Evaluation of the Siltation of River Taquari, Pantanal, Brazil, through 210Pb Geochronology of Floodplain Lake Sediments

The Taquari River basin (TRB) drains an area of 28,000 km in the plateau adjacent to the so-called Pantanal, a large floodplain area in midwest Brazil. It is characterized by sedimentary soils, primarily sandy soils, with areas of accentuated declivities and high erosive potential. These characteristics of TRB, associated with its intensive use and the mishandling of the soil by agricultural activities during the last 25 years have intensified erosion processes. This is evidenced by the presence of recent gullies and by the siltation of rivers of the TRB. The intensification of these processes causes the instability of the riverbed, and consequent flooding of large areas, leading to environmental, social and economic problems. These processes have already been reported by several authors. Direct estimates of sediment production related to agricultural activity are difficult to obtain for such a large and diversified area as the TRB, and no data are available at present. Historical records of suspended sediment loads for the Taquari River are scarce, although attempts have been made to compare such information. The lack of former studies for the characterization of this environment, prior to the expansion of agricultural activities in the plateau of the upper Taquari River region, makes it difficult to evaluate and compare past and present environmental impacts. Such evaluation can however be undertaken using Evaluation of the Siltation of River Taquari, Pantanal, Brazil, through 210Pb Geochronology of Floodplain Lake Sediments