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Annex IVSeychelles (Beau Valon Area) ProfileSituated in the Western Indian Ocean between 4 and 11 degrees south of the equator, theRepublic of Seychelles comprises a group of 115 islands with a land area of 455 km 2 , spreadover an Exclusive Economic Zone (EEZ) of over 1.3 million square kilometres.Forty-one of the islands in the group are granitic and mountainous, considered to befragments of the ancient Gondwanaland. They are all found within a radius of 50 km from themain granitic island of Mahé, which with a land area of 154 square kilometres, amounts toone third of the total land area of Seychelles.The islands are of rugged formation and great scenic beauty, some seemingly rising straightout of the sea to great heights. Because of their mountainous nature there is little flat land.Mahé is the most important island. It lies between 4 and 5 degrees South and 55 and 56degrees East. Mahé is about 27km long and up to 11 km wide. A range of mountain runsdown the whole length, most of which are over 300m, rising to the peak of Morne Seychelloisat 905m.Description of study area. The study area is Greater Beau Vallon; it is situated in the NorthWest of Mahé and covers a total area of 1,100 hectares, elevation varies from 0 to 880metres. The area has an enclosed body of water with two embryonic fringing reefs. The sandybeach extends app. 1.8km bounds to the north with piles of granite rocks and to the west withgranitic reefs. Apart from this beach the coastline of the bay consists of some small creeksseparated from one another by the in-situ rock.Human Development. The site is highly developed with about 20% of the land urbanised.This includes human settlements and hotels. There are relatively dense settlements along thecoast, as well as three of the island’s largest hotels and several guesthouses and restaurants.It is a prime tourism and leisure activity area. It is also an important fish-landing site, withsome limited fishing activity.Urban development includes three categories: a heavily built-up centre around the three mainhotels in the Pascal Village and Bel Ombre districts (about 35 inhabitants/ha), a less densearea at Mare Anglaise (about 13 inhabitants/ha) and the sparsely populated sectors (about 7inhabitants/ha) to the north at a higher elevation. Many dwellings are built on sloping land andare difficult to access. The grounds are very rocky with large granite boulders. In many cases,the ravine will be the only outlet for wastewater.Hydrology. Overlooking the Beau Vallon/Bel Ombre area are heights of up to 880 m inaltitude at the Morne Seychellois mountain group. There are two main rivers emptying into thebay, the Sullivan river and the Mare Anglaise river. These form the main estuaries in the area.There are also five smaller rivers in the study area. Water catchment basins are very small.There is no in-depth seepage and virtually no groundwater reservoirs. In spite of the retardingeffect of the very dense vegetation, the runoff water concentration times are very short (from15 to 60 minutes). As a consequence, rainfall immediately causes flooding in certain areas.The land area of the catchment is between 1000 and 1100 hectares, while elevation variesfrom 0 to 880 metres. Its mean annual rainfall varies from 2000mm to 3200mm at an altitudeof 800 metres. The area is covered by relatively dense vegetation, which protects the groundfrom excessive erosion from tropical rainfall. Most of the streams that empty into the bay arelittered with granite rocks which creates individual pools of stagnant water and irregularities inthe breadth of the river. (Payet, 1996).Climate. The climate of the Beau Vallon area is similar to the other areas of Mahé. The BelOmbre area receives around 3,000mm rain per annum as compared to the mean for Mahé,which is 2,524mm. There are relatively strong Southeast trade winds in May and October,which have an effect on the coastal water movements. Heavy rainfall is typical during theNorthwest monsoons.Final Draft Report – Cost Benefit Case StudiesGPA Strategic Action Plan on Sewage, October, 200088
Oceanography. The oceanographic data shows clear alternate phenomena depending onthe prevailing wind direction: during the trade wind period the currents veer counter clockwisein the bay, while it reverses in a clockwise direction during the Northwest monsoon. Thecurrent speed is in any case extremely week, making the bay a confined area. As the bay issheltered from strong Southeast swells, there is a net surplus input of fresh water from theland (SETOI, 1990).Geology and Soils. Low-lying areas of Beau Vallon are the coastal plain area and low-lyingareas around the main river mouths. The sediments of the former are dominantly calcareouswhilst the latter are characterised by sediments consisting of fine clays and quartz derivedfrom laterites. The coastal shorelands of Beau Vallon consist entirely of calcareous sands.The soil types in the mountainous areas behind the coastal plain comprise laterite andkaolinitc clays forming red earth giving a base of dense vegetation.Beach Characteristics. The sandy beach of Beau Vallon is approximately 1.8 kilometreslong with an average width of 30 metres at low tide. Sand dunes exist only in a few smallareas protected by beach debris and by Takamaka trees. The sand is yellowish-white incolour and fine to medium. The Beau Vallon Beach is the most built-up beach in Seychellesand sea walls and buildings on the high water mark are evident. The beach is very active andseasonal movement of sand takes place. However, there is definite evidence of beacherosion characteristic of such highly disturbed sandy coasts (Shah, 1998).Ecology. The ecological characteristics of the Beau Vallon coastal zone are numerous bothspatially and in biodiversity, which include brackish water marshes, coastal vegetation, coralreefs and other marine fauna and flora (Payet, 1995). There are eight areas that can beconsidered as special ecosystems:Area In m 2 DescriptionNorthern Fringing Reef 700,000 Coral ReefSouthern Fringing Reef 260,000 Coral ReefNorthern Fringing Reef Flat 250,000 Inter-tidal and Littoral EcosystemSouthern Fringing Reef Flat 62,500 Inter-tidal and Littoral EcosystemMare Anglaise River Estuary 5,500 Ecosystems of Estuaries and Enclosed SeasSullivan River Estuary 3,900 Ecosystems of Estuaries and Enclosed SeasMare Anglaise River Wetlands 46,800 River and Stream EcosystemsSullivan River Wetlands 15,600 River and Stream EcosystemsSource: Grandcourt, 1995In the marsh areas, various species of mangroves are predominant with a host of crab andbird species. The amount of dissolved oxygen is usually very poor, ranging from 2 to 4 mg/l.This often allows for the propagation of anaerobic conditions within the marsh area. Thesemarshes act as buffer zones to reduce fresh water intrusions on the coral beds and provide azone of stabilisation and degradation of organic matter (Payet, 1995).Population. The area of Beau Vallon has a population of some 7,000, or 9% of the totalSeychelles population. The annual population growth rate is estimated at 2%, the number ofinhabitants per dwelling is 4.5 and urban development density is at 10–15 dwellings perhectare. Plans for the sub-division of land are already under way, and new development ofapartment buildings in the next five years will increase population and land use conflicts. Atotal of 512 additional units will be completed in the study area in the next years,corresponding to a net population increase of some 1,152 inhabitants.Population Projections for greater Beau VallonYear 1995 2002 2010Population 6,501 7,617 8,924Source: SOGREAH, 1996Tourism. Tourism is the mainstay of the Seychelles economy and it is likely to remain so inthe near future. The sector accounts for approximately 18% of GDP, employs one fifth of theFinal Draft Report – Cost Benefit Case StudiesGPA Strategic Action Plan on Sewage, October, 200089
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TABLE OF CONTENTSPageTable of Conte
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The Report includes four Annexes wi
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4.2 Programme ObjectivesTo facilita
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TERMS OF REFERENCEThis Report has b
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CHAPTER 1. ECONOMIC ANALYSIS AND EN
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aesthetic and recreational value, i
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marginal benefit of pollution reduc
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loss of labour force productivity.
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Population connected to sewerage in
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Threats to the Coastal and Marine E
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fall disposal in deep sea at Kilind
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There are three main categories of
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Child mortality, and death in gener
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6. Estimated Annual Cost of Environ
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2.2 DAR ES SALAAM CASE STUDY2.2.1 I
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Dissolved solids 83,940 45,280 9,83
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4. Institutional Capacity Building
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Table 8: Classification of ValuesTy
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infrastructure. As shown above, the
Page 40 and 41: 6. MangrovesMangroves are an exampl
Page 42 and 43: • The total cost in column (3) is
Page 44 and 45: 2.3 BEAU VALLON (SEYCHELLES) CASE-S
Page 46 and 47: In the marsh areas, various species
Page 48 and 49: Dissolved inorganic nitrogen: The t
Page 50 and 51: TourismSeychelles• Number of tour
Page 52 and 53: lossesHuman Health Indicator: Treat
Page 54 and 55: Dose-response data are not availabl
Page 56 and 57: Table 13: Estimated Potential Annua
Page 58 and 59: CHAPTER 3. ACTION PROGRAMME INPUTS3
Page 60 and 61: Property impacts are widely known t
Page 62 and 63: 3. Wastewater Treatment in Ismailia
Page 64 and 65: • Health costs• tourism income
Page 66 and 67: Annex IRegional OverviewThe Western
Page 68 and 69: • Degradation of coastal and mari
Page 70 and 71: • Resource over-exploitation• S
Page 72 and 73: Annex IIMombasa Regional and City P
Page 74 and 75: Population covered by sewerage infr
Page 76 and 77: Source: Mwaguni & Munga 1997Sewage
Page 78 and 79: 1628 people tested positive for cho
Page 80 and 81: Annex IIIDar-es-Salaam Regional and
Page 82 and 83: are extensively exploited by small-
Page 84 and 85: Solid wastes. It is estimated that
Page 86 and 87: Pollution load to surface water res
Page 88 and 89: Mtoni and Pugu. Existing lakes incl
Page 92 and 93: labour force generating the major p
Page 94 and 95: Vacoa Village ST Algal growth Water
Page 96 and 97: sea grass beds are able to soak up
Page 98 and 99: Sewerage ManagementSewerage managem
Page 101 and 102: REFERENCESA. Background Regional En
Page 103 and 104: 7 GOK 1997: Mombasa District Fisher
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