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SPATIAL AND TEMPORAL WATER QUALITY VARIABILITY IN THE PIRACICABA RIVER BASIN, BRAZIL 1
Author(s) -
Krusche A. V.,
Garvaiho F. P.,
Moraes J. M.,
Camargo P. B.,
Ballester M. V. R.,
Hornink S.,
Martinelli L. A.,
Victoria R. L.
Publication year - 1997
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.1997.tb04129.x
Subject(s) - environmental science , water quality , hydrology (agriculture) , biochemical oxygen demand , nitrate , drainage basin , structural basin , sampling (signal processing) , sewage , spatial variability , water pollution , surface water , environmental engineering , chemical oxygen demand , wastewater , geography , environmental chemistry , ecology , geology , chemistry , paleontology , statistics , geotechnical engineering , cartography , mathematics , filter (signal processing) , computer science , computer vision , biology
The spatial and temporal variability of dissolved oxygen (DO), biochemical oxygen demand (BOD), nitrate concentration and total coliform (TC) were investigated at nine sampling stations distributed along the main rivers of the Piracicaba River Basin, a 12,400 km 2 catchment located in São Paulo State, one of the most developed regions of Brazil. Spatially, a downstream impoverishment of water quality conditions was observed, as seen by the decrease of DO, and increase of BOD, nitrate, and TC. These changes were probably caused by accumulating downstream discharge of domestic and industrial sewage. Temporal evaluation of 18 years of data showed that DO decreased with time for the majority of the sampling stations, while BOD, nitrate, and TC increased. A law, approved at the end of 1991, proposed a new water tax for river water extraction for industrial and agricultural use. The amount of this tax is determined according to the water quality of the extracted water. Therefore, the evaluation of the water quality status in this basin is a first step to help resources managers to determine the values for this tax.