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Tam
Giang Lagoon
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Location:
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16°32'-16°39'N, 107°26'-107°37'E; 10 km north of Hue, southeastern Binh Tri Thien Province. |
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Area:
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7,800 ha. |
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Altitude
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0-2m. |
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Biogeographical
Province:
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4.5.1. |
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Wetland
type:
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08. |
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Description
of site:
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A large, brackish, coastal lagoon, about 20 km long and up to three km wide. The lagoon extends in a northwest-southeast direction parallel to the coast, and is separated from the sea by a sandy ridge formed by coastal deposition. The northern end of the lagoon is the mouth of O Loan River; both the river and the lagoon open into the sea at the Thuan An and Tu Hien channels. Six other rivers also flow into the lagoon: the Bo, Huong, Truoi, Dap Dinh, Thien Hon and Cong Quan. The mean depth of the lagoon is 0.8m; the water is brackish, with a salinity of 16.6-21.8 p.p.t. |
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Climatic
conditions:
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Tropical monsoonal climate with a rainy season from August to December; the heaviest rainfall occurs in October and November. The mean January temperature is 20.1°C, and the mean June temperature 29.2°C. |
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Principal
vegetation:
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Nine species of vascular plants have been recorded in the lagoon, five of which belong to the Hydrocharitaceae. The dominant species is Najas indica, with a biomass of 2,500 gm per square metre. Hydrilla verticillata is dominant in the O Loan River, with a biomass of 200-250 gm per square metre. Eighty-six species of algae have recenty been listed. The species composition varies widely according to season; during the rainy season, freshwater algae predominate, while during the dry season, marine algae predominate. |
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Land
tenure:
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State owned (Province and District). |
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Conservation
measures taken:
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The provincial authorities have developed a policy for the rational utilization of the lagoon. |
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Conservation
measures proposed:
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Land
use:
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Fishing (finfish, shrimps, crabs and bivalves) and recreation; agriculture in adjacent areas. |
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Possible
changes in land use:
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Priority is being given to the development of aquaculture (fish, shrimp and Gracilaria verrucosa) in the lagoon. |
| Disturbances and threats: | The salinity of the lagoon has decreased as the Tu Hien channel has become blocked by continuing coastal deposition. This has had an adverse effect on many aquatic species. Over-exploitation of the fishery resources is also a problem. |
| Economic and social values: | The lagoon supports a major fishery which is important not only as a protein source for the local communities, but also for export. The annual production of finfish alone is estimated at 3,600 metric tonnes. The lagoon also has considerable potential for outdoor recreation and tourism. |
| Fauna: | A very important area for wildlife. The lagoon supports a rich fish and invertebrate fauna, and is a major staging and wintering area for migratory waterfowl, particularly ducks and shorebirds. |
| Special floral values: | No information. |
| Research and facilities: | |
| Criteria for inclusion: | 1b, 1e, 3b. |
| References: | Karpowicz (1985); Vu Trung Tang & Dang Thi Sy (1982). |
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Source:
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Le Dien Duc. |