The Hydrobiological Conditions of Kallang Basin Introduction
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Coastal Living Resources of Singapore: Procee dings of a Sympo sium on the Assessment of Living Reso urces in the Coastal Areas of Singapore. THE HYDROBIOLOGICAL CONDITIONS OF KALLANG BASIN Timothy T. S. Chua and Maylene G. K. Loo Department of Zoology National University of Singapore Lower Kent Ridge Road Singapore 0511 ABSTRACT Kallang Basin was an extremely polluted body of water in the mid- l 970s . In 1977, a ten-year urban clean-up and re-development project of Kallang Basin and its catchment area was started. In February 1987, near the completion of the project, a preliminary hydro-biological survey was conducted. This was followed by a second survey in February of 1988 which showed a marked increase in the number of families of marine organisms from 27 to 51. This re-emergence of life in the Basin could be attributed mainly to the efforts of the clean-up project. INTRODUCTION Located on the south-eastern sector of the Singapore mainland, the Kallang Basin catchment area, together with the Singapore River catchment area, make up about one sixth of the total land area of Singapore (Fig. 1). The Basin itself, is enclosed by the Fig. I Map of Singapore showing Singapore River/Kallang Basin catchment area (shaded) 9 reclaimed land that is now Marina Center to the west, Kallang Park to the east, and what was once Kampong Bugis to the north. The catchment area however, ranges from Ang Mo Kio Industrial Park in the north to Tanjong Rhu in the south. Five main rivers are located within the catchment area, though only three rivers actually open into the Basin. This is because the Pelton and the Whampoa rivers open into the Kallang River, which then flows into the basin proper. The other two rivers are the Geylang and Bukit Timah/ Rochor Rivers (Fig. 2). The basin itself has a water surface area of approximately sixty hectares (Chiang , 1986). The clean-up programme had to be implemented because in the preceeding years, pollutants of various forms from all over the catchment area had adversely affected the waters of the basin . From the outlying areas of the basin 's catchment area, wastes from the thriving pig and duck farms emptied into the basin via the main rivers as the farms were set up mainly along the Whampoa and Kallang Rivers (Fig. 2). f\t its peak in 1977, there were 610 pig farms and 500 duck farms rearing a total of 75,600 pigs and 125,000 ducks (Chiang , 1986). From the central part of the catchment area, rampant and unchecked street hawking, backyard industries and wholesale markets emptied large amounts of filth and pollutants into the basin via the drains and canals . Sanitary facilities I \ \ \ ) I \ '\ ' r ( ,, _; / \ \ ' ' ....- ...... STREET HAWKERS • LIGHTERS/ BOAT YARDS * PIG FARMS * DUCK FARMS 0 2 Q FRUIT/ VEGETABLE WHOLESALERS km kd UNSEWERED PREMISES Fig. 2 Singapore River/Kallang Basin catchment area 10 were also of a poor standard and state, or even non-existent. Many of the residential areas within the catchment area were not properly sewered, and sanitation facilities were not only very primitive, but also in dilapidated conditions. Due to the large variety of activities in the area, many squatter colonies soon emerged and populated a large part of the catchment area. A significantly large portion of the activities was situated in areas near the main rivers that formed the catchment area, resulting in the direct emptying and dumping of rubbish, excreta and toxic substances into the basin (Chiang, 1986). The banks of the basin soon became heavily littered and congested with debris, flotsam, dead and decaying carcasses of animals. The waters of the basin darkened , and an oily layer could be clearly seen. A strong stench of hydrogen sulphide also became an ever present feature of the area. Marine life in the area declined, and the basin soon became a badly polluted body of water. After careful consideration and planning, a ten-year clean-up and re-developn:ient programme of the basin and its catchment area commenced in 1977. This programme involved the removal of the root causes to the pollution by relocation of farms, hawkers, lighters and boatyards, resettlement of squatters and upgrading of sewerage and drainage systems, the actual cleaning up of the basin and its rivers , re-development of the cleaned up areas, and proper education and enforcement as to the laws regarding littering and pollution and to the use of catchment area. The project was completed in mid-1987 (Ministry of Communication and Information, 1987). However prior to its final completion, a two-day hydrobiological survey was conducted of the basin, followed a year later by another similar survey. The surveys were conducted in February of 1987 and 1988. MATERIALS AND METHODS Two field surveys of the Basin were carried out, each survey being of two days duration. The first survey was carried out on 5 and 6 February 1987, and the second on 4 and 5 February 1988. Six sampling stations covering the whole Basi,n were selected (Fig. 3). The following physico-chemical parameters were taken at the six sampling stations: salinity, conductivity, dissolved oxygen content, temperature, pH and light penetration. Light intensity readings were taken only during the second survey . All the parameters, with the exception of light penetration, were recorded at half-metre intervals along the water column. All physico-chemical parameters were recorded in situ. Salinity and temperature were recorded using a portable YSI model 33 Salinity Conductivity-Temperature meter. Dissolved Oxygen values were recorded using the portable YSI model 57 Oxygen meter. A portable pHOX 52E Conductivity meter was used to measure water conductivity. pH values at the various depths were measured using a hand-held electronic pH meter, with water samples from the various depths collected by a water sampler. Light penetration was measured with the use of a Secchi disc. A LI COR underwater light sensor was used to measure the variation of light intensity with increasing depth. 11 .., were also of a poor standard and state, or even non-existent. Many of the residential areas within the catchment area were not properly sewered, and sanitation facilities were not only very primitive, but also in dilapidated conditions. Due to the large variety of activities in the area, many squatter colonies soon emerged and populated a large part of the catchment area. A significantly large portion of the activities was situated in areas near the main rivers that formed the catchment area, resulting in the direct emptying and dumping of rubbish, excreta and toxic substances into the basin (Chiang, 1986). The banks of the basin soon became heavily littered and congested with debris, flotsam, dead and decaying carcasses of animals. The waters of the basin darkened, and an oily layer could be clearly seen. A strong stench of hydrogen sulphide also became an ever present feature of the area. Marine life in the area declined, and the basin soon became a badly polluted body of water. After careful consideration and planning, a ten-year clean-up and re-development programme of the basin and its catchment area commenced in 1977. This programme involved the removal of the root causes to the pollution by relocation of farms, hawkers, lighters and boatyards, resettlement of squatters and upgrading of sewerage and drainage systems, the actual cleaning up of the basin and its rivers, re-development of the cleaned up areas, and proper education and enforcement as to the laws regarding littering and pollution and to the use of catchment area. The project was completed in mid-1987 (Ministry of Communication and Information, 1987). However prior to its final completion, a two-day hydrobiological survey was conducted of the basin, followed a year later by another similar survey. The surveys were conducted in February of 1987 and 1988. MATERIALS AND METHODS Two field surveys of the Basin were carried out, each survey being of two days duration. The first survey was carried out on 5 and 6 February 1987, and the second on 4 and 5 February 1988. Six sampling stations covering the whole Basin were selected (Fig. 3). The following physico-chemical parameters were taken at the six sampling stations: salinity, conductivity, dissolved oxygen content, temperature, pH and light penetration. Light intensity readings were taken only during the second survey. All the parameters, with the exception of light penetration, were recorded at half-metre intervals along the water column. All physico-chemical parameters were recorded in situ. Salinity and temperature were recorded using a portable YSI model 33 Salinity Conductivity-Temperature meter. Dissolved Oxygen values were recorded using the portable YSI model 57 Oxygen meter. A portable pHOX 52E Conductivity meter was used to measure water conductivity. pH values at the various depths were measured using a hand-held electronic pH meter, with water samples from the various depths collected by a water sampler. Light penetration was measured with the use of a Secchi disc. A LI COR underwater light sensor was used to measure the variation of light intensity with increasing depth. · 11 ~ALL ANG !/.SIN LEGEND 1-6 Sampling stations - Dredges 0 metres 500 Fig. 3 Kallang Basin showing locations of sampling stations I to 6 (map adapted from Loo et al., 1987) .J Lifeform sampling was carried out with a ten-minute dredge at each station (Fig. 3) using a naturalist's rectangular dredge (with 75cm x 20cm opening and an attached 50cm long polypropylene net-bag, with stretched mesh-size of2.5cm) , and three grab samples using an Ekman grab (with gap size 15cm x 15cm) from each sampling station.