The Bicol River is the eighth largest river in the Philippines in terms of drainage basin size with an estimated catchment area of 3,770 square kilometres (1,460 sq mi). The river drains the southwestern part of the island of Luzon and passes through Camarines Sur province in the Bicol Region.
The Bicol River at Canaman
Bicol River drainage area
|Native name||Salog Bikol|
|⁃ location||Bato, Camarines Sur and Libon, Albay, Bicol Region|
|⁃ elevation||6 m (20 ft)|
|Between Cabusao and Calabanga, Camarines Sur, Bicol Region|
|0 m (0 ft)|
|Length||94 km (58 mi)|
|Basin size||3,770 km2 (1,460 sq mi)|
|⁃ location||San Miguel Bay (when the sea level is low)|
|⁃ average||165 m3/s (5,800 cu ft/s)|
|⁃ minimum||123 m3/s (4,300 cu ft/s)|
|⁃ maximum||205 m3/s (7,200 cu ft/s)|
The river starts from Lake Bato, 6 metres (20 ft) above sea level, and flows 94 kilometres (58 mi) downstream to its estuarine mouth at San Miguel Bay. It passes through Naga City, the alluvial and coastal plains of the vast Bicol Valley, an elongated, northwesterly trending depression in the Bicol Region, which contains alluvial plains to the coastal plain. Average slope within the river's drainage basin is 0.006%.
Geology and geomorphologyEdit
The Bicol River is bounded on the northeast by the Bicol Cordillera, which consists of a chain of volcanic mountains including Mount Iriga, Mount Malinao, Mount Masaraga and Mount Mayon. On the southwestern side lie the Ragay Hills, which consists of folded and faulted sedimentary formations including limestones, siltstones, conglomerates and shale. In between these higher areas lies the Bicol plain, which is composed of thick alluvial deposits of sand silt and clay.
The main geo-morphological features found in the area include the estuarine plain, a river flood plain, the piedmont plain and the valleys of incised creeks. The estuarine plain is level to nearly level and consists of fine fluvial-marine deposits over sandy layers with marine shells. The fluvial marine deposits are usually saline at depths of approximately 1 metre (3 ft 3 in) and includes depresses areas along the Bicol River. The river floodplain is made up of mixed alluvium. The piedmont plain on the fringe of the Ragay Hills consists of fine alluvium clay and reworked colluviums.
The climate is influenced by the Northeast Monsoon winds and the Pacific trade winds. These Monsoon winds create the low pressure area in the Pacific Ocean, resulting in tropical cyclones that affect the area in November and December.
Rainfall occurs throughout the year with low rainfall between January to May and high rainfall between June and December. In the lower basin, mean annual rainfall ranges between 1,850 to 2,300 millimetres (73 to 91 in). The main factors influencing rainfall are the air streams, the intertropical convergence zone and topography.
The mean temperatures are high throughout the year with the daily mean temperatures in the range of 24.1 to 28.1 °C (75.4 to 82.6 °F) and an annual mean temperature of 27 °C (81 °F).
- "Bicol River Basin and Water Management Project". Regional Development Council - Bicol Region. Archived from the original on 16 September 2008.
- Otieno, Jennifer A. (2004). "Scenario Study for Flood Hazard Assessment in the Lower Bicol Floodplain: The Philippines Using a 2D Flood Model" (PDF). International Institute for Geo-Information Science and Earth Observation. pp. 3–10. Retrieved 12 September 2008.