Chapter 2 General Scenario of Sanitation Problems in Coastal and Waterfront Communities--A Literature Review

The terms "coastal and waterfront communities" refer to settlements built along the seacoasts, estuaries, mangrove swamps, lakeshores, riverbeds and in most cases extended right above the surface waters. Communities built on low-lying areas include those on swampy sites, marshlands and other flood prone areas. A general term that encompasses these coastal and low-lying areas is "wetland." "Wetland" is defined as those transitional areas between dry land and open water, which are characterized by low topography, standing waters and poor drainage.(1) Recent studies on wetlands indicate the difficulty to define these sites precisely, not only because of their great geographical extent, but also because of the wide variety of hydrologic conditions in which they are found. Thumbnail('nav-fig0201-sm.jpg','nav-fig0201.jpg'); ?> As illustrated in Figure 2.1, the distinguishing feature of all these types of wetlands is the interplay between land and water and the sharing of the characteristics of both.(2) From these definitions, no matter how diverse the environmental conditions are in coastal and waterfront communities, the presence of water in their environment is the main factor linking them.

This chapter presents a background on sanitation conditions in coastal and waterfront communities and those occupying low-lying areas. The discussion is based on several examples of these communities in developing countries. The selected communities discussed in this chapter vary in cultural, social, political and economic factors and to some extent, physical conditions. The main objective of this discussion is to characterize the sanitation problems due to their location and environment.

The chapter comprises three parts. The first part cites several examples of coastal and waterfront communities and discusses why they are located on such sites. The second part identifies the sanitation problems prevalent in these communities. The last part discusses the implications of sanitation problems to the health of the people and to the environment.

2.1 Reasons for Settling on Coastal, Waterfront and Low-lying Areas

The settling of communities on coastal, waterfronts and low-lying areas as well as on surface water can be attributed to several reasons. In the historical development of cities in developing countries, most cities are located on coasts or large rivers for trade, transportation, communication and defense reasons, as selected by the former colonial powers. In these countries, the rivers or canals play a vital role in the movement of people, goods and services. In most urban areas, low-lying and flood prone areas are cheap alternatives for settlement sites. For rural regions, livelihoods such as fishing or rice cultivating, require settling on seacoasts or on the sea itself. For some communities, culture and tradition are significant reasons. The following discussion explains these reasons and cites specific examples of communities.

a. Strategic Locations for Cities and Towns

Most major cities in developing countries occupy sites selected by the former colonial powers, with an eye to trade and defense. For this reason, the historical locations of most cities are on the coast or large rivers and are protected by limited access on the landward side. Cities such as Bangkok, Manila, Lagos and Abidjan are examples of these.

Banjarmasin, the largest city in south Kalimantan, Indonesia, has earned the reputation as the "Venice of Indonesia." Its river systems comprising the Martapura River and the Barito River and other connecting canals, provide the major thoroughfares of the city, carrying thousands of watercrafts in and out of the city daily. (3) In Bangkok, a similar scenario exists. Canals and rivers have been used for trading activities, hence, floating markets are a common sight within the city.

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In China, traditional water towns with a historical origin still exist. Examples of these are found in the southern parts of Jiangsu province. They are: Zhou-Zhuang, Tong-Li, Qian-Deng, Cheng-Me, Lue-Zi, Sha-qi and Tai-Chang counties. These towns are all located on the plain of the lower Yangtze, on the eastern coast of China. This land is in the subtropical zone with plenty of rainwater and fertile soil. As shown in Figure 2.1, most of these towns are fishing villages which depend on the natural water resources around them.(4)

b. Cultural Reasons

In some Asian and African countries, characterized by a coastal environment, cultural tribes have long inhabited the waters. Living within the coastal, swampy shores and the waters of Riau province of Indonesia, are the Bugis orang laut. The Bugis are renowned seamen in self-imposed exile from their native Sulawesian homeland, living aboard wooden sailing craft, and trading throughout the archipelago or adjacent seas. Although they have maritime settlements from Burma to the Philippines they more commonly sail or row their boats through a labyrinth of inter-island channels and mangrove swamps, fishing and trading.(5) In the Philippines, sea-gypsies known as Badjaus are scattered over thousands of square miles, from the Sulu Sea to Eastern Indonesia. The Badjaus follow the nomadic life of their ancestors, while others settle at the water's edge.(6)

c. Source of Livelihood

In the most basic sense, because coastal areas are considered among the most productive ecosystems, many communities have depended on these areas for their livelihood and as their source of food, water and resources. The dependence on fish protein is much greater in coastal tropical and subtropical countries than in temperate areas of the world. According to the Food and Agricultural Organization, 60% of the people in developing countries obtain 40-60% of their animal protein from fish. In general, the poorest are the most dependent, since fish is the only protein item within their economic reach.(7) Thus, in rural regions, several fishing communities have occupied the riverbanks and coasts of bays and lakes for their proximity to the fishing waters. In several cases, communities extend towards the lakes or bays by building their settlements right above the shallow waters. Several examples of these communities are discussed below.

For centuries, the people living along the coast of West Africa have fished in the waters of the Atlantic. Many villages of small houses made from bamboo and the palm leaves are built on the shore of the ocean, in which fishermen practice their craft in the traditional manner. On the northwestern shore of Lake Nokwe in southern Dahomey, is a lake dwelling village, called Ganvie. It is a small town devoted to fishing which is entirely built on the lake and the only means of access is by canoe.(8)

In some countries which are made up of several islands and islets, similar types of fishing communities have proliferated along the tidal foreshore of some of the country's coastal regions. In these fishing villages, houses are supported by stilts embedded in mudflats, with many homes located as far as a kilometer from the nearest firm ground. At the northern corner of South Sumatra Province, in Indonesia, lies the Banyuasin Sembilang mangrove swamps which have been occupied by communities engaged in fishing, agricultural activities, husbandry of forest products, hunting and trade in wildlife and artisan fisheries.(9) In the southern provinces of the Philippines, fishing villages exist along seacoasts and on the water itself. Gameranga, Bangladesh, a Muslim village consisting of 202 households, occupies a piece of land densely cut by canals and richly dotted with ponds of varying depths and sizes. Villagers depend on rice cultivation, fishing and tapping of date palms.(10)

In the case of the coastal communities discussed above, which are mostly rural in nature, the coastal environment is considered a productive source of livelihood. In urban areas, the coastal and low-lying sites are perceived as idle lands with limited land use alternatives. These areas are prone to squatter invasions.

d. Low-lying Areas as Settlement Sites for the Urban Poor

Some cities in developing countries are seaports, located on coasts. Many are on estuaries of rivers which served as commercial arteries for the transport of goods to and from the hinterland. The flat estuarine terrain and soft, often impermeable alluvial soil make drainage difficult. Furthermore, such coastal regions of the world are where the highest average rainfall is found.(11) Thus, in urban areas in most developing countries, low-lying land, such as marsh lands, banks of rivers and canals are considered wastelands because they have low commercial value or limited alternative land use. These idle sites, which may be private or public properties, are occupied by the urban poor. Such locations are cheap alternatives for settlement sites. For the urban poor, proximity to place of work, accessibility to the urban center and its services overrule the physical hazards of settling in flood-prone sites or in areas characterized by stagnant polluted waters.

Many cities in developing countries are faced with problems of slums proliferating in these low-lying areas which are prone to flood or tidal inundation. Examples of these include Guayaquil (Ecuador), Recife (Brazil), Monrovia (Liberia), Lagos and Port Harcourt (Nigeria), Port Morsby (Papua New Guinea), Delhi (India), Bangkok (Thailand), Jakarta (Indonesia), Buenos Aires and Resistencia (Argentina) and Accra (Ghana).(12)

In the central city of Jakarta, urban slums known as kampungs occupy the sloping embankments and terraces along the river, as well as the coastal marshlands in the northern periphery of the city. Among the sites occupied by the urban poor in Jakarta, marshlands and coastal areas usually provide sites for rentfree accommodations.(13) In Guayaquil, Ecuador, squatter communities are built over tidal swamplands.(14) Although the site is over an hour by bus from the city center and is located on floodlands, the inhabitants have moved there because of its access to employment and educational establishments and the advantage of owning de facto a plot of land.(15) A similar scenario exists in the southern fringes of Port Harcourt metropolis, Nigeria. The area is characterized by squatter housing units developed on reclaimed land. These settlements have developed on land below the three meter contour marked as unsuitable for development. There are about 14 such waterfront squatter housing areas around the city, comprising 4,331 dwelling units with an estimated population of about 30,000 in 1985.(16)

In other cities, canal right-of-ways, riverbanks and in some cases on the river itself, have been the sites of squatter settlements. In the eastern suburbs of Bangkok, squatter communities, known as klong settlements, build their homes along the canal right-of-way. The canal right-of-way is a strip of land with an average width of twenty meters which runs alongside the canals and originally served as a maintenance strip. Some 68 squatter communities have been identified with an estimated total number of 44,000 inhabitants. Thumbnail('nav-fig0203-sm.jpg','nav-fig0203.jpg'); ?> About 7,390 houses are built on the canal banks or protrude into the canals. The majority of the squatter population lives alongside four major canals in the area: Klong Premprachakorn, Klong Lad Phrao, Klong Bang Sue and Klong Bang Khen.(17) In klong settlements, proximity to urban sub-centers, accessibility of the sites and available infrastructure are of importance. Being close to the port area, the site has also attracted dock laborers. Figure 2.3 illustrates this example.

In the same way, the Sabarmati riverbank squatter settlement in Ahmadabad, India, developed to accomodate the needs of workers in the nearby textile mills. It also provided a refuge for Muslims forced from their homes by riots in 1969. Further growth resulted to more than two dozen squatter settlements to be found on the eroding banks of the river and some even on the riverbed itself. This settlement has a density reaching as high as 2,000 persons per hectare.(18) Thumbnail('nav-fig0204-sm.jpg','nav-fig0204.jpg'); ?> An example of a large community built on the river is Kampong Ayer in Bandar Seri Begawan, the capital of Brunei. In this water village, there are about 27,000 inhabitants which is approximately 32% of the total population of the city. As shown in Figure 2.4, this community is built on the Brunei River itself, near the city's central business area.(19)

In Port Moresby, Papua New Guinea, Koki squatter settlements are built mainly over the sea. The people all came from coastal villages 100 miles east of Port Moresby where they traditionally live in houses built on piles in coastal lagoons. The community started to come to Port Moresby in the late 1950's to sell their products. They moored their canoes near the city's main market. Many obtained jobs in the city, and the settlement evolved from what had been a canoe landing ground. In 1979, there were 225 houses and a population of 1,800. The people retained their strong traditional links with the sea and with their home villages.(20)

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2.2 Sanitation Problems

Coastal and waterfront communities are faced with a wide range of problems caused by their location and environment. Sanitation is a predominant concern. Though sanitation in this thesis refers to the sanitary means of disposing of human waste, the discussion of other related aspects such as water supply, wastewater and garbage disposal are considered significant. Among the communities reviewed, sanitation problems are more complex in high-density urban squatter settlements occupying the low-lying areas such as riverbanks, coastal areas and marshlands than those communities with low-density in rural areas. These problems are associated with a contaminated water supply and a lack of sanitation facilities, specifically, toilets with proper waste treatment. To illustrate the extreme conditions of these problems, the following discussion focuses on the sanitation problems in high-density poor communities

a. Lack of Sanitation Facilities

In most of the communities reviewed, sanitation facilities are absent and direct defecation into the surface water has been the traditional practice. For instance, the people of the Koki squatter settlement, in Port Moresby, Papua New Guinea, relieve themselves in the open sea.(21) Such traditional practice of 'visit or swim to the sea' is also prevalent in communities found in small islands such as those in the South Pacific.(22)

In other communities, the overhung latrine is commonly used. These are simply superstructures with the toilet seat or floor hole built above the tidal flat, river, canal, lake or swamplands. Defecation takes place directly into the water for transport and eventual dilution, onto the mudflat or the beach to await the tide. In worse conditions, excreta is disposed of into the stagnant waters or simply on the ground underneath the built toilet. In Guayaquil, human waste is directly disposed into the mud and polluted waters. Approximately 83% of the inhabitants of the marshlands use a hole on the floor boards for the family toilet, while the remaining 17% has a separate structure at the back of the house.(23) In Jakarta, most people use latrines, private or communal, with outlets to or built directly into swamps and canals.(24) In Gameranga, Bangladesh, the village does not have proper excreta disposal system. A latrine basically consists of a bamboo construction over a hole or pit in an undergrowth behind a hut. Sometime this type of structure is built over a pond and is covered by old mats.(25)

The practice of directly disposing of human waste into bodies of water is considered satisfactory as long as the water is saline enough to prevent its use for drinking, if the feces are dumped into the water and not on the land, and if there are sufficient currents for dilution.(26) This practice, while considered a hygienically acceptable and satisfactory traditional habit, can be a problem with expanding populations. In worse cases, particularly in fresh water rivers over which such latrines are built, the water is used for domestic and personal washing as well as for drinking.

b. Water Supply

Contaminated drinking water supply is another problem related to sanitation. Due to geographical location, the water supply from the site may be either contaminated or with high saltwater content. Hence, in these communities, water is retrieved from another area. The practices of water fetching, sometimes illegally tapping the nearest municipal lines, and water vending are prevalent in these communities.

The nearer the source of water is to the sea, the more chance there is of saltwater intrusion in the ground water. In the case of kampung settlements occupying the seaward side of Jakarta, the groundwater is brackish and contaminated by the subsurface encroachment of salt water from the ocean. Thus, their sources are the waterlines, self-constructed wells, communal faucets, or hand pumps, on the mainland. They acquire water from these sources by either buying it from street vendors or fetching the water themselves. Within the city, several water reservoirs at strategic locations were built, where hundreds of water vendors get their water daily and sell it to families in neighboring kampungs.(27)

In communities where waterlines are available, problems related to water contamination due to poor pipe connections and maintenance of lines occur. In Klong Khum, Bangkok, pipes are laid bare on swampy land or on the wastewater pool. In most of the houses, water supply pipes leak, are not properly connected and are rusted. When these pipes are empty, foul materials from exposed wastewater and latrine waste seep through them.(28)

In the communities of small islands of the South Pacific, the adequate supply of safe water is a problem since the islands are too small to ensure rainfall and too flat and porous to have surface water. In these communities, the people rely on roof catchment and domestic storage of rainwater for drinking, and they use groundwater or seawater for washing.(29)

Contamination of the drinking water supply and the absence of sanitation facilities has implications on the health of the people and a negative impact on the environment. This is amplified by other environmental problems caused by the improper disposal of solid waste. The following discussion covers the health and environmental problems that arise in these communities.

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2.3 Health and Environmental Conditions

The lack of sanitary means of disposing of human wastes, results in a high probability that inhabitants of coastal communities are prone to feco-oral infections transmitted by the consumption of contaminated food and drink. The micro-organisms that cause these infections are found in the excreta of infected people or animals, and surface water becomes contaminated with them from sources such as blocked sewers and overflowing septic tanks, and often from defecation in the open by livestock and by people who have no toilet.(30) This contaminated surface water can infect people through the contamination of their hands, their utensils, or their drinking water supply. Children are particularly exposed to infection when playing or bathing in the water.

In the slums of north Jakarta, where drainage and standing water are major problems, occurrence of diseases and infections is high. Diarrhea is 342 episodes per 1000 population. The peak incidence occurs during the rainy season, affecting the infants from 6-12 months. Intestinal worms are widespread, as a result of environmental circumstances. Approximately 43% of children below five years of age are infected with ascaris and trichuris or both.(31) In Gameranga, Bangladesh, the village has seasonal outbreaks of certain communicable diseases like cholera, scabies, malaria and boils. Also, intestinal infections, worms and influenza are problems throughout the year.(32)

In small ecologically sensitive islands, sanitation and safe waste disposal are inextricably linked with the question of water supply. As populations increase, so do problems of water supply and sewage disposal, if the limited freshwater supply, especially below coral islands, is not to be contaminated. This type of contamination was the cause of cholera outbreak in urban Kiribati, a small island in the South Pacific, in 1977, and prompted the construction of toilets discharging into the open ocean. (33)

In the same way, the resulting problems are obvious when domestic wastes are dumped into the surrounding area. Piles of garbage are scattered by scavengers or animals and serve as food or breeding grounds for disease vectors, primarily flies and rats. Dangers to health also arise in the refuse itself and from the disease vectors which breed or feed there. Where rivers or lakes are polluted with garbage and excreta, this means further extensive site contamination.(34) In Jakarta, where latrines are built above the canals and where garbage is dumped, bathing and laundry in the canal are still being done.(35) In Guayaquil, the marshlands are characterized by polluted mud and stagnant water. Such exposed water of any type is likely to serve as a breeding site for a range of insects and some, even though not blood-suckers, may become an abundant nuisance, especially moth-flies and midges whose cast pupal skins may provoke allergies.(36) Dengue haemorrhagic fever occurs in epidemics in Jakarta slum areas. This condition is caused by the aedes mosquito, and may cause a severe illness in children resulting in death. Malaria may also occur as an epidemic, and this disease is common in areas where drainage and standing water is a problem.(37) In West Africa, some river settlements have been disrupted by vector-borne diseases such as river blindness, Onchocerciasis.(38)

In klong settlements in Bangkok, wastewater from sullage cesspools and surface run-off are directed into the pond or stagnant water beneath the house. This stagnant water has been the playground of children especially during the heavy rains: they swim and play, thereby increasing the risk of contracting diseases. There is no existing sewerage system or wastewater treatment. The pond is likely to become a breeding place for insects.(39) Wastewater from bathing and personal hygiene, washing of clothes, household cleaning, food preparation and dishwashing are all disposed of into the ground beneath the houses. Since there is no sewerage in the area, this adds to the pool of water that has remained in the surroundings. The soil is hardly permeable in nature, resulting in non-absorption of the water.(40)

The discussion of the sanitation and environmental problems of coastal communities raises the question of tolerating the growth of communities in this environment. From an environmental point of view, the process of residential development in coastal areas involves a complex of potential ecological disturbances to coastal waters, due to construction activity and human occupancy. The degree of disturbance is heightened by the increased density of development, closer proximity to the water, extensive alteration of the shorescape, and the ecologic sensitivity of the ecosystem.(41)

In this context, it can be argued that the most fundamental source of problems in coastal and waterfront communities and those in low-lying areas is the occupation of sites that are considered environmentally critical areas and are not appropriate for settlement planning. Such sites are used as easements for maintaining shorelines and waterfronts and low-lying areas prone to flooding. The presence of growing communities in these areas pose negative impact on the environment such as degradation and exploitation of resources and water pollution.

In cases where the environment becomes the priority, eviction and resettlement of the community from the site seems the most logical approach. Considering those informal settlements found in the urban areas, as in the cases of Jakarta, Bangkok and Guayaquil, where there are no available sites to relocate the community, accommodation and regularization of such communities became the other options. To accommodate or regulate the coastal slums, the local government is faced with several issues in improving sanitation and environmental conditions. In more traditional communities, reliance on their environment for livelihood and food are too difficult to outweigh. Hence, what interventions were made in these communities to improve sanitation? Were these interventions successful? What sanitation systems were implemented in these communities? Were they sustained by the community? What are the problems associated with the application of these systems in these coastal and waterfront communities? What are their causes? The next chapter attempts to answer these questions by discussing the sanitation systems used in some of the communities discussed earlier.

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1. Erley, Duncan, et.al., Performance Control for Sensitive Lands: A Practical Guide for Local Administrator, (Washington, D.C. 1975), p.38.

2. Michael Williams, "The Human Use of Wetlands," Progress in Human Geography (1991), 15(1), pp. 2-3.

3. Ginny Bruce, Indonesia: A Travel Survival Kit, (Australia: Lonely Planet Publications, 1986),p.231.

4. Zhang Zhi-Zhong, and Cheng Qui-Guang, "Tradition and Innovation: Planning and Reconstruction of Watertowns in Southern Jiangsu", Open House International, (1989), 14 (1) pp.3-4.

5. Bruce, 1986, p.223.

6. Anne de Henning Singh, "Life Ashore Beckons the Bajaus: Sea Gypsies of the Philippines", National Geographic Magazine, (May 1976), 149 (5), p.659.

7. O. Linden, "Human Impact on Tropical Coastal Zones", Nature and Resources, (1990), 26 (4), pp. 4-5.

8. Miles Danby, "Ganvie, Dahomey" , in Shelter in Africa, ed., Paul Oliver, (London: Barrie & Jenkins, 1971), pg. 36.

9. Verheugt, W.J.M., et. al. "Integrating Mangrove and Swamp Forest Conservation with Coastal Lowland Development: the Banyuasin Sembilang Swamp Case Study, South Sumatra Province, Indonesia, Landscape Urban Planning, (1991), 20, p. 85-91

10. Pirani, 1989, p.32-33.

11. Gerald Krausse, " Intra-Urban Variation in Kampung Settlements of Jakarta: A Structural Analysis", in The Journal of Tropical Geography, (1976) p. 25.

12. Jorge Hardoy and David Satterthwaite, Squatter Citizen: Life in the Urban Third World, (London: Earthscan, 1989), p.53.

13. Krausse, 1975, p. 25

14. Hardoy, 1989, p. 76.

15. Caroline O.N. Moser, "A Home of One's Own: Squatter Housing Strategies in Guayaquil, Ecuador", in Urbanization in Contemporary Latin America, ed. A. Gilbert, J.E. Hardoy and R. Ramirez, (New York: John Wiley & Sons Ltd., 1982), p. 167.

16. Chukudi V. Izeogu, "Public Policy and Affordable Housing for the Urban Poor in Nigeria: A Study of Squatter Redevelopment Programs in Port Harcourt," Habitat International, (1993) 17(2) p. 27.

17. Harry Roovers, et.al., Alternatives to Eviction of Klong Settlements in Bangkok, Third World Planning Review (1989), 11(2), p. 3-4

18. UNCHS, Survey of Communities and Squatter Settlements, (Dublin: Tycooly International Publishing Ltd., 1982), p.33.

19.  Arthur Ling, ed., Urban and Regional Planning and Development in the Commonwealth, (England: Howell Publications, 1988), p. 176.

20. Peter J. Swan, The Practice of People's Participation: Seven Asian Experiences in Housing the Poor, (Thailand: Human Settlements Division, Asian Institute of Technology ,1980) pp.111,113.

21.Ibid., 1980. p.111,113.

22. Tony Marjoram, "Pipes and Pits Under the Palms: Water Supply and Sanitation in the South Pacific", Waterlines, Volume 2, No. 1, July 1983, p.16.

23. Moser, 1982: p. 174.

24. Lars Marcussen, Third World Housing in Social and Spatial Development: The Case of Jakarta, (England: Avebury Grover Publishing Company Ltd.,1990) p. 132.

25. Pirani, 1989, p.34

26.McGarry,1977, p. 247.

27.Krausse, 1978: p. 21.

28. Ali Syed Monsoor, "Adverse Effects of the Environment on the Health of Slum Dwellers: A Case Study of Klong Toey Slum, Bangkok," (Master of Engineering Thesis, Asian Institute of Technology, Bangkok, Thailand, 1990), p.27.

29. Marjoram, 1983, p.15.

30. Sandy Cairncross and E.A.R. Ouano, "Surface Water Drainage in Urban Areas," in Poor Die Young: Housing and Health in Third World Cities, eds., Sandy Cairncross, Jorge Hardoy, and David Satterthwaite, (London: Earthscan Publications, 1990), p.159.

31. C. Jurjadi, "Preliminary Analysis of the Immunization Survey at Subdistrict of West Pademangan and Subdistrict of Penjaringan" (Atma Jaya University,1990) in Trudy Harpham, Paul Garner and Charles Surjadi, "Planning for Child Health in a Poor Urban Environment - The Case of Jakarta, Indonesia," Environment and Urbanization (October, 1990) 2(2), p. 80.

32. Pirani, 1989, p.33

33. Marjoram, 1983, p.16

34. Stenio de Coura Cuentro and Dji Malla Gadji, " The Collection and Management of Household Garbage" , in Poor Die Young: Housing and Health in Third World Cities, eds., Sandy Cairncross, Jorge Hardoy, and David Satterthwaite,(London: Earthscan Publications, 1990), p169.

35.Marcussen, 1990, p.93.

36. C. J. Schofield, et.al., "The Role of House Design in Limiting Vector -Borne Diseases," in Poor Die Young: Housing and Health in Third World Cities, eds., Sandy Cairncross, Jorge Hardoy, and David Satterthwaite,(London: Earthscan Publications, 1990), p.198.

37.Harpman, et. al, 1990,p.80

38. C.J. Schofield et.al., 1990, p. 198.

39. Ilde Balanay Deloria, "Low-Cost Sanitation System Alternatives in Slum Areas: A Case Study of Khlong Kum, Bangkok, Thailand, "(Master of Engineering, Asian Institute of Technology, Bangkok, Thailand, 1991) p.26.

40. Ibid, 1991, p.31.

41. Clark, John, Coastal Ecosystem:Ecological Consideration for Management of the Coastal Zone, (Washington: The conservation Foundation,1974), p. 161.

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