Bihar Floods Defy Tradition: Unusual Patterns Emerge

Bihar experienced three distinct flood spells this year, with the third and longest spell beginning in September. This final inundation, primarily driven by swollen Ganga, Sone, and Punpun rivers, triggered significant concern across the state, especially in Patna. The Ganga River surged past its 2016 high-water mark at Gandhi Ghat in Patna, reaching 50.58 meters. Floodwaters flowed over two meters above danger levels along a substantial stretch of the river within Bihar. By September 13, approximately 48.70 lakh individuals in 15 districts were affected.

This year's floods presented a departure from historical patterns. Typically, Bihar floods are linked to heavy rainfall in Nepal and impact north Bihar plains more severely. However, delayed monsoons, erratic rainfall, and extreme weather events, attributed to climate change, have become more common. This year, prolonged dry spells followed by intense rainfall and a rainfall shortfall during monsoon months contributed to the unusual flood dynamics. Notably, lightning and thunder incidents also increased, prompting warnings from authorities.

The situation escalated in late August when a glacial lake outburst in Tibet led to a surge in the Gandak River. Emergency measures were enacted, including opening all 36 gates of the Valmikinagar barrage, but the threat was ultimately averted. Subsequently, heavy rains in Nepal increased discharge in the Kosi River. In early September, the Ganga and other rivers flowing into it experienced unprecedented water flow, crossing historical flood levels and highlighting the vulnerability of Patna despite existing flood protection infrastructure.