The Ban Merbok area, Kedah state, in the west coast of Peninsular Malaysia has been considered as one of the depressed areas of the country for the 15 000 inhabitants who are mostly farmers.
In the early years from 1961, about 4 000 acres (1 618 ha) of swampland were reclaimed with the construction of a 20-mile (32.2 km) bund (coastal dike) and six drainage gates for tidal control along the estuary at the cost of M$1.351 million. The reclaimed land inside the bund were divided into small “padi” lots and distributed to small village farmers (Figs. 1, 2 and 3). The reclaimed swamplands have not been very productive probably due to the intrusion of sea water, lack of irrigation and inadequacy of drainage, development of an acid sulphate soil condition which resulted to poor soil quality and, generally inadequate infrastructure (Department of Fisheries Feasibility Study, 1978).
A consulting firm for the Kedah/Perlis development study was employed to identify and formulate projects for the development of the area and this led to the formulation of an integrated development project, approved by the Government for implementation. The project package includes agriculture, drainage and irrigation, public and social amenities and brackishwater aquaculture. The firm recommended a pilot project to determine the practical and economic feasibility of brackishwater aquaculture in the area, to be followed by a large-scale development when proven successful. The Government agreed to make further detailed study on the area as recommended by the consultant. The Government felt, however, that the studies include the areas outside the bund, as these areas are more suitable.
Feasibility study for the above development was necessary. Estimates were called from prospective consultants for this work. The consultant's financial proposal was found to be in excess of the allocation. After reviewing the consultant's proposal, it was felt that technical personnel from the Fisheries Department and from the Drainage and Irrigation Department (DID) possess the necessary qualifications and experience in implementing the study. In addition, the Swedish International Development Agency (SIDA) through Project RAS/40/SWE has agreed to support technical assistance to be implemented through the FAO/ UNDP South China Sea Fisheries Development and Coordinating Programme (SCSP).
The consultant's proposal was not implemented but instead a Project Task Force Team was organized to conduct aquacultural and engineering studies for the pilot project. The Project Team consisted of the following personnel:
Mr. Lam Wah Chang - Team Leader
Fishery Biologist
Penyelidikan Perikanan
(Fisheries Research Institute)
Glugor, Penang, Malaysia
Mr. Choy Siew Kiong - Member
Director for Fisheries for Kedah/Perlis States
Pengarah Perikanan Negeri
Alor Setar, Kedah, Malaysia
Mr. Saw Hin Seang
Engineer, DID Headquarters
Kuala Lumpur, Malaysia
Mr. Ricardo G. Hechanova - Member
Aquaculture Engineer Consultant
FAO/UNDP South China Sea Fisheries Development and Coordinating Programme
Manila, Philippines
Dr Banchong Tiensongrusmee - Member
Fishery Biologist (Shrimp Culture)
FAO/UNDP Brackishwater Aquaculture Development Project
Jepara, Central Java, Indonesia
1 M$ = Malaysian Ringgit; M$2.17 = US$1
The Government of Malaysia through the Fisheries Department of the Ministry of Agriculture, requested technical assistance to:
Assist in the selection of the site for family small-holder brackishwater demonstration and pond project and for a multipurpose hatchery at Ban Merbok and adjacent areas.
Prepare the design for the above-mentioned small-holder fishpond demonstration and identify sites for a multipurpose hatchery for the Ban Merbok aquaculture project.
Assist in planning the activities for future operation and management of the Ban Merbok Aquaculture Demonstration Project.
The engineering studies and design will be largely handled by the DID personnel in consultation with the aquaculture engineer consultant. The engineers, in consultation with the fishery biologists, conducted engineering studies including hydrological, hydrographic, tidal survey, topographic survey, soil investigation and survey, design of the farm civil works and construction methods. Design criteria were formulated by the Project Task Force and these were incorporated in an inception report submitted to the Fisheries Department.
The aquacultural studies were conducted in consultation with the Fishery Biologist consultant. These studies were on water supply, soil quality, survey on availability of fish/shrimp seeds, selection of the species for culture and farm management programme.
Further review of the design criteria were carried out by the Project Team as more data were available.
Services of technical advisers from the SCSP were requested from time to time. In consultation with the technical advisers, farm income of each individual farm unit will be reviewed.
With more data available, the groundwork for the following activities were also carried out:
A programme of pre-construction activities for the year 1979 is included as Annex A.
Based on the recommendations of Jamandre and Rabanal (1975), the swampy area at the Sungai Merbok (Merbok river) estuary in the state of Kedah was identified as one of the best sites for development for fishponds along the west coast of Peninsular Malaysia. The study sites, inside and outside the bund, are situated along the Sungai Merbok in Kuala Muda, District of Muda village. It is approximately bounded within the parallels of longitude of 100° 25' and 100° 26' east and between the parallels of latitude of 5°20' and 5°30' north.
The areas are about 4.35 miles (7 km) from the coast (Fig. 3). Outside the bund, the area is bounded by Sungai Gelam (Gelam river) in the west, Sungai Merbok in the south, Sungai Keluang in the east and the Ban Merbok bund in the north. Inside and along the bund, the area consists of vacant and untilled, fallow lands of about 62.32 ha (154 acres).
The area outside the bund is a mangrove swamp with vegetation of medium density consisting of the species of Rhizophora and Sonneratia, roughly about 500 trees to a hectare and with average trunk diameters of from 0.05–0.20 m (2–8 in). Drainage system is formed by a network of tributaries: Sungai Keluang, Sungai Gelam, Sungai Petani and Sungai Terus. Sungai Petani has its upstream end at the Sungai Petani town of Kedah. All these creeks drain into Sungai Merbok, a fairly large river, and finally towards the mouth at Tanjong Dawai (Dawai delta). a big volume of flow during high tide is observed at Sungai Gelam due to the surrounding bund.
The climate on the west coast of Peninsular Malaysia is suitable for brackishwater aquaculture. There are no typhoons, no high waves and destructive floods and currents that may damage the dikes. Rainfall records at Sungai Petani rainfall station indicate two periods of maximum rainfall. The higher of the maximum generally occurs in the months of September and October with a mean monthly total of 33.52 cm (13.20 in) in October; the months of April, May and June with a mean monthly total of 24.89 cm (9.58 in) in June. The lower minimum occurs in January and February with a mean monthly total of 6.98 cm (2.75 in) in January and the secondary minimum in July and August with a mean monthly total of 15.59 cm (6.14 in) in July. The maximum rainfall recorded in a day during a ten-year period from January 1968 to September 1978 was 7.21 cm (2.84 in) of rain in the month of October. October has the most number of rainy days (20 days).
Air temperature during the same ten-year period was 93.9°F (33.88°C) maximum recorded during the month of March and 71.6°F (22.00°C) minimum recorded during the month of January.
Records of observation of the duration and variation of bright sunshine using a Campbell-Stokes sunshine recorder have been maintained by the Malaysian Meteorological Service since 1963 and the data for the period 1963–1972 for the site (Alor Setar data) are presented in terms of mean duration (Fig. 4). It is shown in the figure that the period of bright sunshine applies especially during February to April inclusive and that the average sunshine applies throughout the year. Maximum sunshine is received between 0900–1400 (local standard time) during the months of February to April and in general, the variation of time of duration of sunshine is received from 0800–1400 throughout the year, except September and October when the variation of time is from 0800–1200. The mean annual total sunshine hours is 2 544. The mean monthly values of effective sunshine (amount actually recorded) are shown in Fig. 5. Least sunshine occurs during September and October and the most sunshine occurs during the months of March and April.
The study area is generally flat and slopes gradually towards the Merbok river with an average elevation of 0.915 m (3.0 feet) above Land Survey Datum (LSD)1. A topographic map of the proposed project areas inside and outside the bund is shown (Fig. 7).
Preliminary soil analyses were made in the month of July at areas inside the bund, outside the bund and at the river bottom of Sungai Gelam. Table 1 gives the analyses data for organic matter, textural grain size distribution and pH. Disturbed soil samples were taken at 0.915 m (3.0 feet) below the ground surface. Extensive soil sampling is being conducted at the time of writing this report.
Textural grain size distribution of the soil inside the bund gives three classes of soil types as clay loam, loam and sandy clay loam. For use in embankments, these would, with close control during compaction, give compaction characteristics as fair to good and with low permeability, and a good to fair resistance to piping. Ability to take plastic deformation under load without shearing would be rated as from good to poor for the soil.
The soil outside the bund has a fairly high organic content and this would give a poor to fair property for use in embankments. This would lead to a more conservative design for the dikes and infrastructure facilities.
LSD is 1.42 m above chart datum, taken to be the reference datum plane of elevation 0.00 m (Tide Tables for Malaysia and Singapore, 1979). A bench mark was established by the survey party at Sungai Segantang Garam control gate, at elevation 3.00 m above chart datum.
Tidal records were taken at Sungai Merbok with the installation of two stick gauges and an automatic tide gauge. Annex B gives the tide data from stick gauges for S. Keluang and S. Segantang Garam for the period from 1 August to 30 September 1979.
Tide tables showing predicted tides for the site give Penang as the standard port with Tanjong Dawai as the secondary port. The predicted times and heights of high and low waters from 1 August to 4 September 1979 for Tanjong Dawai were calculated (Annex C) and the data were used in the determination of the ratios of tidal ranges (Table 3).
The highest low water occurs in four days of the months of February, May and June (in 1979) with a predicted height of 1.4 m1 and the lowest of the high waters occurs in two days of the months of February and March with a predicted height of 1.6 m (5.25 feet) 2 (Fig. 9).
The determination of the pond bottom elevations, in order to make the most of the high water tidal flow will necessarily be at 1.4 m (4.59 feet). At this elevation, drainage is possible during the above-mentioned times when low water is at its highest. When high water is at its lowest value of 1.5 m (4.92 feet), there will be insufficient tidal flow to fill the ponds. The use of pumps to provide water change during the period would be necessary for increased water movement for aeration, water temperature control, and filling of the ponds.
The predicted highest high water level is 2.9 m (9.51 feet). This would serve as a basis for the tentative determination of the elevation of the top of the perimeter dike in the absence of an appropriate data for highest astronomical tide. A freeboard of 0.60 m (2:0 feet), it is believed, would give sufficient provision against overtopping during heavy rains that occur during high water.
The tides are generally semi-diurnal throughout the year except for a few isolated days during which mixed tide is experienced. These tides generate variable water stages in the Ban Merbok estuary (Fig. 8).
The suitability of Ban Merbok area for a fishpond site based on tidal water supply in relation to the ground elevation at the site is shown in Fig. 9. The tide levels at Tanjong Dawai obtained from tide tables are as follows:
2 Tide Tables, 1979 for Malaysia and Singapore
| Mean high water spring (MHWS) | = 2.7 m (8.85 feet) |
| Mean high water neap (MHWN) | = 1.9 m (6.23 feet) |
| Mean low water neap (MLWN) | = 1.3 m (4.26 feet) |
| Mean low water spring (MLWS) | = 0.5 m (1.64 feet) |
| Mean tide level (MTL) | = 1.6 m (5.24 feet) |
The pond bottom elevation in relation to these tidal ranges would approximate the level of mean higher low water or mean high water neap, a value of 1.9 m (6.23 feet). A minimum value of 1.4 m (4.59 feet) is preferred.
The deviation of the tidal fluctuation on the farm site from that predicted in the tide tables was measured by setting up tide gauges that observe the tide at two rivers adjacent to the farm site. Table 3 gives the ratios of the tidal range at Tanjong Dawai to that at the Ban Merbok proposed sites.
