Century of Rainfall Dynamics and Drought in Bihar: Patterns, Trends, and Climatic Variability (1901-2021)

Variations in precipitation patterns significantly impact the quality of life, particularly in regions reliant on rainfed agriculture like Bihar, India. Over the past century, global greenhouse gas emissions have caused climate warming and altered hydro-meteorological conditions. These changes have resulted in episodic droughts, floods, increased rainfall variability, and intensified extreme weather events. In Bihar, such variability poses serious risks to the hydrological cycle, especially affecting the reliability of monsoonal rainfall, which is crucial for agriculture. This study examines Bihar's annual and seasonal rainfall distribution, revealing a fluctuating but generally decreasing trend in annual rainfall, particularly in East Bihar. The study finds a significant decline during monsoonal rainfall in Bihar. Dry spells during winter and post-monsoon in Central Bihar have increased, thus affecting soil moisture levels and groundwater recharge. The analysis of the Standardized Precipitation Index (SPI) indicates that occurrences of mild droughts are becoming more frequent in western districts. Effective water management strategies like rainwater harvesting and improved irrigation systems are crucial for enhancing agricultural resilience. Investing in climate-resilient agricultural practices, including drought-resistant crop varieties and improved weather forecasting, will further enhance the state's ability to cope with precipitation variability.