Kahayan River
Coordinates: 2°12′8″S 113°55′19″E / 2.20222°S 113.92194°E
The Kahayan river, or Great Dyak, is the largest river in Central Kalimantan, a province of Indonesia in Kalimantan - the Indonesian part of the island of Borneo. The provincial capital Palangkaraya lies on the river. The main inhabitants are Dyaks, who practice slash-and-burn rice cultivation and pan for gold on the upper reaches. The lower Kayahan flows through a rich and unusual environment of peat swamp forests, which has been severely degraded by an unsuccessful program to convert a large part of the area into rice paddies, compounded by legal and illegal forestry.
Central Kalimantan covers 153,800 km2, with 82% tropical rain forest and no more than 3% agricultural land. The northern part of the province is mountainous, the central area has flat and fertile tropical forests and the southern area is swampy. The forests provide rattan, resin and high-quality woods. The climate is hot and humid, typically around 30° most of the year. Annual rainfall is between 2800 and 3400 mm.
The Kahayan River originates in the northern mountains, then meanders for 600 km southward through the plains to the Java Sea. Tidal effects are felt 50 km - 80 km inland from the sea. A recent study found 28 species of fish throughout the river, 44 species in the Danau Sabuah lake and 12 species in the traditional fish ponds. The riparian wetlands were the main spawning areas. Fishermen are reporting declining yields due to problems with water quality.
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