The hydrological behavior of a watershed is determined jointly by its geoenvironmental, hydrological and landscape characteristics, therefore the study of these attributes is a way of elucidating it. The hydrological behavior of Itacaiunas river watershed, located in southeast Pará, was subject of an assessment based on its geoenvironmental attributes. Besides, regional hydrological variables were defined and the landscape dynamics of the watershed was also investigated. Hydrology applications and Geographic Information Systems were used, as well as data originated from the watershed monitoring. The results indicated that the main sub-watersheds are fourth-order physiographic units, being considered both physically and climatically homogeneous in this study. The probability distribution models which better fit to the maximum, minimum and average discharge data of seven consecutive days and ten years of recurrence related to the dry season of the Itacaiunas river watershed were respectively Pearson 3, Log-Pearson 3 and Log-Normal 2, whereas during the rainy season, it was Pearson 3, Normal and Pearson 3. The water balance of the watershed reported high water availability remaining for water rights concession; however it may have been overestimated. The assessment of the landscape dynamics of the watershed, in turn, has demonstrated a strong trend of modifications in land use for the watershed, during the study period. It also became evident that it happens on the occurrence areas of the more important sub-watersheds inside the hydrological context of Itacaiunas river watershed, making it possible to alter the water supply as an effect of the impacts of such modifications.
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