Pho Chhu
The Pho Chhu is one of the major rivers of Bhutan, which tracks its source to Gasa District on the border between Bhutan and Tibet. It joins with the Mo Chhu at the confluence below Punakha Dzong, the winter residence of Dratshang Lhentshog. Upon Dang Chhu joining below Wangdue Dzong, the trio flows as Puna Tsang Chhu and finally empties into the Brahmaputra, upon being joined by several tributaries on its course through the valley of Assam. Its source is susceptible to glaciers which even destroyed a part of Punakha Dzong.