The Kahayan River, or Great Dayak River, is the second largest river after the Barito River in Central Kalimantan, a province of Indonesia in Kalimantan – the Indonesian part of the island of Borneo. With a total length of 658 km and with a drainage basin of 15,500 km² in South Kalimantan, Indonesia. Mean annual discharge 1,178 m³/s. The provi…The Kahayan River, or Great Dayak River, is the second largest river after the Barito River in Central Kalimantan, a province of Indonesia in Kalimantan – the Indonesian part of the island of Borneo. With a total length of 658 km and with a drainage basin of 15,500 km² in South Kalimantan, Indonesia. Mean annual discharge 1,178 m³/s. The provincial capital Palangkaraya lies on the river. The main inhabitants are Dayaks, 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.