Understanding global desertification: Biophysical and socioeconomic dimensions of hydrology


Book Section

© 2006 Springer. All Rights Reserved. Drylands are regions of the globe where the index of aridity (IA)-defined as the ratio of mean annual precipitation (P) to mean annual potential evapotranspiration (PET)-is less than 0.65 (see Chapters 1 and 8). If we restrict IA to the range of 0.05 to 0.65, drylands consist of arid, semiarid, and dry sub-humid regions, which together cover approximately 5.2 billion hectares or 40% of the land area of the world (Table 1). This definition excludes hyper-arid regions of the globe where IA < 0.05, such as the Atacama, Arabian, and Sahara deserts (ca. 0.98 billion hectares or 7.5% of global land area). Based on human land use, ca. 88% of drylands are classified as rangeland, with the remaining 12% used in agricultural production (3% irrigated cropland, 9% rainfed; Table 1). Combined, Asia and Africa contain 64% of all global drylands, dwarfing the amount of dryland area on other continents. In terms of importance, however, these numbers can be somewhat misleading. While Europe contains only ca. 5% of the world's drylands, this represents over 32% of its landmass and is home to 25% of its population. Similarly, Australia contains about 10% of the world's drylands but they cover over 75% of the continent and are home to 25% of its population.

Full Text

Duke Authors

Cited Authors

  • Maestre, FT; Reynolds, JF; Huber-Sannwald, E; Herrick, J; Stafford Smith, M

Published Date

  • January 1, 2006

Book Title

  • Dryland Ecohydrology

Start / End Page

  • 315 - 332

International Standard Book Number 10 (ISBN-10)

  • 1402042612

International Standard Book Number 13 (ISBN-13)

  • 9781402042591

Digital Object Identifier (DOI)

  • 10.1007/1-4020-4260-4_18

Citation Source

  • Scopus