SEASONAL AND INTERANNUAL HYDROCLIMATIC VARIABILITY OF RAINFALL AND RIVER DISCHARGE IN THE CAETÉ ESTUARY, EASTERN AMAZON COAST: IMPLICATIONS FOR CLIMATE CHANGE ADAPTATION

This study analyzed seasonal and interannual hydroclimatic variability in the Caeté River estuary, located on the eastern Amazon coast, with emphasis on rainfall distribution and freshwater discharge. Rainfall data from the Brazilian National Institute of Meteorology and river discharge data from the Brazilian National Water Agency were evaluated for the monitored periods of 2006–2007 and 2010–2011 and compared with historical series from the Bragança region. The results showed a strong seasonal pattern, with most rainfall and river discharge concentrated during the wet season, mainly between January and July. In 2006, rainfall was close to the historical average, while the beginning of 2007 presented an anomalously dry condition, with precipitation corresponding to only 8% of the expected historical mean. In contrast, rainfall during the dry season of 2010 was approximately 100% higher than the historical average, reflecting the influence of La Niña. River discharge followed rainfall variability, with higher flows during wetter months and significant reductions during dry or anomalous periods. The analysis also indicated that drought events associated with large-scale climatic drivers, such as El Niño, the North Atlantic Oscillation, and the Atlantic Multidecadal Oscillation, may reduce rainfall by up to 40% in the region. These findings demonstrate the sensitivity of the Caeté estuary to climatic variability and reinforce the importance of continuous hydroclimatic monitoring for water resource management, environmental conservation, and climate adaptation strategies in Amazonian estuarine systems.