Physics of desertification

Deserts are parts of the Earth that receive little or no rain; 25 cm or less per year. The physical processes that act upon these parched lands are vastly different from those that shape the more humid parts of the terrestrial landmasses. In the desert, wind is a major agent of erosion and transportation. As the results of recent space missions have indicated, this is also true in the case of the planet Mars. Thus, our understanding of desert processes sheds light on fundamental planetary processes that may apply on any planetary body that is enveloped by a windy atmosphere. An understanding of the physical layout of arid lands, and the nature of processes that initiate changes therein is also fundamental to thoughtful utilization of these lands for the benefit of mankind. It is with this in mind that we prepared this book for publication. We believe that the collection of articles in this book will be useful to scientists who are interested in desert landforms and processes, and to planners of economic develop ment of arid lands. The book also serves as a guide for students as to the state of our knowledge in this field as well as to the topics that require additional research.

Zusammenfassung
`... a valuable compilation of papers which, taken together, indicate something of the scope and character of a problem that is of vital concern to people in countries of all degrees of development.'
Episodes, June 1987

Inhalt
Report on Workshop on Physics of Desertification.- Desertification of Arid Lands.- Wind Versus Water Erosion in the Context of Desertification.- The United Nations Organization and the Issue of Desertification.- The Impact of Desertification on Land Productivity in Sudan.- Desertification Problems in a Humid Region.- The Formation and Motion of Dunes and Sand Seas.- Two-Dimensional Analysis of Dune Profile and the Effects of Grain Size on Sand Dune Morphology.- Stabilization and Afforestation of Sand Dunes Through Biosaline Culture Technique.- Some Aspects of Sand Stabilization in Egypt.- Eco-TechniqueMagic Formula for Reclaiming Desertlfied Semiarid Crop Land.- Monitoring the Sand-Moving Desert Winds.- Aeolian Activity as a Planetary Process.- On the Reddening of Quartz Grains in Dune Sand.- The Wind and Desertification Processes in the Saharo-Sahelian and Sahelian Regions.- The Advance Mechanism of Longitudinal Dunes.- Production of Dust.- Soil Erosion by Wind: An Overview.- Wind Erosion in the Interior Delta of the Niger in Mali.- Aeolian Processes and Features at Amboy Lava Field, California.- Aeolian Processes in the Environmental Wind Tunnel and in the Atmosphere.- Threshold Velocities for Dust Production.- Formation of Ripples, Dunes, and Antidunes in River Beds.- Saltation Threshold Mechanics.- Dust Production by Wind Erosion: Necessary Conditions and Estimates of Vertical Fluxes of Dust and Visibility Reduction by Dust.- The Aeolian Wind TunnelSaltation Similitude.- Shape and Dimension of Dunes in Open Channel Flow.- The Stability and Propagation of Sand Ripples and Dunes.- Turbulent Flow Over Topography With Applications to Sand-Wave Development.