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METHODOLOGIC ESSAY TO IDENTIFY EMERGENT SEDIMENTS DEPOSITS OF 
THE BILLINGS RESERVOIR - SAO PAULO, SP-BRASIL, USING GIS 
Marisa Santas Bitencourt-Pereira 
Luiza Saito Junqueira Aguiar 
Roney Peres dos Santos 
Rosángela Pacini Modesto 
Universidade de Säo Paulo - USP 
Ecologia Geral - IB 
Rua do Matäo, Trav. 14, no. 321 
05508-900 - Säo Paulo - SP, Brazil 
ISPRS Commission VII / Working Group 5 
ABSTRACT 
This paper presents the partial results obtained while developing a methodology to be used to identify 
emergent sediments deposits of the Billings Reservoir affluent and its drainage-basin. The present study 
is being developed by CETESB-USP to ELETROPAULO to quantify clandestine soil occupation in 
these areas as well as increasing sediments carried out to the reservoir which jeopardize its lifetime. The 
basic methodology consists of some geographic analyses to merge physical aspects of the environment 
and the forms of landuse and soil occupation directly related to the formation process of these deposits. 
These analyses will be formed using a GIS integrating data such as reservoir water level, batometry, 
geology, geomorphology and pedology with thematic maps of landuse and soil occupation obtained from 
photointerpretation and from the digital analyse o Landsat images (vegetation index). The 
photointerpretation was performed in two different scales 1:25000 (from 1962) and 1:10000 (from 1985 
and 1989). The satellite images from 1986 and 1992, both obtained by TM-Landsat system. Although the 
methodology that compare spectral data obtained by satellite with other geocoded data is very well know 
nowadays, in this particular case it was not so easy. The reasons were some peculiarities of that reservoir 
such as its water-level variations determined by operational factors rather than the seasonal regime and its 
frequent occupation by emergent aquatic macrophyts determined by the rain period in the region. 
071