Coastal zones are of great importance to the country. Many families of fishermen depend on coastal fisheries for subsistence, the tourism industry has
developed principally along stretches of sandy beaches and for the local population coastal zones are important centres of leisure activities.
Unfortunately, coastal zones are also recipients of land based pollution such as untreated domestic and industrial sewage, solid waste from dumps close to the shore and
agricultural run-offs. The mining of sand, though regulated and limited to selected sites exerts further pressures on the resources of the coastal zones.
The competing and often conflicting demands for access to coastal zones by the population and property developers, the need to preserve the marine and coastal ecology for
future generations and the need to promote sustainable development mean that an integrated approach to coastal zone management is urgently required.
What are coastal zones?
Coastal zones are composed of the coastal plain, the continental shelf, the waters that cover this shelf and includes features such as bays, estuaries, lagoons, small
islets and reefs. It is also the region where marine and continental processes of erosion and deposition interact giving rise to different types of land forms.
Morphology of shores and beaches around the island
The Continental Shelf
In spite of the limited extent of the Mauritian coast, barely 323 km in length, it comprises a great variety of different features. The presence of an appreciable and
shallow continental shelf all round the island has determined in part the nature of the coastal features seen. For example the shallow shelf has enabled the development of the coral reef, which mainly
thrives in shallow and warm waters. The reef then shapes coastal morphology.
Formation of Land forms
Land forms that develop and persist along the coast result from a combination of processes acting upon the sediments and rocks present in the coastal zone. Waves,
currents and tides are the most prominent processes affecting coastal morphology. Climate and gravity are also significant agents of change.
Waves moving towards a coast are the most obvious of the coastal processes under consideration. As waves enter shallow waters they interact with the sea bottom. As a
result sediment can become temporarily suspended and is available for movement by sea currents. The larger the wave, the deeper the water in which this process can occur and the larger the particles that
can be moved.
Generally, small waves cause sediment, usually sand, to be transported toward the coast and deposited along a beach. Larger waves, during a storm for example, can remove
sediment from the coast and carry it out to into deeper water.
Waves erode the bedrock along the coast largely by abrasion. Similarly, suspended sediment particles, pebbles and rock debris have an abrasive effect on a surface. Waves
which have considerable force can break up bedrock simply by impact.
Long shore currents
Waves usually approach a coast at an acute angle rather than head on, in a direction perpendicular to the coast. When the waves enter shallow waters at an angle, they are
bent ( refracted). As this happens, the bent waves generate a current that runs along the shore and parallel to it. This current is called a longshore current. The current's speed depends on the power of
the waves and their angle of approach with the shore. It can vary from 10 centimetres per second to over one metre per second under stormy conditions.
Waves and longshore currents together transport large quantities of sediment along the shallow zone adjacent to the shore.
Longshore currents may move in either direction along the shore depending upon wave direction. As this is determined in part by wind direction, it follows that the wind
is the ultimate factor in determining the direction of longshore currents and the transport of sediment along the shoreline.
Typically waves lift up the sediment and longshore currents carry it along the coast.
In Mauritius, the coral reefs act as barriers and absorb most of the impact of waves. Those overflowing hit the shore almost orthogonally. However, where the coral reef
barrier is absent, at river mouths for example, waves can approach the coast at an angle and produce a longshore current.
It appears ( Reference 1 P 272) though that a long shore current exists along the western and south western coasts that causes a drift of sediment. It does not appear to
be continuous and its strength has not been measured.
High frequency waves can cause the accumulation of considerable volumes of water in the lagoon, raising its level by up to 1.5 metres. This excess water then flows out of
the lagoon through gaps in the coral barrier reef thus creating a current called an intra-lagoonal current which may reach up to 3.5 knots. This current can transport loose sediment on the lagoonal floor
out to the gaps in the barrier reef.
Tides are semi-diurnal and have a mean amplitude of 0.8 metres and generally vary between 0.5 to 1.3 metres. The relatively low tidal amplitude means that tidal currents
generated are of low magnitude. Hence their effects on coastal morphology is weak.
Climate, Winds and Gravity
The climatic elements of importance in the development of land forms are rainfall and wind. Rainfall is
important because it provides the run off in the form of streams and is an important factor in producing and transporting sediment to the coast.
The importance of wind comes about in its relationship to waves. The presence of strong winds is associated
with high energy waves. The direction and intensity of winds determines both the direction and energy of the waves.
Cyclones ( Tropical storms ) with their associated strong winds and considerable rain water increase in magnitude the usual processes that affect land forms.
Gravity also plays an important role in coastal processes. It is indirectly involved in processes associated with
wind and waves and it is directly involved through down slope movement of sediment and rock.
This role is particularly evident along shorelines cliffs where waves attack the base of the cliffs and undercut
the slope. That results, eventually, in the collapse of rocks into the sea or accumulation of debris at the base of the cliffs.
Depositional And Erosional Coasts
There are two major types of coastal morphology. One type dominated by erosion and the other by deposition.
Generally erosional coasts have little or no sediment in contrast to depositional coasts with abundant sediment accumulation.
Sea cliffs and wave cut platforms are characteristic of erosional coasts. Wave cut platforms arise when the
face of the sea cliff recedes under wave action. In Mauritius erosional coasts occur mainly where coral reefs
are absent. This occurs along part of the western coast at Pointe Aux Caves and Montagne Jacquot and along the southern coast.
Waves and wave-generated currents significantly influence the development of depositional land forms.
Waves crashing on the barrier reef lose most of their energy, but enough is left permitting sediment to be lifted off the reef flat, transported to the shore and deposited there.
In Mauritius, beaches are the most common depositional land form found along the coastline and sandy
beaches made up of carbonate sediment are the most frequent forms seen.
The Use of coastal lands and lagoons
Considerable pressure is exerted on coastal zones ecosystems and its resources. It is clear that it is a matter of
urgency for the country to determine what forms of coastal development is possible and desirable within the
constraints imposed by local conditions. Provided, of course, the aim is to promote sustainable human
development and not to maximise returns and profits at all costs for a minority of private operators at the expense of the community.
Coastal Land Use
St Antoine Sugar Estate
Source: Ministry of Land, Housing and Town Planning
The first historical use of coastal zones has been for artisanal fisheries. It is still a very important activity
which provides a means of livelihood for thousands of families.
Sand mining at selected places have been going for years and is still going on unabated. Close to 800,000
tonnes are extracted yearly form the lagoon and inland deposits close to the shore. It is government policy to eliminate completely this activity by the year 2001.
For decades, very few mauritians were wealthy enough to be able to enjoy the sea for recreational purposes.
Few bungalows existed around the coast and before independence (1968) only a couple of hotels were in operation. The environmental stresses on coastal zones were minimal.
The increased affluence of the seventies (due to an increase in sugar prices on the world market), a
governmental policy of encouraging tourism as from the eighties and the success of industrialisation as from the mid eighties, have had the greatest of incidence on the use of coastal resources.
The above mentioned factors have resulted in:
(1) more wealthy mauritians leasing beach frontage for the erection of private bungalows.
(2) a host of new hotels built upon prime beach frontage (more than a hundred hotel complexes currently dot
the coastline) to accommodate an ever increasing flow of tourists.
(3) a spectacular increase in the number of mauritians heading for the beaches for recreational purposes.
(4) a haphazard urbanisation of a number of previously sleepy coastal villages. Grand Baie and Flic en Flac being prime examples.
(5) a spectacular increase in the number of leisure boats operating in the lagoon.
(6) a greater demand for the local varieties of fishes.
(1) Private Bungalows
Nearly all of the strip of land all round the island from the high water mark to 81.21 metres inland is known as
Pas Geometriques and is the property of the Government. However it can be leased for a maximum of 30 years
renewable against a fee that is ridiculously low. Over the past decades, the different governments have been
generous in leasing away most of that land either to individuals or to hotel developers. The result of which is
that bungalow sites occupy 52 kilometres of coastal land representing 16% of the total. Though that does not
appear to be such a high proportion, it is important to realise that the vast majority of bungalows are built on lands adjacent to sandy beaches.
The erection of bungalows tend to preclude the population from gaining access to those beaches, though this
is unintentional in most cases. But on numerous occasion, owners of bungalows have erected fences and
walls in order to prevent access by the public. Laws had to be passed to render illegal fencing off access to the beaches.
It is clear that any future governments will find it increasingly difficult to justify leasing off further tracts of
Pas Geometriques to private individuals when the public is facing rather crowded public beaches with few if any amenities.
In fact, public pressure will soon demand that leases be not renewed and the land so freed be transformed into
public beaches with proper amenities. A perfectly reasonable demand.
(2) Tourism And Coastal land Use
The vast majority of tourists come to the island to enjoy the beaches, the sea and the sun. Hence tourists are
concentrated on coastal zones. The north, the west, the south west, the east of the island being the principal tourist zones.
Prior to the seventies, few tourists visited the island and there were few hotels. Since independence (1968), it
has been Government policy to encourage tourism in order to increase foreign currency reserves and provide
much needed employment. It is beyond reasonable discussion that the tourism industry has played a pivotal
role in the development of the country. It has boosted foreign reserves and provided employment. The influx
of foreign tourists has increased the exposure of the public to the outside world and influences. It has spurred
the development of service industries that cater for the need of tourists, like restaurants, travel agencies, car hire services, retail shops, bars & discotheques, and so on.
The vast stretches of sandy beaches adjacent to unoccupied Pas Geometriques lands, have enabled the first
hotel developers to lease from Government, for a small yearly sum of money, hectares of prime coastal land. In
the seventies or even in the eighties, this aroused little attention from the public because few could afford to go regularly and frequently to the beach for a day out.
The sugar boom of the seventies, industrialisation of the eighties steadily increased the welfare of the
population. Once the basic needs more than satisfied, people naturally looked for better recreational facilities.
Inevitably they turned to the sea and its beaches. Furthermore, the increased wealth enabled more people to
purchase or erect bungalows from leased lands on the Pas Geometriques. Hence competition for access to
sandy beaches inevitably arose among the three groups: hotel developers, bungalows owners and the public.
Unfortunately, the pressure to build new hotels directly on the beach frontage is relentless because tourism is
one of the few growth areas of the local economy and is highly lucrative. Very powerful commercial interests
are at play in this sector. More hotels on the beach means less beach frontage for the public. At the present,
hotel sites occupy 41.9 kilometres of coastal zones which represent 13% of the total which does not seem to
be considerable but again it must be reminded that hotels tend to be built along the most beautiful stretches
of sandy beaches, obviously their share of sandy beaches must be much greater than the above percentage figure.
The insistence from property developers to have prime beach frontage and the demand from the public for
more public beaches with better amenities will inevitably lead to uneasy situations that could lead to confrontation.
(3) Recreational Purposes & Public Beaches
Coastal zones have become, over the years, important centres of leisure activities for the local population, and
it is expected to grow in importance in the years to come. Currently, public beaches total 26.6 kilometres which
represent 8.2% of coastal land use. It is clear that bungalows and hotel site with a combined total of 29% fare
much better than the public with a mere 8.2% of the total. Any government, present or future will have to come
up with more public beaches to dissipate mounting public concern for a better access to beaches and better
amenities on site. A visit to the hugely popular beaches at Flic En Flac ( west coast) on Sundays is sufficient
to convince anyone of the urgency of the situation, the public beach there is packed with people, cars and
buses. Amenities like toilets and water points are far and few between, and thus totally insufficient. The same
scenario repeats itself in the north at Mon Choisy and La Cuvette, two very popular public beaches.
((5) Leisure Boats
Tourism has considerably increased the number of pleasure crafts operating in the lagoons round Mauritius,
whether it be motor boats for water skiing or para sailing, or the usual sailing crafts. The operation of pleasure crafts is regulated by law.
Environmental impacts of human activities in coastal zones
Human activities with impacts on coastal ecology and environment can broadly be divided up into:
(a) activities that are situated in coastal zones
(b) activities occurring elsewhere (principally inland).
The category (a) can be subdivided into the following activities:
- The construction and operation of hotel complexes and bungalows
- Sand mining
- Artisanal Fisheries
- The recreational use of beaches
- The operation of pleasure boats
Similarly category (b) can be subdivided into the following activities
- The disposal of industrial sewage
- The disposal of domestic sewage & storm water
- The disposal of waste water from sugar mills
- The disposal Of Solid Waste
- Agricultural run off
Environmental Impacts of Hotel & Bungalow Construction and Operation on Coastal Zones
Apart from occupying beaches and rendering access difficult to the public, the construction of hotels directly on the beach head may have significant environmental impact. For instance, though hotels with more than 75
rooms must have, by law, a water treatment plant on site, it is not known whether all the different hotels'
treatment plants are really adequate to cope with the load or whether some seepage does occur at times which could have adverse effects on the lagoon.
Furthermore, hotels construct piers or jetties that can severely interfere with the long shore movement of sand
creating sand erosion further down the coast and can interfere greatly with the free passage of the public up and down the coast.
Sand erosion caused by the construction of piers and by sand mining is beginning to be a significant problem
though no studies are publicly available on the matter. The seriousness of the problem can be gauged by the
fact that the Government has, over the past years, built sea defences at certain places round the coast like
Grand Baie, Cap Malheureux and Flic en Flac. The defences consist of placing at selected places gabions
which are wire netting cages 1 metre cube in volume filled with rocks. This method is thought to hold the sand in place and permit local accumulation of sand.
The clearing of sea weeds, corals and other rocks in the lagoon close to the shore has regularly been carried
out to create suitable bathing areas or sky lanes. Though, in some cases, the clearing is fairly innocuous, on a
couple of occasions, it cannot be said to be so. For example, at Balaclava ( west coast of Mauritius), where a
marine park has just been set up, a couple of hotels obtained the permission to create water skiing lanes by
clearing corals over a long stretch of the lagoon. Notably, The Victoria Hotel, in 1995, cleared corals for a
water skiing lane 750 metres long and 30 metres wide and further proceeded, in 1996, to clear another site for
the creation of a bathing site and this amidst much opposition from local fishermen who feared for their
livelihoods. Needless to say that the hotel had the necessary permits and Environmental Impact Assessment reports to back up this operation.
In 1993, the Touessrok Hotel at Trou D'eau Douce (east coast) carried out very important works in the lagoon
with the necessary Environmental Impact Assessment report. The government of that time informed the
management that "the ministry has no objection to the implementation of the proposed works in relation to (i)
the dredging of the inner cover and of the two channels (ii) dredged material treatment and handling onshore
(iii) beach recharging and widening (iv) erection of a groyne and (v) the construction of an artificial
breakwater to protect the cove beach, provided that the following conditions are observed" ( Le Week End 20th of June 1993).
Though the local fishermen went to court to obtain an injunction, it does not appear that they managed to influence the course of things.
Unfortunately, very little is at present known on the impacts of hotel development on the coastal and lagoon ecology.
Bungalows built along the coastline have never been connected to the sewage system and disposal of sewage
is done exclusively through absorption pits or cess pits. It is possible that nutrient enrichment of the lagoon occurs through seepage of sewage to the lagoon. But that is at present purely speculative.
At several places, bungalows and even hotels have been built on wetlands or marshy grounds, for example at
Flic en Flac or Grand Baie. This has resulted in a drastic reduction of wetlands around the coast, hence
wetlands are no longer there to act as natural filtering systems of either sewage or storm waters. The water
table at Grand Baie has risen significantly, for example, and is now only a metre deep. Flooding and pollution by sewage is now a reality in parts of Grand Baie.
At Flic en Flac also, construction of hotels and bungalows has been going on for years on marshy lands. And
now certain parts of Flic En Flac is prone to flooding after heavy rains.
Environmental Impact of Recreational Use of Beaches
One of the main impacts of the use of beaches by the public on the environment is the fact that a fair
proportion of the public fails to use the dust bins provided on the beaches for the proper disposal of solid
waste. Hence, at times and on certain beaches, there is solid waste accumulating on site. This waste, apart
from being unsightly and a source of bad smells attracting rodents, can drift into the lagoon waters polluting
it. Furthermore, at certain places, the lagoon is used by some people as a huge and uncontrolled dumping
ground. Regularly, non governmental organisations working in the field of the environment and professional
divers team up to remove from the lagoon bottom large quantities of solid waste which found its way there. For example on the 7th of June 1997, during the "World Environment Day" divers removed from the lagoon of
Blue Bay ( South of the island ) car and truck tyres, old nets, discarded plastic bags and bottles, broken plates and even radio sets!
Anchor damage by pleasure crafts or fishing boats is thought to be a significant factor in the destruction of corals.
Coastal zones are undoubtedly under heavy use, and the pressure will not cease in the foreseeable future, on
the contrary it can only increase significantly with a greater number of tourists visiting the island every year,
with more of the population going to the sea side for leisure activities. It is indeed, high time that a
comprehensive policy of coastal management be set up by government before irremediable damage is inflicted
upon coastal zones. Already, there are signs that all is not well, a decrease in the catch of fishes over the
years, nutrient enrichment of the lagoon due to sewage, sand erosion, industrial pollution are but a few of the
problems that have to be addressed fully. As a fair share of the stresses on coastal zones originate inland, it is
clear that coastal zone management cannot be seen in isolation from what happens elsewhere, making proper management a challenging and interesting task of supreme importance.