Kathmandu, July 11 -- An outburst of a previously unnoticed supraglacial lake formed in Tibet above the Rasuwagadhi border point is responsible for Tuesday's devastating flood on the Bhotekoshi river, according to two separate reports by the Department of Hydrology and Meteorology and the International Centre for Integrated Mountain Development (ICIMOD).

Issuing a preliminary study report and satellite pictures of before and after the flood on Thursday, the department said that a supraglacial lake is located at an altitude of 5,150 metres, approximately 36 kilometres upstream of Rasuwagadhi.

The flood is a clear sign of Nepal's growing vulnerability as climate change drives the formation and rapid expansion of glacial lakes in the Himal...