Yom River Floodplain
Location:
 16°40'-17°00'N, 99°50'-100°15'E; the floodplain of the Yom River, from the city of Sukkhothai downstream as far as the city of Phitsanulok. Highway 12 skirts to the north and east of the site, linking the two provincial capitals.
Area:
 c.50,000 ha.
Altitude:
 38-53m.
Biogeographical Province:
 4.10.4.
Wetland type:
 14, 15 & 19.
Description of site:

An extensive alluvial basin bounded to the south and west by low hills and to the east by the Nan River, downstream of Phitsanulok. The area is intensively cultivated (chiefly paddy); scattered throughout the basin there are many small permanent swamps and areas prone to seasonal inundation. Parts of the area are relatively well-wooded by comparison with areas in the southern Central Plains and there is a wide scattering of trees among the rice paddies. The area encompasses the following marshes or water bodies identified from Land Use Classification Division (1977-1979):

  • Beung Phing: 16°40'N, 99°55'E; 160 ha.
  • Beung Kradao: l6°4l'N, 99°57'E; 80 ha.
  • Beung Raman l6°42'N, 100°07'E; 210 ha.
  • Beung Takhreng: l6°43'N, l00°05'E; 210 ha.
  • Nong Thaling Chan (Beung Chan): 16°47'N, 100°07'E; 140 ha.
  • Nong Thale Kaeo: 16°50'N, 100°13'E; 130 ha.

One other site, Ban Lung Tua, which is not marked as a marsh on any map, acts as a major waterfowl refuge as a result of enlightened management by its owner. Situated in Bang Rakham District at approximately l6°46'N, l00°06'E, this site, together with the nearby state owned Nang Nam Kao, has been established as the Nong Nam Kao Non-Hunting Area (57.3 ha).

The wetlands are subject to occasional inundation from the Yom River during the late wet season (July to October), and much of the area is actively irrigated during the late dry season (January onwards). Away from the rivers and canals, the wetlands are very shallow, with usually less than one metre of water in the permanent water bodies. There may be little or no flooding in many years.
Climatic conditions:
 Tropical monsoonal climate with an average annual rainfall of 1,113 mm, 86.4% of which falls during the southwest monsoon (May to October). The mean annual temperature is 28.3°C (range 6.1-43.7°C).
Principal vegetation:
 Principally Eichhornia crassipes and Nelumbo nucifera, with some areas of Cyperus spp and Typha angustifolia. Considerable areas are marked as "natural marsh grassland" on the Land Use Classification Map, 1978. In adjacent areas, mainly cultivation with many scattered trees, including much Butea monosperma, some scrub and bamboo, and occasional patches of mixed deciduous or dry dipterocarp woodland.
Land tenure:
 The wetland is mainly privately owned farmland; surrounding areas are also mainly privately owned.
Conservation measures taken:
 The Nong Nam Kao Non-Hunting Area (57.3 ha) has been established in Bang Rakhom District, Phitsanuloke. This encompasses Ban Lung Tua, an area of fish ponds and semi-natural swamp habitat on a privately-owned small-holding managed as a waterfowl reserve by an enlightened owner, together with the adjacent, state owned water body of Nong Nam Kao.
Conservation measures proposed:
 The entire Yom River floodplain between Sukkhothai and Phitsanuloke should receive a detailed survey in order to assess its conservation value. Particular attention should be paid to locating areas which serve as wintering or feeding areas for wintering waterfowl as well as those areas which may continue to support breeding colonies of egrets and other large waterbirds.
Land use:
 The principal activity at the wetland and in surrounding areas is the cultivation of rice, but increasing areas are being turned over to vegetables.
Possible changes in land use:
  
Disturbances and threats: There is much illegal hunting of waterbirds away from the one site where they are actively protected. Continued intensification of agriculture is certain to lead to the removal of many existing clumps of trees and bamboo, and may lead to further drainage or flood control works in some areas. The maintenance of standing water to support wildfowl at Ban Lung Tua is dependent upon releases of water from the Royal Irrigation Department. In drier winters, the Irrigation Department does not always agree to make water available for this purpose.
Economic and social values: Ban Lung Tua is a major recreational attraction for the people of Phitsanulok, and serves to attract tourists from further afield. Such wetlands as are retained and managed for fish farming are an important source of income for those farmers for whom rice yields too low an economic return.
Fauna: The wetlands have been stocked with common species of food fish.

In recent winters, up to 9,000 Dendrocygna javanica, 6,000 Anas acuta, 5,000 A. querquedula, and 170 Aythya baeri have been recorded at Nong Nam Kao-Ban Lung Tua together with smaller numbers of Anas penelope, A. crecca, A. clypeata and other ducks. Over 17,000 ducks were present in mid-January 1988, including:

6,400 D. javanica 5,000 A. acuta
4,740 A. querquedula 170 A. baeri

it is possible that the importance of the Nong Nam Kao Non-Hunting Area for wildfowl has increased with greater levels of recreational disturbance on Beung Boraphet. The site also supports many Hydrophasianus chirurgus as well as small numbers of Egretta garzetta, E. intermedia, E. alba, Ardea purpurea, A. cinerea and shorebirds such as Charadrius dubius, Tringa nebularia, T. glareola, Gallinago gallinago and Calidris temminckii. Harriers Circus spp occur in winter, along with the occasional Spotted Eagle Aquila clanga.
Special floral values: None known.
Research and facilities: There is no accommodation or office in the Non-Hunting Area, but the landowner, Lung Tua, makes visitors welcome. An observation platform has been constructed.
References: Land Use Classification Division (1977-1979).
Criteria for inclusion: 2b, 3a.
Source:
 Jira Jintanugool and Philip D. Round.