A digital elevation model applied to the mobility dynamics in an interfluve of southern Brazil

Resumo

In recent years, some topographic metrics (Gilbert metrics) have been proposed to investigate the degree of mobility and stability of drainage divides, through erosion rates between basins that share the same divide. Here, we investigated the mobility dynamics in the main divide of the Ibicuí and Jacuí river basins in southern Brazil, considering several indicators of erosive processes in this region. The mobility and stability of the Ibicuí-Jacuí interfluve were assessed based on the χ and Gilbert (elevation, gradient, and local relief) metrics extracted from the Copernicus DEM (COP-30) and field data, including aerial images. Our results showed that mobility occurs throughout the studied interfluve. In particular, the central region showed a high level of drainage divide mobility, likely due to its geographical location in the Central Depression geomorphological unit, which is dominated by low-resistant sedimentary rocks and relatively low elevations. The results also indicated that the main direction of the interfluve’s mobility is from east to west, highlighting that sub-basins from the Jacuí basin are potentially more erosive and, thus, are migrating toward the Ibicuí basin. Once connected, these sub-basins may alter the regional fluvial dynamics of this important region in southern Brazil.