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Year: 2011 Revision date: -- Revision type: --

Regional report: Water Report 37, 2012

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Geography, climate and population


The Kingdom of Bhutan has a total area of 38 390 km2 and is landlocked between the extensive borders of China and India (Table 1). The country shares a 470 km long border with Tibet, China’s Xizang Autonomous Region, to the north and northwest and 605 km with the Indian states of Sikkim to the west, West Bengal to the southwest, Assam to the south and southeast, and Arunachal Pradesh to the east. Sikkim is 88 km wide, and separates Bhutan from Nepal, while West Bengal, which is 60 km wide, separates Bhutan from Bangladesh. The border with Tibet follows the watershed of the Chumbi valley in the northwest and the crest of the Himalayas in the north, while the southern border with India was established by treaty with the British in the nineteenth century and follows the line made by the Himalayan foothills with the plains. For administrative purposes, Bhutan is divided into 20 dzongkhag (districts).

Bhutan, being in the eastern Himalayas, is mostly mountainous, with flat land limited to the broader river valleys and along the foothills bordering the Indian subcontinent. Altitudes range from 7 500 m at the summit of Kula Kangri on the northern border to about 200 m at the Indian border in the south. The country has three major landform features: the southern foothills, the inner Himalayas and the higher Himalayas.

Owing to the extremely rugged mountainous terrain, only 100 000 ha or 3 percent of the total area is cultivated in 2009, of which 25 000 ha is under permanent crops. The country is heavily forested, 72.5 percent being under forests, and 10 percent is covered with year-round snow and glaciers.


Bhutan has perhaps the greatest diversity of climate of any country of its size in the world. The climate is humid and subtropical on the southern plains and in the foothills, temperate in the inner Himalayan valleys of the southern and central regions, and cold in the north, with year-round snow on the main Himalayan summits. Bhutan’s generally dry spring starts in early March and lasts until mid-April. Summer weather starts in mid-April with occasional showers and continues through the early monsoon rains of late June. Autumn, from late September or early October to late November, follows the rainy season. It is characterized by bright, sunny days and some early snowfall at higher elevations. Winter sets in from late November until March, with frost throughout much of the country and snowfall common above elevations of 3 000 m.

Temperatures vary according to elevation. In the capital Thimphu, located at 2 320 m above sea level in west-central Bhutan, temperatures range between 14 °C to 25 °C during the monsoon season of June through September but drop to about –4 °C and 14 °C in January. Most of the central portion of the country experiences a cool, temperate climate year-round. In the south, a hot, humid climate helps maintain a fairly even temperature range of between 15 °C and 30 °C year-round; although temperatures sometimes rise above 35 °C in the valleys during the summer.

Average annual precipitation in Bhutan is roughly 2 200 mm. It varies widely in various parts of the country, from a low of 477 mm at Gidakhom in Thimpu district to as high as 20 761 mm at Dechenling in Samdrup Jhongkhar district. The climate of the north is severe and cold with only about 40 mm of annual precipitation, primarily snow. In the temperate central regions, a yearly average rainfall of around 1 000 mm is more common and 7 800 mm has been registered at some locations in the humid, subtropical south, giving rise to the thick tropical forest. Thimphu experiences dry winter months from December through February and almost no precipitation until March, when rainfall averages 20 mm/month and increases steadily thereafter to a high of 220 mm in August making a total annual rainfall of about 650 mm. The summer monsoon lasts from late June through late September with heavy rains from the southwest. The monsoon weather, blocked from its northward progress by the Himalayas, brings heavy rains, high humidity, flash floods and landslides, and numerous misty, overcast days. Western Bhutan is particularly affected by monsoons that bring between 60 and 90 percent of the region’s rainfall. The winter northeast monsoon brings gale-force winds down through high mountain passes.

Bhutan is divided into six agro-climatic regions as shown in Table 2.


In 2009, the total population was an estimated 714 000 inhabitants, of which 66 percent live in rural areas. During the period 1999-2009, the annual population growth rate was around 2.6 percent. With an average of 19 inhabitants/km2, the population density is relatively modest by regional standards. The population is unevenly distributed with the highest population densities at the lower altitudes. About 95 percent of the population lives in the southern subtropical zone or in the central mid-mountainous zone, mainly in the relatively gentle sloping areas of the river valleys.

In 2008, 92 percent of the population had access to improved water sources (99 and 88 percent in urban and rural areas respectively) and 65 percent of the population had access to improved sanitation coverage (87 and 54 percent in urban and rural areas respectively). In 2003, about one-quarter of Bhutan’s population was classified as living below the poverty line.

Economy, agriculture and food security

In 2009 the gross domestic product (GDP) was US$1 259 million. Agriculture accounted for around 18 percent of GDP, while in 1999 it accounted for 30 percent.

In 2009, the total economically active population was 324 000 inhabitants, or slightly more than 45 percent of the total population. Agriculture has a dominant role in the economy and is the primary source of livelihood many. About 301 000 (93 percent of the total active population) are economically active in agriculture; of which 34 percent are women. Agriculture in Bhutan is labour intensive with relatively low farm inputs.

Major crops are cereals, which cover around 70 percent of the cultivated area, mainly maize (30 percent), rice (25 percent), wheat (9 percent) and other cereals (16 percent). Rice is the major staple crop, which is irrigated. Maize is mainly cultivated in dryland regions at lower elevations. Other crops are potatoes or tuber crops, oilseeds, pulses, apples. Production of cash crops such as apples, oranges and cardamom have increased and have become profitable. In several areas shifting cultivation is being replaced by orchards.

In Bhutan, the primary goal of agriculture is to raise the per capita income of people living in rural areas, to enhance self-sufficiency in staple crops, and to increase the productivity per unit of farm labour and agricultural land. Agriculture is constrained because of problems related to irrigation, rough terrain, poor soil quality, limited extent of arable land, lack of improved quality seeds for cereals, oilseeds, vegetable crops, fertilizers, farm machinery and agricultural experts.

Water resources

Total annual internal renewable surface water resources are an estimated 78 km3 (Table 3). Because of the mountainous character of the country, groundwater resources are probably limited and are drained by the surface water network, which means they are more or less equal to overlap between surface water and groundwater. Surface water leaving the country to India is an estimated 78 km3.

Nearly every valley in Bhutan has a swiftly flowing river or stream, fed either by the perennial snow, the summer monsoon or both. Except for a small river in the extreme north, which flows north, all rivers flow south towards India. The river basins are oriented north-south and are, from west to east, the Jaldhaka, Amo (Torsa), Wang (Raidak), Mo, Puna Tsang (Sankosh), Mao Khola/Aie, Manas (Lhobrak) and eastern river basins, this last basin is composed of the Bada and Dhansiri rivers.

Most rivers are deeply incised into the landscape and hence the possibilities for run-of-the-river irrigation are limited.

There are only two wastewater collection and treatment projects in the cities of Thimphu and Phuntsholing.

There are numerous natural lakes, many are located above 3 300 m and some above 4 200 m, which are primarily used to raise fish.

Several large dams have been constructed to generate hydroelectric power. These include the 40 m high Chhuka dam (CHPP) on the Wang river in Chhukha district in the southwest, the 91 m high Tala-Wankha dam further downstream on the Raidak river near Phuntsholing town, the 33 m high Kurichhu dam on the Kuri river in Mongar district in the east, the Basochu dam (BHPP) near Wangduephodrang town in the centre-west. The 141 m high Punatsangchu dam on Puna Tsang river downstream of Wangduephodrang town is under construction.

Total hydropower generation capacity was 477 MW in 2006, of which 336 MW from the Chhukha hydropower plant, 60 MW from the Kurichu hydropower plant and 24 MW from the Bashocu hydropower plant. Hydropower represented 96 percent of the country’s electricity generating capacity and 99.9 percent of its electricity generation in 2006. With the commissioning of the first two units of the Chhukha hydroprojects in 1986, and the other two units in 1998, the electricity generation capacity substantially increased and Bhutan became a significant exporter of electricity to India. With the commissioning of the Tala Hydro Power Project in 2007, there has been a substantial improvement in the country’s energy generation.

The expansion of hydropower production capacity has had an enormous impact as, by the end of the Ninth Five-year Plan (2002-2007), the energy sector contributed to around one-quarter of GDP. With a further doubling of capacity envisaged by the end of the Eleventh Five-year Plan (2014-2019), the energy sector will probably contribute close to half of GDP.

The following hydroelectric projects have been identified for future development:

  • Mangdue Chu Hydroelectric Project, with the cooperation of Norway, was planned in the Ninth Five-year Plan (2002-2007) and it is expected to be completed in the Tenth Five-year Plan (2008–2013). The project comprises two dams.
  • Sunkosh Multipurpose Project (SMP) is the largest proposed hydroelectricity project in Bhutan.

International water issues

The Chhukha Hydropower Corporation (CHPC) was entirely funded by the Government of India. The construction of the Chhukha hydroelectric plant started in 1978 and was operational in 1988.

The Tala Hydroelectric Project Authority (THPA) is the biggest Indo-Bhutan joint project, entirely funded by the Government of India (GOI) by way of grants and loans and has been fully operational since 2007.

The Basochu Upper Stage Hydropower Project, commissioned in 2005, is financed by the Austrian Government.

The Punatsangchu Hydroelectric Power Project (PHPP) is a proposed project between Bhutan and India signed in 2003. It is a run-of-the-river scheme along the course of the Puna Tsang river, downstream from the town of Wangduephodrang. It will have an installed capacity of 870 MW with an annual average generation of 4 330 GWh.

Water use

In 2008, total water withdrawal was about 338 million m3, all surface water. This represents a mere 0.43 percent of the annual renewable water resources. About 94 percent of this water withdrawn is used for agriculture, while domestic and industrial sectors use 5 percent and 1 percent respectively (Table 4 and Figure 1).

Irrigation and drainage

Evolution of irrigation development

Wherever irrigation water is available on arable lands below 2 600 m, farmers have traditionally chosen to grow rice. Irrigated rice cultivation takes place during the summer-autumn period. Other irrigated crops, though at a very limited scale, are wheat, barley, oil seeds, potato and different vegetables. Maize is mainly cultivated in dryland regions at lower elevations.

There are an estimated 1 500-1 800 irrigation schemes. Irrigation systems in Bhutan are typically less than 100 ha in extent. Only two large-scale systems have been developed by the Government: the Taklai Irrigation Scheme (1 350 ha) and the Geylegphug Lift Irrigation Scheme (800 ha). There is little possibility of further development of large schemes owing to the geographical conditions. River diversion is the source of water for almost all Bhutanese schemes (98 percent of the irrigated area), except in the Geylegphug lift irrigation scheme (2 percent). Generally, the diversion structures are temporary, and in a large number of rehabilitated schemes part of the project consists of improving the intake structure to make it permanent.

Two types of small-scale schemes can be found:

  • valley bottom schemes, located on relatively gently sloping terraces next to the major rivers, where water is usually reliably provided by purely gravity fed channels from secondary rivers; and
  • hill schemes, located at higher elevations, on more steeply sloping land where tertiary streams and rivers are the sources of water.

The irrigated areas are called wetland in the local classification. This means that they have been terraced for basin irrigation. In 2007, these areas were an estimated 27 685 ha, which corresponds to actually irrigated area.

In 1995, total irrigated area was an estimated 27 020 ha and large schemes (> 100 ha) represented 6 percent of the total irrigated area, while small schemes (< 100 ha) represented 94 percent (Table 5 and Figure 2).

Irrigation schemes, all managed by farmers, can be classified according to their origin:

  • indigenous irrigation systems, which have evolved with little or no government assistance. No technical assistance has been provided, and the maximum involvement of the government may have been the provision of a few bags of cement;
  • assisted farmer-initiated irrigation systems, which have been constructed by the beneficiaries, but which have received technical and other government assistance on one or more occasions to restore or improve the system; and
  • government-initiated irrigation systems, which have been constructed under the government assistance programme.

Irrigation canals have an acute sedimentation problem, caused by sand accumulation from subsidiary sources and runoff into irrigation canals during heavy monsoon rains. Generally, sand and silt traps are constructed and periodically flushed to alleviate this problem.

Role of irrigation in agricultural production, the economy and society

In summer, almost all wetland is under rice cultivation. Double cropping of rice is limited to the lowest altitudes where the winter temperatures allow its cultivation. Where rice cannot be cultivated, wheat, buckwheat, mustard and potatoes are cropped on wetland areas during the winter season (Table 6). The wetland areas can be cropped during the winter season, though watering of these winter crops is generally limited to one irrigation at the time of land preparation. To a limited extent, farmers have started to irrigate horticultural crops, including orchards, using hose pipes and surface irrigation methods. In 1994, total irrigated cropped area was around 27 900 of which 98 percent was rice and 2 percent potatoes (Figure 3).

The average cost of irrigation development varies widely depending on the region. The National Irrigation Policy (1992) suggests that the maximum capital investment for the main canal development should be US$630/ha and US$950/ha for renovation schemes and new schemes respectively, while it should be US$160/ha for the development of the distribution system.

Status and evolution of drainage systems

As most of the schemes are terraces, no drainage network has been constructed.

Water management, policies and legislation related to water use in agriculture


No institution is specifically responsible for water resources. Because of the high hydropower potential, the Department of Power has been given responsibility for hydrological and meteorological data collection.

The Irrigation Agency is composed of irrigation offices at three levels:

  • Central level: the Irrigation Section of the Research, Extension and Irrigation Division under the Ministry of Agriculture, which is responsible for the coordination of all sector activities, including policy formulation, monitoring and evaluation.
  • Regional level: the Project Facilitation Offices, which provide technical, logistic, communication and accounting support for two IFAD financed projects covering three and six districts of Bhutan.
  • District level: the District (Dzongkhag) Irrigation Offices, which are fully responsible for the planning and implementation of all irrigation facilities in their district.

A National Environment Commission (NEC) received the mandate to ensure effective coordination of national-level planning and development for all natural resources including water resources, formulation of water policy and the necessary legislation, setting up of water quality standards and guidelines, monitoring, evaluation and regulation of water use. It is also responsible for research and development, capacity building and human resources development, technical backstopping, data collection and dissemination, flood disaster management, etc.

Water management

Until the 1970s, all irrigation schemes had been constructed and maintained by the beneficiaries themselves. With the start of the government’s irrigation development programme in the late 1960s and early 1970s, many schemes were built or improved with external assistance, while management remained in the hands of water users. With the irrigation policy, adopted in 1992, government assistance to the irrigation sector has been redefined, with three basic principles: meaningful farmer participation, support to water user associations (WUAs), and multidisciplinary teamwork. The emphasis is on scheme renovation rather than new irrigation development.

Currently, Bhutan experiences localized and seasonal water shortages for drinking and irrigation even though the nation is bestowed with substantial water resources. There is uneven spatial distribution of precipitation, increasing sediment load in the rivers and wide variation between lean season and monsoon flows. Furthermore, the pressure on water resources is gradually increasing as a result of competing demands from various sectors. Floods and land slides accentuate the problem of water resources management.

The existing water-related institutions have weak functional linkages with other subsectors relevant to water at policy, planning and implementation levels. This required the formulation of a national perspective on water resources and a Bhutan Water Policy was formulated in 2003.

The Tenth Five-year Plan (2008–2013) for the Renewable Natural Resources (RNR) Sector (or the agricultural sector) has a goal to increase national rice self-sufficiency from about 50 percent to 65 percent by the end of the Plan. The policy, as defined in the Plan, also emphasizes the need for a greater degree of commercialization of agriculture, with efforts to enhance household food security through the market rather than through complete dependence on self-reliance. A total of 29 programmes are defined in the Plan. The Irrigation and Water Management Programme has a goal to increase the portion of wetland with dry season irrigation (Tillier et al., 2010).

Policies and legislation

The Bhutan Water Policy (2003) recognizes that water is a precious natural resource that is basic to all social, economic and environmental well-being and, as such, the water resources need to be conserved and managed efficiently, while ensuring sustainability and without damaging the integrity of the environment. The Policy adopts an integrated approach that recognizes natural linkages and covers all forms of resources including snow, glaciers, rivers, lakes, streams, springs, wetlands, rainwater, soil moisture and groundwater, to achieve poverty alleviation and increase Gross National Happiness (GNH). The Policy was framed within a broad multi-sectoral perspective which recognizes the responsibilities of the sub-sectors to play their role in meeting policy objectives. The Policy primarily addresses the following components: i) water user interests and priorities, ii) principles for water resources development and management, iii) international waters and iv) institutional development for water resources management.

The first component includes the issues of water allocation, water for drinking and sanitation, water for food production, water for hydropower development, water for industrial use, and resolution of conflicting user interests. The second component includes water resources that are developed to ensure sustainability by adopting appropriate technologies and good management practices. The water resources are planned to be developed in an environmentally sustainable, economically feasible and socially acceptable manner with full participation of all stakeholders. Prevention and control of pollution and flood management are to be incorporated into the planning.

Prospects for agricultural water management

The research and development needs, identified in the Bhutan Water Policy, include: hydro-meteorology, assessment of national water resources, surface water resources and watershed protection, groundwater hydrology and recharge, water-harvesting, water balance studies, crop–water requirements and cropping systems, soil erosion and bio-engineering, flood control and mitigation, erosion of the water course and sedimentation of the reservoirs, safety of hydraulic structures, recycling and reuse of water, best practices, economic and financial planning, wastewater handling, water pollution and prevention.

The government plans to effectively use the water resources for sustainable agricultural development, harnessing hydropower potential and industrial development for socio-economic development.

In 2009, Bhutan requested support from FAO to explore the feasibility of irrigation in the southern zone of Bhutan (districts of Sarpang, Samdrup Jongkhar and Samtse). The original proposal aimed to increase rice production to meet an enhanced share of domestic needs through expansion of the cultivated area and double cropping. Its objective was: (i) to conduct a comprehensive study on irrigation development in the southern belt to assess its potential to contribute to national food security and local livelihoods; and (ii) to conduct a groundwater study to explore its potential as an alternative to surface water for their joint use. After a reconnaissance mission, fielded by FAO at the end of 2009, the conclusions were (Tillier et al., 2010):

  • Southern Bhutan offers much potential for irrigation. The climate is favourable, surface water resources are abundant, groundwater is possibly available in some parts, multiple use of water is possible (water diverted for irrigation can also be used for other purposes such as fisheries, livestock, etc.), there is scope for increasing yields, and there is sufficient market for agriculture products both within the country and in the neighbouring Indian market.
  • Investment in irrigation in the southern zone is warranted from an agronomic viewpoint. The difference in yields between irrigated and non-irrigated crops was observed in the field. Yields of up to 4.4 tonnes/ha were reported from the best farmers under fully irrigated conditions, which is better than the average yields in neighbouring India (3.1 tonnes/ha), while the average in Bhutan is 2.4 tonnes/ha. However, to fully maximize the benefits from investment in irrigation (and rice production) farmers will need to improve their farming practices, including water management, varieties, fertility (and soil) management and pest management.
  • While potential for irrigation development exists, there is also much potential and requirement for improvement of water management both in the distribution systems and at field level and there is much potential for both irrigated and rainfed productivity gains by introducing the System of Rice Intensification (SRI) and Conservation Agriculture (CA).


The expressions ‘Chu’ and ‘Chhu’ that are often added to the names of rivers, mean ‘river. Therefore, in this English version of the country profile, these words have been removed from the name of the river and replaced by the word “river”. As an example, Wang Chu has been changed to Wang river.

Main sources of information

FAO. 1999. Irrigation in Asia in figures. FAO Water Report No. 18. Rome.

Inter Press Wire Service English. 2008. UNICEF+WWF Press Release April 21, 2008

National Statistics Bureau. 2007. Statistical Year Book of Bhutan –2007. Royal Govt.of Bhutan

National Statistics Bureau. 2009. Statistical Year Book of Bhutan –2009. Royal Govt.of Bhutan

Tillier, S., O’Brien, B., Upadhyay, B.M., Sijapati, S. 2010. Bhutan. Southern zone irrigation. Reconnaissance mission. FAO.

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