Water profile of Brunei
Geography and population
The Water profile of Brunei is dominated by the use of surface water, which provides over 99 percent of the water utilised for all purposes. There are four major river basines in Brunei: the Temburong, Belait, Tutong and Brunei basins; the largest of these watersheds within Brunei is the Belait River basin. Brunei has two large dams which impound the majority of the stored water within the country.
Brunei lies in Southeast Asia, on the northwest coast of the island of Borneo. It is bordered on the landward side by Sarawak, one of the two eastern states of Malaysia. The country consists of two enclaves separated from each other by the valley of the Limbang River in Sarawak. Brunei is divided into four districts with a total area of 5770 square kilometres.
The districts of Brunei-Muara, Tutong and Belait, which form the larger western portion, are dominated by hilly lowlands, swampy plains and alluvial valleys. Mountainous topography abounds in the eastern district of Temburong. The highest elevation of the country is 1850 metres (m) (Bukit Pagon).
The cultivable area is estimated at 13,000 hectares (ha), which is about 2.5% of the total land area. In 1995, the cultivated area was estimated at 7000 hectares, about 54% of the cultivable area. About 4000 ha consisted of permanent crops, the remaining 3000 ha being under annual cultivation. The main crops include rice, cassava, bananas and pineapples.
Brunei has a population of 300,000 inhabitants (1996 estimate), of which about 42% is rural. The annual population growth rate is estimated at 4.4%. The district of Brunei-Muara, which includes the capital, Bandar Seri Begawan, has the largest population with 201,100 inhabitants, while Temburong district in the east is sparsely populated with a total of 8,700 inhabitants. The average population density in the country is 52 inhabitants/square kilometre.
In Brunei, agriculture accounts for less than three percent of gross domestic product (GDP) and the country imports 80% of its food. In 1996, out of an economically active population of 127,000, only 2000, or less than 2%, were engaged in the agriculture.
Climate and water resources
Brunei has a tropical climate characterized by high rainfall and temperature throughout the year. Climatic variations follow the influence of the monsoon winds. The northeast monsoon system is active from December to March, while the southeast monsoon occurs around June to October.
The total rainfall was 2654 millimetres (mm) in 1994. There area two rainy seasons: from September to January and from May to July. The average precipitation in the nearby city of Kota Kinabalu (Sabah, Malaysia) is 2691 mm and this could be considered as a reasonable estimate for the average precipitation in Brunei.
The temperature is relatively uniform throughout the year, with an annual average of 27.9° C, ranging from 23.8 to 32.1 °C. The drought months of March and April are the warmest. Due to high temperature and rainfall, humidity is high throughout the year with an average of 82%.
There are four principal river basins in Brunei: Temburong, Belait, Tutong and Brunei. The Temburong, the smallest of the rivers, drains a catchment area of about 430 square kilometres.
The Belait is the largest basin, with an area of 2700 km2. The lower catchment comprises an extensive area of peat swamp forest. The river narrows at the town of Kuala Belait and a sandbar restricts the discharge of water to the South China Sea. Some areas in the upper catchment have been cleared for agriculture.
The Tutong Basin, which is about 1300 km2, has a complex estuary system formed between two sand spits. Subject to fairly high tidal influence, its lower catchment is mainly floodplain. The upper catchment is jungle with patches of agriculture.
The Brunei River flows into Brunei Bay. The upper reaches of the river are a major freshwater source particularly for the western part of the country.
By analogy with the rest of the island of Borneo, the runoff coefficient is estimated at 1.5 m/year corresponding to a surface flow of 8.5 cubic kilometres. Limited reserves of groundwater have been identified in the Sungai Liang and Seria areas of the Belait district and in the Berakas area of the Brunei-Muara district. The estimated safe yield is 17.3 million cubic metres/year. Also by analogy with the rest of the island of Borneo, the total groundwater resources are estimated at 0.1 cubic kilometre/year, all being drained by the rivers.
Lakes and dams
Brunei has two dams with a total storage capacity of 45,013,000 cubic metres. The Tasek reservoir used for water supply has a total capacity of 13,000 cubic metres and a catchment area of 2.8 square kilometres. The Benutan dam, an impounded reservoir used to regulate the Sungai Tutong River, has a total storage capacity of 45,000,000 cubic metres and a catchment area of 28.6 square kilometres.
There is at present no hydropower dam, although one suitable site has been located within the National Forest Reserve of Temburong.
In 1994, the total water withdrawal was estimated at 91.59 million m3. Urban water supply is entirely from surface water. The major use of water in industrial processes is for the liquefied natural gas industry which abstracts and treats its own water from the Sungai Belait River. Other industrial uses are on a smaller scale for timber/sawmills, dairy farms, soft-drink manufacture and workshops which account for an estimated 25% of overall water demand.
Initially, groundwater abstraction was undertaken in the 1950s for use by the oil and gas industries. This has been replaced by surface water sources. Groundwater abstraction, which accounts for 0.5% of the total water supply, is currently limited to the local bottled water industry.
Irrigation and drainage development
All irrigation facilities were equipped in 1980. There are only minor irrigation schemes (up to 0.9 ha). Irrigated agriculture represents 1,000 ha, and all irrigation is surface irrigation. The existing infrastructure and facilities are being upgraded in rural areas, but the irrigated area has remained unchanged since 1980.
The major irrigated crops are rice, vegetables and fruits. The figures for rice show that the country is able to meet only 3.6% of the total demand of 27,500 t/year. Lack of labor is the main constraint on agricultural development in the country.
Trends in water resources management
The water demand for 2000 will be 105 million m3, and will basically depend on the growth of the population and expected increase in per capita consumption as a result of increased urbanization.
Efforts are being made to diversify the economy away from a heavy dependence on oil and gas towards a more independent agriculture sector. The first of the Government's four major objectives in agriculture is to enhance domestic production of paddy, vegetables, poultry and livestock. The Government is trying to stimulate greater interest in agriculture through the establishment of model farms, and by providing training, advice and support.
- Water Profile of Brunei, Food and Agriculture Organization.
- World Factbook: Brunei, Central Intelligence Agency.
- Economist Intelligence Unit. 1997. Brunei: 1997/98 country profile.
- ESCAP. 1995. Guidebook to water resources, use and management in Asia and the Pacific, p. 301. Water resources series No. 74. Volume 1. New York.
- Statistic Division, Ministry of Finance. 1993. Brunei Darussalam statistical yearbook, p. 196.
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