The river system throughout the country is so fast flowing that there is no possibility of using the rivers for transport of food or non-food items during a crisis.

The rivers (excepting the Manas and Lhobhrak) flow from the side of the Great Himalayas through the narrow defiles at the foot of the mountains, emerging into the Duar and eventually draining into the Brahmaputra River. 

There are no flood problems in the mountain regions but serious threats of floods exist in the plains, although the alluvium makes the soil there fertile.

The total length of rivers, with their tributaries, in Bhutan is about 7,200 km. The principal rivers are, from west to east: Amo Chu or Torsa, Wong Chu or Raidak, Mo Chu or Sankosh and Manas.