Cagayan River

Cagayan River; Rio Grande de Cagayan
	The river as it passes through Jones in Isabela
	Drainage area of the river and its tributaries in northeastern Luzon
	Cagayan River mouth Cagayan River (Philippines)
Native name	Bannag
Location
Country	Philippines
Region	Cagayan Valley
Province	Cagayan; Isabela; Nueva Vizcaya; Quirino;
Physical characteristics
Source	Caraballo Mountains
• coordinates	16°11′08″N 121°08′39″E
• elevation	1,524 m (5,000 ft)
Mouth	Babuyan Channel
• location	Aparri, Cagayan
• coordinates	18°22′N 121°37′E
• elevation	0 m (0 ft)
Length	505 km (314 mi)[1]
Basin size	27,753 km2 (10,715 sq mi)[2]
Basin features
Tributaries
• left	Chico River; Magat River;
• right	Ilagan River; Pinacanauan River;

The Cagayan River, also known as the Rio Grande de Cagayan, is the longest river[3][1] and the largest river by discharge volume of water in the Philippines. It has a total length of approximately 505 kilometres (314 mi) and a drainage basin covering 27,753 square kilometres (10,715 sq mi).[2] It is located in the Cagayan Valley region in northeastern part of Luzon Island and traverses the provinces of Nueva Vizcaya, Quirino, Isabela and Cagayan.

Topography

X

Topography of the Cagayan Valley

(marked by an X)

in northeastern Luzon.

The river's headwaters are at the Caraballo Mountains of the Central Luzon at an elevation of approximately 1,524 metres (5,000 ft). The river flows north for some 505 kilometres (314 mi)[4] to its mouth at the Babuyan Channel near the town of Aparri, Cagayan. The river drops rapidly to 91 metres (299 ft) above sea level some 227 kilometres (141 mi) from the river mouth. Its principal tributaries are the Pinacanauan, Chico, Siffu, Mallig, Magat and Ilagan Rivers.

Magat River, is the largest tributary with an estimated annual discharge of 9,808 million cubic meters. It lies in the southwestern portion of the basin, stretching approximately 150 kilometres (93 mi) from Nueva Vizcaya down to its confluence with Cagayan River about 55 kilometres (34 mi) from the river mouth.

Both Magat and Chico Rivers have extensive drainage areas which comprise about 1/3 of the whole basin.

The Ilagan River originates from the western slopes of the Sierra Madre and drains the eastern central portion of the Cagayan River basin with an estimated yearly discharge of 9,455 million cubic meters. It flows westward and joins the Cagayan River at Ilagan, Isabela, 200 kilometres (120 mi) from the mouth.

The Siffu-Mallig system lies on the slope of the Central Cordillera ranges flowing almost parallel to the Magat River. Marshes and swamps are found in some parts of its lower reaches.

Cagayan River and its tributaries have deposited sediments of Tertiary and Quaternary origin, mostly limestone sands and clays, throughout the relatively flat Cagayan Valley which is surrounded by the Cordillera Mountains in the west, Sierra Madre in the east and the Caraballo Mountains in the south.

The river has a drainage area of about 27,300 square kilometres (10,500 sq mi). in the provinces of Apayao, Aurora, Cagayan, Ifugao, Isabela, Kalinga, Mountain Province, Nueva Vizcaya, and Quirino.

The estimated annual discharge is 53,943 million cubic meters[5] with a groundwater reserve of 47,895 million cubic meters.

Flooding

Upstream Cagayan River at Lamut bridge in Dupax del Norte

The Cagayan River and its tributaries are subject to extensive flooding during the monsoon season in Southeast Asia from May to October.

The average annual rainfall in 1,000 millimetres (39 in) in the northern part and 3,000 millimetres (120 in) in the southern mountains where the river's headwaters lie. Water from the mountains flow down very slowly because of surface retention over the extensive flood plain, the gorges in the gently-sloping mountains and the meandering course of the river.

The inundation of the Cagayan River and its tributaries have caused great loss of life and property and substantial losses to the local and national economies. The Philippine government has established several flood warning stations along the river. Experts are specifically monitoring the lower reaches from Tuguegarao to Aparri and the alluvial plain from Ilagan to Tumauini, Isabela.

Flora and fauna

The Cagayan River passes through one of the few remaining primary forests in the Philippines.

It supports the lives of numerous endemic and endangered species, like the Luzon bleeding-heart pigeon (Gallicolumba luzonica), Philippine eagle (Pithecophaga jefferyi) and a rare riverine fish, locally called ludong (Cestreaus plicatilis).

The ludong spawns in Cagayan River's upper reaches in Jones, Isabela. In late October until mid-November, the fish travel down the river to release their eggs at the river mouth near Aparri.

In February, ludong fry by the millions are again caught in fine nets as these travel upstream.

Due to the dwindling number of ludong caught yearly, local governments have imposed a ban on catching the fish and its fry, but the ban has failed.

People

The river traverses four provinces: Nueva Vizcaya, Quirino, Isabela and Cagayan. These provinces have an approximate population of two million people, mostly farmers and indigenous tribesmen.

The Ibanag people derive their tribe's name from Cagayan River's ancient name, Bannag. The Gaddang tribe lived in the upper reaches of the Cagayan River and its tributaries.

An old drawn geographical description of Cagayan River (Juan Luis de Acosta, Circa 1720)

Economic importance

The river drains a fertile valley that produces a variety of crops, including rice, corn, bananas, coconut, citrus and tobacco.

There are dams in two of the river's tributaries, the Magat and Chico Rivers, and there are also several mining concessions in the mineral-rich Cordillera Mountains near the headwaters of the two tributary rivers.

The provincial governments along the river have also developed tourism programs that offer activities on the river, particularly whitewater rafting.

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gollark: I turned it off for now.

gollark: This is a highly testing test.

gollark: Apiaristic bee.

gollark: Wow, that WORKED?

References

Kenneth Kimutai too (24 July 2018). "Longest Rivers In The Philippines". worldatlas.com. WorldAtlas. Retrieved 9 September 2019.
Vicente B. Tuddao Jr. (September 21, 2011). "Water Quality Management in the Context of Basin Management: Water Quality, River Basin Management and Governance Dynamics in the Philippines" (PDF). www.wepa-db.net. Department of Environment and Natural Resources. Retrieved 5 April 2017.
"Taming the Cagayan River, Inquirer.net". Retrieved 20 May 2017.
"Principal River Basins of the Philippines", Published by the National Water Resources Board, October 1976 (p. 12)
"Flood Forecasting and Warning System for River Basins; The Cagayan River Basin". Philippine Atmospheric, Geophysical and Astronomical Services Administration. Archived from the original on 12 March 2016. Retrieved 12 March 2016.

External links

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[worldatlas-1] Kenneth Kimutai too (24 July 2018). "Longest Rivers In The Philippines". worldatlas.com. WorldAtlas. Retrieved 9 September 2019.

[DENR-2] Vicente B. Tuddao Jr. (September 21, 2011). "Water Quality Management in the Context of Basin Management: Water Quality, River Basin Management and Governance Dynamics in the Philippines" (PDF). www.wepa-db.net. Department of Environment and Natural Resources. Retrieved 5 April 2017.

[Taming_the_Cagayan_River-3] "Taming the Cagayan River, Inquirer.net". Retrieved 20 May 2017.

[4] "Principal River Basins of the Philippines", Published by the National Water Resources Board, October 1976 (p. 12)

[PAGASA-5] "Flood Forecasting and Warning System for River Basins; The Cagayan River Basin". Philippine Atmospheric, Geophysical and Astronomical Services Administration. Archived from the original on 12 March 2016. Retrieved 12 March 2016.