Efficacy of methods for estimating total solid load in bedrock rivers

Abstract

The objective of this study was to verify the efficacy of methods for estimating solid fluvial solid in predominantly bedrock rivers, in catchments with different types of land use, in Guarapuava, in the central region of the state of Paraná. Using hydrosedimentological data measured in the Cascavel catchment, and in four of its sub-catchments, during 13 rain events between July 2015 and November 2016, the Colby, Karim, Engelund & Hansen, and Cheng indirect methods for calculating total solid fluvial load were applied and assessed. In the Cascavel catchment, the Cheng method, followed by the Colby method, provided the best results for estimating total solid discharge, with a percentage difference between the measured and estimated data of 67.77% and 73.66%, respectively. Large differences between total measured and estimated solid discharges were found in the sub-catchments. The method with the lowest relative percentage difference between total measured and estimated solid load varied in the rain events and sub-catchments. We found that there is no indirect method for calculating total solid discharge that is more appropriate for bedrock rivers, because the efficiency of the methods varied in the events and catchments. Fluvial sediment transport was found to be complex and is mainly associated with local environment specificities and soil management practices.