Ksn Index and SL Index Application in the Study of the Knickpoints in Ribeira de Iguape River Longitudinal Profile, São Paulo State, Brazil

Abstract

Longitudinal profiles have been extensively researched by geomorphological science, since it constitutes a fundamental parameter for the understanding of fluvial processes and dynamics. Although studies using this approach have been increased, several questions have arisen regarding the applicability of these indices due to the great complexity of fluvial systems, especially those of mixed bed and located in humid tropical regions. In this paper, the main aim was to evaluate the relationship between the knickpoints found in the longitudinal profile of the Ribeira de Iguape River (São Paulo southern coast), with lithologic, structural and autogenic processes. Ksn index and SL index were used because it use different variables with sensitivities to unlike aspects of the fluvial system. The results indicate that the processes which gave origin to the knickpoints are high complex due to the multiple environmental features, which include lithology, tectonics, climate (current and past), and autogenic processes; as well as the scale used in the study. Finally, the indexes used presented different sensitivities to the physical characteristics of the basin, especially those related to slope.