BOTTOM SEDIMENTS AND IN SUSPENSION IN FLUVIAL CORRIDOR OF THE PARAGUAY RIVER, NORTH PANTANAL OF MATO GROSSO, BRAZIL

Abstract

To understand the variation of solid and liquid discharges during flood and drought periods, the present study aimed to analyze the types of sediments transported on the Paraguay River - the upstream in the city of Caceres (MT). The methodology consisted of collections of bottom and suspended sediments, flow monitoring and laboratory analysis with pipetting/screening and evaporation. The flow values ranged from 615,12 m³/s-1 to 135,74 m³/s-1 on the Paraguay River and from 62,28 m³/s-1 to 0,71 m³/s-1 at the entrance of the Long Bay with 56,61 m³/s-1at the exit of the Long Bay. Concerning to the average depth it was recorded a maximum of 4.73 and minimum of 0.10m. The bottom sediments showed higher sand volume (concentration above 70 %) with the presence of silt and clay. The volume of suspended solids on the Paraguay River ranged from 15412.44 tons/ day and 2111.02 tons/day. It was registered 1076.08 tons/day and 978.22 tons/day of suspended solids at the entrance and the exit of the channel of the morphological feature in the rainy season. It should be emphasized that the results of flow were higher than the historical average (1966-2002) and the values of the bottom sediments were similar to those obtained by Silva et al. (2008). The study proved relevance for the particle size characterization of the bottom sediments, and estimate of the quantity of suspended solids carried by the Paraguay River to morphological features of the floodplain.

Key words: seasonality, siltation, channel abandonment.