The Kayan River is a river of

Borneo Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...

island, flowing in the

North Kalimantan North Kalimantan () is a Provinces of Indonesia, province of Indonesia. It is located on the northernmost of Kalimantan, the Indonesian part of the island of Borneo. North Kalimantan borders the Malaysian states of Sabah to the north and Sarawa ...

province of

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...

, about 1,600 km northeast of the capital

Jakarta Jakarta (; , Betawi language, Betawi: ''Jakartè''), officially the Special Capital Region of Jakarta (; ''DKI Jakarta'') and formerly known as Batavia, Dutch East Indies, Batavia until 1949, is the capital and largest city of Indonesia and ...

Course

The Kayan is a large river in

. It is one of the largest and most important rivers in the province of Kalimantan Utara. It rises in the northern part of the island's central mountain range in the ''Ukeng Mountains'' and flows in a large delta into the Sulawesi Sea below the provincial capital

Tanjung Selor Tanjung Selor is the capital of both the North Kalimantan province in Indonesia, and of the Bulungan Regency. It is among those provincial capitals in Indonesia that as of 2025 does not yet have city status, together with Mamuju in West Sula ...

Geography and hydrology

The Kayan River rises on Mount Ukeng, passing

city, and discharges into the Sulawesi Sea, with a total length of about and a basin size of , forming a wide area at the upstream and narrower in the center until downstream. The Kayan River is named after the Kayan Dayak tribe. Its headwaters originate in the ''Ukeng Mountains'' at an altitude of about above sea level. The river cuts through mountainous areas in a south-east, east-east and then north-east direction with high gradient rapids. It flows over

for more than 70 km through coral and limestone hills to the town. Its banks are typically lined with nipas, with some coconut trees. Below the town it eventually ends in the wide ''Kayan Delta'' in the Sulawesi Sea. The average width of its lower reaches is around . At the mouth it rises between . Depth is generally around . Tanjung Selor (about 60 km from the sea) is navigable by larger boats. Higher up, it can be navigated by small boats, and the more rapids only by boat. The catchment receives between 3,500 and 4,000 mm of

rainfall Rain is a form of precipitation where water droplets that have condensed from atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. ...

per year ('' Köppen's climate classification'' ''Af'' type).

Delta

The tidal delta covers an area of about 3,000 square kilometres. The deltas of the Kayan, ''Sekatak'', Sesayap and Sembakung rivers form a continuous ‘delta complex’ ( Tarakan, the largest city in North Kalimantan Province, is located on Tarakan Island, opposite the deltas).

Discharge

Tributaries

Kayan has 12 major tributaries. The Bahau is the largest of these. The main tributaries from the mouth:

Ecology and economy

The Bulungan district of the Kayan River in northern Kalimantan is characterised by rich biodiversity and includes ecosystems such as lowland

tropical rainforest Tropical rainforests are dense and warm rainforests with high rainfall typically found between 10° north and south of the Equator. They are a subset of the tropical forest biome that occurs roughly within the 28° latitudes (in the torrid zo ...

montane forest Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

, peat swamps, mangroves and

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

. The ''Kayan Delta'' is home to at least 6 native

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

species ( Rhizophora apiculata, Osbornia octodonta, Lumnitzera littorea, Avicennia sp., Rhizophora sp., Sonneratia sp.). The interior of the delta is dominated by nipah (

Nypa fruticans ''Nypa fruticans'', commonly known as the nipa palm (or simply nipa, from ) or mangrove palm, is a species of palm native to the coastlines and estuarine habitats of the Indian and Pacific Oceans. It is the only palm considered adapted to the ...

), while parts of the delta are home to mixed freshwater and ''saltwater ecosystems''. The Kayan is vital for communities living along the river and in its delta, as they depend on it for freshwater, fisheries and agriculture. Dayak people living along the river depend on farming,

agriculture Agriculture encompasses crop and livestock production, aquaculture, and forestry for food and non-food products. Agriculture was a key factor in the rise of sedentary human civilization, whereby farming of domesticated species created ...

and

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

. Their vast rice fields have been cultivated for generations. Today, the Kayan watershed has become a centre for investment. Large areas have been converted into

palm oil Palm oil is an edible vegetable oil derived from the mesocarp (reddish pulp) of the fruit of oil palms. The oil is used in food manufacturing, in beauty products, and as biofuel. Palm oil accounted for about 36% of global oils produced from o ...

and timber plantations, mining areas, fish ponds and agricultural land.

Uses

Transportation

For ages, the Kayan River served as the main transportation route for the inhabitants of Malinau and Bulungan Regency to reach the inland region of

Malinau Regency Malinau Regency is a Regencies of Indonesia, regency of North Kalimantan Province in Indonesia. It was created on 4 October 1999 from the western districts of Bulungan Regency. The administrative centre is the town of Malinau Kota, Malinau. The r ...

using traditional boats or out of the Bulungan Regency using speed boats, while downstream there are some river ports for passengers and goods, such as Port of Kayan and Port of Pesawan.

Fishery and agriculture

The people along the Kayan River utilize the water for agriculture and fishery, either by traditional fishing or netting, especially in the upstream area, whereas about 30,000 hectares of land of the Delta Kayan is used as a Food Estate area, for fish ponds and farmlands.

Hydroelectricity

The Kayan River is used to produce

hydroelectricity Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...

using some power plants, such as the Diesel-powered one in the village of Long Nawang, Kayan Hulu subdistrict. The river can produce around 900 megawatts (MW). There is also a dam for the hydroelectric power plant in the village of Desa Long Peso, Peso sub-district, Bulungan Regency.

Villages along the Kayan River

Antutan

Antutan village (Bahasa Indonesia – ''Desa Antutan'') is one of the many villages situated along the Kayan River. The population of the village consists of Dayak sub-tribes: the Kenyah and the Kayan as well as the Tidung and the Bulungan. There are several main sources of income in this village, such as paddy plantation, farming, fishing, and crafts selling. The majority of the villagers heavily depended on the paddy rice plantation to make a living. However, some are also public servants, for example, teachers, nurses, soldiers, and police personnel.

References

{{Rivers of Kalimantan Rivers of North Kalimantan Kayan basin