Kali Gandaki valley

The river flows southward through a steep gorge known as the Kali Gandaki Gorge, or Andha Galchi, between the mountains Dhaulagiri (8167 m) to the west and Annapurna (8091 m) to the east. If one measures the depth of a canyon by the difference between the river height and the heights of the highest peaks on either side, the Gorge is the world's deepest. The portion of the river between the Dhaulagiri and Annapurna massifs is at an elevation of between 1300 metres and 2600 metres[1], 5500 to 6800 metres lower than the two peaks.
South of the gorge the river is joined by Rahught Khola at Galeshwor, Myagdi Khola at Beni, Modi Khola near Kushma and Badigaad at Rudrabeni. The river then takes a right-angle turn and runs east. The largest hydroelectricity project in Nepal is located along this stretch of the river. Kali Gandaki is joined by a major tributary, Trishuli, at Devghat, just as the river exits the foothills of the Himalayas into the southern plains of Nepal. From Devghat, the river flows southwest and is known as Narayani or Sapt Gandaki. The river later curves back towards the southeast as it enters India. The river flows southeast across the Gangetic plain of Bihar state, eventually merging with the Ganges near at Hajipur, or Patna.