depth: very much for the early-undergraduate market. Also introduces biological systems and human issues in deserts.

• Parsons, A. J., and A. D. Abrahams, eds. 2009. Geomorphology of desert environments. 2d ed. Heidelberg, Germany: Springer.

  DOI: 10.1007/978-1-4020-5719-9

  First published in 1992 (London: Chapman & Hall), the content of the second edition of this edited volume provides expert-derived, and research-oriented, coverage of arid geomorphology, including key chemical, water, and wind-driven processes. An e-version is available.

• Thomas, D. S. G., ed. 2011. Arid zone geomorphology: Process, form and change in drylands. 3d ed. Chichester, UK: Wiley-Blackwell.

  DOI: 10.1002/9780470710777

  First published in 1988, each edition has been rewritten and reorganized to capture more-recent research developments in arid environments, with chapters authored by relevant experts. This edition integrates environmental change and environmental processes, covering chemical, water, and wind-driven processes and living with dryland geomorphology. Regional examples are used throughout to provide context to the science. An e-version is available.