The Barak River flows through the states of Manipur, Nagaland, Mizoram and Assam in India. Further it enters Bangladesh where it bifurcates into the Surma river and the Kushiyara river which converges again to become the Meghna river before forming the Ganges Delta with the Ganga and the Brahmaputra rivers and flowing into the Bay of Bengal. Of its length is in India, on the Indo–Bangladesh border and the rest is in Bangladesh. The upper part of its navigable part is in India — between Lakhipur and Bhanga, declared as National Waterway 6, (NW-6) since the year 2016. It drains a basin of , of which lies in India, 1.38% (rounded) of the country. The water and banks host or are visited by a wide variety of flora and fauna. The principal tributaries are all in India: the Sonai (or Tuirial), the Jiri, the Tlawng (or Dhaleswari, or Katakal), the Jatinga, the Longai and the Madhura. Tipaimukh Dam is a proposed dam on the river itself. Sources From its source at Liyai Kullen Village in Manipur state where most people are of the Poumai Naga tribe, the river is known as Vourei. Near its source, the river receives streams such as the Vehrei originating from Phuba Village, the Gumti, Howrah, Kagni, Senai Buri, Hari Mangal, Kakrai, Kurulia, Balujhuri, Shonaichhari and Durduria. It flows west in Manipur, and borders Nagaland, then southwest to Assam where it leaves India and enters Bangladesh at Bhanga Bazar. Main tributaries The local rainfall run off of the valley along with that of adjacent hilly areas flows through river Barak and its various tributaries and is drained out to Bangladesh. The Katakhal, Jiri, Chiri, Modhura, Longai, Sonai, Rukni and Singla are the main tributaries of the valley. The tributaries are mainly rain-fed and cause flood problems when precipitation occurs. The Barak sub-basin drains areas in India, Bangladesh and Burma. The drainage area lying in India is 41723 km2 which is nearly 1.38% of the total geographical area of the country. It is on the north by the Barail range separating it from the Brahmaputra sub-basin, on the east by the Na Lushai hills and on the south and west by Bangladesh. The sub-basin lies in the States of Meghalaya, Manipur, Mizoram, Assam, Tripura and Nagaland. In Manipur, in its flow south-west to Tipaimukh, it is joined by the Tuivai, and then flows northward to Jirimukh where