MALAYSIA: Malaysia Awakens to Erosions Threat
Along Its Extensive Coast
Coastal erosion along Malaysia's nearly 5000 km coastline is reaching
crisis proportions even without sea level rise and is the most
serious climate change impact facing the nation. Inundation and
increased flooding also pose severe threats particularly to the
dominant coastal activity - agriculture.
A majority of the population lives in the coastal zone which
can be divided into two major types: sandy beaches, and silt and
clay mud flats, fringed by mangroves. The major towns, ports,
large agriculture and aquaculture projects of Malaysia's coasts
contribute significantly to the nation's economic development
and the physical and economic impact for the whole nation of a
greenhouse-induced sea level rise could be devastating.
The country is separated into two regions: Peninsular Malaysia
and, 640 km across the South China Sea, the States of Sarawak
and Sabah, known as East Malaysia, on northern Borneo Island.
Sarawak's coast has long, straight beaches and mangroves; Sabah
is more rugged, with offshore islands and coral reefs.
Because of awakening concern, coastal erosion is being studied
on a national basis. A control plan has been formulated, with
a conscious effort toward mitigation. Besides natural processes,
beach erosion occurs when upstream dams trap sediment. But numerous
dams are projected for the future because of the government's
aim to provide the population with adequate and safe water. Watershed
development, especially dam construction, has a strong bearing
on the stability of the coast, especially near river mouths. The
cost to mitigate coastal erosion in 47 critically eroding areas
is estimated at US $85 million.
The stronger waves accompanying a rise in sea level will exacerbate
the wearing away of the beaches. In some places the average rate
of retreat of the shoreline is 1- 8 meters per year. Bunds and
dikes, which also compensate for anticipated ground settlement,
are now the standard approach for protection. But as the sea rises
the waves will overtop these. Dunes offer some security but on
developed coasts these have been artificially flattened or removed.
The other major threat - besides erosion - if the seas rose would
be inundation and flooding. About 12 percent of the area of Peninsular
Malaysia, where the western low plains of muddy sediment are home
to 2.5 million people, is flood prone. Erosion of mud coasts is
poorly understood, and improved understanding in the near future
is not considered likely.
Along the sandy beaches and bays of the east coast of Peninsular
Malaysia, more than 200,000 people and another 12,600 km2 are
in danger of floods. The causes are a combination of excessive
precipitation and runoff, inadequate river capacity, flood plain
encroachment, blocking of river mouths, and high tide. Tidal flooding,
is now largely prevented by extensive coastal and river bunds
which are important to polder development in this area. More than
150 river systems in the country are used for inland navigation,
transportation, irrigation, water supply and hydropower. Accentuated
by high tides, river flooding is a frequent source of harm to
people, property and public facilities, totaling an estimated
annual damage of $38 million.
The wetlands, primarily the mangrove forests, are important for
firewood and charcoal, as habitats for aquatic life and food and
for prawn, and for protection from erosion. More than half the
nation's annual fishery income is related to the mangroves, and
the livelihoods of 300,000 fishermen depend on them. Sea level
rise is not yet perceived as a direct threat, but "it is highly
probable that the mangrove buffer may vanish altogether," say
the authors, "exposing the previously protected coastal development
to direct wave attack." Wetlands are considered wastelands by
developers. Clearance and conversion to agriculture or aquaculture,
industrialization, urbanization, and pollution all menace the
mangrove forests.
Of the various threats to the coasts - and some may together
affect the same area - tidal submergence is likely to come first,
then wetland loss, and finally coastal erosion. Flooding is a
nuisance unless it is prolonged. Areas can easily be protected
from inundation. Wetland loss, while small in terms of area, would
have serious economic repercussions, and reclamation could cause
the mangrove firests of Peninsular Malaysia to disappear by the
year 2000.
Among possible responses, the authors feel a wait-and-see attitude
is untenable given the "overwhelming scientific evidence that
points to a rise in sea level and the potentially large costs
of inaction." Given "the long lead time required to transform
a policy into reality," they continue, "makes it prudent to begin"
to incorporate adaptation measures into development and land use
planning.
(Zamali Midun and Say-Chong Lee, Drainage and Irrigation Department,
Malaysia)
