The threat of devastating floods loomed large over Bihar on Monday following incessant rainfall in north Bihar and Nepal, coupled with massive discharge of water from the Gandak and Kosi rivers from the barrages along the Indo-Nepal border.

Alarmed by the development, chief minister Nitish Kumar undertook an aerial survey of the West Champaran, East Champaran and Gopalganj districts where floodwaters are already spreading in the low-lying areas. The situation is expected to worsen in the coming days if heavy showers continue in Nepal and Bihar.

The Gandak river has emerged as a particular cause of concern with over 4.4 lakh cusecs of water discharged from the barrage at Valmikinagar in West Champaran on Sunday morning. Though the discharge was showing a falling trend, it was still over 2.4 lakh cusecs on Monday afternoon and the river was flowing 1.02 metres above the danger level at Dumaria Ghat in Gopalganj district.

One cusec or "cubic foot per second" is a flow of 28.32 litres crossing any particular point or mark per second.

Nitish also inspected the Gandak barrage at Valmikinagar and chaired a review meeting with water resources minister Vijay Kumar Choudhary and senior officials. He directed them to stay completely alert, monitor the situation and be ready to meet any possible circumstances in the low-lying areas where water was rising.

“The district magistrates should maintain a continuous vigil and senior officers should camp at various locations. Necessary instructions as per the standard operating procedure (SOP) have been given to all the districts and departments concerned. They should be fully implemented,” Nitish said.

The chief minister also asked the officials to be fully prepared with boats, polythene sheets, relief material, medicines, cattle fodder, flood shelters, community kitchen and dry ration packets.

The officials have also been instructed to protect the embankments along the Gandak in light of the rising water level and the increased pressure on the flood-protection structures.

Around 4 lakh cusecs of water were released from the Birpur barrage into the Kosi river on Sunday. The discharge decreased to 2.26 lakh cusecs on Monday afternoon, but floodwaters entered low-lying villages, settlements and agriculture fields.

“The situation was a bit alarming on Sunday because the water discharge from Birpur barrage went up to 3.96 lakh cusecs. However, this was the first flood of the season and the Kosi river was empty with the water level in the Ganga also low, so the increased flow passed on smoothly. All embankments and spurs are safe and the situation is under control. We have started operating 117 boats on the demand of the people living in the low-lying areas,” Supaul district magistrate Kaushal Kumar told The Telegraph.

While the Kosi river, also called "the sorrow of Bihar" has breached the danger level in Khagaria district, the Bagmati and Mahananda rivers crossed the danger level in Muzaffarpur and Purnea districts, respectively.

The Bihar government accepts that floods have come only after an area is inundated or houses are surrounded by water for four to five days with no means of transport other than boats.