Recognition of technogenic relief features in the Paraibuna River Basin (MG) through the use of retrospective geomorphological cartography

Abstract

The reproduction of geographical space is associated with economic, political, social, and/or cultural processes that reveal the role of human agency and can be recorded in technogenic relief features. This study aims to identify, measure, and interpret these features present in the Paraibuna River watershed, located in the southeastern part of the state of Minas Gerais. The operationalization was based on the use of detailed retrospective/evolutionary geomorphological cartography techniques, with the preparation of representative maps of land cover and use and the identification of technogenic features for the years 1983 and 2010-2011, on a scale of 1:5.000. Cadastral plans, old aerial images, satellite images, and Google Earth Pro images were used, in addition to photographic collections and f ield investigations to map and record technogenic interventions. The morphodynamics of cumulative processes and material losses in the direct and indirect conformation of the relief made it possible to record the transformations that have occurred over time and that imply a change from the original morphology to a technogenic one. The classification of technogenic features focused on the recognition of excavated and silted terrain, erosive features, soil horizons altered by physical and/or chemical processes, linear alteration segments, artificial lakes, among others. Changes were identified in the Paraibuna riverbed, such as rectification points and landfills, the creation of dams and reservoirs, and urban expansion mixed with the relief of hills. The lower course is adjusted to the geological structures and is associated with the significant dissection of the river channels, with segments used for the installation of small hydroelectric plants for water supply and electricity generation. Finally, it is noteworthy that the use of detailed retrospective/evolutionary geomorphological cartography was fundamental in the diagnosis of technogenic changes and essential in identifying features more susceptible to erosion processes.