Drought Assessment, Management, and Planning: Theory and Case Studies
Drought is an insidious hazard of nature. It originates from a deficiency of precipitation that results in a water shortage for some activity or some group. Africa has suffered the most dramatic impacts from drought during the past several decades the re
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NATURAL RESOURCE MANAGEMENT AND POLICY Editors: Ariel Dinar Dept. of Agricultural Economics University of California, Davis Davis, CA 95616-8512
David Zilberrnan Dept. of Agricultural and Resource Economics University of California, Berkeley 107 Giannini Hall Berkeley, CA 94720
EDITORIAL STATEMENT There is a growing awareness to the role that natural resources such as water, land, forests and environmental amenities play in our lives. There are many competing uses for natural resources, and society is challenged to manage them for improving social well being. Furthermore, there may be dire consequences to natural resources mismanagement. Renewable resources such as water, land and the environment are linked, and decisions made with regard to one may affect the others. Policy and management of natural resources now require interdisciplinary approach including natural and social sciences to correctly address our society preferences. This series provides a collection of works containing most recent findings on economics, management and policy of renewable biological resources such as water, land, crop protection, sustainable agriculture, technology, and environmental health. It incorporates modem thinking and techniques of economics and management. Books in this series will incorporate knowledge and models of natural phenomena with economics and managerial decision frameworks to assess alternative options for managing natural resources and environment. This book is a timely collection of theory and case studies addressing drought assessment, management and planning. The book includes up-to-date techniques used to cope with drought at local, regional and national levels. The book includes also case studies from countries which have a long-standing history of drought, and have accumulated drought experience over time. This experience is shared with the reader for a better understanding of future drought awareness.
The Series &litors Previously Published Books in the Serie.!(d2-d j ) f, =0.01
if d < d l and ifd l ~d ~d2 if d > d 2
Monitoring Regional Drought Conditions
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where the tenn d refers to the vapor pressure deficit and the subscripts I and 2 represent threshold values ofU and d at which these functional relationships are going to change. The actual evapotranspiration (ET) is the total of transpiration and evaporation: ET=T+E Evaporation on a given day (E) for the current version of the model is calculated from:
where the potential soil evaporation (Ep) for that day was taken as ETp' The variable do was set to 1.0 on the day ofthe most recent wetting, and d is the number of days since the last wetting. The result is that evaporation decreases exponentially from the day of the last wetting. ABOUT THE AUTHOR Kenneth G. Hubbard is an associate professor in the Department of Agricultural Meteorology and director of the High Plains Climate Center at the University of Nebraska-Lincoln. He specializes in monitoring and modeling the effects of weather on the biosphere. Dr. Hubbard is coeditorofImpacts ofClimat
