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World Water and Climate Atlas


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The World Water and Climate Atlas is being developed jointly by the International Irrigation Management Institute (IIMI) and the Utah Climate Center at Utah State University. It aims at providing easily accessible climatic information necessary for the planning, design, operation, and management of water resources and irrigated agricultural systems.

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The atlas uses climatic data from over 56,000 stations world-wide with coverage from 1961 through 1990 and includes monthly and/or annual averages for evapo-transpiration, daily temperatures, precipitation, and the probability distributions of rainfall frequency and amount. The climatic factors are mapped at a 2.5 km resolution using state-of-the-art
spatial interpolation techniques incorporating elevation modelling. The data sets contain best available data from international and local sources. The quality of the data varies, and has been partly improved by removing stations responsible for outlying values not explained by known effects. (Since there are many locations with sparse data, short periods of record, and spatially highly variable climate, it is still strongly recommended that the atlas be used together with local information.) Additional parameters included in the atlas are the moisture availability index that can be used to identify areas of rain-fed agricultural potential and to evaluate needs for irrigation and drainage, and the net evapo-transpiration which is an indication of the required depth of irrigation.

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The atlas can be a basis for a number of applications, such as:
  • estimation of synthetic virgin stream-flow;
  • evaluation of flow development potential;
  • exploration of the impact of climate change on irrigated areas;
  • salinisation studies.
The atlas is being produced in six parts. Part 1, covering Asia and based on data from nearly 14,000 meteorological stations, is available on CD-ROM and on the Internet .

January and July moisture availability index A75 (A75= P75/ETo; P75 - amount of precipitation with 75% excedence probability, ETo-total evapotranspiration calculated by Hargreaves method)

The project is supported by the Government of Japan

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Contact : E-mail: atlas@cgnet.com | http://atlas.usu.edu/
David Seckler, International Irrigation Management Institute (IIMI), P.O. Box 2075, Colombo, Sri Lanka
Phone: +94 1 867404 Fax: +94 1 866854 E-mail: iimi@cgnet.com | http://www.cgiar.org/iimi/
Donald Jensen, Utah Climate Center, Utah State University, Logan, UT 84322-4825
Phone: +1 801 797 2190 Fax: +1 801 797 2117 E-mail: djensen@cc.usu.edu | http://climate.usu.edu/