Our Water Sources

The Water Cycle
Highland forests are usually high-rainfall areas. Precipitation or rain is formed in the highlands resulting from the condensation of moisture in the atmosphere. Scientific evidence shows that forests at elevations above 1,500m also have the ability to strip moisture from the wind-blown dusts. This function is important especially during low rainfall periods.

Forests in the highlands have been likened to a giant sponge that absorbs and accumulates rainwater intercepted by vegetation and the forest floor. Highland forests release water continuously into streams and rivers that flow downstream to coastal areas where they merge with the sea. The sun’s energy causes water from the sea and other water bodies to evaporate into water vapour that forms clouds. This repeated process of water dispersal, absorption and evaporation is known as the ‘water cycle’.
Where the River Begins
The highland forests are often referred to as natural ‘water towers’. This is because most rivers originate from there and a significant amount of water from rainfall is captured and accumulated by these forests. In fact, a large proportion of the river volume originates in the highlands.

Among the eight prominent mountain ranges forming Peninsular Malaysia’s highland landscapes, the Main Range is the longest and most contiguous. It stretches some 500km across five states - Kelantan, Perak, Pahang, Selangor and Negeri Sembilan. The Main Range is the peninsula’s most important catchment area, since many of the major rivers supplying freshwater in these five states originate from its forest base.

In the East Malaysian states of Sabah and Sarawak, there are at least 18 mountain ranges and isolated mountain areas, all of which perform important roles in providing sources of freshwater supply.
About Malaysian Rivers
Sungai Perak (390 km), Sungai Selangor (80km) and Sungai Muar (190 km), which drain into Straits of Malacca and Sungai Kelantan (250 km) and Sungai Pahang (500 km), which drain into the South China Sea, are among the major rivers in Peninsular Malaysia.

In East Malaysia, the two principal rivers are Sungai Rajang in Sarawak and Sungai Kinabatangan in Sabah. Sungai Rajang (760 km) is the longest river in Malaysia while Sungai Kinabatangan (560 km), draining much of the eastern region of Sabah, ranks as Malaysia’s second longest river.

The Importance of Rivers
1. Rivers and Agriculture
In Malaysia, rivers support agricultural development and productivity. The highest percentage of water demand in Malaysia is for irrigation in the agriculture sector. Irrigation is employed primarily to cater for the double cropping of paddy.

2. Rivers for Domestic and Industrial Water Supply
In Malaysia, more than 90% of our water supply comes from rivers and streams. The demands for residential and industrial water supply has grown rapidly following the country’s economic shift towards industrialization in the 1980s, coupled with an increase in population and urban growth.

3. Rivers as Sanctuary for Biodiversity
Malaysian rivers are endowed with rich plant and animal life. Our rivers support and sustain biodiversity within the river itself, along riverbanks and in the surrounding environment. As a river journeys from its highland origins on to its lower reaches, plants and animals, especially aquatic life, differ along its seaward course.

4. Rivers for Provision of Food Sources
Traditionally, the importance of freshwater fisheries relates more significantly to the livelihood of rural riverine populations. In recent years, however, recreational or sports fishing has expanded rapidly, adding a new economic dimension to the freshwater fisheries resource. Besides the popular edible fish species like Lampam Sungai (Puntius schwanenfeldii) and Jelawat (Leptobarbus hoeveni), freshwater prawns and certain aquatic plants are also major food sources derived from rivers.

5. Rivers for Transportation
Some of the remote and interior villages in Sarawak, Sabah, Perak and Pahang depend on rivers for transportation. This traditional role of rivers continues today but at a much smaller scale than before. Without alternative modes of transportation and limited access, rivers provide the sole means to get in touch with the outside world.

6. Rivers for Generating Hydropower
For the period from 1996 to 2000, hydroelectric power output constituted between 7% -12% of the total national energy generated annually. It was estimated that 85% of the total hydropower potential of the country is found in the states of Sabah and Sarawak.

7. Rivers for Recreation
Many Malaysian rivers have high recreation value, which provide many opportunities for outdoor activities. For the adventurous, the Pelagus rapids on Rajang River in Sarawak and the Padas, Tuaran and Papar Rivers in Sabah are popular for white-water rafting, while the Nenggiri River in Kelantan and Tembeling River in Pahang are favourite locations for kayaking and canoeing.

There are a number of relatively accessible scenic rivers in Malaysia for those who prefer nature and wilderness experiences. Among them are the Endau River in Johor, the Tembeling River in Pahang, the Skrang River in Sarawak and the Menanggol River in Sabah. Rivers such as the Tembeling and Nenggiri are also well-known historic routes, making them ideal for educational recreation. For those seeking relaxation and fun retreats, there are many beautiful waterfalls throughout the country that have become popular spots for such use. Recreational or sports fishing is also becoming popular with many anglers hiking to the upper reaches of rivers to fish.
Facts on Water
About 70% of all available freshwater is used for agriculture. Yet because of inefficient irrigation systems, particularly in developing countries, 60% of this water is lost to evaporation or is returned to rivers and groundwater aquifers.
Water withdrawals for irrigation have increased by over 60% since 1960.
Water use increased six-fold during the last century, more that twice the rate of population growth.
By the year 2025, it is predicted that water withdrawal will increase by 50% in developing countries and 18% in developed countries.
Water losses due to leakage, illegal water hook-ups and waste total up to about 50% of the amount of water used for drinking in developing countries.
About 40% of the world’s population currently lives in areas with moderate to high water stress. By 2025, it is estimated that about two thirds of the world’s population (about 5.5 billion people) will live in areas facing such water stress.

Source: International Year of Freshwater 2003 Fact Sheet
The World’s Water
Earth may be a water planet, but freshwater is scarce….

97% of water is salty or otherwise undrinkable, and almost 3% is locked away in ice caps, glaciers or deep underground……

It is estimated that only 0.003% is actually available for use.

If all the earth’s water is represented by a litre, only a teaspoon is available for us to use.
Pollution Doesn’t Pay…It Kills!
Asian rivers are the most polluted in the world, with 3 times as many bacteria from human waste as the global average and 20 times more lead than those from industrialised countries1.

Every year1
300-500 million tonnes of heavy metals, solvents, toxic sludge and other wastes accumulate in water resources from industries.
More than 2.2 million people die from diseases related to contaminated drinking water and poor sanitation.

Every day1
About 2 million tones of waste are dumped into rivers, lakes and streams.
6,000 people, mostly children under the age of 5, die from diarrhoeal disease.

Every litre1
1 litre of wastewater pollutes about 8 litres of freshwater. There is an estimated 12,000 km3 of polluted water worldwide, which is more than the total amount of water contained in the world’s largest river basins.

At any one time2
Half the world’s hospital beds are occupied by patients suffering from water-borne disease.

Source 1: Executive Summary UN World Water Development Report (www.wateryear2003.org/en)
Source 2: International Year of Freshwater 2003 Factsheet (www.wateryear2003.org/en)

River Basins Water Quality Trend 1993 - 2003
Note:
The Department of Environment (DoE) started monitoring river water quality in Malaysia in 1978. As of 2003, there were 926 manual stations located in 120 river basins. In addition to the manual stations, 15 automatic water quality stations have been installed at major rivers to capture real time data on specific parameters to monitor river water quality changes continuously.
Appraisal of Malaysian River Water Quality
River water quality appraisal is based on the Water Quality Index (WQI) consisting of five parameters, namely, Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Ammoniacal Nitrogen (NH3N), suspended solids (SS) and pH. Water quality data collected from monitored rivers are then compared with the Interim National Water Quality Standards for Malaysia (NWQS) to determine their status as clean, slightly polluted or polluted.