Assessment of Spatiotemporal Trends in Rainfall and Rainfall Extremes in the Hyderabad City, India

Rainfall is a crucial climate variable, shows irregular spatial and temporal variations. Significant spatial variability and persistent changes in land use intensify the complexity of urban weather systems. Therefore, climatological rainfall variables deserve attention from both a scientific and technological perspective. The rapid urban expansion of Hyderabad city, coupled with extreme weather variations, has led to increased environmental vulnerability. The present study aims to assess the spatiotemporal trends of annual rainfall and rainfall extremes in Hyderabad city from 1990 to 2020. This study employed the RClimDex model and daily gridded rainfall data to analyze annual rainfall and rainfall extreme indices, focusing on Consecutive Dry Days (CDD), Consecutive Wet Days (CWD), Total Precipitation (PRCPTOT), Rainfall Events Exceeding 10 mm (R10MM), 20 mm (R20MM), Total Precipitation from Very Wet Days (R95PTOT), Maximum 1-Day Precipitation (RX1DAY), and Maximum 5-Day Precipitation (RX5DAY). The trends in annual rainfall and rainfall extremes were assessed using the Mann-Kendall (MK) test, and spatial distribution variations for the identified trends were evaluated with the Inverse Distance Weighting (IDW) interpolation technique. The results of the study showed that no significant annual rainfall trends from 1990 to 2020, indicating natural variability rather than consistent long-term changes. However, extreme Consecutive Dry Days and Maximum Wet Spell trends show increasing trends. The PRCPTOT pattern remains almost stable, and R10MM rainfall events exhibit an increasing trend at a few locations, suggesting potential shifts in precipitation patterns. Conversely, a decreasing trend for rainfall extremes R20MM, R95PTOT, RX1DAY, and RX5DAY indicate a general reduction in extreme rainfall events and very wet days in GHMC suggesting localized reductions in extreme events and varied impacts of prolonged rainfall reductions at annual scale. The study reveals Hyderabad's high spatial variability in annual rainfall distribution and rainfall extremes, emphasizing the importance of analyzing high resolution gridded rainfall data for effective decision-making and efficient water resource management.