9
The justifi cation of these mountain masses
demarcates the major drainage basins on the peninsula. Three large rivers are said to originate
from these mountains. These being the Sg. Perak ,
Sg. Kelantan and Sg. Pahang (Sg. = Sungai means
river), the Sg. Perak (drainage area: 15,151 km
2 )
fl ows from between the Bintang and Central
Terengganu Highlands, and the Sg. Kelantan
(drainage area: 12,691 km
2 ) fl ows northward to
discharge into the South China Sea. The Sg.
Pahang (drainage area: 29,137 km
2 ) fl ows fi rst
south and then eastward to fi nally debauch into
the South China Sea as well. This is briefl y tabulated below:
River
Catchment area (km
2 )
Sungai Pahang
29,137
Sungai Perak
15,151
Sungai Kelantan
12,691
Sungai Muar
6,062
Sungai Muda
4,273
Sungai Johor
2,720
Sungai Linggi
1,306
Sungai Kelang
1,212
High rainfall contributes greatly to the increasing fl ow of freshwater in the fl uvial system within
most watersheds. The rivers are generally narrow
and shift in their upper courses. In the lower
courses the rivers sometimes fl ow through swampy
land. An account of the limnology of lowland
streams in West Malaysia has been given by Ho
and Furtado ( 1982 ).
Most rivers and systems fl ood more or less
regularly during the NE monsoon season, especially on the east coast. Sg. Pahang fl oods annually. The tendency for the equilibrium of the hill
forest ecosystem as well as the natural hydrological regimes of rivers are different.
An alluvial plain runs northeast to southwest
all along the coasts of Sarawak and western
Sabah. This low-lying coastal land varies from
less than one to tens of kilometres. It is interrupted in a few areas by encroaching cliffs of low
mountains. Coastal swamps are less extensive in
Sabah than in Sarawak. The Sabah coastline is
transected by about 37 rivers and several large
estuaries, many of which are swift fl owing and
laden with silt. Sarawak is drained by about
20 rivers of various sizes. They generally fl ow
northeast into the South China Sea.
One notable feature is that Malaysian rivers
are generally short and swift in the upper
reaches, and many carry a high silt load in their
lower reaches. Thus, while abundant rainfall
ensures perennial river fl ow, the volume of water
transported in a river fl uctuates widely. This
means that much of the water resources could
not be tapped for our fl ood control (Leigh and
Low 1973 ).
The natural topography of Malaysia also
favours the formation of waterfalls. The prevailing mountains, terrain, geology and the country’s
heavy rainfall provide ideal conditions for the
formation of waterfalls. No less than 114 waterfalls have been documented (Anon 1990 ). Most
Malaysian waterfalls occur on hardened sandstone or on granite, while some are formed over
limestone.
Malaysia has very few natural lakes. The two
better known freshwater swamp lakes, namely,
Tasik Bera and Tasik Chini, are located in Pahang
and have drainage linkage with the Pahang River.
Tasik Bera was the subject of extensive limnological study under IBP/PF Programme (Furtado
and Mori 1982 ). Another example is the Ulu
Lepar river-like wetland ecosystem also in
Pahang (see Nather Khan 1990a ).
With regard to impoundments, there are 51
man-made dams in Malaysia, of which 46 are
located in Peninsular Malaysia, 3 in Sabah and 2
in Sarawak. These range in water surface areas
from 10 ha (Mahang Dam, Pahang) to 37,000 ha
(Kenyir Dam, Terengganu). The oldest being the
Bukit Merah Reservoir (3,500 ha) in Perak which
was built in 1906. The dams serve for hydroelectric power generation, irrigation, drinking water
supply, river fl ow regulation, fl ood mitigation,
inland water fi sheries development, etc.
1.10.3 Natural Vegetation
The natural vegetation of Malaysia is tropical
rainforest. Lowland dipterocarp forest occupies
areas below 300 m, hill dipterocarp forest dominates between 300 and 1,300 m and montane
1.10 Limnology in a Typical Developing Country
The justifi cation of these mountain masses
demarcates the major drainage basins on the peninsula. Three large rivers are said to originate
from these mountains. These being the Sg. Perak ,
Sg. Kelantan and Sg. Pahang (Sg. = Sungai means
river), the Sg. Perak (drainage area: 15,151 km
2 )
fl ows from between the Bintang and Central
Terengganu Highlands, and the Sg. Kelantan
(drainage area: 12,691 km
2 ) fl ows northward to
discharge into the South China Sea. The Sg.
Pahang (drainage area: 29,137 km
2 ) fl ows fi rst
south and then eastward to fi nally debauch into
the South China Sea as well. This is briefl y tabulated below:
River
Catchment area (km
2 )
Sungai Pahang
29,137
Sungai Perak
15,151
Sungai Kelantan
12,691
Sungai Muar
6,062
Sungai Muda
4,273
Sungai Johor
2,720
Sungai Linggi
1,306
Sungai Kelang
1,212
High rainfall contributes greatly to the increasing fl ow of freshwater in the fl uvial system within
most watersheds. The rivers are generally narrow
and shift in their upper courses. In the lower
courses the rivers sometimes fl ow through swampy
land. An account of the limnology of lowland
streams in West Malaysia has been given by Ho
and Furtado ( 1982 ).
Most rivers and systems fl ood more or less
regularly during the NE monsoon season, especially on the east coast. Sg. Pahang fl oods annually. The tendency for the equilibrium of the hill
forest ecosystem as well as the natural hydrological regimes of rivers are different.
An alluvial plain runs northeast to southwest
all along the coasts of Sarawak and western
Sabah. This low-lying coastal land varies from
less than one to tens of kilometres. It is interrupted in a few areas by encroaching cliffs of low
mountains. Coastal swamps are less extensive in
Sabah than in Sarawak. The Sabah coastline is
transected by about 37 rivers and several large
estuaries, many of which are swift fl owing and
laden with silt. Sarawak is drained by about
20 rivers of various sizes. They generally fl ow
northeast into the South China Sea.
One notable feature is that Malaysian rivers
are generally short and swift in the upper
reaches, and many carry a high silt load in their
lower reaches. Thus, while abundant rainfall
ensures perennial river fl ow, the volume of water
transported in a river fl uctuates widely. This
means that much of the water resources could
not be tapped for our fl ood control (Leigh and
Low 1973 ).
The natural topography of Malaysia also
favours the formation of waterfalls. The prevailing mountains, terrain, geology and the country’s
heavy rainfall provide ideal conditions for the
formation of waterfalls. No less than 114 waterfalls have been documented (Anon 1990 ). Most
Malaysian waterfalls occur on hardened sandstone or on granite, while some are formed over
limestone.
Malaysia has very few natural lakes. The two
better known freshwater swamp lakes, namely,
Tasik Bera and Tasik Chini, are located in Pahang
and have drainage linkage with the Pahang River.
Tasik Bera was the subject of extensive limnological study under IBP/PF Programme (Furtado
and Mori 1982 ). Another example is the Ulu
Lepar river-like wetland ecosystem also in
Pahang (see Nather Khan 1990a ).
With regard to impoundments, there are 51
man-made dams in Malaysia, of which 46 are
located in Peninsular Malaysia, 3 in Sabah and 2
in Sarawak. These range in water surface areas
from 10 ha (Mahang Dam, Pahang) to 37,000 ha
(Kenyir Dam, Terengganu). The oldest being the
Bukit Merah Reservoir (3,500 ha) in Perak which
was built in 1906. The dams serve for hydroelectric power generation, irrigation, drinking water
supply, river fl ow regulation, fl ood mitigation,
inland water fi sheries development, etc.
1.10.3 Natural Vegetation
The natural vegetation of Malaysia is tropical
rainforest. Lowland dipterocarp forest occupies
areas below 300 m, hill dipterocarp forest dominates between 300 and 1,300 m and montane
1.10 Limnology in a Typical Developing Country