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Catubig
River and Estuary
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Location:
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12°20'N, 125°00'E; south of Laoang, Northern Samar Province. |
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Area:
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54 km of river in a total valley area of 83,600 ha; 444 ha of mangrove and nipa swamp. |
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Altitude:
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Sea level to 800m. |
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Biogeographical
Province:
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4.26.12. |
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Wetland
type:
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02, 06, 07, 11 & 12. |
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Description
of site:
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The Catubig River from its source in the highlands of northern Samar to the estuarine mangroves and intertidal mudflats at its mouth near the town of Laoang on the north coast of the island. The valley remains very much in its natural state, especially in the upper part of the watershed. Human interference with the indigenous terrestrial and aquatic ecosystems has occurred only in settled areas and on cultivated lands which comprise 30% of the total area. The pH values in the river range from 6.3 to 8.0. In the estuarine portion of the river, the average tidal rise and fall is l.19m, and the overall range 1.4m. |
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Climatic
conditions:
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Humid tropical climate with no dry season, but a very pronounced period of maximum rainfall from November to January (Type II). The site lies on the typhoon path. |
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Principal
vegetation:
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There are 444 ha of mangrove and nipa swamps in the estuary, dominated by Nypa frulicans and Rhizophora sp. No information is available on the freshwater aquatic vegetation. Much of the water catchment area, particularly the southern (upper) part, is covered in primary dipterocarp forest. The dominant commercial species are Pentacme contorta, Shorea negrosenses, S. polysperma, S. guigo, Dipterocarpus grandiflora and Hopea accumulata. |
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Land
tenure:
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No information. |
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Conservation
measures taken:
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None. |
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Conservation
measures proposed:
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Land
use:
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Forestry and agriculture, mainly cultivation of rice and coconuts. Logging licences have been issued in the water catchment area. The valley includes 15,604 ha of rice paddies, 10,994 ha of coconut plantations, 1,118 ha of grassland, 4,694 ha of scrub, 444 ha of nipa and mangrove, 5,022 ha of secondary forest and 43,254 ha of primary forest. |
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Possible
changes in land use:
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Several development projects have been proposed which would have a profound effect on the river. These include (a) the construction of a multipurpose reservoir with a total capacity of 150.4 million cubic metres and a dam height of 55m; (b) the construction of low dikes; (c) the construction of irrigation networks covering approximately 4,550 ha; (d) the construction of a hydro-electric power station with two 15 megawatt generators. |
| Disturbances and threats: | The creation of a large reservoir would destroy much of the valley. |
| Economic and social values: | No information. |
| Fauna: | No information is available on the aquatic fauna. Forest wildlife includes the pig Sus celebensis philippinensis, the deer Cervus unicolor and the monkey Macaca philippinensis. |
| Special floral values: | The valley possesses some of the finest virgin forests remaining in the Philippines. |
| Research and facilities: | Sanya Consultants Incorporated, a Japanese company, has carried out a comprehensive development study of the valley for the Samar Integrated Rural Development Project. |
| References: | Sanya Consultants (1984). |
| Criteria for inclusion: | 1b. 2b. |
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Source:
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Haribon Foundation and Perla M. Magsalay. |