Digital Atlas of World Water Balance

This Digital Atlas of the World Water Balance is our first attempt at
creating an integrated set of data files and models in GIS format that
can be used to characterize the water balance of the earth. The
concept arises out of a project called the FAO/UNESCO Water Balance of
Africa, sponsored by the Land and Water Development Division of the UN
Food and Agriculture Organization, Rome, Italy, and the Division of
Water Sciences, UNESCO,Paris, France. The goal of this project is to
provide data and exercises for using the data for water resource
analysis in Africa. This project involved was built around a Water
Balance of the Niger Basin in West Africa. A Conference Proceedings
paper prepared for presentation at the 1997 ESRI User Conference, and
contained also on this CD-ROM explains the methodology. As many of the
data sets were compiled for that project, they were drawn from data
sets of global extent, so we decided to compile the global data into
one location and add to that the data files and sample exercises that
we had produced in our work on the Water Balance of Africa, to form a
product with which similar tasks could be accomplished for other parts
of the world. Some of the exercises were developed during a Technical
Cooperation Project on the Souss Basin in Morocco in collaboration
with the Direction Generale de l'Hydraulique of Morocco. Additional
applications have been made to the Urubamba River Basin in Peru, and
to the Aral Sea Basin in Central Asia.The data and exercises which
support this Digital Atlas are designed to be used with the Arcview
Version 3.0 Geographic Information System, though Version 2.1 can be
used for many of the exercises. The descriptive material contains
graphic files, some of them animated, which explain the origin and
processing of the data. The Water Balance of the Niger Basin paper,
explains the background and methodology This Digital Atlas contains
five types of data: precipitation, temperature,radiation, runoff and
political boundaries. The precipitation, temperature and radiation
data are depicted on a 0.5 degree grid spanning the earth (720 cells
East-West, and 360 cells North-South, or 259,200 cells in all),
covering both the land surface and the oceans. On each grid cell is
presented the mean monthly and mean annual values of each variable in
Arcview shapefiles. More information on these data can be found in
the section on Data Sources. Mean monthly and mean annual runoff at
160 stations are found in the runoff directory. The political
boundaries are used to delimit particular regions of interest in the
data sets.