Determinação da curva-chave das concentrações de sedimentos em suspensão na bacia do rio Quaraí, na fronteira oeste do Rio Grande do Sul

Abstract

Analyze qualitative and quantify the flow carried along a watershed is a matter of strong influence in what concerns several sectors covered by the catchment, such as the aquatic life preservation, the animal inhabitants of the local, the treatment and the man usage of the available water resources. Understand the way these sediments are transported and the course they tend to take will be fundamental to the prevention and/or problem corrections from this subject. Taking into account such considerations, the present work was made based in the Quaraí river watershed, which is used mostly for agriculture. The main objective was to determine the existing suspended solid discharges in the catchment. The studied point is located at the middle of the catchment and the data were collected from campaigns carried out in the municipality of Quaraí (RS), by the Companhia de Pesquisa de Recursos Minerais (CPRM). The liquid discharge values are used or flow rate and concentration of suspended sediment to obtain the solid discharges in suspension. Based in hydrosedimentometric data, a key curve was plotted for the sediments. The obtained values through an excel spreadsheet have shown the collections were made mostly in low flow, where the sediment transport is smaller. With the finality of guiding how to acquire a greater reliability in the data series, where high flow records are needed, a proposal was described, which resorts to the use of the turbidimeter, as an indirect measure, which is capable of high temporal frequency sampling, in order to complement the absence of suspended sediment concentration information.