The Koshi or Sapt Koshi drains eastern Nepal. It is known as Sapt Koshi because of the seven rivers which join together in east-central Nepal to form this river. The main rivers forming the Koshi system are – the Sun Kosi, the Indravati River, the Bhola Koshi, the Dudh Koshi, the Arun River, Barun River, and Tamur River. The Dudh Kosi river originates from the high-altitude areas of Mt Everest (8848) and the snow and glacier melt contributes significant portion of streamflow, especially during the dry season. The combined river flows through the Chatra Gorge in a southerly direction to emerge from the hills.
^Nepal. S, Krause. P, Fluegel, W-A. Fink. M, Fischer. C, (2014). "Understanding the hydrological system dynamics of a glaciated alpine catchment in the Himalayan region using the J2000 hydrological model.". Hydrological Processes28 (3): 1329–1344.