IWRA World Water Congress 2008 Montpellier France
3. Climate Change and Disasters
GIS, river basins, drainage areas, Environmental
AbstractLong years of observing hydrological networks by Orstom
lead hydrologists to editing monographies of major West and Central African rivers (Congo, Niger,
Data processing permitted to manage a high quality data base of all the data collected. More recently,
new computer tools permitted us to build a geographical data base and finally an Environmental Information System
gathering chronological and spatial data within SIEREM.
What we show on this poster is the constitution of the
Geographical part of this EIS. The first aim was to model the hydrological basins of Western and Central Africa so
the processed stations had to fill two conditions: the first one was a long enough observation period (20 years at
least) and the second one was to drain a large enough basin (at least 2500 km²).
The process was first an
automatic one, using ArcInfo tools, GTOPO30 digital elevation model, and Digital Chart of the World drainage
network. But, the topography is so that the flat areas are numerous and the automatic process is unable to delineate
the basins in those areas. We had so to refer to the monographies and reports edited by IRD.
The result is a
geographical data base spread over more than 6 million square kilometres of West and Central Africa. Other basins
have been delineated and added, located in South and East Africa.
This poster shows the operating processes
used to carry out this work.
The GIS products can be browsed on the web site
(http://www.hydrosciences.fr/sierem) and the “product” part of this site offers the visitor to download freely the
geographical “layers”. Let’s add that this work is available and shared with researchers participating to international
programs and cooperation such as FRIEND projects.