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Morphological Changes in Stretches of the São Francisco River Due to Uncontrolled Agricultural Expansion in Its Watershed

Author(s): Wilson Junior Gerardo, Fernando Roversi, Mário Grüne Souza E Silva

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Keywords: Sedimentological and morphological processes; São Francisco River; Remote sensing; HEC-HAS;

Abstract: The springs of São Francisco River (SFR) are in the State of Minas Gerais, Southeast of Brazil. Known as the National Integration River, it drains seven states and flows 2,830 km towards the Northeast Atlantic region. It is perennial and has a 1,391 km navigable segment. Brazilian government has invested in three fronts: (1) partial diversion of its waters to the Northeastern Semiarid region; (2) construction of nine hydroelectric plants in its main course, with a generation of 9,400 MW, and (3) agricultural expansion. The Iuiú Irrigation Basic Project, elaborated at 2000, intended for agricultural development of an area of 500 km2, at the mouth of Verde Grande River (VGR), in a navigable 10.0 km stretch of the SFR. Assisted by Remote Sensing techniques, six sediment bars corresponding to the period of 1985 to 2011 were analyzed. The stretch of the Iuiú Irrigation Project gradated from 1985 to 2001, and later (2003-2011) reached a sedimentological equilibrium. The challenge and motivation for improving morphodynamical studies on the SFR was to understand the behavior of its moving bars. The studies were therefore extended to 2018, with conclusive results: (i) in less than 10 years, there arose numerous projects of water diversion from tributaries of the SFR; (ii) several tributaries dried up due to uncontrolled water outtake for agricultural development; (iii) the number of exposed sediments bars has multiplied; (iv) nowadays, the 10.0 km of the Iuiú Project, which was in sedimentological equilibrium from 2003 to 2011, presents tendencies to braiding and (v) conflicts have aroused between landowners and peasants.


Year: 2019

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