Extreme rainfall events in Amazonia: The Madeira river basin

Monitoring and understanding the behavior of precipitation is a major challenge of the hydrological cycle and a key issue with respect to the corresponding impact and assessment of risk management in watersheds, notably in the Amazon region. This work investigates the frequency of extreme rainfall events in the largest Amazon sub-basin, the Madeira river basin, using information from the CHIRPS product dataset (Climate Hazards Group Infrared Precipitation with Station) acquired at a spatial degree resolution of 0.05. in a daily basis. Images from 1981 to 2017 were used, spanning a historical time series period of 36 years. Subsequently, these data were analyzed by applying the Gumbel distribution, with trend estimates determined by the Mann-Kendal test at the 95% confidence level. The historical time series revealed that the average maximum rainfall of 1 day, examined throughout the basin, showed variations ranging from approximately 30 to 300 mm. day(-1). It should be noted that there is a substantial influence of the El Nino/La Nina climatic phenomenon in the studied region. In addition, the results of the trend assessment showed a reduction in the magnitude of extreme rainfall in regions without vegetation cover in the study area accordingly to the scale of observation of the water balance.