Kapuas River

This article is about the river in western Borneo. For the river in southern Borneo, see Kapuas River (Barito River).

Kapuas
Aerial view of Kapuas river
Location
Country	Indonesia
Physical characteristics
Source
• location	Mount Raya at Müller Mountain Range
• elevation	2,278 m (7,474 ft)
Mouth
• location	South China Sea
• coordinates	0°4′0″S 109°10′59″E
• elevation	0 m (0 ft)
Length	1,143 km (710 mi)[1]
Basin size	98,749 km^2 (38,127 sq mi)[2]
Depth
• maximum	40 m (130 ft)[1] to 50 m (160 ft)[2]
Discharge
• location	Kapuas Delta, South China Sea, Indonesia, Borneo (Kalimantan)
• average	(Period: 2016–2020)7,803 m^3/s (275,600 cu ft/s)[3] (Period: 2003–2016)6,012 m^3/s (212,300 cu ft/s)[4] (Period: 1971–2000)6,260.1 m^3/s (221,070 cu ft/s)[5] (5,500 m^3/s (190,000 cu ft/s) to 6,500 m^3/s (230,000 cu ft/s)[2][6][7]
• minimum	2,000 m^3/s (71,000 cu ft/s)–3,000 m^3/s (110,000 cu ft/s)[2][1]
• maximum	8,900 m^3/s (310,000 cu ft/s)–9,000 m^3/s (320,000 cu ft/s)[2][1] 22,000 m^3/s (780,000 cu ft/s)
Discharge
• location	Sanggau (285 km upstream of mouth; Basin size: 77,000 km^2 (30,000 sq mi)
• average	(Period: 2000–2015)5,900 m^3/s (210,000 cu ft/s)[2] (Period: 2013–2015)5,220 m^3/s (184,000 cu ft/s)[1] (Period: 1971–2000)5,069.3 m^3/s (179,020 cu ft/s)[5]
• minimum	1,117 m^3/s (39,400 cu ft/s)[1]
• maximum	9,394 m^3/s (331,700 cu ft/s)[1]
Discharge
• location	Putussibau (902 km upstream of mouth; Basin size: 9,800 km^2 (3,800 sq mi)
• average	(Period: 1971–2000)886.3 m^3/s (31,300 cu ft/s)[5] 674 m^3/s (23,800 cu ft/s)
Basin features
River system	Kapuas basin (DAS320470)[8]
Tributaries
• left	Bungan, Keriau, Manday, Bunut, Embau, Silat, Melawi, Tempunak, Sepauk, Sekadau
• right	Mandalam, Sibau, Awin, Palin, Embaloh, Tawang, Ketungau, Belitang, Sekayam, Tayan, Landak

Kapuas

main mouth

class=notpageimage|

Kapuas River in Kalimantan

A 1945 map showing the two Kapuas rivers of Borneo (Kapoeas on the map)

The Kapuas River (Old Indonesian spelling: Kapoeas River) is a river in the Indonesian part of Borneo island, at the geographic center of Maritime Southeast Asia. At 1,143 kilometers (710 mi) in length, it is the longest river in the island of Borneo and the longest river in Indonesia^[9][10] and one of the world's longest island rivers.^[11] It originates in the Müller mountain range at the center of the island and flows west into the South China Sea creating an extended marshy delta. The delta is located west-southwest of Pontianak, the capital of the West Kalimantan province.^[12] This Kapuas River should be distinguished from another Kapuas River, which starts on the other side of the same mountain range in central Borneo but flows to the south, merging with the Barito River and discharging into the Java Sea.

Geography and hydrology

The river is 1,143 km (710 mi) long and up to 700 m (0.43 mi) wide at its delta; ~99,000 km² (38,000 sq mi)^[2] the river basin covers more than 67% of West Kalimantan.^[10][13] The average annual rainfall in the catchment area is 3,666 mm. The average runoff is around 2,339 mm.^[14] The discharge rate varies through the year, averaging around 5,600–7,800 m³/s (200,000–280,000 cu ft/s)^[15][16] at the delta and 2,000 m³/s (71,000 cu ft/s) upstream, at the confluence of the Tawang. The discharge peaks during the rainy seasons in April and November, during which the water level may rise by 10–12 m (33–39 ft) overnight, overflowing river banks and flooding the nearby areas.^[10][17][18]

The river originates near the center of Borneo, south of the Indonesian-Malaysian border, in the joint between the western slope of the Müller Mountain Range, which runs through the island center, and the southern slope of the Upper Kapuas Range (Indonesian: Kapuas Hulu), which is located more to the west. For about 165 km (103 mi) it flows through a mountainous terrain and then descends to a marshy plain.^[17] There, the elevation decreases by only 50 meters (160 ft) over 900 km (560 mi) from Putussibau to the river delta.^[19] About 350 km (220 mi) from the source, near the northern shore of the river, lies a system of Kapuas Lakes which are connected to the river by numerous channels. These lakes are Bekuan (area 1,268 hectares), Belida (600 ha), Genali (2,000 ha), Keleka Tangai (756 ha), Luar (5,208 ha), Pengembung (1,548 ha), Sambor (673 ha), Sekawi (672 ha), Sentarum (2,324 ha), Sependan (604 ha), Seriang (1,412) Sumbai (800 ha), Sumpa (664) and Tekenang (1,564 ha).^[20] When the monthly precipitation exceeds about 300 mm (12 in), the river overflows its banks, diverting much of its waters to the lakes at a rate of up to 1,000 m³/s (35,000 cu ft/s), and forming a single volume of water with them. This outflow prevents massive flooding of the lower reaches of the river; it also promotes fish migration from the river to the lakes for spawning, but drives birds away from the lakes.^[18]

The river discharges into the South China Sea creating a marshy delta, which spreads both inland and into the sea, with the silt deposits extending up to 50–60 km (31–37 mi) from the Borneo coast.^[19] The delta is located west-southwest of Pontianak, the capital of West Kalimantan province, which lies at the equator.^[21] The delta has five arms, of which the northernmost one is the widest, and is therefore called the Big Kapuas (Indonesian: Kapuas Besar). The largest tributary is the Melawi River, which occurs to the left near the city of Sintang, about 465 km from the mouth. Other major tributaries are the Landak, Kubu, Punggur, and Sekayam rivers.^[21]

Tributaries

The main tributaries from the mouth:^[5]

Left tributary	Right tributary	Length (km)	Basin size (km^2)	Average discharge (m^3/s)
Kapuas		1,143	98,749.1	6,260.1
	Landak	178	8,461.5	471.9
	Sê Lamboe		380.2	20.1
	Tayan		2,089.2	107.5
Emboewan			455.1	24.1
	Sekayam	221	5,162.6	305.3
	Kedukul		368.1	17.1
Sekadau		117	2,672.2	136.8
	Aja		395.2	18.2
Sepauk			1,137.9	53.5
	Belitang		2,584	128.8
Tempunak			1,092.4	50.2
Melawi		471	22,585.8	1,243.4
	Ketungau	186	5,496.2	320.8
Silat			1,374	78.5
Seberuang			481	28
	Kenapai		292.8	17.3
	Tawang		3,826	264.8
Suhaid			340	23.6
Embau			769.3	51.1
Boyan			330.6	24.6
Bunut			3,403.3	267.5
	Embaloh	95	3,469.8	289.5
	Palin		1,155.5	99.8
	Awin		509.3	44.4
Manday			2,896.2	251.6
	Sibau	90	1,687.7	150.3
	Mandalam	30	1,771.9	157.1
Keriau			1,635.8	138.4
	Goeng		275.1	24.3
Lapung			199.4	17.4
Bungan		50	1,019.7	87.7
Tanjan			327.7	28.7
Tahoem			302.8	26.3

Climate

The climate is warm and very humid, with the average annual precipitation ranging from year to year between 2,863 to 5,517 mm (112.7–217.2 in), and the number of rainy days between 120 and 309; the largest precipitation was observed in 1976 (120 rainy days) and the wettest in 1988, with only 184 rainy days.^[13] The temperature is rather stable with a typical minimum of 24 °C (75 °F) and a maximum of 32 °C (90 °F) throughout the whole year.^[22]

Flora and fauna

A bridge on the outskirts of Pontianak

In the upper and middle reaches, the river flows through dense tropical forests; the rich flora and fauna are the subject of international research.^[13] Discoveries of new species are frequent, such as the Kapuas mud snake (Enhydris gyii), which was discovered in 2003–2005 by German and American herpetologists. This species is remarkable in that it can spontaneously change its skin color, similar to the chameleon.^[23][24]

Otters and crocodiles are common in the Kapuas River, but frogs are nearly absent.^[25] Agile gibbons (Hylobates agilis), Müller's Bornean gibbons (Hylobates muelleri), Prevost's squirrels (Callosciurus prevostii), and treeshrews inhabit the trees above the river.^[26]

There are two national parks on the river banks, Betung Kerihun with an area of 8,000 km², and Danau Sentarum (an area of 1,320 km²), the latter includes the Kapuas Lakes.^[13][27]

Fish

The super red arowana, either considered a variant of the Asian arowana or its own species, is only found in Kapuas

About 300 species of fish have been identified in the river basin, of which 234 are of high economic value.^[9] There are more fish species than any other river basin in Indonesia.^[28] They belong to 120 genera and 40 families with the two major groups being cyprinids and catfish. More than 30% of the species originate from the sea and inhabit the delta areas.^[29] Among the economically important species are food fish such as Pangasius catfish, giant gourami, kissing gourami, snakeheads, and large cyprinids such as Tor mahseers and barbs such as Leptobarbus and Puntioplites, and species for the aquarium trade such as the super red arowana and various rasboras.^[28] Because of overfishing and habitat degradation, several species are threatened. Among these endangered species are the arowana and white-edge freshwater whipray, and the wallago catfish, which formerly migrated in large schools up and down the Kapuas River.^[28]

Part of the high species diversity in the Kapuas is related to the many different habitats in the river basin. In the headwaters are fast-flowing highland streams, typically dominated by small loaches, and small —often acidic (blackwater)— forest streams and peat swamps with species such as the tiny Sundadanio rasboras, Sphaerichthys gouramis, and macropodusine gouramis.^[28] The main river itself also includes several habitats, ranging from the nearshore to open waters. In the deepest sections, no light exists and in one species, Lepidocephalus spectrum, this has resulted in a complete reduction of both eyes and pigmentation (similar to cavefish).^[30]

Female Hemirhamphodon pogonognathus, about 4 cm (1.6 in) long

Owing to the warm climate and abundance of food, most fishes breed all through the year with only a few species like fire eel (Mastacembelus erythrotaenia) having certain reproductive periods. The number of individuals per species is relatively low.^{[clarification needed]} The large variety of species may be explained by the fact that some 6,000 years ago, the Kapuas River, as a tributary of the Sunda River, was connected to other tributary rivers of South Sumatra, Java, and the Malay Peninsula. Apart from fish, there are numerous crabs, prawns (such as the giant freshwater prawn Macrobrachium rosenbergii),^[31] water striders, and other aquatic insects.^[32] The rich flora and fauna result in very complex food chains, with fishes consuming foods ranging from fruits to other fish. For example, Hemirhamphodon pogonognathus feeds exclusively on terrestrial insects. Abundant fruits and seeds enter the river after falling from large trees that bend over its waters.^[33] The feeding habits of the fish in the Kapuas River are distributed as follows: 54% are omnivores; 36% are carnivorous and eat other fish (14%), insects (5%), and mixed small forest animals (17%). The remaining 10% are herbivorous, with 4% of them specialising in algae.^[25]

Transport and economic value

The Kapuas River is the major waterway connecting the center of the island with its western coast. The large river width and depth (up to 27 meters^[11]) support intensive cargo and passenger shipping over most of the river length. Ships with a draft of up to 3 meters can navigate up to Sintang, 465 km from the mouth, and those with a draft of up to 2 meters can reach the town of Putussibau (902 km from the mouth). Logging and rafting of timber occur all along the river. Fishing is also common, especially at the Kapuas Lakes and near the river delta.^[17][34] The Tayan Bridge which opened in 2016, crosses over the river and is the longest bridge in Kalimantan.^[35] Another major bridge over the area is the Kapuas I Bridge. In 2022, the local government decided to build a newer bridge to accommodate increased traffic in commuters and goods, located to be in parallel with the existing bridge.^[36]

See also

• Geography of Indonesia
• List of drainage basins of Indonesia
• Mae Klong
• Chao Phraya River

References

1. David Fernando, Munõz Pauta (2017). Tidal influence on the discharge distribution at two junctions of the Kapuas River (West Kalimantan, Indonesia) (Thesis).
2. Karl, Kästner (2019). Multi-Scale Monitoring and Modelling of the Kapuas River Delta. doi:10.18174/468716. ISBN 978-94-6343-411-9.
3. Delphine, Dobler; Elodie, Martinez; Rinny, Rahmania; Budhi Gunadharma, Gautama; A. Riza, Farhan (2021). "Floating marine debris along Indonesian coasts – An atlas of strandings based on Lagrangian modelling" (PDF). Archived (PDF) from the original on 7 January 2022. Retrieved 7 January 2022.
4. Ting-Hsuan, Huang; Chen-Tung, Arthur Chen; Hsiao-Chun, Tseng; Jiann-Yuh, Lou; Shu Lun, Wang; Liyang, Yang; Selvaraj, Kandasamy; Xuelu, Gao; Jough-Tai, Wang; Edvin, Aldrian; G.S., Jacinto; Gusti Z., Anshari; Penjai, Sompongchaiyakul; B.J., Wang (May 2017). "Riverine carbon fluxes to the South China Sea: Riverine carbon fluxes to the SCS". Journal of Geophysical Research: Biogeosciences. 122 (5): 1239–1259. doi:10.1002/2016JG003701. S2CID 135024272.
5. "Kalimantan-Borneo".
6. "Indonesia-Integrated Swamps Development Project" (PDF). November 1992. Archived (PDF) from the original on 5 February 2022. Retrieved 5 February 2022.
7. Radhika, Radhika; Firmansyah, Rendy; Hatmoko, Waluyo (November 2017). "Computation of surface water availability in Indonesia based on satellite data". Jurnal Sumber Daya Air. 13 (2): 115–130. doi:10.32679/jsda.v13i2.206. Archived from the original on 14 February 2022. Retrieved 10 April 2023.
8. Hukum Online. "Keputusan Menteri Kehutanan No. SK.511/MENHUT-V/2011" (in Indonesian).
9. Göltenboth, Friedhelm (2006) Ecology of insular Southeast Asia: the Indonesian Archipelago, Elsevier, ISBN 0-444-52739-7 p. 157
10. MacKinnon, p. 133
11. Noni Arnee (21 August 2009). "Pesona di Bawah Garis Katulistiwa" (in Indonesian). Suara Merdeka. Archived from the original on 8 March 2012. Retrieved 22 March 2010.
12. Kapuas River Archived 26 April 2015 at the Wayback Machine, Encyclopædia Britannica on-line
13. "Betung Kerihun National Park (Transborder Rainforest Heritage of Borneo)". UNESCO World Heritage Centre. 2 February 2004. Archived from the original on 24 December 2019. Retrieved 26 December 2019.
14. Supplement of Lehmann, Fanny; Vishwakarma, Bramha Dutt; Bamber, Jonathan (2021). "How well are we able to close the water budget at the global scale?" (PDF). Hydrology and Earth System Sciences. 26: 35–54. doi:10.5194/hess-26-35-2022. Archived (PDF) from the original on 4 January 2022. Retrieved 21 February 2022.
15. Etko, Kuusisto (26 August 2004). "WORLD WATER RESOURCES AND PROBLEMS" (PDF). Archived (PDF) from the original on 21 February 2022. Retrieved 21 February 2022.
16. Delphine, Dobler; Elodie, Martinez; Rinny, Rahmania; Budhi Gunadharma, Gautama; A. Riza, Farhan (2021). "Floating marine debris along Indonesian coasts – An atlas of strandings based on Lagrangian modelling" (PDF). Archived (PDF) from the original on 7 January 2022. Retrieved 7 January 2022.
17. Great Soviet Encyclopedia. Vol. 11. Moscow. 1969–1978. p. 367. reduced electronic version Archived 24 March 2012 at the Wayback Machine
18. MacKinnon, p. 160
19. MacKinnon, p. 131
20. MacKinnon, pp. 152, 159
21. "South Kalimantan". Archived from the original on 3 March 2016. Retrieved 4 November 2010.
22. Pontianak, Borneo Climate Archived 10 September 2017 at the Wayback Machine. ClimaTemps.com
23. Murphy, John C.; Voris, Harold K.; Auliya, Mark (2005). "A new species of Enhydris (Serpentes: Colubridae: Homalopsinae) from the Kapuas river system, West Kalimantan, Indonesia" (PDF). The Raffles Bulletin of Zoology. 53 (2): 271–275. Archived (PDF) from the original on 17 March 2009. Retrieved 4 November 2010.
24. "Snake displays changing colours". BBC News. 26 June 2006. Archived from the original on 19 March 2018. Retrieved 9 January 2007.
25. MacKinnon, p. 162
26. MacKinnon, pp. 52–53
27. Yuliani, Elizabeth Linda; Indriatmoko, Yayan; Ernawati, Seselia; Prasetyo, Leon Budi; Zul MS (October 2007). "Promoting Good Governance in Danau Sentarum National Park under Decentralization" (PDF). Archived from the original (PDF) on 8 October 2012. Retrieved 4 November 2010.
28. Roberts, T.R. (1989). "The freshwater fishes of Western Borneo (Kalimantan Barat, Indonesia)". Memoirs of the California Academy of Sciences. 14: 1–210.
29. MacKinnon, p. 143
30. Deein, Gridsada; Tangjitjaroen, Weerapongse; Page, Lawrence M. (2014). "A revision of the spirit loaches, genus Lepidocephalus (Cypriniformes, Cobitidae)". Zootaxa. 3779 (3): 341–352. doi:10.11646/zootaxa.3779.3.2. PMID 24871728.
31. Samuel, Samuel; Aida, Siti Nurul. "AKTIVITAS PENANGKAPAN DAN DISTRIBUSI UDANG GALAH (Macrobrachium rosenbergii) DI DAERAH ALIRAN SUNGAI KAPUAS, KALIMANTAN BARAT". researchgate.net. Jurnal Penelitian Perikanan Indonesia. Retrieved 7 September 2024.
32. MacKinnon, p. 132
33. MacKinnon, p. 161
34. MacKinnon, p. 457
35. "Jembatan Terpanjang di Kalimantan Ini Tahan 100 Tahun". Tempo (in Indonesian). 23 March 2016. Archived from the original on 14 April 2016. Retrieved 4 July 2017.
36. Caratri, Endah (14 July 2022). "Duplikasi Jembatan Kapuas I Mulai Dibangun Kementerian PUPR – Berita Daerah". Archived from the original on 10 April 2023. Retrieved 14 July 2022.

Bibliography

• MacKinnon, Kathy (1996) The ecology of Kalimantan, Oxford University Press. ISBN 0-945971-73-7

0.2660°S 109.8754°E / -0.2660; 109.8754