Assessment of Spatio-Temporal Rainfall Variability and Trends across West Bengal, India

Abstract

Climate change manifests prominently through long-term variations in rainfall, influencing both spatial and temporal water availability. This study examines rainfall variability across 18 districts of West Bengal, India, using long-term records analysed at annual, seasonal, and monthly time scales. The Mann–Kendall test and Sen’s Slope estimator were employed to assess the direction and magnitude of rainfall trends. The annual rainfall analysis revealed statistically significant trends in five districts: North 24 Parganas and South 24 Parganas exhibited increasing trends, whereas Birbhum, Maldah, and Uttar Dinajpur showed significant declines at the 95% confidence level. Seasonal analysis indicated that only the monsoon season experienced notable trends in several districts, while the post-monsoon period showed significance at just one location. Monthly trend evaluation reflected a heterogeneous pattern across the state, with no uniform direction of change. The findings support district-level water planning by highlighting zones of rising or diminishing rainfall, enabling better management of water resources under evolving climate conditions.