Initial assessments suggest an earthquake triggered an ice-rock avalanche on the Lhende Khola river, a Bhote Koshi tributary, that led to severe flooding in Nepal.The authorities in Uttar Pradesh and Bihar are on high alert and have stepped up preparations to deal with a potential rise in the water level of the Gandak river. Directions have been issued to evacuate people from low-lying areas.The Lhende Khola river runs through both Tibet and Nepal.The outburst reportedly occurred in Tibet, triggering an approximately three-metre surge in the Bhote Koshi. The US Geological Survey recorded a magnitude 4.4 earthquake in the Tibetan territory at 8.37 am.Speaking to The Tribune, Prof Rijan B Kayastha, Professor, Department of Environmental Science and Engineering, Kathmandu University, Nepal, said, “The flood was likely caused by an ice avalanche blocking the Lhende Khola on the Nepalese side near the Tibet border. However, we are assessing satellite images. It will take us 24 hours to assess these and only after that we will get to know the reason behind the flood in Nepal.”Professor Kayastha said glacial lake outburst flood was common in the Himalayan ecosystem. “Climate change has led to an increase in temperature, which results in melting of ice. This leads to glacial outbursts,” he said.Nepal’s National Disaster Risk Reduction and Management Authority said an initial study based on an analysis of satellite images by Planet Labs indicated that a glacier-inclusive flood occurred in the Lhende Khola due to a snow-rock landslide that took place on the Nepal-China border approximately 20 km northeast of the Nepal-China Rasuwagadhi border crossing.In an advisory, the Central Water Commission stated that the flood wave would travel downstream in the Gandak with peak attenuation. The authorities in Bihar and Uttar Pradesh near the India-Nepal border along the Gandak have been asked to remain alert and monitor the situation closely.North Bihar’s districts — Champaran, Sitamarhi, Supaul, Darbhanga, Madhubani, Madhepura and Saharsa — and four districts of the Seemanchal area — Kishanganj, Purnea, Araria and Katihar — face flooding every year owing to their proximity to Nepal.The Gandak (also known as the Narayani) and the Kosi rivers originate in the Himalayas and Tibet before flowing through Nepal into Bihar. The water level of the Ganga has reached the danger level in several districts, including Patna.“The Chief Secretary has directed the district magistrates of Gopalganj, Chapra, Bettiah and Motihari to evacuate people from low-lying areas. A team of the Water Resources Department that is at Valmikinagar will open all 36 gates to let the water flow,” Santosh Kumar Mall, Principal Secretary of the Bihar Government’s Disaster Management Department, told this newspaper.Bihar Chief Minister Samrat Choudhary said a high-level committee had been formed to monitor the situation in the state.“A high-level team of officials, comprising the Chief Secretary and the Director General of Police, is monitoring the situation. I am also holding meetings with them,” Choudhary told reporters.In Uttar Pradesh, vigilance has been intensified in the border districts of Maharajganj and Kushinagar. UP Chief Minister Yogi Adityanath directed the authorities in the two districts to monitor the water level of the Gandak.Meanwhile, Jal Shakti Minister CR Patil said, “Whatever assistance is required will certainly be provided to Nepal by the Centre. For now, we will assess the extent of the loss and damage, and then decide accordingly. The water level in the Gandak is receding. The Bihar Chief Secretary held a meeting with all district magistrates. Prime Minister Narendra Modi is also keeping a watch.”