Wind erosion occurs in many arid, semiarid and agricultural areas of the world. It is an environmental process in?uenced by geological and climatic variations as well as human activities. In general, wind erosion leads to land degradation in agricultural areas and has a negative impact on air quality. Dustemissiongeneratedbywinderosionisthelargestsourceofaerosolswhich directly or indirectly in?uence the atmospheric radiation balance and hence global climatic variations. Strong wind-erosion events, such as severe dust storms, may threaten human lives and cause substantial economic damage. The physics of wind erosion is complex, as it involves atmospheric, soil and land-surface processes. The research on wind erosion is multidisciplinary, covering meteorology, ?uid dynamics, soil physics, colloidal science, surface soil hydrology, ecology, etc. Several excellent books have already been written about the topic, for instance, by Bagnold (1941, The Physics of Blown Sand and Desert Dunes), Greeley and Iversen (1985, Wind as a Geological P- cess on Earth, Mars, Venus and Titan), Pye (1987, Aeolian Dust and Dust Deposits), Pye and Tsoar (1990, Aeolian Sand and Sand Dunes). However, considerable progress has been made in wind-erosion research in recent years and there is a need to systematically document this progress in a new book.

Understanding and predicting the behaviour of natural and human environmental systems is crucial for the effective management of the Earth’s limited resources. Recently, great advances have been made through spatial modelling. This book provides a snapshot of the latest research in modelling technologies and methodologies within five environmental fields; the cryosphere, hydrology, geomorphology, vegetation interfaces and urban environments. Spatial Modelling of the Terrestrial Environment deals with the use of remote sensing, numerical models and GIS in addressing important natural and human environmental sciences issues, focusing on the theory and application of modelling remotely sensed data within the context of environmental processes. Extensive case material exemplifies the latest research and modelling paradigms presented in the book.

This proceedings includes 33 papers presented during the International Symposium on Applied Soil Physics in Stress Environments held in 22-26 January 1989 in Islamabad, Pakistan. The papers are divided into four technical sessions. The first session (5 paper) provides an overview of irrigated and barani (rainfed) agriculture. The second session (13 papers) was focused on measurements and methodologies appropriate for use under condition prevailing in Pakistan and similar situations. Specific topics in the second session included soil water and solute movement, soil-water-plant interaction, and soil structure. The third session (9 papers) was concerned with defining the role of tillage and land use practices in soil and water conservation, and the fourth session (6 papers) was focused on conceptual and mathematical modelling applicable to stress environments. Recommendations relating to soil physics research needs, human resource development and research management in Pakistan, are also presented.