How does the monsoon influence Bihar’s agriculture and flood pattern?

The southwest monsoon is the single most important climatic factor in Bihar, influencing its agriculture and flood patterns in a dual-edged manner.

Influence on Agriculture

• Basis of Kharif Crop: The monsoon (June-September) provides the essential water for Bihar's primary agricultural season, the Kharif season. The state's main crop, paddy (rice), is entirely dependent on the timing and quantity of monsoon rains.
• Groundwater Recharge: Monsoon rains recharge the groundwater, which is crucial for irrigation during the dry Rabi (winter) season for crops like wheat.
• Economic Dependency: A good, well-distributed monsoon leads to a bumper harvest and a strong economy. A weak or failed monsoon can lead to widespread drought conditions, particularly in South Bihar.

Influence on Flood Pattern

• Causes Devastating Floods: While essential, the monsoon is also the direct cause of the annual floods in North Bihar.
• Himalayan Catchment: The rivers of North Bihar (like Kosi, Gandak, Bagmati) originate in Nepal. They carry not only the heavy rainfall from Bihar's plains but also the massive volume of water from their catchment areas in the Himalayas.
• Silt Deposition: This high-velocity water carries immense silt, which gets deposited in the plains, raising riverbeds and forcing rivers to overflow their banks, leading to the catastrophic floods that affect millions annually.