South Kalimantan Danau Bankau and other swamps in the Barito Basin

Written by on November 19, 2010 in Kalimantan South Kalimantan Nature Reserve with 0 Comments

Danau Bankau and other swamps in the Barito Basin

Location:2-ª00′-3-ª15’S, 114-ª20′-115-ª25’E; in the lower Barito Basin, north from Banjarmasin to the region of Butong, South Kalimantan.

Area:480,000 ha (excluding marginal areas under traditional intensive use).

Altitude:Near sea level.

Description of site:
The vast alluvial plain of the lower Barito Basin and its left bank tributaries, notably the Negara River. On first emerging onto the plain, the tributaries form a complex depositional network of levees and back-swamps that supports the densest rural population in Kalimantan (towns of Amuntai, Kandangan and Rantau). The tributaries then flow through a zone of deep water swamps (including Danau Bankau, Danau Panggang and Alabio Polder) which serves as a sump or floodwater storage area. The deep water swamps then drain slowly across the extensive, level, marine coastal plain into the Barito River and the sea. Peat swamps are located in the shallow basins between the rivers which are permanently wet. Although the largest peat swamps in the Pulau Petak area have peat depths up to 190 cm or more and have a typical domed structure, most of these peats are young and comparatively shallow. The rivers have rather stable courses, but the Sungei Murung has changed its course in geologically recent times, leaving remnant channels in the lower Pulau Petak area. Annual flooding occurs during the wet season, from December to March. Brackish water incursion reaches about 30 km inland during the dry season, while tidal influences are felt up to 100 km inland during the wet season and up to 150 km during the dry. There are two open water lakes, Danau Bankau and Danau Panggang, with a depth of three metres or more.The four major zones are as follows: (a) riverine alluvial plain consisting of levees and back-swamps, subject to intensive land use including the cultivation of rice; (b) deep swamps (128,000 ha) consisting of open marsh with some permanent lakes; (c) peat swamp forest (186,000 ha); (d) marine alluvial plain (166,000 ha) consisting of alluvial forest with extensive secondary forests of Melaleuca, and potential acid-sulphate soils.

Climatic conditions:
Humid tropical climate, with an average annual rainfall of 2,500 mm. The wet season is from December to March, and the dry season from July to October.

Principal vegetation:
Deep swamps with lake vegetation, grassy swamps and open forest; peat swamp forest; marine alluvial plains with swampy grassland, alluvial forest and Melaleuca scrub. There is intensive, rice-based agriculture in the riverine zone, and kerangas forest and sandy terraces to the north. The acidic swamps and peat swamps continue west of the Barito Basin.

Land tenure:
The wetland is state owned (Indonesian Government); surrounding areas are under customary tenure.

Conservation measures taken:None.

Conservation measures proposed:
Consideration should be given to the establishment of nature reserves in the deep water swamps, at Danau Bankau or the lake area west of Alabio, as there are reasons to believe that these lakes support some unique elements of aquatic fauna and flora, not found elsewhere in Kalimantan (Central Planning Consultancy Jakarta, 1979). Detailed surveys are needed to investigate the importance of the area for waterbirds and determine possible reserve boundaries.

Land use:
Fishing, cultivation of floating rice and reed-cutting in the deep water swamps. The riverine zones of the Amuntai, Kandangan and Rantau Rivers are densely populated and under intensive cultivation, An attempt was made in 1936 to convert 6,000 ha of swamp at Alabio, upstream of the Sungai Negara, into polder, but the pumping capacity was too low and the project failed. Large areas of the polder have since fallen into disrepair. About 3,000 ha are planted with rice between May and August, when water levels are at their lowest. The polder supports an important fishery (8,000 metric tonnes per year) and is also an important duck-farming area (24 million eggs per year).

Possible Changes in Land use:
Many reclamation schemes are planned, especially in the riverine areas and marine alluvial plains but also in the swamps, despite the fact that peat areas and deep water swamps are usually considered to be unsuitable for reclamation.

Disturbances and threats:
Reclamation schemes and drainage projects; some 279,700 ha have been listed as suitable for reclamation. Fishing, reed-cutting and bird-trapping may be excessive in the deep swamps, especially those lying adjacent to densely populated regions. Extensive forest clearance in the water catchment area is likely to affect water quality.

Economic and social values:
The deep water swamps have a high value for flood control and as a source of water during dry periods. They are also important for fisheries and other traditionally harvested products. The peat swamp forests also play an important role in the hydrological balance of the region, as well as providing a good example of this ecosystem. At least 63,300 ha of swamps are listed as unsuitable for reclamation. In view of the large-scale reclamation schemes which are currently planned, these areas should be considered of high conservation value as they will eventually represent the only natural swamp habitats in the region.

Fauna:
A very important area for a wide variety of waterbirds. Species recorded during brief surveys in recent years include Anhinga melanogaster, Ixobrychus cinnamomeus, 1. flavicollis, Butorides striatus, Ardea purpurea, Leptoplilos javanicus, Dendrocygna arcuata, Nettapus coromandelianus, !chthyophaga ichthyaetus. Rallus striatus, Porzana cinerea, P. fusca, Gallisuila chioropus, Rostratula benghalensis, Tringa nebularia, Chlidonias hybrida (a common visitor) and Pelargopsis capensis. The endangered White-shouldered Ibis Pseudibis davidsoni has been reported and may occur in significant numbers in the more remote areas. Large roosts of Ardeola sp (500) and Egretta intermedia (2,000) have been located, and it is likely that there are breeding colonies of large waterbirds in the area. Other waterfowl known only from 19th Century reports, but which are still likely to occur, include Phalacrocorax sulcirostris, P. niger, Ixobrychus sinensis, Bubulcus ibis, Plegadis falcinellus, Gallinula tenebrosa and Himantopus himantopus.

Special floral values:
Probably the most important freshwater swamp in Kalimantan.

Research and facilities:
Basic faunal and floral surveys have been carried out, and there have been several feasibility studies for reclamation schemes.

List of Birds (28 species)
Species Red Data Book Cites

Anhinga melanogaster Lower Risk
Ardea purpurea
Ardeola speciosa
Bubulcus ibis
Butorides striatus
Dendrocygna arcuata
Dupetor flavicollis
Gallicrex cinerea
Gallinula chloropus
Gallinula tenebrosa
Himantopus himantopus
Ichthyophaga ichthyaetus Lower Risk App II
Irediparra gallinacea
Ixobrychus cinnamomeus Ixobrychus sinensis
Leptoptilos javanicus Vulnerable
Nettapus coromandelianus
Pelargopsis capensis
Phalacrocorax niger
Phalacrocorax sulcirostris
Plegadis falcinellus
Porphyrio porphyrio
Porzana cinerea
Porzana fusca
Pseudibis davisoni Endengered
Rallus striatus
Rostratula benghalensis
Tringa nebularia

 

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