Sangu River

{{About|the river|other uses|Sangu (disambiguation)}}

{{Infobox river

| name = Sangu River

| image = Sangu River from Bandarban Town, 18 Nov, 2004.JPG

| image_caption = View of the Sangu River from Bandarban Town in 2004.

| subdivision_type1 = Country

| subdivision_name1 = Bangladesh

| source1_location = North Arakan Hills

| mouth_location = Bay of Bengal

| length_km = 270

| basin_size =

}}

The Sangu River is a river in Myanmar and Bangladesh. Its source is in the North Arakan Hills of Myanmar, located at 21°13´N 92°37´E. The Arakan Hills form the boundary between Arakan and the Chittagong Hill Tracts. It follows a northerly circuitous course in the hill tracts{{cite web |url=http://en.banglapedia.org/index.php?title=Sangu_River |title=Sangu River |website=Banglapedia}} and then enters Bangladesh near Remaikri, Thanchi Upazila, Bandarban District, from the east. It flows north through Thanchi, Rowangchhari and Bandarban Sadar Upazilas of Bandarban district. It then flows west through Satkania and Banshkhali Upazilas in Chittagong district and flows into the Bay of Bengal near Chittagong, at 22°6´N 91°51´E, or about {{convert|16.09|km}} south of the mouth of the Karnafuli River. The length of the river is {{convert|270|km}} of which {{convert|173|km}} are located within Bangladesh.

The major tributaries of the river are the Chand Khali Nadi and Dolukhal. The Chand Khali Nadi flows through the Patiya Plains, and the Dolukhal drains into the Satkania Plains. Another tributary is the Kumira Khali, which drains into the Kutubdia Channel. It has a connection with the Karnafuli River through the Chand Khali River.

Its estimated annual flow is 4.5 million acre-feet.

The Sangu River drainage basin has a total area of {{convert|3843|km2}}.{{cite journal |last1=Adnan |first1=Mohammed Sarfaraz Gani |last2=Dewan |first2=Ashraf |last3=Zannat |first3=Khatun E. |last4=Abdullah |first4=Abu Yousuf Md |title=The use of watershed geomorphic data in flash flood susceptibility zoning: a case study of the Karnaphuli and Sangu river basins of Bangladesh |journal=Natural Hazards |date=October 2019 |volume=99 |issue=1 |page=427 |doi=10.1007/s11069-019-03749-3}} The river drains Banshkhali, Satkania, and Patiya Upazilas.

In 1876, William Wilson Hunter described the river as shallow, but navigable year round by large cargo boats for a distance of {{convert|30|mi|order=flip}}. He also mentioned considerable river traffic at Bandarban.{{cite book |last=Hunter |first=William Wilson |author-link=William Wilson Hunter |title=A Statistical Account of Bengal|url=https://books.google.com/books?id=t8pCAAAAYAAJpg=PA27 |year=1876 |volume=VI |publisher=Trübner & Company |pages=27, 126}} A century later the Bangladesh District Gazetteer for the area said the river is not navigable late in the dry season.{{cite book |last1=Ishaq |first1=Muhammad |title=Bangladesh District Gazetteers: Chittagong Hill Tracts|year=1971 |publisher=Bangladesh Government Press |location=Dhaka |page=147}}

In its upper course there are two waterfalls and several rapids.{{cite book |last1=Harun Er Rashid |title=Geography of Bangladesh |year=1977 |location=Boulder, Colorado |publisher=Westview Press |isbn=0-89158-356-4 |page=82}}

The offshore Sangu Gas Field is located in the Bay of Bengal about {{convert|50|km}} southwest of Chittagong at a depth of {{convert|10|m}}.