Bicol River
Encyclopedia
Bicol River is the eight largest river in the Philippines
in terms of drainage basin
size with an estimated catchment area of 3,770 km². The river drains the southwestern part of the island of Luzon and passes through Camarines Sur
, Albay
, and Camarines Norte
provinces in the Bicol Region
.
The river starts from Lake Bato
, 6 meters above sea level, and flows 94 kilometers downstream to its estuarine mouth at San Miguel Bay
. It passes through 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%.
The basin has an influence area of 10,058 square kilometers including its drainage basin. It lies between 13°0 to 14°N and 123°0 and 124°0 E. It is extensively a coastal flood plain.
, 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 meter 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.
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 1,850-2,300 mm. The main factors influencing rainfall are the air streams, the inter-tropical convergence zone and topography.
The mean temperatures are high throughout the year with the daily mean temperatures in the range of 24.1°C to 28.1°C and an annual mean temperature of 27°C.
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
in terms of drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
size with an estimated catchment area of 3,770 km². The river drains the southwestern part of the island of Luzon and passes through Camarines Sur
Camarines Sur
Camarines Sur is a province of the Philippines located in the Bicol Region in Luzon. Its capital is Pili and the province borders Camarines Norte and Quezon to the north, and Albay to the south...
, Albay
Albay
Albay is a province of the Philippines located in the Bicol Region in Luzon. Its capital is Legazpi City and the province borders Camarines Sur to the north and Sorsogon to the south. Also to the northeast is Lagonoy Gulf....
, and Camarines Norte
Camarines Norte
Camarines Norte is a province of the Philippines located in the Bicol Region in Luzon. Its capital is Daet and the province borders Quezon to the west and Camarines Sur to the south.-Demographics:...
provinces in the Bicol Region
Bicol Region
The Bicol Region or Bicolandia is one of the 17 regions of the Philippines. Its regional center is Legazpi City...
.
The river starts from Lake Bato
Lake Bato
Lake Bato is a freshwater lake and the 7th largest in the Philippines. It is located in the town of Bato, approximately 9 km southwest of Iriga City, Camarines Sur Province, Southeastern Luzon, Philippines. It has extensive marshes and swamp forests. The lake drains into a tributary of the...
, 6 meters above sea level, and flows 94 kilometers downstream to its estuarine mouth at San Miguel Bay
San Miguel Bay
San Miguel Bay is a large bay in the southern part of Luzon island, Philippines, at ....
. It passes through 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%.
The basin has an influence area of 10,058 square kilometers including its drainage basin. It lies between 13°0 to 14°N and 123°0 and 124°0 E. It is extensively a coastal flood plain.
Geology and Geomorphology
The Bicol River is bounded on the northeast by the Bicol Cordillera, which consists of a chain of volcanic mountains including Mount IrigaMount Iriga
Mount Iriga, also known as Mount Asog, is one of the active volcanos in the Philippines, in the province of Camarines Sur, in the Philippines....
, 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
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
. In between these higher areas lies the Bicol plain, which is composed of thick alluvial deposits of sand silt and clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
.
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 meter 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.
Climate
The climate is influenced by the Northeast Monsoon winds and the PacificPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
trade winds. These Monsoon
Monsoon
Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea...
winds create the low pressure area
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
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 1,850-2,300 mm. The main factors influencing rainfall are the air streams, the inter-tropical convergence zone and topography.
The mean temperatures are high throughout the year with the daily mean temperatures in the range of 24.1°C to 28.1°C and an annual mean temperature of 27°C.