Karishma Sarma, Mayuri Chetia and Ujjal Deka Baruah
Abstract
Rainfall, a major driver in climate dynamics, is emerging as a pressing concern in the context of climate change, yet studies on long-term rainfall patterns in Northeast India remain limited. This research analyzes 123 years of rainfall data to examine trends and distribution in two prominent cities, Gangtok and Itanagar, from 1901 to 2023. Our findings reveal a significant increase in annual rainfall in Gangtok, with a positive trend of 3.20 mm/year and a mean annual rainfall of 2929.85 mm, varying across a broad range of 1860.54 mm to 4170.61 mm. In contrast, Itanagar displays a declining trend of -4.86 mm/year, with an average annual rainfall of 2380.24 mm and a standard deviation of 415.11 mm, indicating marked interannual variability. The observed shifts in rainfall patterns emerged primarily in the 1970s and 1980s for Gangtok, while Itanagar exhibited shifts around the mid- to late 1970s. This positive trend in Gangtok aligns with broader observations in the Himalayan region, where increased rainfall has been associated with climate change impacts, possibly linked to changes in monsoonal intensity and shifting seasonal rainfall patterns. Conversely, the decreasing trend in Itanagar is concerning, as a consistent decline in annual rainfall can impact water resources, agriculture, and ecosystems.