Applicability of sediment rating curves: analysis in the state of Rio Grande do Sul

Abstract

The transport of sediments is present in all watercourses, occurring naturally, however, in different ways and characteristics. Its quantification in watersheds becomes extremely important for the planning and management of water resources. The sediment rating curve, which empirically describes the relationship between stream flow and suspended sediment concentration (Css), is an alternative tool to the lack of continuous monitoring of sediment transport. The aim of this research was to evaluate the use of rating curves in sedimentometric stations in Rio Grande do Sul, Brazil. Three Css data handling scenarios were tested for the analytical fitting of sediment rating curves considering a power function as follows: complete data sets, data sets subdivided into 10-year periods and subdivided into stream flow ranges. The approaches adopted in the present study were evaluated taking as reference  58 sedimentometric stations in the state. The goodness-of-fit tests used in this study - coefficient of determination, Relative Average Percentage Error and Nash Sutcliffe coefficient, indicated that the best results of the estimation of sediment transport were observed when the sediment rating curve was fitted to the 10-year period data set.