Retrospective geomorphological mapping and geoindicators in the analysis of relief changes in mining areas: the case of Monte Mor (SP)

Abstract

Sand mining, as a driver of landform alteration, promotes the creation of new forms and the reorganization of natural processes, resulting in hybrid and markedly anthropogenic landscapes. Thus, the objective of this research is to evaluate the potential of retrospective analysis in geomorphology, through geomorphological mapping, in understanding environmental transformations associated with mining in the Capivari River basin (Monte Mor municipality, São Paulo, Brazil). The methodology consisted of comparing geomorphological mappings from 2010 and 2022, allowing the differentiation of previous and derived morphologies resulting from mining activity, the identification of stages of intervention, and the estimation of the magnitude of changes. The results indicate the intensification of anthropogenic morphologies, especially in active mining areas, where deep pits, in some cases below the water table, mining benches and technogenic deposits are observed. Significant changes were also recorded in hydrographic features, including the reduction of pluvial channels and the modification of the distribution of natural and artificial lacustrine bodies. In rural and peri-urban sectors, linear erosive features such as rills, ravines and gullies stand out, enhanced by the interaction between agricultural practices and the proximity of mining fronts. These data reveal the spatial heterogeneity and cumulative nature of the transformations, reinforcing the complexity of the interaction between anthropogenic dynamics and natural processes. From a methodological perspective, the combination of retrospective geomorphological cartography and geoindicators allowed the clear identification of the most recent changes in the relief, highlighting the expansion of pits, the reorganization of channels and the intensification of erosive processes, proving to be an effective approach for the detection and quantification of recent geomorphological changes in mined areas. The results indicate that mining acts as a central agent in the reconfiguration of the relief in Monte Mor, producing persistent and difficult-to-reverse features. In this sense, understanding such transformations is essential to guide recovery measures and to monitor the evolution of mined areas.