Características físicas e químicas de sedimentos em suspensão durante eventos fluviométricos em bacias hidrográficas do sul do Brasil

Abstract

The observed high sediment load in the rivers of southern Brazil is strongly related to the degradation of agricultural soils due to water erosion. Currently there is great interest in describing the erosive processes and hydrosedimentological at the catchment scale to quantify the impact of land degradation on water resources because erosion is the driving process in the nutrients and contaminants transfer into the water resources. In this context, particle size information is essential to define the processes of detachment, transport and deposition of the particles as well as the transport capacity of P and C. Considering this background, the objective of this study was to characterize the particle size distribution and the concentration of P and C in suspended sediment samples during rainfall-runoff events in the three catchments of the Rio Grande do Sul (119 ha, 800 to 1980 km2). The events were characterized by their hydrological variables and material was sampled for granulometric distribution and chemical characterization (total carbon and phosphorus fractions). The results show the particle size and the inter- and intra-event chemical characteristics. The different catchments showed sediments with important differences for understanding the impacts of agriculture on water resources as well as to its hydrosedimentological behavior.