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EMPLOYMENT OF THE GEOGRAPHIC INFORMATION 
SYSTEM ON THE ASSESSMENT OF DRAINAGE EXPLOSURE 
DEGREE TO NON-POINT SOURCE POLLUTION 
Sidney T. Rodrigues 
Sergio Bernardes 
Universidade de Säo Paulo - Instituto de Biociéncias 
Depto. de Ecologia Geral 
Rua do Matáo, s/ n? - Cidade Universitária 
01000-000 - Säo Paulo - SP 
ISPRS Commission VII / Working Group 7 
ABSTRACT 
The lack of use conservation practices allied to an intense an unsuitable use of regions with high 
susceptibility to erosion, make streams receive, periodically, great amounts of sediments. Together to this 
runoff, nutrients and toxic wastes, coming from agricultural practices, are also loaded, contributing directly 
to the eutrophization and to the increase on pollutants level in the reservoirs. The understanding of agents 
emissions an circulation dynamics, mainly nonpoint ones, as far their interaction with several basin 
components are considered of remarkable importance in promoting the control of such processes. The main 
aim of this work is the characterization of a hydrographic basin according to the stream degree of exposure to 
nonpoint source pollution. In this way, the mapping of following factors will be considered: a)susceptibility 
to erosion through the present potential of basin erosion; b) buffering capacity of sediment load supported by 
occurrence and height of riparian vegetation and c) surface runoff pathways. These information are being 
treated by means of Geographic Information System through weighted operations considering the factors 
approached. As a product of such analysis, a map will be generated indicating the extream exposure level to 
sediments, toxic wastes and nutrients runoff. This map can be useful in management practices, establishing 
priorities areas for reforestation, recuperation and conservation. 
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