Fear among the locals rose further following rumors that the Imja Tsho glacial lake, known as a potentially dangerous one, had overflowed overnight. Thanks to quick responses by locals and by Ang Chiri Sherpa, chairperson of the Everest Buffer Zone Area consumers group, it became visually clear that Imza lake was okay. Sherpa inspected the area in question by helicopter.
The overflow had taken a trail between Lhotse and Island Peak near Everest Base Camp (EBC). "There has been no impact on Imja lake. The water had overflowed from some other small lake. The locals call this Chu Rawa," said Sherpa.
However, the overflow phenomen has left experts puzzled as to whether the source of overflowing water was a glacier, a small lake or a supra glacier lake such as are formed on the surface of large glaciers.
The Department of Meteorology and Hydrology (DHM) was informed about the overflow incident only on Tuesday morning. Neither experts from DHM nor those at the International Center for Integrated Mountain Development (ICIMOD) have been able to offer a definite explanation for the lake's existence.
Senior glaciologist and Assistant Professor at Kathmandu University (KU), Dr. Rijan Bhakta Kayastha, believes the flow was from the melting of a supra glacier lake. "Our preliminary study shows that the water had been released near Lhotse glacier. The draining of a supra glacier pond in the area must have resulted in this sudden flow," he said.
According to Kayastha, a similar incident had occurred near the Tsho Rolpa glacier area in 1981.
"A large quantity of water had leaked from a supra glacier lake in the area and drained the whole area," he further said.
Supra glacier lakes are formed atop large glaciers. Most of them are ephemeral but records show they can extend for kilometers and be several meters deep.
However, a glacier hydrologist at ICIMOD, Joseph Shea, demurred over comments on a supra glacier lake.
"It is pretty early to note the melting of water from a major glacier or a supra glacier. We are in the process of identifying the case and only the final report will make the final claim. However, I believe the water was released from small lakes found amply in the area," he said.
"Even if it was a supra glacier melting, it is a natural process and certainly does not rise any serious concern about climate change," he further added.
Bikram Shrestha Juwa, a hydrologist at DHM, shared a similar concern. "We too are looking into the matter but to say whether the impact was a glacial lake or supra glacier lake requies further research," he said.
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