Chiang Saen Basin
Location:	20°10'-20°18'N, 99°57'-100°11'E; the basin extends from the Golden Triangle, 10 km north of Chiang Saen, downstream along the Mekong River for 29.5 km to Ban Suan Dok, below the confluence of the Nam Mae Kok. It also extends for about 18 km southwest from Chiang Saen, encompassing Nong Wiang, Chiang Saen and Mae Chan Districts, Chiang Rai Province, and upstream along the Nam Mae Kok for approximately 15 km.
Area:	10,000 ha.
Altitude:	350-400m.
Biogeographical Province:	4.10.4.
Wetland type:	11, 13, 14, 15, 18 & 19.
Description of site:	Open, deforested rivers, with sand banks and small islands. The Mekong River at this location is over 0.5 km wide. The banks of the rivers are cultivated right up to the water margins, but patches of dense scrub remain. The area includes the basin of Nong Wiang (4,000 ha), which is largely paddy interspersed with patches of seasonally flooded grassland, grazing marshes and small pools, together with Nong Bong Khai (also known as Chiang Saen lake; approximately 200 ha). Low deforested foothills lie around the margins of the site. These are cultivated in parts. There is a fairly high human population density and many houses are scattered throughout the drier parts of the area. The Laotian shore of the Mekong, though also populated, is still largely wooded. There are great fluctuations in the depth of the Mekong River at Chiang Saen. The river is at its deepest in November to December and reaches its lowest depth in April. There is usually little or no overspill from the banks, and flooded areas inland are confined to the basin of Nong Wiang.
Climatic conditions:	Tropical monsoonal climate.
Principal vegetation:	Patches of Saccharum arundinaceum along rivers. Many areas along the river banks are overgrown with a dense scrub of Mimosa pudica. Land Use Classification Division (1977-1979) lists 3,000 ha along the floodplain of the lower Nam Mae Kok as "abandoned land". There is little emergent vegetation in the ponds and lakes other than Nelumbo nucifera and small patches of Cyperus spp. There are extensive areas of rice paddy and other cultivation in the low-lying areas along rivers. The deforested foothills support patches of bamboo scrub (Bambusa sp) among other woody secondary growth. Most such areas are, however, cultivated.
Land tenure:	The areas of open water are state owned. The Thai-Laotian border runs along the Mekong, close to the Thai shore. The Nam Sop Ruak at the Golden Triangle forms the Thai-Burmese border. Most areas of marshland and riverine floodplain are in private ownership. Surrounding areas are mainly privately owned agricultural land.
Conservation measures taken:	Nong Bong Khai was declared as a Non-Hunting Area in 1985. The Non-Hunting Area encompasses only open water and no adjacent shoreline other than one small area which has been set aside for building the reserve headquarters. The Department of Fisheries collaborates with local fishermen in obtaining eggs and sperm from the endangered Mekong Giant Catfish Pangasianodon gigas in order to rear fry for release.
Conservation measures proposed:	The establishment of an additional Non-Hunting Area at Nong Wiang has been proposed. The burning and cutting of waterside vegetation, together with the hunting of waterfowl, should be suppressed. At Nong Bong Khai and elsewhere, "scrapes" might be made around the lake shore in order to improve feeding opportunities for shorebirds.
Land use:	Fishing, using gill nets, throw-nets and electrocution. Fishermen at Nong Bong Khai are able to catch approximately one kilogram of fish per day. In addition, small freshwater shrimps are harvested and are used for making chilli paste. One crop of irrigated or rain-fed rice is grown per year. Many areas of riverine floodplain are used for cultivating maize or green vegetables, and it is not unusual for cultivauion to be practised right up to the water's edge. As the water levels drop, from late December onwards, so the cultivation proceeds further into the fertile alluvial soils along the river margin. There are fruit orchards (mainly lychees) and fields of hill rice and maize in surrounding areas.
Possible changes in land use:	Increasing tourism is leading to a gradual proliferation of guest bungalows, restaurants and other facilities around the lake shore at Nong Bong Khai and along the Mekong. In the water catchment area, there is likely to be an increase in already deforested land under cultivation due to the adoption of lucrative cash crops such as coffee.
Disturbances and threats:	Each dry season, there is much burning of scrub, reeds and other riverine vegetation in order to open up areas for cultivation. Such massive habitat disturbance certainly deprives some species, such as Saxicola jerdoni, of suitable undisturbed habitat. Fishermen walk or swim out to riverine sand bars in the drier months, causing indirect disturbance to nesting and migrant waterbirds. In addition, there is a certain amount of direct disturbance, both from shooting and the taking of eggs for food. The area is heavily-fished. Almost the entire width of the Mekong at Chiang Khong, downstream of the present site, is blocked off by nets during the dry season in order to catch the endangered Mekong Giant Catfish Pangasianodon gigas. The Department of Fisheries has never attempted to halt this practice.
Economic and social values:	Many people, both Thai and Laotian, are dependent upon the Mekong fisheries. In addition, tourism is rapidly expanding in the area and generally attracts the younger, lower-budget foreign travellers as well as a great many Thai nationals. Income from this source at present goes directly into the pockets of local people since there are no outside, large-scale tourist developments. Already, such tourists include a small proportion of bird-watchers.
Fauna:	The Mekong Giant Catfish Pangasianodon gigas has been recorded from both the mainstream of the Mekong River and its tributary, the Nam Mae Kok (Rainboth et al., 1976). The wetland supports a wide range of wintering and possibly some resident bird species which are scarce or absent elsewhere in Thailand. The Mekong River may act as a major flyway for waterfowl. In addition to those species which winter regularly, occasional vagrants such as Anser indicus (four birds in January 1984) have been recorded. Ciconia nigra has been recorded on a number of occasions, the last as recently as December 1983. Tadorna ferruginea is an an occasional visitor, and this may be the only site where Anas poecilorhyncha is regular (up to 50 birds have been recorded). Small numbers of other ducks have been found: Dendrocygna javanica (up to 200), Anas acuta, A. crecca, Aythya spp including A. baeri. The riverine sand banks also support a variety of shorebirds, some of which may breed. These include flocks of over 200 Glareola lactea and up to eight Vanellus duvaucelii, together with occasional Burhinus oedicnemus. Esacus magnirostris, Sterna aurantia and S. acuticauda were formerly recorded (Deignan, 1945; King, 1966) and may still be present. Other riparian birds include Ceryle rudis and a colony of at least 40 nests of the scarce and local Riparia paludicola. Scrub on riverine sand banks supports small wintering flocks of Emberiza spodocephala. Freshwater marshes and paddies support wintering flocks of egrets and a few herons (Ardea cinerea, A. purpurea), the harriers (Circus (aeruginosus) spilonotus, C. melanoleucos), and Vanellus cinereus. A survey of wetland and scrub habitats around Nong Bong Khai in December 1985 produced 69 bird species, with a further seven species being recorded from Nong Wiang (Amget et al., 1985). There is no recent information on breeding birds. Saxicola jerdoni was formerly present (King, 1966) and almost certainly still occurs.
Special floral values:	None known.
Research and facilities:	Information collected by bird-watchers in 1983-86 is held on file at the Center for Wildlife Research at Mahidol University in Bangkok. A temporary office has been established at the Nong Bong Khai Non-Hunting Area, and the Superintendent, Mr Pramook Onlamai, is collecting some basic information on local human use of the site.
References:	Amget et al. (1985); Deignan (1945); King (1966); Land Use Classification Division (1977-1979); Rainboth et al. (1976).
Criteria for inclusion:	1b. 2b.
Source:	Jira Jintanugool and Philip D. Round.