Rapid large-scale hydrological and geomorphic response to deforestation in a large tropical fluvial system.
Michael
T
Coe, The Woods Hole Research Center, mtcoe@whrc.org
Edgardo
M
Latrubesse, Universidad Nacional de La Plata-FCNyM, latrubesse@igs.edu.ar
Laerte
G
Ferreira, Universidade Federal de Goiás, laerte@iesa.ufg.br
Eric
A
Davidson, The Woods Hole Research Center, edavidson@whrc.org
(Presenting)
The Araguaia River, one of the main fluvial arteries draining the Cerrado of Brazil, offers a unique opportunity to evaluate the impact of deforestation on a large tropical river. The drainage area has suffered a rapid conversion from native Cerrado to pasture and to a lesser extent agriculture, with about 70% of the basin having been deforested since 1970. Continuous discharge measurements have been recorded at numerous sites since before deforestation began and no major alterations of the channel of the Araguaia have occurred, no dam or levee construction, channelization, meander rectification, or dredging has taken place. In this paper we present evidence of changes to the discharge, channel morphology, and sediment flux of the Araguaia River derived from data analysis, field studies, and numerical ecosystem simulations and quantify the role that deforestation has played in these changes. The results represent one of the more spectacular examples, of rapid large-scale hydrological and geomorphic response to deforestation in a large tropical fluvial system. They provide the first unequivocal quantification of the scale of human influence on the water balance and geomorphology of a large river system and as such inform our understanding of historical changes in rivers and the future of the many other tropical rivers being affected by rapid deforestation.
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