BUNG BORAPHET (BORAPED RESERVOIR)

Fishing boats on the lake


Photo: T. Kira

A. LOCATION

• Nakhon Sawan Province, Thailand.
• 15:50N, 100:10E; 23.8 m above sea level.

B. DESCRIPTION

Bung (= big pond) Boraped is a half man.made reservoir originating from a natural retarding basin situated close to the city of Nakhon Sawan, where the two rivers, Mae Nam Nan and Mae Nam Ping. unite into Mae Nam Chao Phraya (sometimes erroneously called the Menam River). The lake area had been a vast retarding basin known as the Boraped Swamp, which formed a big lake of 600 km2 in seasons of high water level while turning into a grass-covered plain with scattered ponds and swampy depressions during the dry season. A dam was built at the head of the main outflowing channel (Klong Boraped) by the Fishery Department of Thailand in 1926-30 mainly for increasing fish production. Part of the swamp thus turned into a lake which has since been known as Bung Boraped. The present lake area is about 106 km2 at the spill level, but it varies extensively owing to the water level fluctuation, amounting to as much as 300 km2 in time of floods.
The majority of some 30,000 people living around the lake gain their livelihood from both farming and fishing. Since the lake is the largest source of fishery products for central Thailand, the Nakhon Sawan Fishery Station was established at Klong Boraped for the study of fish biology and for stocking the lake with artificially grown fry. Bung Boraped and surrounding swampy areas form one of the non-hunting nature reserves established by the Royal Thai Forest Department. Two development projects have been drafted for tourism development, upgrading aquaculture and utilizing the lake as sources of irrigation and domestic water supply (Q, 1, 2, 3).

C. PHYSICAL DIMENSIONS

Surface area [km2]	106
Volume [km3]	0.2764
Maximum depth [m]	5.8
Mean depth [m]	2
Water level	Regulated
Normal range of annual water
- level fluctuation [m]	1-1.2
Length of shoreline [km]	53-62.5*
Catchment area [km2]	4,200

* Minimum-maximum.

D. PHYSIOGRAPHIC FEATURES

D1 GEOGRAPHICAL

• Sketch map: Fig. ASI-19-01.
• Number of outflowing rivers and channels (name): 1 (Klong Boraped).

D2 CLIMATIC (Q)

• Climatic data at Nakhon Sawan, 1951-1970

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Ann.
Mean temp. [deg C]	24.9	27.7	30.2	31.4	30.5	29.4	28.9	28.5	28.0	27.6	26.3	24.4	28.2
Precipitation [mm]	12	25	43	72	141	134	144	167	264	152	30	6	1,187

Fig. ASI-19-01
Sketch map of Bung Boraped and its drainage basin (1).

• Water temperature [deg C](2)

Open water area, 1975
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	29.0	28.0	28.0	33.5	34.0	31.0	29.0	28.0	30.0	31.0	29.0	29.0

* Surface.

• Freezing period: None.
• Mixing type: Polymictic.
• Notes on water mixing and thermocline formation
  The thermocline is not formed.

E. LAKE WATER QUALITY

E1 TRANSPARENCY [m](2)

Open water area, 1975
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
	1.4	1.7	1.2	1.8	1.5	1.3	1.3	1.1	1.1	1.3	1.2	1.2

E2 pH (2)

1975
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*	7.6	7.4	7.4	7.0	7.4	7.0	7.2	7.3	6.7	6.6	7.0	6.9

* Surface.

E3 SS [mg l-1](1)

Surface water*, 1981: 14.8 (July), 2.0 (August).
* Mean of five sampling points.

E4 DO [mg l-1](2)

1975
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*1	8.0	8.0	8.0	6.0	8.0	7.0	9.0	8.0	3.0	8.0	8.0	7.0
B*2	7.0	5.0	7.0	6.0	6.0	6.0	9.0	7.0	3.0	8.0	7.0	7.0

*1 Surface. *2 Bottom.

E5 COD [mg l-1](1)

Determined by KMnO4 method.
Surface water*, 1981: 40.5 (July), 22.4 (August).
* Mean of five sampling points.

E6 CHLOROPHYLL CONCENTRATION

No information.

E7 NITROGEN CONCENTRATION [mg l-1](1)

Mean of five sampling points, 1981 Surface water

• NH4-N: 0.50 (July), 0.01 (August).
• Org-N: 1.5 (July), 1.0 (August).

E8 PHOSPHORUS CONCENTRATION (2)

• PO4-P [mg l-1]

1975*1
Depth [m]	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
S*2	0.07	0.10	0.13	0.13	0.07	0.07	0.07	0.07	0.10	0.13	0.07	0.10

*1 Converted from the original determination of phosphate.
*2 Surface.

F. BIOLOGICAL FEATURES (Q, 2, 4, 5)

F1 FLORA

• Emerged macrophytes
  Phragmites karka, Colocasia esculenta, Nelumbo nucifera, Coix aquatica, Isachne globosa, Leesia hexandra.
• Floating macrophytes
  Salvinia cucullata, Eichhornia crassipes, Pistia stratiotes, Nymphaea stellata.
• Submerged macrophytes
  Utricularia flexuosa, Potamogeton sp., Hydrila verticillata, Najas graminea, Ceratophyllum demersum.
• Phytoplankton
  Sphaerozosma vertebratum, Oedogonium sp., Micrasterias foliacea, Synedra ulina, Volvox aureus.

F2 FAUNA (5)

• Zooplankton
  Bosmina excisum, Bosminopsis deitersi, Heliodiaptomus kikuchii, Keratella valga.
• Benthos
  Chironomids, Oligochaeta, Mollusca (Ensidens ingallsianus, Unio thaiensis, Corbicula larnaudieri, C. petiti, Mekongia hainesiana), Crustacea (including a big prawn, Macrobrachium rosenbergii).
• Fish
  Pristolepsis fasciatus, Notopterus notopterus, Osteochei hasselti, Hampala microlepidota, Ambasis siamensis, Cyclochcilichthys armatus, Mystus vittatus, Ophiocephalus striatus, Clupeoides hypselosoma, Labiobarbus liniatus.

F3 PRIMARY PRODUCTION RATE

No information.

F4 BIOMASS [g m-3](Q)

	Wet weight	Dry weight
Phytoplankton	146,000	0.143
Zooplankton	245,300	0.104
Total Biomass	0.247

• Population density (open water area, Sep.-Nov., 1981)(1).
  Phytoplankton 4.847.5 [l-1]; zooplankton 76.5 [l-1]; benthos 248 [m-2].

F5 FISHERY PRODUCTS (2)

• Annual fish catch [metric tons]
  1975: 723,048.

G. SOCIO-ECONOMIC CONDITIONS

G1 LAND USE IN THE CATCHMENT AREA* (1)

1980
	Area [km2]	[%]
Natural landscape
- Woody vegetation	1,734	16.3
- Swamp	104	1.0
- Others (open water)	213	2.0
Agricultural land	7.258	68.3
Residential area	1.314	12.4
Total	10,622	100.0

* In Nakhon Sawan Province. Statistics for the drainage basin of Bung Boraped only, which accounts for 40% of the area of the whole province, were not available.

• Main types of woody vegetation (4)
  Secondary forests derived from the original semi-deciduous seasonal forest.
• Main kinds of crops
  Rice, sugarcane, sorghum, maize, cassava, soybean, tobacco, sesame and lotus.
• Levels of fertilizer application on crop fields: Light.
• Trends of change in land use in recent years (Q)
  Increasing number of acreage is now being allocated to fish ponds and livestock raising. Area used as fish ponds amounts to 2.78% of the catchment area.

G2 INDUSTRIES IN CATCHMENT AREA*1 AND THE LAKE (1)

	No. of persons engaged	No. of establishments	Main products or major industries
Primary industry
- Agriculture	521,800	N.A.
Secondary industry
- Manufacturing	114,900	831*2	Sugar, cement. matches Marble, gypsum,iron, lime
- Mining	6,437*3	N.A.
Tertiary industry	22,700	N.A.

*1 In nakhon sawan province only.
*2 Besides there are 401 rice mills.
*3 Including the number of persons engaged in commerce.

G3 POPULATION IN THE CATCHMENT AREA*1

1980
	Population	Population density [km-2]	Major cities (population)
	979,200	92.19?*2	Nakhon Sawan (86,000)

*1 In Nakhon Sawan Province.
*2 Population density for the subdistricts around Bung Boraped: 153.8 km-2.

H. LAKE UTILIZATION

H1 LAKE UTILIZATION (Q)

Sources of water, fisheries, navigation and tourism.

H2 THE LAKE AS WATER RESOURCE (Q)

1980
Domestic: 300 [m3 day-1].

I. DETERIORATION OF LAKE ENVIRONMENTS AND HAZARDS

I1 ENHANCED SILTATION (Q)

• Extent of damage: Not serious.
• Supplementary notes
  Heavy rainfall in the later part of the year and resultant soil erosion cause high turbidity of water and reduction of plankton, benthos and fish populations.

I2 TOXIC CONTAMINATION: No information.

I3 EUTROPHICATION (Q)

• Nuisance caused by eutrophication: Foul smell of tap water.

I4 ACIDIFICATION: No information.

J. WASTEWATER TREATMENTS (Q)

J1 GENERATION OF POLLUTANTS IN THE CATCHMENT AREA

f) Limited pollution without wastewater treatment.

J2 APPROXIMATE PERCENTAGE DISTRIBUTION OF POLLUTANT LOADS

No information.

J3 SANITARY FACILITIES AND SEWERAGE

• Public sewerage system: Not present.

L. DEVELOPMENT PLANS (Q)

The policy of Department of Fisheries (DOF) in the rehabilitation and development of these swamps is directed toward optimizing fish production by controlling floods, ensuring domestic water supply and sanitary facilities, and allowing limited water use for agricultural purposes.

M. LEGISLATIVE AND INSTITUTIONAL MEASURES FOR UPGRADING LAKE ENVIRONMENTS

M1 NATIONAL AND LOCAL LAWS CONCERNED (Q)

• Names of the laws (the year of legislation)

1. Fisheries Act BE 2490
2. Land Law
3. Forestry Law
4. Environmental Act

• Responsible authorities
1. Department of Fisheries
2. Land Department
3. The Royal Forestry Department
4. National Environment Board
• Main items of control
1. Conservation of fishery resources and control of fishing gears
2. Control of land use development
3. Conservation of forestry and wildlife
4. Control of environmental quality

M2 INSTITUTIONAL MEASURES (Q)

1. Department of Fisheries

M3 RESEARCH INSTITUTES ENGAGED IN THE LAKE ENVIRONMENT STUDIES (Q)

1. Nakhon Sawan Fishery Station, Department of Fisheries, Klong Boraped

N. SOURCES OF DATA

17. Questionnaire filled by the Office of the National Environment Board of Thailand, Bangkok.
1. Asian Institute of Technology (1982) Rehabilitation and Development of Bung Boraped and Mong Han. Vol. 1. Bung Boraped. 196pp. Office of the National Economic and Social Development Board, Bangkok.
2. Suraswadi, Plodprasop (1976) Newly covered grass as a habitat for fish in Bung Boraped, Thailand. Ph. D. Thesis, Department of Zoology, University of Manitoba, Canada.
3. Dobias, R. J. (1982) The Shell Guide to the National Parks of Thailand. 137pp. The Shell Company of Thailand, Ltd., Bangkok.
4. The editors' observation.
5. Mizuno, T. & Mori, S. (1970) Preliminary hydrobiological survey of Southeast Asian inland waters. Biol. J. Limnol., Soc., 22: 11-117.
6. Department of Fisheries (1985) Large Swamps Inland Fisheries Project (LSIFP). Bangkok.