(Period of data: 2009–2013)720m3/s (25,000cuft/s)[1]
The Siak River flowing through the town of Perawang. Photo taken on the Maredan bridge.
The Siak is a major river of Riau province, in the east of Sumatra, Indonesia, about 1000km northwest of the capital Jakarta.[2] Approximately 370 kilometres in length, the Siak is a blackwater river which owes its brown color to dissolved organic matter (DOM) leached from surrounding, heavily disturbed peat soils; it is heavily polluted, notably by the petroleum industry. It flows through the city of Pekanbaru and other large towns such as Siak Sri Indrapura before emptying into the Strait of Malacca.[3]
Geography
The river flows through the central region of Sumatra with a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).[4] The annual average temperature in the area is 23°C. The warmest month is October, when the average temperature is around 25°C, and the coldest is January, at 22°C.[5] The average annual rainfall is 2673mm. The wettest month is November, with an average of 418mm rainfall, and the driest is January, with 106mm rainfall.[6]
