Changes in fluvial dynamics of Santa Bárbara Hydrographic Basin – Pelotas (RS)

Abstract

This paper aims to analyze the main alterations occurred in the fluvial dynamics of the Santa Bárbara hydrographic basin, during 42 years (1953 - 1995). The study area is located in south-east portion of the municipal district of Pelotas (Rio Grande do Sul state) composing the Patos-Mirim lacustrine system. The changes in the fluvial dynamics were appraised through the elaboration of maps that represent the characteristics of drainage net in 1953, 1965 and 1995. These maps were obtained starting from the interpretation of aerial photographs that turned possible, in the same way, to analyze the land use characteristics and the main transformations in the original morphology, addressing the field activities for the critical points of alteration in drainage net. Human intervention on the natural system unchained several transformations in the fluvial dynamics. Human mechanisms of control were identified in all the analyzed sections and the capacity of intervention of these artificial components were recorded more intense in each mapped scenery. The system reacted to these forces trying to adjust itself to the new characteristics imposed on natural processes.