| Barumun Sungai Barumun, Aek Baroemoen | |
|---|---|
 | |
  Location of river mouth Show map of Sumatra Barumun River (Indonesia) Show map of Indonesia | |
| Location | |
| Country | Indonesia |
| Physical characteristics | |
| Source | |
| • location | Siraisan, Padang Lawas, North Sumatra |
| • elevation | 1,500 m (4,900 ft) |
| Mouth | |
• location | Malacca Strait |
• elevation | 0 m (0 ft) |
| Length | 440 km (270 mi) |
| Basin size | 13,383.86 km2 (5,167.54 sq mi)[1] |
| Discharge | |
| • location | Near mouth |
| • average | (Period: 2003–2015)544.1 m3/s (19,210 cu ft/s)[2](Period: 2006–2010)824.45 m3/s (29,115 cu ft/s) |
| Basin features | |
| River system | Barumun River |
Barumun River is a Sumatran river that begins in Siraisan,Padang Lawas Regency in the southeasternNorth Sumatra,Indonesia, about 1,200 km northwest of the capitalJakarta.[3][4]
The river flows northward throughNorth Padang Lawas,South andLabuhan Batu Regency before reaching Sumatra's east coast with its estuary inMalacca Strait.
The largest city on the Barumun isKotapinang, in South Labuhan Batu Regency, with a population of 68,943 people in mid 2023. While the largest city in the Barumun River basin isRantau Prapat (in Labuhan Batu Regency), which is located on theBilah tributary with a population of 177,912 people in mid 2023. It is the largest river in Sumatra with a length of about 440 km.
Tributaries include theBilah, Kanan, Batang Pane, Sihapas and Aek Sangkilon. All tributaries of Barumun River are sourced from mountainous areas alongBarisan Mountains.
The river flows in the northern area of Sumatra with predominantlytropical rainforest climate (designated asAf in the Köppen-Geiger climate classification).[5] The annual average temperature in the area is 23 °C. The warmest month is May, when the average temperature is around 25 °C, and the coldest is January, at 22 °C.[6] The average annual rainfall is 2801 mm. The wettest month is November, with an average of 381 mm rainfall, and the driest is March, with 126 mm rainfall.[7]