Geomorphological patterns in the estuary of the Assu river, NE - Brazil

This study describes the geomorphological patterns in the estuary of the Assu river, state of Rio Grande do Norte, northeastern of Brazil. The 20 m contours of the topographic maps (Macau and Porto do Mangue), at the 1:50,000 scale, were manually digitized and analyzed using SPRING 5.2. Afterwards, the techniques used in this study consisted of the preparation and analysis of hypsometric, slope, hillshade maps, topographic profiles, and 3D models. These data helped in the geomorphological mapping. The results show that there are three morphostructural class in 1st Taxon: i) Quatemary sediments; ii) platform sediments (Barreiras Formation and Post-Barreiras units) and iii) Mesozoic units of the Potiguar basin. The 2nd Taxon consists of two morphostructural classes: i) coastal plain and ii) coastal platforms or tablelands. The 3rd and 4th Taxons are the erosional and depositional patterns of landforms. There are four forms of denudation in the study area. The 5th Taxon is the hillside shape. We also identified two patterns. The first form flat and rectilinear forms, which are found in the main river, with extensive plains. The second pattern is concave and rectilinear, which occur in mainly secondary rivers of the basin, between 1st and 2nd order. Inactive cliffs, gullies and dejection cones were identified in the 6th active Taxon. We show that the functionality of the maps derived from the Digital Terrain Model. This study is thus a basic instrument for further analysis and diagnostics to understand the dynamics of the landscape in an integrated manner