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B. THE NAM PONG BASIN (THAILAND) (contd.)

6. SOCIO-ECONOMIC ASPECTS OF THE FISHERMEN

The Mekong Secretariat conducted the first study on socio-economic aspects of the fishermen in Ubolratana reservoir in 1971 (Mekong Secretariat, 1972). Six years later, the second study was made during June 1977 to September 1978 as part of the Nam Pong Environmental Management Research Project (Suetrong et al., 1979). This study covered three major areas of the Nam Pong River Basin development project, the lake-side villages, the Nong Wai irrigation area, and the resettlement areas. The investigation was designed for collecting socio-economic information on fishery sector which is considered necessary to the development and management of the fisheries in Ubolratana reservoir. Details of collected data are elaborated in Table 7.

6.1 Social aspects

Every adult farmer in Thailand regardless of sex knows how to catch fish. Prior to the development of the Nam Pong river project, fish were caught mainly for household consumption, with only a few being for sale, particularly in Khon Kaen province. After the Ubolratana Dam was closed, farmers living in the villages nearby found it advantageous to fish the new reservoir. Their catches were good and they had a good income from fishing due to the high fish production during the first few years. At that time there were also relatively few fishermen in the area. Soon, however, there was an influx of others, mostly rice farmers who were attracted by better prospects of fishing instead of rice farming.

A survey around Ubolratana reservoir in 1971 indicated that 88.4% of the fishermen were previously engaged in rice farming, 1.6% in upland farming (mostly kenaf), 6.1% were wage labourers, and only 1.8% were fishing for a living before moving to the lakeshore. The rest (2.1%) were unidentified (Mekong Secretariat, 1972). Most of the farmers who changed their occupation to fishing were mainly those who lived in the same vicinity for some time before the reservoir was established. About 40% were moved in from elsewhere. About half of the latter were from other parts of Khon Kaen and Udon Thani, the provinces at the border of which the reservoir is located. The other one-third were from other provinces in the northeast and the rest were from other regions of the country.

Table 6

Number of fish farms, areas and total fish production in Khon Kaen Province, during 1975 – 1982

Categories19751976197719781979198019811982
Number of fish farms        
- fish ponds1,7522,4112,6463,3963,1163,1832,6224,336
- Paddy fields417479440424404375357608
Sub-total2,1692,8903,0863,8203,5203,5582,9794,944
Area of fish farm (ha)        
- fish ponds166223244382457487432665
- paddy fields253298282296335294256437
Sub-total4195215266788927816881,105
Fish production (metric ton)        
- pond culture220277302440420417460740
- paddy field culture61557411111482103394
Sub-total2813323765515344995631,134
Value (1,000 baht)*        
- pond culture2,7963,7734,9617,0328,7249,46713,42318,156
- paddy field culture8878661,3211,7592,4142,1533,0279,678
Sub-total3,6834,6396,2828,79111,13811,61016,45027,834

* 1 U.S. dollar = 23 baht (1983)

Table 7

Summary information on a socio-economic survey of the people living in the Nam Pong River Basin during 1977 – 1978

CategoriesNong Wai
Irrigation area
Nam Pong
Resettlement
Lake-side
villages
Number of households
9 230.0
900.0
7 408.0
Average household size
6.3
6.3
6.5
Land-holding (percentage)
90.5
83.5
83.0
Crop growing households (percentage)
95.9
100.0
80.6
Cultivated area per household (ha)
3.10
2.35
2.48
Average yield (ton/ha)
 
 
 
-  paddy
2.04
1.0
1.21
-  cassava
9.41
9.37
5.06
Annual gross income from crop/household (baht)
12 757.80
7 383.0
5 770.0
Percentage of households raising livestock and poultry
100.0
100.0
100.0
Annual gross income from livestock/household (baht)
1 938.0
1 157.0
1 902.0
Percentage of fishing families
79.1
25.4
75.5
Annual gross value of fish catches/household (baht)
735.40
260.0
4 435.0
Annual income from fish sale per household (baht)
148.80
101.0
3 536.0
Annual gross income from other sources (baht)
3 788.0
1 672.0
2 952.0
Annual gross income per household (baht)
19 219.20
10 472.0
15 059.0
Annual expenditure per household (baht)
7 475.40
8 255.0
6 760.0
Annual net income per household (baht)
11 743.80
2 217.0
8 299.0

Adapted from: Suetrong et al., (1979)

The average size of a fisherman family increased from 6.0 to 6.5 persons. The fishermen population was classified into young independents (0–14 years), work-force (15–64 years), and old dependents (over 65 years) representing 43.0%, 53.9% and 3.1% respectively. There was a higher percentage of females over males for all age groups, giving an average of 52.4% females to 47.6 males. About two-thirds of the population were married.

The majority of the population (74.7%) had some education. Primary school Grade 4 was the highest level reached by most, representing 68.9%. Primary school Grades 5–7 education had only been reached by 3.1% and secondary education by 2.0%. A mere 0.2% went to college. It was found that 74.9% of the economically active group (work-force) were farmers by occupation. Fishing (6.4%) and working as labourers (4.3%) were the second and third most common occupations. Merchants and government civil servants made up less than 2%.

Dwelling units in the fishing villages belonged to three types, permanent (67.9%), semi-permanent (27.7%) and temporary (4.4%). The permanent type dwellings, mostly native style of two storey house with open ground floor, were generally owned by large, long settled well-off families. The other two types were owned by those who had moved in after the construction of the dam. In general, a house had 2–3 rooms.

Rice is the single major crop grown by farming households (60.9%). The others grow rice and other crops, 15.8% grow rice and kenaf, 8.5% rice and cassava, and 8.0% rice, fruits and vegetables. Other crops are grown in limited quantities. The gross production value of rice alone accounted for 89% of the total gross value of all crops grown. Kenaf and cassava accounted for a further 4.6% and 2.5% respectively.

6.2 Economic aspects of fishing operations

Fishing operation as practised in Ubolratana reservoir involves only one or two persons in each family. The operation is simple and consists of setting gill-nets. Another method is light attraction of the freshwater sardine-like Corica goniognathus during moonless nights. Other methods of fishing involve the use of cast-nets, hooks and line, lift-nets, bamboo traps, and some others to catch fish. The results of this fishing is largely insignificant in terms of the number of persons involved or the quantity of fish caught compared to those from fixed gill-nets.

A sampling survey of the type and number of fishing gears owned by fishermen households in selected villages of the lakeside was conducted during the socio-economic studies in 1977–78 (Suetrong et al., 1979). It was found that gill-nets were owned by 77.6% of the fishing households, averaging 4.7 nets per fishing household (Table 8). 40.3% of the households possessed hook and long-line. Life-nets and cast-nets were owned by only 8.6% and 13.4% of the fishing household respectively. The possession of a boat in this area also indicated that one is seriously involved in the pursuit of fishing. Unmotorized boats were owned by 53.5% of the fishing households, and motorized boats by 18.6%. 17.9% of the fishing households did not own boats which indicates that they engaged mainly in farming.

Table 8

Type and number of fishing gears owned by fishermen households in the sample villages in the lake-side area (from Suetrong et al., 1979)

Fishing gearsNumber of fishing gearsHouseholds with gearAverage
number/household
Nong RuaPhu WiangNon SangSi Bun RuangNumberPercentage of
 
 
 
 
  (All households = 397) 
Rowing boats
31
78
94
78
252
63.5
0.7
Motor boats
20
28
16
10
74
18.6
0.2
Gill-nets
300
664
583
325
308
77.6
4.7
Hooks
2,542
11,799
9,224
4,792
100
40.3
79.9
Cast-nets
16
5
66
1
53
13.4
0.2
Lift-nets
3
0
11
38
34
8.6
0.1

Table 9

Total value of fish caught and sold in the sample villages in the Nong Wai irrigation area, the Nam Pong resettlement and the lake-side villages during 1977–1978 (from Suetrong et al., 1979)

CategoriesNong Wai
irrigation area
Nam Pong
Resettlement
Lake-side
villages
Fish caught   
Number of household
179
16
397
Value in baht
194,383
16,350
2,333,061
Average per household (baht)
1,086
1,022
5,876.7
Fish sold
 
 
 
Number of household
58
4
397
Value in baht
39,560
6,350
1,860,144
Sales per household (baht)
682
1,587.5
4,685.5

Capital investment in fisheries in Ubolratana reservoir was rather small. It was estimated to be on the average 594.56 baht per household in 1971 (Mekong Secretariat, 1972), and increased to 949.10 baht in 1978 (Suetrong et al., 1979). Although the average amount of capital investment was small, there were still some fishermen who did not have enough cash to invest. In case he could not afford to pay the total cost in cash, he would pay for part of it leaving the balance to be paid by installments. In some cases when the fisherman did not have any cash he would rely entirely on credit, in which case he would normally be obliged to sell fish only to his creditor, sometimes at a price slightly lower than that prevailing.

Fishing was an additional source of income for the 179 households in the sample villages in Nong Wai irrigation area. The total value of annual fish caught was 194,383 baht or 1,086 baht per fishing household. Of this amount, 80% was used for home consumption and the balance sold or bartered (Table 9).

Sixteen households in the sample villages in the resettlement area, a quarter of the total number of sample households, enjoyed some income from fishing. The fish they caught was valued at 16,350 baht, averaging 1,021.90 baht per household per annum. Only four households had fish left over from consumption for selling (Table 9).

In the lakeside area, 397 households in the sample villages engaged in fishing. The average household catch was 1,193 kg of fish annually worth 5,877 baht. Of these fish, they sold 947.3 kg (79.4% of the catch) worth 4,686 baht. The remaining 245.7 kg was consumed by the household (Tables 9 and 10).

The distribution of fish caught from Ubolratana reservoir starts daily early in the morning after fishermen return with their catch. Almost every lakeside village has one or more fishmongers who move about in motor driven boats. A fishmonger usually buys fish from fishermen who live in the same village and sells to the wholesaler at landing places, mainly at Tha Rua Ubolratana. There, the fish is sold principally to:

(a) the wholesalers who buy fresh fish for resale at retail markets;

(b) the fish processors who buy fish for fermenting, salting or smoking.

Those who buy fish for fermentation engage labourers, mostly women, to process it manually in the vicinity of the purchase area. Those who process the fish by salting and smoking buy only a few, mainly snakeheads and catfish, to process them in the backyard of their house, usually not far away from the landing place. The wholesalers occasionally arrive to buy the processed fish and take them to consumers, mainly in Khon Kaen, Udon Thani, and in the nearby provinces.

Table 10
Information on fishing, home consumption, sales, total production, prices, expenditure and profits in the sample villages in the lake-side area (from Suetrong et al., 1979)
ItemsNong RuaPhu WiangNon SangSi Bun RuangTotalPercentage
Number of fishing households
58
95
158
86
397
75.5
Home consumption
 
 
 
 
 
 
Total consumption (kgs.)
15,194.0
34,889.0
33,249.0
14,226.0
97,558.0
20.6
Average consumption per household (kgs.)
262.0
367.2
210.4
165.5
245.7
 
Total value of consumption (baht)
75,440.0
118,492.0
191,495.0
87,490.0
472,917.0
20.3
Average value of consumption per household (baht)
1,300.7
1,247.3
1,212.0
1,017.3
1,191.2
 
Total sales (kgs.)
100,970.0
162,334.0
71,069.0
41,696.0
376,069.0
79.4
Average sale per household (kgs.)
1,740.8
1,708.8
449.8
484.8
947.3
 
Total value of sales (baht)
478,280.0
666,459.0
456,475.0
258,930.0
1,860,144.0
79.7
Average value of sales per household (baht)
8,246.2
7,015.4
2,889.1
3,010.8
4,685.5
 
Total production
 
 
 
 
 
 
Total production (consumption plus sales) (kgs.)
116,164.0
197,223.0
104,318.0
55,922.0
473,627.0
100.0
Average production (consumption plus sales) per household (kgs.)
2,002.8
2,076.0
660.2
650.3
1,193.0
 
Total value of production (baht)
553,720.0
784,951.0
647,970.0
346,420.0
2,333,061.0
100.0
Average value of production per household (baht)
9,546.9
8,262.6
4,101.1
4,028.1
5,876.7
 
Price per kilogram (baht)
4.77
3.98
6.21
6.19
4.93
 
Fishing expenditure
 
 
 
 
 
 
Total expenditure (baht)
57,648.0
104,002.0
113,456.0
88,054.0
363,160.0
15.6
Average expenditure household (baht)
993.9
1,094.8
718.1
1,023.9
914.8
 
Profits
 
 
 
 
 
 
Total profits (baht)
496,072.0
680,949.0
534,514.0
285,366.0
1,969,901.0
84.4
Average profits per household (baht)
8,553.0
7,168.0
3,383.0
3,004.0
4,962.0
 

7. OVERALL PROJECT COSTS AND BENEFITS

The Government of Thailand has made considerable investment in developing the Nam Pong River Basin in Khon Kaen for hydroelectric power, irrigation, fisheries, flood control and recreation. It has been argued whether this project really serves these purposes and whether it has been worth the investment. To answer this question, Miss Sangsriratanakul (1981) of Mahidol University, Bangkok, Thailand, conducted a study on evaluation and reappraisal of cost-benefit analysis for this project. In her study she summarized all costs related to the overall project development as presented in Table 11. She assumed the project life is 50 years and gave the year 1966 as the base year for economic comparison. Summations of all annual costs including those incurred prior to 1966 are made to the year 2016.

The total project cost was estimated at 6,548 million baht. It consisted of 1,022 million baht for power features and joint use facilities at the Ubolratana head-work; 1,565 million baht for irrigation system; 331 million baht for resettlement development; 1,652 million baht for foregone output from forest, and 1,979 million baht for foregone output from paddy fields.

She also demonstrated the monetary value benefits from power generation, irrigation, flood control, fisheries and recreation. All of the anticipated benefits are summarized in Table 12. The overall project benefit is estimated at 11,644 million baht, comprising 2,948 million baht from hydroelectric power, 5,651 million baht from irrigation; 1,314 million baht from flood control; 1,651 million baht from fisheries and 80 million baht from recreation.

The benefit-cost ratio estimate was based on a project life of 50 years and interest rate of 6, 8 and 10%. It gives the ratio of 1.08, 0.91 and 0.77 for discount rates of 6, 8 and 10% respectively (Table 13). The outcome indicates that the project provides negligible benefits, in other words, it is a poor investment.

8. SUMMARY AND CONCLUSIONS

Since 1959, and especially after the completion of the dam in 1965, the Government of Thailand has been developing the Nam Pong River as a multiple-use water project for generating hydroelectric power, irrigation, fisheries, navigation, and recreation. The produced electricity is distributed to 8 provinces of the northeastern Thailand, namely to Khon Kaen, Udon Thani, Kalasin, Maha Sarakam, Roi-et, Chaiyaphum and Nakhon Ratchasima. The average annual energy production is 65 million kilowatt-hours.

The irrigation system of this project is designed to provide water for agriculture on an area of 42,287 ha. By the end of 1982 about 93% was completed, with the remaining 7% to be completed by the end of 1985. Two resettlements have been established, i.e. at Nam Pong in Khon Kaen province and at Non Sang in Udon Thani province. These resettlements have 4,000 families or about 20,000 persons.

The establishment of Ubolratana reservoir has provided an ideal fishery resource to the rural inhabitants, who are mostly rice farmers. Many farmers have become fishermen and they earn more income from fishing than from farming. The survey in 1978 showed that there were over 5,600 fishermen operating on this reservoir. The average annual fish catch was estimated to be 1,800 metric tons.

Table 11
Summary of the cost of the Nam Pong river development project (from Sangsriratanakul, 1981)
YearPower and joint use facilitiesIrrigation facilitiesResettlement 
 Construction costs MOM&Amp;A MTotal Cost MConstruction and OM&A, MTotal Project Cost, M (1)Forest foregone output M (2)Paddy field foregone output (3)Total project cost M (1+2+3)
Construction MOM&A MMain irrigation systemNong Wai on farm
1964
 
 
 
 
 
 
14.83
14.83
2.26
12.63
29.72
1965
 
 
33.78
 
 
33.78
14.83
48.61
2.46
14.31
65.38
1966
463.67
4.84
30.16
 
 
30.16
65.83
564.50
2.80
14.02
581.32
1967
 
5.90
54.69
 
 
54.69
5.83
66.42
2.56
4.02
73.00
1968
 
6.09
62.53
 
0.48
63.01
5.83
74.93
3.04
11.63
89.60
1969
 
6.33
64.59
 
2.01
66.60
2.92
75.85
2.56
18.42
96.83
1970
 
6.29
56.19
 
1.97
58.16
2.92
67.37
2.62
14.64
84.63
1971
 
4.33
50.36
 
1.98
52.34
2.92
59.59
3.02
12.01
74.62
1972
 
5.82
38.95
 
2.07
41.02
3.01
49.85
3.50
15.16
68.51
1973
 
4.83
35.79
 
3.04
38.83
3.01
46.87
5.61
19.75
72.03
1974
 
7.44
46.69
 
3.71
50.40
3.01
60.85
5.19
33.40
99.44
1975
 
10.88
28.90
0.18
3.41
33.39
3.01
47.28
1.93
32.75
31.96
1976
 
13.58
51.18
37.10
4.42
92.70
3.09
109.37
7.36
26.48
143.71
1977
 
11.46
30.22
146.36
2.15
178.73
5.12
195.31
7.15
26.74
229.90
1978
 
11.46
23.26
68.94
2.68
94.88
5.12
111.46
9.81
34.41
155.68
1979
 
12.40
110.46
62.10
3.67
176.23
5.12
193.75
12.26
41.68
247.69
1980
 
12.40
110.46
84.36
4.92
199.74
5.12
217.26
15.32
47.05
279.63
1981
 
12.40
-
58.56
5.99
64.55
5.12
82.07
19.16
46.38
147.61
1982
 
12.40
-
4.38
6.39
10.77
5.12
28.29
23.95
45.30
97.54
1983
 
12.40
-
4.96
6.39
11.35
5.12
28.87
29.94
46.64
105.45
1984
 
12.40
-
4.28
6.39
10.67
5.12
28.19
37.43
47.79
113.41
1985
 
12.40
-
4.78
6.39
11.17
5.12
28.69
49.79
46.88
122.36
After
 
 
 
 
 
 
 
 
 
 
 
1985
 
12.40
--
6.39
6.39
5.12
23.91
46.79
45.55
116.25
Total
 
 
 
 
 
 
 
 
 
 
 
1964–1985
463.67
558.05
828.21
467.21
260.66
1,564.86
330.72
2,917.31
1,651.62
1,978.59
6,547.52

Table 12

Summary of the benefits of the Nam Pong river development project (from Sangsriratanakul, 1981)

YearPower MIrrigation MFlood control MFishery MRecreation MTotal Project benefit M
1966
31.41
-
11.0
2.41
0.60
45.62
1967
38.33
-
11.1
3.88
1.21
54.52
1968
36.08
-
10.6
6.12
1.05
53.85
1969
34.30
2.99
11.1
12.90
0.90
62.24
1970
35.84
3.30
10.7
10.04
1.21
61.09
1971
45.58
3.29
10.4
16.79
1.47
77.53
1972
40.43
3.06
11.6
14.42
1.60
71.11
1973
29.68
20.59
14.3
18.79
1.54
84.90
1974
40.95
29.95
18.1
27.45
1.28
117.78
1975
40.32
38.46
20.2
18.15
1.10
118.23
1976
62.18
29.61
21.0
38.0
1.66
152.47
1977
55.20
0.94
21.8
38.0
1.68
112.62
1978
56.08
12.28
22.7
38.0
1.68
130.74
1979
59.43
38.24
23.6
38.0
1.68
160.95
1980
60.40
68.87
24.6
38.0
1.68
193.55
1981
61.39
106.76
25.5
38.0
1.68
233.35
1982
62.41
147.70
26.6
38.0
1.68
276.39
1983
63.17
154.13
27.6
38.0
1.68
284.38
1984
64.55
155.96
28.7
38.0
1.68
286.69
1985
65.65
155.96
29.9
38.0
1.68
291.19
After 1985
65.65
155.96
31.1
38.0
1.68
292.39
Total benefit
 
 
 
 
 
 
1966–2016
2,955.73
5,650.89
1,314.10
1,650.95
79.71
11,643.63

Table 13

Estimated benefit cost ratio of the project (with total costs) (from Sangsriratanakul, 1981)

 Interest rate 6 per centInterest rate 8 per centInterest rate 10 per cent
Consecutive Year YearAnnual cost MAnnual benefit MPresent worth factorPresent worth ValuePresent worth factorPresent worth valuePresent worth factorPresent worth Value
Cost M Benefit M cost M Benefit M cost M Benefit M
-196429.72-1.12433.40-1.16634.65-1.21035.96-
-196565.38-1.06069.30-1.08070.61-1.10071.91-
01966581.3245.621.000581.3245.621.000581.3245.621.000581.3245.62
1196773.0054.520.93468.8651.430.925967.5950.480.909166.3649.56
2196889.6053.850.890079.7447.920.857376.8146.160.826474.0444.50
3196996.8362.240.839681.2952.250.795876.8649.400.751372.7446.76
4197084.6361.090.792167.0448.380.735012.2044.900.683057.8041.72
5197174.6277.530.747355.7657.930.680650.7852.760.620946.3348.14
6197268.5171.110.705048.2950.130.632043.1744.810.564538.6740.18
7197372.0384.900.665147.9156.460.583542.0249.530.513236.9643.57
8197499.44117.730.627462.3873.860.540353.7263.600.466546.3854.92
9197581.96118.230.591948.5169.980.500240.9959.130.424134.7150.14
101976143.71152.470.558480.2485.130.463266.5670.620.305555.4058.78
111977229.90112.620.5268121.1159.320.428998.6048.300.350580.5739.47
121978155.68130.740.497077.3764.970.397161.8251.910.316849.6341.42
131979247.69160.950.4688116.1275.450.367791.0759.180.289771.7548.36
141980279.63193.550.4423123.6885.600.340595.2165.900.266373.6251.54
151981147.61233.350.417361.5997.370.315246.5273.550.239435.3355.86
16198297.54276.390.393638.39108.780.291928.4780.670.217621.2260.14
171983105.45284.880.371439.16105.800.270328.5077.000.197820.8556.35
181984113.41288.890.350339.73101.190.250228.3772.280.719920.4051.97
191985122.36291.190.330540.4396.230.231728.3564.460.163520.0047.61
20–501986–2016116.25292.394.2919498.931,254.902.4148280.72706.061.4008162.84409.58
 Total6,547.5211,643.53-2,480.552,688.70-2,054.911,879.32-1,774.831,379.97

Besides the capture fisheries in the Ubolratana reservoir, fish farming was also introduced into the project area. At present, there are 183 fish ponds with a total surface area of 31 ha and 96 paddy fields covering a surface area of 65 ha which are used for fish culture in the Nong Wai irrigation area.

Gill-net is the most popular fishing gear in the Ubolratana reservoir. Capital investment in fishing is low, less than 1,000 baht per year. Fishermen usually sell their fish to fishmongers who buy fish in villages and/or on fishing grounds. Fishmongers then transport the fish to landing centres and sell them to wholesalers. From there, the wholesalers transport the fish to retail markets which are situated mainly in Khon Kaen and Udon Thani provinces. The average annual income of a fisherman is estimated to be 5,000 baht per person.

The total cost of the Nam Pong river development project is estimated at 6,547.52 million baht and the overall project benefit estimate is 11,643.53 million baht. When based on the project life of 50 years, the benefit-cost ratio is estimated 1.08, 0.91 and 0.77 for interest rates of 6, 8 and 10% respectively. The project appears therefore to be uneconomic.

9. REFERENCES

Bhukaswan, T. and S. Pholprasith, 1977 The fisheries of Ubolratana reservoir in the first ten years of impoundment. Proc.IPFC., 17(3):195–205

Jaiyen, K. et al., 1979 Plankton. In Nam Pong Environmental Management Project Working Document Number, 13. Bangkok, Mekong Secretariat.

Jindarojana, J. et al., 1979 Water quality. Nam Pong Management Research Project Working Document Number, 11. Bangkok, Mekong Secretariat.

Mekong Secretariat, 1972 Socio-economic aspects of fishery operations in the Nam Pong Reservoir 1970–1971. Bangkok, UN/ECAFE

Nookour, A. and O. Pawapootanon, 1983 Fish population investigation in Ubolratana Reservoir. Annu.Rep.Ubolratana Reservoir Fish Res.Stn., (1981–1982):48–56 (in Thai)

Parkla, S. and A. Deerat, 1977 Fisheries operations in Ubolratana Reservoir in 1977. Annu.Rep.Ubolratana Reservoir Fish.Res.Stn., (1977):77–85 (in Thai)

Sangsriratanakul, O., 1981 Evaluation and reappraisal of cost-benefit analysis for dam and reservoir projects in Thailand. Master's Thesis, Mahidol University, Bangkok, Thailand

Sethaputra, S. et al., 1979 Hydrological studies. In Nam Pong Environmental Management Research Project Working Document Number, 10. Bangkok, Mekong Secretariat

Sidthimunka, A. et al., 1968 Fisheries surveys in Ubolratana Reservoir between 1965–66. Tech.Pap.Inland Fish.Div.Dep.Fish., Bangkok (6) (in Thai)

Srisuwantach, V., 1970 Hydrobiological studies of Ubolratana Reservoir. Annu. Rep.Fish.Biol.Surv.Unit, (1970):174–90 (in Thai)

Suetrong, S. et al., 1979 Socio-economic studies. In Nam Pong Environmental Management Research Project Working Document Number, 8. Bangkok, Mekong Secretariat

Ubolratana Reservoir Fisheries Research Station, 1984 Fish landing statistics at the Ubolratana Reservoir, Khon Kaen province during 1969–1983. Rep.Ubolratana Reservoir Fish.Res.Stn., (1)

Varikul, V. et al., 1980 Water weeds and studies on fish, fish production and productivity. In Nam Pong Environmental Management Research Project Working Document Number, 12. Bangkok, Mekong Secretariat

Wacharakitti, S. et al., 1979 Land use. In Nam Pong Environmental Management Research Project Working Document Number, 3. Bangkok, Mekong Secretariat

Watanadilokgul, K. and C. Sribanjaem,1982 Aquatic vegetation in Ubolratana Reservoir. Annu.Rep.Ubolratana Reservoir Fish.Res.Stn., (1981–1982):24–32 (in Thai)


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