Abstract

Rio de Janeiro, a tropical and densely populated Brazilian state, has been recording severe impacts associated with heavy rain such as flooding, erosion, storm surges, and landslides. This situation may worsen as rainfall becomes increasingly concentrated. Therefore, the study evaluated recent trends of rainfall distribution in the region. The database consisted of forty-two stations for a homogeneous period of fifty years (October 1970–September 2020, P0), to assess spatial variability and compare changes between two subperiods: P1 (October 1970–September 1995) and P2 (October 1995–September 2020). The Concentration Index (CI), which identifies the participation of the most exceptional occurrences in the series, was used to determine the degree of irregularity of the daily rainfall distribution. Annual and seasonal assessments provided complementary information on the distribution of rainfall. The results showed that there was no significant change in annual rainfall totals over the fifty years. Nevertheless, there was a general trend in the concentration of rainfall in the rainy season, which runs from October to March, as well as increased daily extremes and higher annual maximum values, which have tended to be higher in recent years. Given the recent history of catastrophic events in the state of Rio de Janeiro (SRJ), the results are relevant for natural disaster management and for improving natural disaster preparedness and local to regional climate adaptation strategies.