Mudanças recentes de leito no baixo curso do rio Taquari, no Pantanal Mato-Grossense

Abstract

The Taquari river flows from the Parana Basin Plateaus of Mato Grosso State to the lowland region of Pantanal. The Pantanal Cenozoic Sedimentary Basin is made up of unconsolidated Quaternary sediments deposited over the pre-cambrian basement and showing geological boundary on the east side with rocks of Paleozoic and Mesozoic age from the Parana Basin. One can notice that the Taquari river in its upper course has a meandering channel. The sinuosity is decreased very sharply in the middle and lower courses due to intense sediment deposition. The consequence of this alluvial sedimentation process can be easily seen in the middle of the river course by several lobes causing an unstable drainage pattern with many points of avulsion, like one named "Arrombado Zé da Costa" which is responsible for 70% of the actual discharge and shifting the main channel course. The subject of this work was to map the lower course changes of the Taquari river that took place from 1966 to 1997 by the Landsat TM-05 satellite images interpretation and GPS data. The natural changes in the lower Taquari river, were expressive for 31 years and these changes have been accelerated by the effects of human activities in the area.