Gyobyu Reservoir
Location:
17°21'-17°26'N, 96°02'-96°05'E; in the southwestern extremity of the Pegu Yoma hill range, near Taikkyi township, 65 km north of Rangoon, Rangoon Division.
Area:
518 ha.
Altitude:
65m.
Biogeographical Province:
4.4.1.
Wetland type:
17
Description of site:
A small water storage reservoir with a catchment basin of 3,344 ha, surrounded by the Hlaing Yoma and Paunglin Reserved Forests. The reservoir was created in 1940 by damming the Gyobyu Chaung. It has a highly convoluted shoreline, numerous islands and a maximum depth of 30m. Although the surface area remains fairly constant, the water depth fluctuates by up to 9m between wet and dry seasons. The catchment area consists of slopes, ridges and valleys with a network of streams draining off the southwestern spur of the Pegu Yoma hills. Some of the streams are perennial. Steeply sloping hills surround the reservoir, resulting in an absence of a foreshore even at low water levels. Soils are generally light, and either sandy or loamy.
Climatic conditions:
Tropical monsoonal climate with an average annual rainfall of about 2,500 mm, most of which falls between June and October. A cold dry season persists from November to February, and a hot dry season from March to May.
Principal vegetation:
The steep shoreline of the reservoir has largely precluded development of emergent aquatic vegetation, but there are floating mats of grasses. The mixed deciduous forest on the surrounding slopes and ridges features an open to scattered tree cover, which includes Tectona sp and Xylia dolabriformis with an understorey of bamboo. Evergreen forest is found in the moister valley bottoms, and is characterized by heavier stocking of larger trees, principally Dipterocarpus spp, and an understorey of canes and creepers.
Land tenure:
State owned; administered by the Rangoon City Development Corporation.
Conservation measures taken:
Prior to the construction of the dam in 1940, the area was part of the Hlaing Yoma Reserved Forest. Control of the lake and its catchment area (3,862 ha) was subsequently transferred from the Forest Department to the Rangoon Municipality and currently rests with the Rangoon City Development Corporation.
Conservation measures proposed:
In 1982, it was proposed that the area might be developed for recreational purposes. This was rejected and an alternative proposal was made to restore management of the area to the Forest Department, and to establish plantations to reduce exploitation of both the catchment area and the surrounding reserved forests (FAO, 1982c).
Land use:
Water supply for the city of Rangoon. Some ten policemen and their families are the only residents in the area. There is, however, agricultural land adjacent to the catchnient basin and a number of villages to the south and southwest. In 1977, Section 144 of the Security Act was imposed, and all human access and use of the area was prohibited, with the exception of dam maintenance and protection of the watershed.
Disturbances and threats:
Local demand for firewood, bamboo, fishing and grazing is met in part by exploitation of the area. These activities appear to be tolerated by the security patrols. Logging, extraction of canes and firewood, and burning have already degraded much of the forest in the catchment area.
Economic and social values:
The reservoir is one of the main sources of water for Rangoon.
Fauna:
The lake supports a wide diversity of waterfowl including Tachybaptus ruf icollis, Phalacrocorax niger, Anhinga melanogaster, Ixobrychus cinnamomeus, Ardeola grayii, Bubulcus ibis, Egretta intermedia, Ardea purpurea, A. cinerea, Amaurornis phoenicurus and Metopidius indicus. Winter visitors include Pandion haliaetus, Circus melanoleucos and Larus brunnicephalus. The area is too small to support viable populations of large mammals, although several noteworthy species are occasionally reported. These include Panthera tigris, P. pardus, Cuon alpinus and Elephas maximus (3-7 individuals). Bos javanicus and B. gaurus move into the area during the monsoon season.
Special floral values:
None known.
Research and facilities:
The area was surveyed in October 1981 and April 1982 to assess its suitability for recreational development. Access to the area has been restricted since 1977, and at present there are no facilities for visitors.
References:
FAO (1982c & 1985a); IUCN (in prep).
Criteria for Inclusion:
2b.
Source:
See references.