Efeitos do desmatamento sobre o ciclo hidrológico: uma comparação entre a Bacia do Curua-Una e a Bacia do Rio Uraim

Abstract

This work focuses on the hydrological response (ie precipitation, discharge and evapotranspiration) to deforestation, for two individual basins, where the processes of changing vegetation cover are at different levels. Search is thus ratifying the results mentioned in literature in the sense that above certain level of deforestation hydrological responses are to give due to local and non-local atmospheric interactions. Two basins were seleceted: the Curua-Una (micro-region of Santarem PA) and Uraim (Paragominas-PA). These basins were chosen because they represent examples of two different situations in respect of the advance of deforestation. The first is at a level of approximately 25%, while the second basin has experienced even more significant deforestation in the order of 65%. Using the time series data were performed for each basin statistical analysis to test the hydrological differences between two periods, representing different situations of deforestation, that is, a more preserved moment and a more deforested one. The results confirm that, in fact, different levels of deforestation cause different hydrological responses, to point out that for the basin with lower levels of deforestation 25% (i.e. Curua-Una Basin) there is not significant change in precipitation and even so the discharge increases, while the most devastated area (i.e. Uraim Basin) shows a reduction in precipitation (ranging from 25%), consequently decreasing the channel’s flow. These results are particularly relevant for confirming with field data that the assumptions made by various simulations of future scenarios in practice are already occurring, if not on a regional level, at least for one specific area where the level of deforestation is enhanced both as a percentage as of total length.