Probabilistic Rainfall Assessment and Climate-resilient Crop Strategies for North Bihar's Zone II

Abstract

This research investigates the long-term rainfall behaviour across Zone II of North Bihar by analysing historical data spanning a century. Employing probability distribution methods and regression modelling, the study explores the variability of rainfall across seasonal intervals winter, pre-monsoon, monsoon, and post-monsoon. The outcomes reveal significant inconsistencies in rainfall patterns, influencing water availability and agricultural planning. Based on these findings, season-specific adaptive cropping strategies are proposed for wetlands that remain non-submerged, aiming to improve agricultural resilience amid climatic uncertainties. The wetlands of Zone II in North Bihar are facing increasing climatic challenges, especially erratic rainfall patterns, which critically affect agriculture. This study analyzes 30 years (1991–2020) of daily rainfall data from Muzaffarpur, Samastipur, and Darbhanga to determine monthly and seasonal variability and identify probabilistic rainfall thresholds useful for crop planning. Statistical tools including mean, standard deviation, and coefficient of variation (CV) were used to assess variability. At a 75% probability level, June rainfall was below 90 mm at all locations, suggesting limited reliability for rice sowing. In contrast, July rainfall exceeded 210 mm at a 50% probability level, making it suitable for transplanting rice or introducing medium-duration crops. The rainfall in September dropped below 150 mm at 50% probability, posing risks to rice maturity and harvest. Based on these probabilistic thresholds, crop planning was formulated: short-duration pulses and oilseeds are suggested for early kharif, while flood-tolerant paddy or jute is proposed for mid-season sowing. This approach promotes adaptive crop strategies and supports climate-resilient farming practices in the wetland ecosystems of North Bihar.