THE LANGAT RIVER BASIN - UM Repositoryrepository.um.edu.my/1223/5/Chapter 3 Revised.pdf · THE...

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Chapter 3

THE LANGAT RIVER BASIN

3.1 INTRODUCTION

This chapter describes the physical environment of the area under study. The location

of Peninsular Malaysia and the Langat River are described in Section 3.1 and the

general characteristics of the Langat drainage system are explained in Section 3.2.

Catchment characteristics based on topographic map analysis are discussed in Section

3.3, while Sections 3.4, 3.5 and 3.6 emphasise the topography, geology, and soil of

the catchment area. River regulation (impoundment) is covered in Section 3.7,

followed by a more contextual climatic analysis (Section 3.8). Local authorities

within the Langat River Basin is discussed in Section 3.9. Existing land use is

discussed in Section 3.10. Section 3.11 concludes this chapter.

Langat Basin is an important water catchment area providing raw water supply and

other amenities to approximately 1.2 million people within the basin. Important

conurbations served include towns such as Cheras, Kajang, Bangi, Government

Centre of Putrajaya and others. There are two reservoirs (Semenyih and Hulu Langat)

and 8 water treatment plants (4 of which operates 24 hours), which provide clean

water to the users after undergoing treatment.

Use of Langat River is not only limited to water supply but also for other purposes

such as recreation, fishing, effluent discharge, irrigation and even sand mining, to

name a few. These multi faceted usage of the river results in conflicting interest from

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the perspective of the various stakeholders. Therefore, there is a need for proper

resource optimization and resolution of conflict.

Lately, the Langat Basin water resource is under stress due to poor water quality.

Areas starting from Sg. Cheras downstream to Permatang Pasir near the sea, are of

Classes III to V. Point and non-point sources of pollution from domestic and

industrial sources of pollution be either it soluble organic or solid, found their way

into the rivers resulting in heavy pollution and poor water quality.

3.2 STUDY AREA

3.2.1 The Peninsular Malaysia

Peninsular Malaysia is located at the southern end of the Malay Peninsula which is at

the southern extremity of Southeast Asia. It extends from 1o 15’N to 6

o 45’N latitudes

and 99o 40’E to 104

o 35’E longitudes. To the east it is bounded by the South China

Sea and to the west by Straits of Malacca. It shares a common boundary with

Thailand in the north and is separated from the island of Singapore in the south, by

the narrow Straits of Johor. Peninsular Malaysia covers an area of 127,560 km2. Its

maximum length is 736 km, while its maximum width is 322 km. Its coastline extends

some 1930 km. Altogether, Malaysia has more than 150 river systems spread over a

total land mass of 329,760 km2.

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The constant and heavy rainfall of the Peninsular Malaysia gives rise to a dense

network of rivers and streams (Figure 3.1). The largest river in Peninsular Malaysia,

the Pahang River has a length of about 434 km and a catchment area of approximately

29000 km2. The catchment areas of the other three large rivers are 15,151 km

2 (Perak

River), 12,612 km2 (Kelantan River) and 4273 km

2 (Muda River).

Streams flow in the upper and middle reaches of Peninsular Malaysian rivers and is

usually swift and strong, but slow and sluggish in the lower course. The main

mountain ranges which run more or less parallel to the west coast form a continuous

watershed from the northern borders of Peninsular Malaysia to Malacca. The rivers

west of this watershed have relatively short courses. Their gradients in the upper

courses are very steep: some rivers drop about 1219 m in less than 24 km before they

emerge onto the coastal plains (Oii, 1963). The very rapid decrease in the flow rates

of the rivers at the foot of the mountains reduces the carrying capacity of the rivers.

This causes them to drop their load of coarser-grained material and are carried by the

slow meandering rivers and deposited at the river mouths and along the coastal

stretches. There is therefore a roughly parallel zoning of marine and riverine

sediments on the west coast.

While the headwaters of most river exhibit steep gradients, waterfalls and rapids, the

lower courses, in contrast, characteristically show signs of maturity such as channel

braided, meanders, ox-bows and levees. The river profiles thus present a typically

flattened appearance, and have been influenced by quaternary changes in sea level

and progressive sedimentation by the over-loading of rivers.

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Figure 3.1: General river system of Peninsular Malaysia.

Floodplain

River

State

Town

State border

District border

Legend

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3.2.2 Langat River Basin

The Langat River has a total catchment area of approximately 1815 km2. It lies within

latitudes 2o 40’M 152” N to 3

o 16’M 15” and longitudes 101

o 19’M 20” E to 102

o

1’M 10” E. The catchment is illustrated in Figure 3.2. The main river course length is

about 141 km mostly situated around 40 km east of Kuala Lumpur. The Langat River

has a several tributaries with the principal ones being the Semenyih River, the Lui

River and the Beranang River. There are two reservoirs, the Langat Reservoir and the

Semenyih Reservoir respectively. The Langat Reservoir, built in 1981 has a

catchment area of 54 km2 while the Semenyih Reservoir, built in 1982 with the

purpose to supply domestic and industrial water has a catchment area of 41 km2. For

the Langat Reservoir, it is also used to generate power supply at moderate capacity for

the population within the Langat Valley.

The study areas include selected impacted and non-impacted stretches of the Sungai

Langat Basin (Figure 3.2). Areas surveyed and identified begin from the upstream;

starting with the Semenyih and Hulu Langat Dams down to the lowest area at the

estuary near Permatang Pasir with a total distance of 78 km. Since the total catchment

area of Sungai Langat Basin is substantial (1987.7 km2), it is realistic only to consider

the critically impacted areas that give rise to the lowering of water quality within the

river basin. The water quality at the Semenyih Dam and upstream of the Semenyih

Dam is of Class I. In comparison, the water quality is seen to deteriorate further

downstream from the Semenyih Dam; varying from Class III to V water quality due

to various land use activities.

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3.3 CHARACTERISTICS OF LANGAT RIVER BASIN

Langat River Basin is drained by three major tributaries – Langat River, Semenyih

River, and Labu River (Figures 3.3 and 3.4). The main tributary, Langat River, flows

about 182 km from the main range (Banjaran Titiwangsa) at the Northeast of Hulu

Langat District in south-southwest direction, and draining into the Straits of Malacca.

Both Langat River and Semenyih River originate from the hilly and forested areas in

the western slope of Banjaran Titiwangsa, northeast of Hulu Langat. The main reach

of Semenyih River can be considered to start from the Semenyih Dam flowing south-

southwest direction through the town of Semenyih, Bangi Lama and finally merges

with Langat River at about 4 km to the east of Bangi Lama town. Semenyih River is

also supplemented by Beranang River and Pajam River. Both of these rivers originate

from the northern part of Seremban District, Negeri Sembilan (Territorial division

Lenggeng, Seremban).

Labu River, meanwhile, is the smallest of the three tributaries. The reach begins in

Territorial division Labu, Seremban and flows through the town of Nilai and finally

meets Langat main river at about 3 km south of Dengkil town.

The basin covers an area of about 2,282 km2 and ranges from 10 to 40 km wide. The

physical characteristics of the drainage basin are given in Table 3.1 using a series of

topographic maps obtained from the Department of Agricultural, Malaysia namely:

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Kuala Lumpur

Petaling

Kuala Langat

Sepang

Seremban

JelebuKlang

Kuala Selangor

Gombak Pahang

Straits o

f Malacca

Figure 3.2 : Preliminary Survey to Pristine and Impacted Areas of the Sungai Langat Basin.

Permatang Pasir

Semenyih Dam

Hulu Langat

Dam

BANTING

DENGKIL

KAJANG

BANGI

PEKAN

CHERAS

PEKAN BT. 18

LABU

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iii) Topographic map series L7039, sheet 3857(1993), scale 1:50,000

iv) Topographic map series L7030, sheet 3856(1996), scale 1:50,000

Drainage density (D) is the ratio of the total channel lengths accumulated for all orders

within the catchment area (Horton, 1945). Based on Strahler’s (1957) texture

classification, the drainage density of the Langat Basin can be said to be that of low

density (Table 3.1).

The bifurcation ratio was defined by Horton (1945) as the ratio of the number of streams

of one order to the number of streams of the next highest order (n + 1). In the Langat

River catchment, the average value of the bifurcation ratio of 4.93. Taking Peninsular

Malaysian examples from Sabry (1997) at Tekala River (5.1), Koh (1978) at Lui River

(3.75) and Mykura (1989) at Klang River (5.9), the mean bifurcation ratio at most of the

catchment areas in the Peninsular tends to approximate 5.

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Figure 3.3: Langat Drainage Basin.

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Table 3.1: Physical characteristics of Langat River catchment.

Characteristics

Symbol

Value

Area (km2) A 1815

Total stream length (km) Ct 2530.46

Catchment length (km) L 828.4

Catchment width (km) C 894.3

Length of the main channel (km) LMC 142.38

Catchment relief m Hb 2103

Relief-area ratio 1.16

Stream order U 5

Mean length stream order 1 km 88.98




Total number of stream order 1 182





Mean of bifurcation ratio: Br

Order 2

Order 3

Order 4

Order 5

Average Br

1.14

2.48

7.1

9

4.93

Mean of stream length ratio RL 8.21

Drainage density km/km2 Ct/A D 1.39

Relief ratio Hb/L 2.54

Catchment width ratio A/L 2.191

Slopes 28.31o

(Source: Various topographic maps, geology and soils maps, Malaysia)

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3.4 TOPOGRAPHY

3.4.1 Peninsular Malaysia

Topographically, Peninsular Malaysia is characterized by a central mountain range

(the Banjaran Titiwangsa) surrounded by coastal plains with more than half of the

total area being higher than 150 m above sea level. Almost all rivers originate from

Banjaran Titiwangsa range flows either into the Straits of Malacca or the South China

Sea.

3.4.2 The Langat River Basin

Langat River basin can be divided into 3 distinct zones (Saharudin Idrus, 2004). The

first can be referred to as the mountainous zone of the northeast corner of Hulu

Langat district. The average height of the highland ranges is about 960 meter above

mean sea level. Most of the mountainous region is below 500 m from the mean sea

level.

The second zone is the hilly area characterised by gentle slopes spreading widely

from north to the east in the middle part of Langat basin. The area is generally below

100 m and the lower part of the hills extends to Putrajaya, Cyberjaya, and Dengkil in

Sepang. Langat River flows gently in the hilly area. The river sediment changes

composition gradually from boulder/gravel in the mountainous zone, to sand, and then

silt in the hilly areas.

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The third zone is a relatively flat alluvial plane located in the southwest of Langat

Basin. This zone is bounded by the hilly area to the north and east, and by the Straits

of Malacca to the west. Most of this area is characterised by peat with clay and silt

soil.

Figure 3.4: Main Tributaries of Sungai Langat and its Catchment.

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3.5 GEOLOGY

3.5.1 Regional geology of Peninsular Malaysia

Peninsular Malaysia is part of the orogenic belt extending from north-west China,

through east Myanmar and west of Thailand and Indonesia in the south. It consists of

various types of rocks that show a variety of palae environmental origins, with ages

ranging from Upper Cambrian to Quatenary. The Upper Cambrian strata are

characterized by orthoquartzitic sedimentary rocks, whereas the Silurian rocks are

predominantly of an argillaceous and carbonate rocks. These argillaceous rocks

include shale and calcareous shale. Volcanic activity produced mainly acidic tuff

during this period. During the Devonian, a thick succession of limestone was

deposited. These limestone forms hills in a few states, with steep slopes or vertical

cliffs protruding from the flat alluvial areas.

Peninsular Malaysia is also a Palaeozoic-Mesozoic structure which is part of the

Pacific orogeny which has experienced complex tectonic activity, orogenic and post-

orogenic. During the Mesozoic era, the layering of the sedimentary rocks was

transformed into a series of gigantic folds. At the same time, a number of granitic

instrusions occurred throughout the peninsular. Subsequently, Peninsular Malaysia

has been transformed into part of the stable Sunda shield. A number of sedimentary

valleys of Tertiary age are found and are rich in coal deposits. Tjia (1978) divided

Peninsular Malaysia into three mineral belts, known as the West Tin Belt, the East Tin

Belt and Central Belt.

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3.5.2 Geology of the Langat River Basin

Bedrock in the mountain area near the source of the river is granite that forms the

mountain bone of the peninsula and it extends around hilly areas near Kg. Cheras.

Layers of the hilly areas are called Kenny Hill Formation and Kajang Formation,

consisting of metamorphosed sandstone, shale, mudstone, and schist. The upper part

of the bedrock including those of granite is weathered. Some parts are heavily

weathered with depths of several meters (JICA, 2001).

In the low flatlands, thick quaternary layers are deposited on the bedrock. The

quaternary layer, from the top to the bottom, consists of 0.5 to 5.5m deep Beruas

Formation with peat layer at the top, clayey Gula Formation and Kempadang

Formation starting in the hilly areas and having a 40 to 50 m depth near the seacoast.

Lying underneath is the Simpang Formation of sand and gravel with thickness of

several meters in the hilly area and about 50 m to more than 100 m in the low

flatlands (JICA, 2001).

3.6 SOIL

3.6.1 Regional soil of Peninsular Malaysia

Two broad groups of soils are evident in Peninsular Malaysia. The first consists of

soils developed on igneous, metamorphic and sedimentary rocks. These are the

sedentary soils of interior hills and mountainous. The second group is formed on

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alluvial deposits. The sedentary soils are generally deeply weathered and have a few

reserves of weatherable minerals. The overriding influence of parent material under

the hot and humid climate is indicated by the high proportion of resistant minerals left

in situ, the weathering sequence from parent material to soil being expressed as a

decomposition and removal of soluble minerals and an accumulation of resistant types

such as quartz and the formation of end products including ferric minerals (e.g.

haematite and goethite, aluminium minerals-gibbsite, clay-kaonite and amorphous

material).

Soil on the alluvial plains and terraces are formed on three major types of deposits:

riverine and marine alluvia and organic residues. The riverine alluvia consists of

present day alluvia which generally occur at higher elevations.

3.6.2 Soil of the Langat Basin

In the study area, the soil is formed by granite and sandstone. It has been designated

as a steepland ‘serdang’ and lowland ‘Selangor-Kangkung’ soil series (Figures 3.5

and 3.6). The soil profiles in steep area at high elevation are always more than one

metre. In the Langat River catchment, the soil extends to more than two metres, a

feature described by Sabry (1997). On occasion, outcrops of granite boulders and core

stones can be seen at the surface particularly within the main stream and its

tributaries.

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3.7 IMPOUNDMENTS

As mentioned in Section 3.2, there are two reservoirs operating in the Langat

catchment are namely the Langat Reservoir and the Semenyih Reservoir. They are

situated at the upstream of Langat and Semenyih Rivers with a total catchment area of

approximately of 95 km2. Puncak Niaga Sdn. Bhd., the agency responsible for

supplying the fresh water to the people in Langat and Klang Valleys manages both

reservoirs. The Langat Reservoir impounds 37.5 million m3 of water at peak elevation

of 220 m, and regulates the flow of the Langat River in the dry season according to

the demand of the water treatment plant downstream. Besides their main purpose to

supply fresh water by regulating stream flow at the intake point, the reservoirs are

also important in controlling flood discharges particularly at the down stream of

Langat River. The Langat Reservoir is also used to generate hydroelectric power. The

hydroelectric power facility is operated by an independent power supplier and has a

generating capacity of up to 33 kV and 37,440 kWh of electricity per day (Puncak

Niaga Annual report, 1997). Currently, there are four major water treatment plants

operating 24 hours along the Langat River (Table 3.2). This is part of the Langat

River scheme, which was designed to augment the water supply to Kuala Lumpur and

the Klang Valley region. According to Tenaga Nasional Berhad (TNB) (1993), the

Langat Reservoir impoundment commenced in 1981. Because of the unusually wet

monsoon of 1981/82, the reservoir filled rapidly and reached minimum operating

level of elevation (200 m) by April 1982. Meanwhile, the Semenyih Reservoir

(relatively small compared with the Langat Reservoir) was sufficiently completed to

enable storage to commence in October 1982. The Langat Reservoir over-spilled on

two occasions between 1993 and 1995 respectively.

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Figure 3.5: Langat River catchment: Geology

Figure 3.6: Langat River catchment: Geology.

Legend Selangor-Kangkung Serdang-Bugor Steepland-Serdang Keranji Munchung-Seremban

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Table 3.2: Location of intake points along the Langat River.

Intake Point

Latitude-Longitude

Langat River at Bukit Tampoi 2o 50” 48’ – 101

o 40” 48

’

Langat River at Cheras Batu 11 3o 01” 36’ – 101

o 46” 36’

Langat River at Hulu Langat 3o 04” 42’ – 101

o 47” 18’

Semenyih River 2o 59” 00’ – 101

o 52” 00’

3.8 CLIMATE

3.8.1 Regional climate of Peninsular Malaysia

Malaysia falls within the humid tropics (Chang, 1993) and has a climate which is

equatorial and greatly influenced by both North East (NE) and South West (SW)

monsoons. The monsoons typically bring heavy rainfall while convectional rain is

common during inter-monsoonal periods. Much of the rainfalls are received mainly

during SW and NE monsoons. The NE monsoon brings rains to the east coast of

Peninsular Malaysia during November to February while the SW monsoon prevails

for the period of June to early October at the west coast of Peninsular Malaysia.

Neverthless, localized thunderstorms occur all the year round and at times can be very

intense particularly during the intermonsoon months of March-May. The highest

rainfall exceeds 5000 mm and the lowest is about 1750 mm. The average annual

rainfall is 2820 mm in Peninsular Malaysia, but there is considerable temporal and

spatial variation.

Dale (1959) divided the rainfall pattern in Peninsular Malaysia into four periods based

on the Southeast Asian Monsoon.

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1. The NE monsoon, prevailing from November or early December until March.

2. The transitional period or inter-monsoon, occurring in April until May (five to

seven weeks).

3. The SW monsoon, predominating in June until September or early October.

4. The transitional period or inter-monsoon, wide-spreading in October and

November.

3.8.2 Climate of the Langat River Basin

The climate of the study area in Langat River is similar to the climate of Peninsular

Malaysia which is equatorial-monsoon. This climate is characterized by high average

and uniform annual temperatures, high rainfall and high humidity. This climate has a

dominant impact on the hydrology and geomorphology of the study area. Generally

the study area experiences two types of season: the wet season in April to end of

November, and a relatively drier period from January to March. The weather is very

much influenced by the SW monsoon which blows across the Straits of Malacca.

Flooding is common in the study area during this period particularly when it coincides

with localized rainfall.

3.8.2.1 Precipitation

The rainfall for the west is differentiated on the basis of a double maximum occurring

during the two inter-monsoon seasons in April and October to September, but the

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double minimum is prevalent during the two monsoons seasons. The highest intensity

storms normally occur during the months of October, November, December and

April. The driest month in the west is July, and February is the second driest month.

3.8.2.2 Temperature

The mean annual temperature of the lowland in Peninsular Malaysia varies within +

1.7oC to 26.70

oC (the lowlands are classified as the area below 152 m). The eastern of

the Peninsular Malaysia is cooler than the western side (difference by 1.7o C) and the

difference in temperature between the two sides of Peninsular Malaysia decreases

northward (Dale, 1963).

Although the study area reaches are located in three different land characteristics (the

upland area, an intermediate or transitional area between upland and lowland area and

the lowland area), temperatures remains relatively uniform throughout the year. At the

University Kebangsaan Malaysia (UKM), Bangi station for instance, the mean annual

temperature over 16 years is around 24.25oC (Table 3.3).

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Figure 3.7: Rainfall regions in Peninsular Malaysia.

Table 3.3: Climate data of UKM Bangi Station from 1985 – 2000.

Climate data Annual Unit Average

Mean daily sunshine 5.71 Hour 16 years

Mean daily temperature 24.3 oC

16 years

Mean daily evaporation 3.48 Mm 16 years

Mean daily relative humidity 93.9 % 4 years

Mean surface wind speed 1.59 m s-1

16 years

3.9 LOCAL AUTHORITIES WITHIN THE LANGAT RIVER BASIN

Sungai Langat Basin extends to two states. A large proportion of the Langat basin

(about 76 %) is located within the districts of Hulu Langat, Sepang, and Kuala

Langat, Selangor. About 20% of the basin area is in Seremban, Negeri Sembilan. A

Source: Dale (1959)

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small portion (about 3.6%) of the basin covers part of Klang, Petaling and Federal

Territory of Kuala Lumpur.

There are 9 local government authorities administering 6 City Councils and

municipalities (Majlis Perbandaran) within the Langat basin. The proportion of

Langat basins within the various city municipalities are as shown in Table 3.4 and

Figure 3.8.

With the establishment of new city councils (i.e., Majlis Perbandaran Kajang, Kuala

Langat, Nilai, and Putrajaya), about 56 percent of the basin areas are now within

certain city councils jurisdiction. Bordering the Klang River in north, Sungai Langat

is subjected to tremendous urban development pressure. High rate of population

growth intensify pressure for urban land development. This aspect will be further

discussed in the land use and population characteristics sections below.

Table 3.4 : Local Authorities within Langat River Basin.

State City or District Councils Area as percent of

Langat Basin (%)

Majlis Perbandaran Kajang 21.89

Majlis Perbandaran Kuala

Langat 27.12

Majlis Perbandaran Klang 3.36

Majlis Daerah Hulu Langat 13.21

Selangor

Majlis Daerah Sepang 11.22

Negeri Sembilan Majlis Perbandaran Nilai 19.50

Federal Territory of Putrajaya

including of Cyberjaya

Perbadanan Putrajaya,

Cyberjaya 3.51

Federal Territory of Kuala

Lumpur DBKL 0.19

Note: Estimated Total Langat Basin Area = 2,282 km2.

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Figure 3.8: Local Authorities within Sungai Langat Basin.

3.10 LAND USE IN LANGAT RIVER BASIN

3.10.1 Forest Status

The forestry sector in Selangor is one of the main sources of income to the state

government. In 1997 for example, a total of RM25 million was generated by this

sector. The forested areas are located in the eastern and northern part of Hulu Langat

and managed by the The Forestry Department under the ‘Forestry Act, 1985’ and ‘Act

127 (Surrounding Environmental Quality Act) PU (A) 326/1987’. Areas in the

catchment including Langat and Semenyih were gazetted as ‘Reserved Forest’;

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however logging activities are still carried out under the ‘Selective Logging Scheme’.

These areas have proper limited logging licenses in order to reduce the environmental

hazard in the lowland area related to mud flows, siltation and flash floods. The Hulu

Langat Forest Reserve is one of nine reserves (representing about 26 per cent of the

total forest reserves) in Selangor. The Hulu Langat Forest Reserve is covered with hill

dipterocarps at altitudes ranging from 120 m to 1265 m above sea level. Prior to the

establishment of the Langat Dam, the Hulu Langat Forest Reserve had been logged

for timber production as early as 1944, particularly in the Congkak sub-catchment.

However, logging ceased in 1987.

Natural forest cover in this catchment is part of the Tropical Forest and is one of the

most complex ecosystems in the world. Generally, there are three major forest types

in the Langat Catchment: dipterocarp, peat swamp and mangrove forests. In the Hulu

Langat and Seremban Districts only lowland and hill dipterocarp forests are found.

Peat swamp forests are mostly found in Sepang and in parts of Kuala Langat Districts

whereas mangrove forests are found on the islands on the coast and along the coastal

margins of the mainland.

Over the years, diptrerocarp forests remained the main type of forest cover in the

basin, comprising 40-55 per cent of the total forest cover. The proportion of swamp

forests in the catchment declined rapidly (Table 3.5) and by 1991/1992 constituted

only 18.6 per cent of the total forest type. The proportion of mangrove forests

remained about the same from 1971 to 1982 but because of the rapid loss of peat

swamp forests, increased to 27 per cent by 1992.

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The total area of diptrerocarp forest in the catchment declined by about 10.9 per cent

between 1971 to 1992. The increase reported in 1981/1982 might have been caused

by inaccuracies in the base map but there was essentially no difference in the area

under dipterocarp forests in the catchment between the 1970s and 1980s (Saiful,

2000). A similar aberration was also assumed to affect the estimates of the total area

under mangrove forests. As shown in Table 3.5, the forest was reduced in size by

almost 4.0 per cent in 1981/82 from 215.6 km2 in 1971/72, but in 1991/92 it increased

by a similar amount. Peat swamp forests declined considerably over the same period

when the majority of areas originally under such forests were converted to agriculture.

Table 3.5: Size of each type of forest of the Langat Catchment in 1971/72, 1981/82

and 1991/92.

Years Type of forest

1971/72 (km2) 1981/82 (km

2) 1991/92 (km

2)

Dipterocarp 492.7 (44.6) 501.0 (50.0) 438.9 (54.6)

Peat swamp forest 396.2 (35.9) 293.1 (29.3) 149.4 (18.6)

Mangrove forest 215.6 (19.5) 207.0 (20.0) 215.5 (26.8)

Total 1, 104.5 1, 001.1 803.8

3.10.2 Industry

In Selangor, particularly within the Langat River catchment achieved, over a period of

slightly more than two decades, tremendous growth occurred in the manufacturing

sector, and had become the most industrialised state in Peninsular Malaysia.

Presently, there are 30 industrial estates housing more than 330 factories located in

the Langat River catchment. These factories engage in 22 categories of industrial

production ranging from the manufacture of agricultural end-products to high-

technology products such as consumer electronics.

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3.10.3 Mining

Mining remains a major activity within the Langat River catchment. The major

minerals produced in this catchment are aggregates, clay and earth materials, gravel,

kaolin and tin concentrated minerals such as gold, ilmenite, monazite, zircon, pyrite

and silica (Joy, 2000). The main rock-type exploited as aggregates in the Langat River

catchment is granite. A total of 21 quarries are located in the catchment while 46 pits

and excavation sites were reported at the time of this study as operating within this

catchment (Table 3.6). Most of them are located in the upper eastern section of the

Langat Catchment. Joy (2000) studies on the potential area for aggregate resources

show that forests, which include the Langat, Semenyih and Galla Forest Reserves,

cover 50 per cent of the main high potential area for aggregate resources.

Table 3.6: Number of mineral extraction sites in the Langat River catchment.

Mineral Selangor Langat

Catchment

(north)

Negeri

Sembilan

Langat

Catchment

(south)

Langat

Catchment

(total)

Granite quarries 24 10 18 11 21

Clat pits 13 3 18 0 3

Earth material extraction 133 24 64 19 43

Kaolin pits 1 1 0 0 1

Limestone 1 0 0 0 0

Sand and Gravel 140 81 58 5 86

3.10.4 Settlements/Urban Centres

Since 1970 urban expansion has occurred in the Langat River catchment, including

extensive land conversion from agriculture use to urban-industrial-commercial

landscape. From the government census reports of 1970, 1980 and 1981, Selangor as

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one of the more populated states in Malaysia has recorded a rapid growth from a total

of less than one million in the 1970 Population Census, through 1.4 million in 1980 to

close to 2.3 million in 1991 Census. It has been estimated that the population in

1998/1999 was around 3.1 million people (Abdul Hadi and Samad, 2000).

Figure 3.9 shows the population in the Sg. Langat Basin for Kuala Langat, Sepang

and Hulu Langat, Selangor. Based on the latest population census ( 2000 ) the

population statistics by territorial division and districts show that there are a total of

1,176,173 persons in the entire Sg. Langat Basin, of which 1,165,267 persons occupy

the three ( 3 ) districts of Selangor. Among the three districts, Ulu Langat showed the

highest increment of population from 413,900 persons in year 1990 to 864,451

persons in year 2000, followed by Kuala Langat where the population increased from

130,000 persons in year 1990 to 192,167 persons in year 2000 and Sepang District

from 54,671 in year 1990 to 108,640 in year 2000 (Department of Statistics Malaysia,

1990; 2000). The significant increment was recorded in the population of these three

districts during the last 11 years, from 598,661 persons in year 1990 to 1,165,267

persons in year 2000, an increase of 94.66% or 8.6% per annum.

67

0

100000

200000

300000

400000

500000

600000

700000

800000

900000

1000000

Kuala Langat Sepang Ulu Langat

Population

1990

2000

Figure 3.9: Population densities of Langat River Basin, by district, in years 1990 and

2000.

3.11 CONCLUSION

This chapter explores in particular the physical environment of the Langat River

catchment. Salient aspects of physical catchment characteristics are discussed in

details. This provides a clear picture of Langat River Basin and the need for further

investigation and analysis which will be discussed in the next chapter (Chapter 4).

THE LANGAT RIVER BASIN - UM Repositoryrepository.um.edu.my/1223/5/Chapter 3 Revised.pdf · THE...

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