HYDROCLIMATIC CHANGES IN THE CAETÉ RIVER WATERSHED, EASTERN BRAZILIAN AMAZON

Hydroclimatic variability in the Amazon region is closely linked to large-scale ocean–atmosphere interactions, particularly the El Niño–Southern Oscillation (ENSO) and the Atlantic Dipole (AD). This study investigates the interrelationships among Sea Surface Temperature (SST), Rainfall (R), Maximum air Temperature (Tmaxair), Evapotranspiration (Et), and Flow (F) in the Caeté River Watershed (CRW), located in the Eastern Amazon, Brazil. Hydroclimatic datasets from 1985 to 2023 were analyzed using mapping, trend detection (Mann–Kendall and Pettitt tests), and correlation analyses. The results revealed significant warming trends in SST anomalies from Tropical Atlantic, suggesting increased persistence and intensity of AD events. Rainfall in the CRW exhibited high interannual variability and strong correlations with SST anomalies, particularly from the Atlantic domain. Although no statistically significant trends were detected for R, Tmaxair, or Et, the F of the Caeté River showed a decreasing trend (MKz = –1.47), indicating potential future reduction in water availability. The spatial analysis confirmed uneven distributions of hydroclimatic variables across the watershed. Notably, anthropogenic factors—such as deforestation in river headwaters—may amplify hydroclimatic imbalances, even under climatically favorable conditions. These findings underscore the importance of continuous hydroclimatic monitoring and integrated assessments of land use dynamics to anticipate long-term socio-environmental impacts in Amazonian coastal basins.