Coastline
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The
landmass of Bangladesh is connected to the Indian Ocean through a
700 km long coastline. The coastal region is marked by a vast
network of river systems, an ever dynamic estuary, interaction of
huge quantities of fresh water that are discharged by the river
systems, and a saline waterfront --penetrating inland from the sea.
In addition to the coastal plains, there are a number of small
islands that are subject to strong wind and tidal interactions
throughout the year, and are inhabited by a large number of people.
As described in the earlier section, the coastal areas are highly
prone to cyclone induced storm surges.
The eastern coastline is extended from the Big Feni river to Badar
Mokam, the southern tip of the mainland. This part is more or less
unbroken, characterized by flat beaches comprising of clay and
sand. Karnaphuli, Matamuhuri, Sangu and Naf rivers discharge fresh
water through the
plains.
In the southwestern coastal areas of Bangladesh, the Sundarbans, a
large patch of naturally occurring mangrove forest is located. The
Sundarbans stretches further west into the southeastern part of the
state of West Bengal in India. It occupies a total area of about
one million hectares, about 62 percent of which is situated within
Bangladesh. The central region of the coastline is situated between
the eastern and western coastal areas. Most of the combined flow of
the GBM system is discharged through this low-lying area. The lower
Meghna river is highly influenced by tidal interactions and
consequential backwater effect. Heavy sediment inputs from the
rivers result in a morphologically dynamic coastal zone. Cyclones
and storm surges bring about the most catastrophic damages here.
The 1991 census recorded the size of the population of the coastal
districts as approximately 24 million (BBS, 1991) whereas in 1901,
the population of the coastal districts was only 7.2 million.
Coastal districts have a population density of 959 inh/km2,
compared to the national average of 861 inh/km2.5
Between 1901 and 1991, 20 to 22 percent of the total population
lived in the coastal area.
A
predominant linear type settlement pattern in the coastal districts
has been identified in the west and central districts, where an
extensive network of rivers and canals exist, and water is the
principal mode of transportation.
Coastal plains are mainly used for
crop agriculture and for grazing of livestock. Regular or periodic
inundation and saline water intrusion has been a problem for
agricultural activities in the coastal
areas.
Coastal water resources not only support
agriculture and industrial activities but also provide extensively
used navigational routes. There are two sea ports in Bangladesh:
Chittagong and Mongla. They support most of the international trade
of Bangladesh, and might provide a good headway for Nepal and
Bhutan’s international trade in the future (especially if
Bangladesh is connected to the proposed Trans-Asian road
network).
Industrial activities concentrate in the Khulna and Chittagong
districts. In Anwara upazila, adjacent to Chittagong city, an
export promotion zone has been established.
| Description of the Coastal
Resources |
Coastal Bangladesh is rich with natural
resources; including both renewable and non-renewable
resources.
Geological Resources
In recent years, coastal areas received international attention due
to high potential for the exploration of in-shore and off-shore
natural gas. In the southeastern Sangu valley, a large natural gas
field was discovered and subsequently put into commercial operation
in 1998. Offshore drilling is also underway to explore untapped
fossil fuel resources found in the coast. This has opened up new
possibilities for installation of gas-based power plants in the
Bhola Island and in Bagerhat, which would promote export promotion
zones, and rapid industrialization. Natural gas is well- recognized
to be cleaner than other green house gas emitting fossil fuels such
as coal.
Besides natural gas, commercially important
minerals such as monazite, ilmenite, rutile, zircon and ceseum have
been found in the sandy beaches along Cox’s Bazar. These resources
are yet to be exploited for commercial use.
Mangrove Forests
The coastal region houses several mangrove ecosystems, including
the Sundarbans. These mangroves forests are transitional zones
between fresh and marine waters, and are rich in marine and
terrestrial flora and fauna. While sundri (Heretiera fomes), gewa
(Excoecaria agallocha) and goran (Ceriops decandra) are the most
abundant species found in the forests, many other flora species
exist in these areas. Dicotyledonous tree species are represented
by 22 families and 30 genus, and Rhizophoraceae is represented by
all the 4 known genera and at least 6 species. There are also 12
species of shrubs, 11 species of climbers, 13 species of orchids
(epiphytic parasites) and 7 species of ferns in the Sundarbans. In
addition, the forests support a total of 425 species of wildlife
including mammals (49 species), birds (315 species), reptiles (53
species) and amphibia (8 species).
Among fish resources, the water bodies within the forest ecosystems
provide 53 species of pelagic fish, 124 species of demersal fish,
24 species of shrimps, 3 species of lobster, 3 species of turtles,
10 species of sea snakes and 7 other snake species. The forests
also provide basic ecological support systems as nursery for many
species of marine invertebrates including the fresh water shrimps
(Macrobrachium rosenbergii) and brackish water prawn (Penaeus
monodon) that are exported.
The Sundarbans was declared a World
Heritage Site. It is known as the single largest stretch of
productive mangrove forest in the world, and is inhabited by one of
the most elegant creatures of nature, the Royal Bengal Tiger
(Panthera tigris tigris). The dimensions and richness of
biodiversity in the Sundarbans is also proven by the availability
of 3,033 ton of fish, 375 ton of mud crab, 3,600 ton of oyster
shells and 35 ton of gastropod shells which are obtained from the
forest every year.
In addition, about 1,500 million tiger prawn fries are collected
per year from the forest and its adjacent areas. The forest
contains a total of 10.6 Mm3 standing tree volume, 64 percent of it
is occupied by the most commercially important species sundri . The
most important non-wood forest product is Nypa fruiticans. Leaves
from this plant are widely used for thatching of roofs of houses
and boats, and also for fencing the houses of millions of families
around the coastal districts.
Land Resources
For the local inhabitants, the flat plains in the coastal areas are
the most important resource that supports crop production,
livestock rearing, salt manufacturing from the sea water, shrimp
culture activities, ship manufacturing, harbor activities and
different types of industries.
Water Resources
Coastal areas are endowed with both fresh and brackish water
resources. During monsoon, fresh water there is abundant fresh
water, whereas during the winter, water becomes a scarce resource.
Due to reduced flows in the rivers in winter, the surface water
systems suffer from saline water intrusion, making the resource
unsuitable for agricultural, domestic and industrial purposes. The
groundwater aquifers in the coastal districts are under growing
stress of salinization resulting from over-extraction . Sea level
rise and low river flows would substantially contribute to that
stress. Winter agriculture in the coastal areas is dependent on
groundwater. Rural water supply almost entirely depends on fresh
water source.
Beaches
The beach along the southeastern coastal areas is continuous and
flat. Although it stretches 120 km along the shore, there are only
a few patches of sandy beaches, the rest are muddy. There is
another important sandy beach in Kuakata in the central coastal
area. Production of salt and shutkee (dried fish) is done in the
beach areas. A long sandy beach of about 145 km runs from Cox’s
Bazar to Badar Mokam. Most of these sandy beaches offer good
tourism opportunities.
Fisheries
Although the Extended Economic Zone of Bangladesh covers an area of
70,000 km2, effective fishing areas for marine fish and shrimp have
been estimated at about 10,000 km2 and 5,000 km2
respectively. Total annual marine fisheries catch is estimated at
0.23 million ton which is around 28 percent of all fish produced
per year.
Coral Reefs
Bangladesh has a tiny island at the tip of its southeastern reach,
namely Narikel Zinzira, where coral colonies are located. Existing
environmental conditions around the coral island are poor due to
several reasons including: frequent spillage of bulge waters from
sea-going vessels, increasing turbidity of coastal waters because
of deforestation followed by land erosion in the hilly reaches of
Chittagong Hill Tracts, and exploitation of corals by local
traders. Without immediate and adequate conservation activities,
the already endangered ecosystems of the coral island are likely to
suffer further degradation.
| Impacts on
the Availability of Coastal Resources |
Coastal zone resources
highly endangered by the climate change include land and water
resources, as well as the mangroves forests. More specifically, the
impacts would be:
1. changes in water levels and induced inundations and water
logging;
2. increased salinity in ground and surface water, and
corresponding impacts on soil
salinity; and
3. increased coastal morphological dynamics (erosion and
accretion).
Water Levels,
Inundations and Water Logging
Any rise of the sea level will
propagate upstream into the river system. In Bangladesh, this
backwater effect will be more pronounced because of the
morphologically dynamic rivers, which will adapt their bed levels
in a relatively short time period. This whole process will lead to
decreased river gradients, increased flood risks and increased
drainage congestion.
Since most of coastal plains are within 3 to 5
meters from the mean sea level, it was previously thought that a
significant part of the coastal areas (as high as 18 percent of the
country) would be completely inundated by rising sea waters. Such a
speculation was made based on two major approximations: (a) the
coastal plains are not protected and (b) the seawater front with
follow the contour line. In reality, however, it is found that most
of the coastal plains in the central regions are protected. Due to
the backwater effect, embankments further land inwards may be
topped and areas flooded. This could still turn most of the seaward
polders into islands.
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Coastal Morphology
The morphological dynamism of deltaic Bangladesh is manifested in
the coastal zones. The coastal areas have experienced natural
erosion and accretion in the past, as well as anthropogenic
accretion and subsequent erosion in more recent years. Although
current literature suggests that coastal land is in the process of
slow accretion at an approximate rate of 8 km2/year during the past
210 years (Allison, 1998, Martin and Hart, 1997), much of this may
be attributed to cross dams that have been built to reclaim land
from the shallow continental shelves. Nevertheless, due to climate
change induced alterations in thermal energy at the
ocean-terrestrial interface and the expected changes in the inflow
of riverine sediments, the dynamics of coastal morphology appears
to be highly uncertain. Furthermore, new embankments for reclaiming
additional land would affect the morphological dynamics of the
coast.
| Impacts on the Use of Coastal
Resources |
In addition to the above described
impacts on the coastal resources (drainage congestion, saline water
intrusion and coastal morphology), the occurrence of cyclones and
storm surges reduce the economic potential and employment
opportunities in the coastal areas. For example, high intensity
storm surges might jeopardize the expansion of energy-recovery
activities in the coastal areas and supporting industries,
especially in the off-shore areas. Salinity intrusion, without
climate change induced effects, has already inhibited growth of
industrialization in the coastal districts. A number of industries
in Khulna, including the only newspaper producing industry in the
country have been facing shortage of fresh water during the dry
season. As a consequence, no new heavy industry has emerged in the
recent years despite increasing infrastructure facilities
(sea-ports, etc.) in the coastal areas.
Agricultural activities will suffer greatly
from impacts of climate change. Increased salinity levels will
reduce fresh water availability for irrigation, while growing
drainage congestion problems will result in longer periods of flood
inundation. This will reduce the areas suitable for rice
production. In addition, increased coastal morphological dynamics
will contribute to the existing problem of loss of valuable
agricultural land due to erosion.
