Rokan River
Hydrology
The river originates in the Barisan Mountains in the west, and drains northeast-ward along Rokan Hulu Regency and Rokan Hilir Regency with estuarine located near the port town of Bagansiapiapi draining the water to Malacca Strait.
Tributaries include the Rokan-kiri River, Rokan-kanan River, Kumu River.
Geography
The river flows in the central area of Sumatra with predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification). The annual average temperature in the area is 23 °C. The warmest month is March, when the average temperature is around 24 °C, and the coldest is January, at 22 °C. The average annual rainfall is 3766 mm. The wettest month is November, with an average of 336 mm rainfall, and the driest is July, with 113 mm rainfall.