The Paraense coast stands out in the Brazilian coastal context for the singularity of its extremely jagged coastline, composed of alternating tapered bays (estuaries) and sandy tips. Given the lack of cartographic data of these areas, the present work aims to characterize the Mojuim River drainage basin, according to parameters established by HOWARD (1967), SOARES & FIORI (1976), CHRISTOFOLETTI (1980), SUMMERFIELD (1991). The interpretation of the drainage network allows us to infer that: The Mojuim River, presents its sources located near the Municipality of Santo Antônio do Tauá, with about 81.34 km of extension from the source to the mouth, whose dominant characteristic, except for the mouth, is of a meandering type alluvial channel, flows into the Marajó Bay, where it develops a tapering mouth in estuary, with about 3 km of maximum width. As for its drainage basin, it is not very elongated, when compared to the drainage basin of the Marapanim River, however, it has a high hierarchical degree, and can be considered a Fifth Order segment. The defined drainage patterns are: Dendritic, with high density and fine texture, characterized by a very branched and disordered (multidirectional) drainage network, developed in muddy tidal plains; Sub-dendritic, with low density and coarse texture, which develops under the domain of the coastal plateau, structured in sandy-clay sediments of the Barreiras Group, exhibiting a low degree of branching and more spaced watercourses, organized in an ordered multidirectional way. Modified dendritic-type sub-patterns with radial and annular enclave and associated anomalous forms (contorted meanders and rectilinearity) were also identified in this basin, probably related to interactions of geological-geomorphological factors and terrain permeability.
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