Rescue operations continued searching through thick layers of mud and debris in flood-hit Nepal on Friday as authorities remained on high alert over a newly formed lake near the Nepal-China border, raising fears of another flash flood in the region.The warning comes two days after devastating floods swept through the Himalayan border region, killing more than 500 people and leaving over 1,500 missing.Nepal's disaster management authorities said satellite imagery and preliminary assessments indicated that a river had been blocked upstream, creating a growing lake that could burst and send a sudden surge of water downstream.Where is the newly formed lake?Satellite imagery shown by Chinese state broadcaster CCTV indicated that the lake had formed in the same area where a glacial detachment occurred on Wednesday, triggering the chain of events that caused widespread destruction downstream.CCTV reported that the lake's barrier was more than 10 km from Gyirong Port, a key border crossing with Nepal that was inundated by mud and floodwater. The lake is located at an elevation of about 2,950 metres, nearly 1,000 metres above Gyirong Port.Nepalese authorities have directed security personnel, rescue workers and others involved in relief operations to remain on high alert and move to safer locations if necessary.How did the lake form?Experts said the lake was formed after an ice-rock avalanche caused by the glacial collapse on August 26. Debris and rocks blocked part of the river, creating a temporary natural dam and causing water to accumulate behind it."Another dammed lake was formed by the August 26th ice-rock avalanche and this has begun to outflow," Qianggong Zhang of the International Center for Integrated Mountain Development said, the Associated Press reported.Zhang said the lake contains a few million cubic metres of water and is located in a valley with a limited elevation drop towards downstream areas. The volume of water is equivalent to roughly 1,200 Olympic-sized swimming pools.Why are authorities worried?Scientists have warned that continued glacial melt, high temperatures and debris blocking river channels could lead to further flooding."There is still a lot of glacial melts going on because of high temperatures and the water is accumulating at various points, as there is bound to be a lot of debris and rock on the river’s path," said Jakob Steiner, a geoscientist at the University of Graz in Austria.Both Zhang and Steiner said the warnings should be taken seriously, particularly as rescue teams continue searching for people missing in the floods. However, they said another flash flood on the same devastating scale was unlikely.India monitoring situationAt least 320 Indians remain missing, while around 400 others are stranded on the Chinese side following the floods along the Nepal-Tibet border, the ministry of external affairs (MEA) said in a media briefing.MEA spokesperson Randhir Jaiswal said India was ready to provide all possible assistance to Nepal in its rescue efforts. He said 96 Indian nationals stranded on the Chinese side had safely crossed into Nepal by land.Twenty-one Indians also arrived in New Delhi on Friday, a day after reaching Kathmandu from the flood-affected areas of Nepal, PYI reported. Since Wednesday night, India has also sent a total of 47.5 tonnes of emergency supplies to Nepal in two military transport aircraft and is in the process of sending more relief materials.