2. SITE SELECTION

2.1 Criteria for site selection

(03) The Terms of Reference given to the Soil Specialist restricted site selection for BFRS to the Khulna District. It was clarified, that Khulna District would mean the “old” Khulna District, recently divided into 3 new districts: Khulna, Bagerhat and Satkhira.

(04) Other important criteria given for selection of the site are as follows:

• the site should comprise at least 52 acres (21.5 ha);
• the site has to be located in a place representative for the greater part of the penaeid shrimp culture area in the region;
• the site should be easily reachable by road and not too far from a main city with adequate provision of schools and medical care;
• the land should be available on short notice.

It was also felt that the station should be located within or adjacent to a good human habitation and not isolated from it.

(05) The research plan for BFRS, prepared by the Shrimp Specialist Dr. A.N. Ghosh, requires inter alia construction of 12 unexcavated ponds, covering 7.5 ha area. It is assumed that at least 0.5 m water depth would be desired in those ponds for about 2 months from January, 0.5 – 1.0 m or more depth for the rest of the year, and that the ponds could be completely drained at every low tide. The research programme as drawn up would also require about 5 – 7 ha of high land, safe from tidal inundation, for construction of laboratories, hatcheries, offices, and residential buildings and roads in the experimental farm complex itself.

2.2 Site searching

(06) While searching for a site the following major questions were kept in mind:

• is the site easily approachable, particularly by road?
• is the site close to a main city?
• is the site within or adjacent to a good human habitation with reasonably good facilities for school and college education, drinking water, health, and marketing?
• is the site within a large production area for (penaeid) shrimp?
• is the land elevation suitable to allow the site to have 0.5 – 1 m depth of tidal water throughout most part of the year and be completely drained at any low tide?
• will the water salinity be 10 – 25 ppt at least for 4 – 5 months for good growth of penaeid shrimp (particularly Penaeus monodon, Bagda chingri) and for hatchery operations with Macrobrachium rosenbergii, Golda chingri (10 – 12 ppt)?
  (N.B.: Appropriate water salinity for a penaeid hatchery is 28–32 ppt; this salinity is not expected to occur naturally in the Khulna region).
• is the soil texture heavy enough (clay, silty clay, silty clay loam) to be suitable for pond dyke construction and water retention?
• is the soil pH within a suitable range (6.5 – 8.5) for good survival and growth of shrimp and fish?
• does the site include soil types most representative of the region?
• will the river/canal for water supply remain sufficiently deep and active for at least 10 years?
• are there good sources of fresh water near the site?
• is any suitable land owned by the state available for the research station?
• will the selected land be quickly available?
• is the land within any existing polder to allow site development and pond construction at a low cost?
• does the land already have sufficient raised area for undertaking construction of buildings immediately and without land filling and waiting for land settlement?

(07) With the above questions in mind, the following organizations were contacted for broad information:

• Water Development Board (WDB),
  Surface Water Division,
  Ground Water Division;
• Road and Highway Department (R&H);
• Directorate of Fisheries (DOF);
• Soil Resources and Development Institute (SRDI);
• selected District and Upazila administrations;
• private shrimp farmers.

(08) To begin with, every upazila with substantial shrimp farming activities was considered to be a prospective place. Most of these upazilas have at least some arguments in favour of siting the station in them. However, it is the intention to conduct research on various aqua-agro farming systems for the brackishwater region in one single research station. Therefore the environmental requirements for such a diversified programme were critically analyzed, together with the accessabilty of the sites, and it proved that most of the upazilas could be screened out. In fact only 5 upazilas survived this preliminary selection, based on accessability and salinity only. These upazilas were:

• Rampal and Mongla in Bagerhat District;
• Paikgacha in Khulna District;
• Satkhira and Kaliganj in Satkhira District. Another upazila, Shyamnagar, located on the westernmost part of Satkhira district, was also included in view of certain special considerations described in section 2.4.5.

(09) In these 6 upazilas closer studies were made and 9 potential sites were identified (annex A):

• 2 sites in Rampal upazila (“Rampal R&H”, “Rampal town”);
• 1 sites in Mongla upazila (“Digraj”);
• 3 sites in Paikgacha upazila (“Shiberbati-south”, “Shiberbati-north”, and “Batikhali”);
• 1 site in Satkhira upazila (“Benerpota”);
• 1 site in Kaliganj upazila (“Kaliganj”);
• 1 site in Shyamnagar upazila (“Munshiganj”).

2.3 Supporting data

(10) Relevant hydrological data (computerized or otherwise) on tides, ground water levels, rainfall, evaporation, and river salinities were collected from the WDB. Some salinity data were also collected directly by the consultant. General information on soil was made available by the SRDI.

(11) The tidal and salinity data maintained at Mongla have been used for the Rampal sites. The data recorded at Bajua Hydrological Station of the WDB have been applied to Digraj. The information provided for the sites in Paikgacha is almost site specific. The tidal data used for Kaliganj actually refer to those recorded for the Ichamati River at Basantpur.

(12) The topographic surveys for the sites in Rampal and Paikgacha were carried out with the help of the WDB. The soil sampling and laboratory analyses were made through BARI and SRDI.

(13) Data collected from the various sources or generated as a result the consultant's field work are appended to this report. They comprise:

• Tide water levels (Annex B);
• Calculated tidal inundation (Annex C);
• Salinity (Annex D);
• Soil associations (Annex E);
• Distribution of acid soils (Annex F);
• Distribution of saline soils (Annex G);
• Rainfall (Annex H);
• Temperature, evaporation, humidity and sunshine (Annex I);
• Sites surveyed for soil quality (Annex J (I-V));
• Soil texture, pH and nutrient levels (Annex K (I-V));
• Proposed site at Munshiganj (Annex L).

2.4 Site evaluation

2.4.1 General

(14) For judging the degree of suitability of the sites, a point and ranking system was applied. Depending on the relative importance of the factors considered, various scores were assigned to various factors, dependent on their degree of relevancy. The results of this exercise were laid down in one comparative table (Table 1). The scores of the sites under review were then added to develop a ranking order.

Table 1 - Comparison of sites
(figures between brackets mean the rate given for the item of evaluation)

Table 1, could not be completed, however. Full marking of all the sites was not possible because of lack of information and therefore not all sites could be ranked. This was not considered a large problem, since absence of information appeared to be highest in sites that were of lesser interest (far from city, low salinity etc.).

(15) The ranking system as practized in Table 1 poses a problem: the system awards a certain value to a large number of factors some of which are of lesser importance. The total score on account of the less important factors may be quite high and may unduly overweigh the crucial factors, leading to erroneous judgment of a site. Therefore it is necessary to score these crucial aspects separately. For a brackishwater research station under Bangladesh conditions those aspects are:

• Tidal inundation should be at least 0.5 m during January - February, and above 0.75 m (preferably 1 m) for another 6 – 8 months or more;
• The land should be completely drainable during any month;
• Water salinity of the supply river/canal should be above 10 ppt for at least two months to allow hatchery experiments with M. rosenbergii;
• Soil should be rich in clay, so that water can be effectively retained in the pond without much seepage loss either horizontally or vertically;
• Soil pH should be neutral or slightly alkaline. But it would be most ideal if the site comprises a few of the most representative types of soil (viz. non-acidic with or without calcium carbonate, slightly acidic, acid-sulphate and peaty or mucky layers), suitably arranged, permitting pond grouping for experimentation around the varied soil pH which would govern pond productivity;
• Proximity to a good human habitation, with freshwater sources of acceptable quality, and facilities for marketing, health care and education upto college level;
• The supply river must stay active at least for 10 years.

(16) Table 2 presents a ranking of the nine sites based on the crucial aspects only. The relative position of the sites obviously has changed as compared to Table 1. Irrespective of the total scoring, a site fails to qualify for the proposed research station if it does not fulfil the minimum requirement of any of the crucial aspects.

Table 2 - Ranking of 9 sites based on selected crucial factors

F Fails (disqualifies)

a) 1 = RAMPAL R & H;
    2 = RAMPAL TOWN;
    3 = DIGRAJ (MONGLA);
    4 = MUNSHIGANJ;
    5 = KALIGANJ;
    6 = BENERPOTA;
    7 = PAIKGACHA-SOUTH SHIBERBATI;
    8 = PAIFGACHA-BATIKHALI;
    9 = PAIKGACHA-NORTH SHIBERBATI.

b) Not actually surveyed; figures based on interviews and personal judgment.

c) Salinity is perennially high, precluding the site from being considered for paddy-cum-fish/shrimp culture research. The site is very suitable for perennial culture of P. monodon and other penaed shrimp and brackishwater fin-fish.

(17) From the comparative Tables 1 and 2 it can be noted that none of the sites fulfils all the desired conditions at the most satisfactory level, as could be expected. Some weak points and strong points of the most qualified sites are highlighted in the following sections.

2.4.2 Shiberbati-north site

2.4.2.1 Strong points

(18) Among all the places considered, Shiberbati-north (Paikgacha) has the best combination of water salinities required for the proposed integrated research on:

• Penaeid shrimp culture;
• Macrobrachium hatchery operation during several months;
• Aquaculture in rotation with paddy.

(19) This site has also the best combination of soil types characteristic for the shrimp culture areas in the Khulna region. The site comprises non-acidic soils of calcareous and non-calcareous types, soil with low pH and also soil with a mucky layer. Thus the site will offer an opportunity to carry out problem-oriented research on pond construction in the various types of soils, and also on management of low-pH soils under varied conditions of use of fertilizer, soil texture, pH, nutrient availability, etc. It may be mentioned that the site comprises about 20 acres of calcareous, 22 acres of non-calcareous and non-acidic, and 30 acres of acid soil in more or less well-defined segments; this will allow construction of pond groups under various soil conditions.

Extensive shrimp culture areas in the Khulna, Barisal and Cox's Bazar regions have soils with varying degrees of acid problems. Such areas can be utilized only for one crop of paddy during the wet season when the soil acidity remains suppressed due to the overlying water on the field. During the dry season, the underlying acid (so also salt) rises to the top due to capillery action and may not allow any second crop to grow on economic basis. Irrigation with river water is not feasible since the river water is saline during dry months. Keeping the land submerged with tide water immediately after paddy harvesting and utilizing the field for brackishwater aquaculture is possibly the most desirable way to optimize utilization of lands having acid (so also salt) problems. Currently, large areas of such land are under shrimp culture with fluctuating results. The farmers often face baffling problems, like softshellness, sponginess in the muscles, slow growth and mortality of the shrimp; these problems are likely to originate from soil acidity. In view of the vastness of such problem-lands, systematic aquaculture research to find out appropriate management techniques for acid soils is essential. This type of research can be conveniently integrated at the Shiberbati-north site.

(20) The predominant soil association in Paikgacha upazila is Barisal-Pirojpur (B-P) type. This soil assocation covers the highest percentage (24.8) of the total tidal flood plain area in the Khulna region. For comparison, it may be mentioned that the predominant soil association in Rampal is Barisal-Dumuria (B-D), which represents 9.6 % of the total tidal plain area in the Khulna region (Table 3). The contribution of B-P association in Paikgacha is 57 % while the B-D type makes up 40 % of the soil association in Rampal. The distribution of the two soils is given in Table 4. Improved farming techniques to be developed under Paikgacha soil conditions may be of direct relevance to the greater part of the region.

(21) Tidal inundation well over 60 cm will be possible even during the leanest tidal phase.

(22) Since the site is situated within a WDB polder, massive perimeter dykes can be obviated. Not much land would be occupied by the two side perimeter dykes. Land development will also be easier than in an open place ouside a polder.

Table 3 - Percentages of various soil associations in the Ganges tidal floodplain area in Khulna region

Table 4 - Distribution of Barisal-Pirojpur and Barisal-Dumuria soil associations by upazilas

(23) The Shiberbati-north site is situated close to the World Bank supported shrimp culture project in polder 20. There will be opportunities for constant feedback between research and development, which is most desirable for successful extension purposes.

(24) Since Paikgacha town is located more or less centrally in the greater Khulna district, shrimp and fish seed surveys over the entire region can be carried out quite advantageously from this site.

(25) The site has a few creeks, at least one of which can be used as a natural srainage canal. One of the canals is in fact already in use as an outlet from the field. However, control of the outlet sluice may require a satisfactory arrangement with the WDB.

(26) Being located within the WDB polder, the town is already fairly well developed with playgrounds and open spaces for recreational purposes.

2.4.2.2 Weak points

(27) Location of the site is such, that about 10–15 acres of land (in excess of the proposed 52 acres) will have to be acquired in order to be contiguous with the DOF fish seed farm and a neighbouring community. (Acquisition of extra land will be required for the second best site (Rampal town) also, although the land is expected to be cheaper there).

(28) About 15 km of the Tala-Paikgacha road is still to be tarred; the brick-soled road in its present condition does not allow comfortable and quick transportation. The local administration is however hopeful that the road will be metalled during the current financial year. They also report that tenders have been called for undertaking the construction work during the current financial year (1986–87).

(29) Use of the natural creek for drainage of the project saline water may cause problems. The owners of the neighbouring paddy fields may object to saline water discharge through the creek running accross the paddy fields. However, there will be no agricultural activities in the field from January - mid July, which represents the main shrimp culture season. From July until November the salinity will be low and the monsoon water is expected to remove any deletarious effects of salinity from the land bordering the creek.

(30) The portion of the river adjacent to the site forms a deep loop. A small shoal appears near the site-ward bank. The WDB engineer (Mr. Khalilur Rahman Bhuiyan, Executive Engineer, Khulna) rules out the possibility of any river blockage by shoaling at the region in question in near future. A similar view was also expressed by an experienced soil scientist (Mr. Abul Kalam) of SRDI, Khulna. However, it may be appropriate to further examine this matter when this site is selected.

(31) The advantage of having a variable soil profile at the site (see (19)) may also be a disadvantage from the point of view of experimental designs. Carrying out of practical pond research requires simultaneous repetitions, and this, in turn, requires an as even as possible distribution of soil factors. In other words: detailed design of the experimental area in this site will ask for a very elaborate soil sampling exercise. Pond designing itself should be done with utmost care.

(32) Since culture experiments on soil as it exists in its original condition would be most desirable, it would not be advisable to remove the top soil to construct dykes or for other purpose. This means that much of the dyke material may have to be borrowed from outside the perimeter dykes; this will lead to an extra cost. However, the importance of practical research in brackishwater aquaculture is so great that the extra cost may be well justified.

2.4.3 Rampal town site

2.4.3.1 Strong points

(33) The soil is physically and chemically very uniform: mostly silty clay -silty clay loam in the upper strata of about 150 cm and thereunder silty loam or fine sand loam. The pH of the soil is above 7 throughout. Experimenting the effects of certain introduced variable factors will be quite convenient in such a site, since a series of identical pond conditions can be created.

It must, however, be noted that the most commonly encountered soils in the mangrove areas are not as ideal as the soil at this site and therefore results from the experiments will always have to be tested under a series of deviating circumstances in field trials.

(34) The site is only 45 minutes drive from a big city (Khulna), which is well linked with all the major cities in the country. The Mongla port is only 24 km by road, and about 7 km by river. This will permit shrimp seed surveys in the Sundarban mangrove areas quite conveniently by a mechanized boat. It will also easily link laboratory work (quality control) at the station with practice in the processing plants in Khulna and Mongla.

(35) A tidal creek suitable for use as a natural drainage canal exists at the far end of the site.

(36) Land is offered by most of the owners themselves for the research station; so land acquisition is not likely to be a problem. The local Shrimp Growers Association showed positive interest in co-operation.

2.4.3.2 Weak points

(37) If no excavation is carried out at the site, about 7 ha extra land as source of fill material is required for perimeter dykes and a building area for offices, laboratories and residences. The four massive dykes will occupy about 3 ha, which is lost for other purposes. Construction of the dykes will be rather expensive.

(38) The tidal inundation is such that excavation of ponds is needed. In fact, The land is high compared to the spring tide levels so that supply and maintenance of appropriate water depth will not be possible for 5–7 months without massive excavation (Annex C).

(39) The river side dyke will have to be constructed 76 m away from the river bank, leaving a strip of about 70 m wide between the existing care road and the project dyke. This strip of land will remain without any specific purpose, unless the research programme could make a special use of it.

Situated on the south of the site, the Mongla river is very wide. The characteristic southerly and southeasterly wind is strong and prevalent from March-October. This means that the northern dyke along with any water control sluices of the project will be subject to continuous threat from wind and wave erosion. Expensive measures will be required to protect the structures.

(40) Construction of buildings on unsettled land is technically more difficult. This will however be more or less true for other sites also.

(41) The town (Rampal) and the adjacent unions are not protected by tide control dykes, so that the whole area looks almost immersed during every high tide, leading to a psychological depression for outsiders. It causes also non-existence of recreational facilities in the form of playgrounds; if they are wanted they will have to be created inside the residential area at the site itself.

(42) The relatively low river salinity would allow operation of a Macrobrachium hatchery at best for 2–4 months.

2.4.4 Kaliganj site

2.4.4.1 Strong points

(43) 20 acres of Government land are available; the site is within a WDB polder, so that land development costs will be low.

(44) Favourable salinity for a Macrobrachium hatchery will be available for at least 4 months. The Kakshiali river is a rich source of P. monodon seed.

2.4.4.2 Weak points

(45) From the heavy siltation trend in the Kakakhali area, the WDB-engineers maintain reservation about the future of the Kakshiali river, the source of water for the Kaliganj site. The silt load in the river throughout the year is very high.

(46) The site is located at a far corner and not in a central place in the region. The approach road to the site is very narrow and would be difficult to widen and improve for motor vehicles.

(47) The town is divided into two parts isolated by the Kakshiali river. This will create many practical problems for the research personnel either to discharge their official duties or to attend their personal matters. An underground freshwater source is unlikely to be available nearby.

2.4.5 Munshiganj site

(48) Tables 1 and 2 indicate that this site does not fulfil the requirements of the proposed research station. One of the fundamental research objectives of the station would be to generate further knowledge to optimize land productivity through integrated development of agriculture and aquaculture. In the Shyamnagar area, the river salinity throughout the year is too high to permit meaningful integration of paddy and shrimp. Year round salinity information in the area is not available, but the level is probably never below 8 ppt. The consultant recorded 16 ppt salinity on 29 August 1986 in the meeting point of the Kadamtoli and Chunar rivers at Munshiganj Bazar. On the same day the salinities in the Kakshiali river at Kaliganj and the Sibsa river at Paikgacha were respectively 6 ppt and 2 ppt.

(49) In the southern parts of Satkhira and Khulna, extensive high saline areas exist. Parts of them are already under shrimp culture. Extensive high saline areas also exist in the Cox's Bazar zone. These areas offer excellent opportunities to practice year-round culture of penaeid shrimp. Three crops a year are possible. The Munshiganj site can be considered representative for those circumstances.

(50) Seeds of P. monodon and of some other valuable and culturable species of shrimp and finfish are reportedly available throughout the year. The P. monodon seed price drastically declines during June-November; in this period salinity in the upper areas remains quite low and the farmers do not stock their ponds. Most of the seed is wasted in nature and the seed collectors get unemployed or underemployed. If culture activities could expand both in time and in areas, the valuable seed resources would find avenues for economic utilization. This development could take place in the typical high-saline areas mentioned in (49).

(51) In view of the large production potential of the perenially high saline areas, a part of the research programme should be related to them, e.g. for development of rather intensive, year-round shrimp farming systems. Establishment of a research sub-station at a suitable place may be worth considering for this purpose. The Munshiganj site apprears to be a suitable place. A 20 acre site has been identified (Annex M).

(52) In addition to research on year-round penaeid shrimp and selected fish culture, such a sub-station can be used for seed survey activities. The Munshiganj area is known to be very rich in the seeds of P. monodon and varieties of other culturable shrimp and fin fish.

2.5 Site demarkation

(53) Only tentative demarkation of the best site has been made in the report (Annex J-V). It was felt that exact delineation of the site could best be suggested by the Aquaculture Engineer. Given the opportunity to adjust the shape and exact position of the site with relation to the soil quality and the existing natural creeks, the Engineer could design the pond complex most effectively. However, based on the topographic survey map and the aerial photographs, it has been estimated that the site would approximately measure 850 × 300 m = (25.5 ha or 63 acres). The internal creeks belonging to the Government would possibly measure 1.5 ha. This area subtracted, the net area for acquisition would stand at 24 ha or 59 acres. These preliminary data will be made final by the Aquaculture Engineer.