Promoting Irrigation


Irrigation of rice fields in Cambodia dates back to the Khmer empire that started more than 1,000 years ago. Today most farmers in Cambodia still cultivate rice only in the wet season and too often famers’ crops have low yields. The most profitable rice producing period is during the dry months from December to May however, most farmers have no access to irrigation to plant and harvest cost-effective dry season rice.

Until recently farmers who irrigated relied on natural or constructed reservoirs that retain water from the wet season. Most of the rice growing areas in Cambodia are located on flat land which means that storing enough water for irrigation of paddy fields would require large areas to be inundated as reservoir depths are shallow. During and after the 1970’s large numbers of reservoirs were constructed. Unfortunately, too many of these reservoirs have broken down or are only partly functioning as maintenance is seldom done and still relies heavily on funding from foreign donors or limited government budgets.

Irrigation in Cambodia is still considered a public good and as such is seen to be something that the government should provide to rural communities. In the situation where water fees are collected from farmers, it is often not enough to cover operational and maintenance costs.

Over the past 10 to 15 years however, the availability of affordable irrigation pumps and engines has led to greater involvement of companies and private businesses in irrigation infrastructure. Pumping allows farmers in some areas to use water from rivers and other natural water courses all year round. Availability of water is not a major problem in the Mekong delta, however the distance to the river can be.

Access to irrigation can increase a farmer’s yield significantly. Additional irrigation in the wet season (from June to November) can increase yields by approximately one-half ton per hectare. Irrigation in the dry season (from January to March) allows for yields of around five tons of paddy per hectare. With access to irrigation, an additional crop can also be cultivated between April and July yielding three to four tons per hectare. Therefore, access to year-round irrigation may produce an additional eight tons of paddy per hectare annually. This enables rice farming to become profitable and allows farming households to break out of the poverty cycle.

Irrigation and Water Management in Cambodia

Despite the enormous potential irrigation development for poor Cambodian farmers, only very few farmers currently have year round access to water supplied by irrigation. Irrigation systems need yearly maintenance and repair. Without this most irrigation schemes will become dysfunctional within five to seven years. Farmers are expected to pay water fees to cover the operation and maintenance costs of irrigation schemes, however, famers often see this fee as a government tax and not related to assuring maintenance for the schemes they rely on and therefore actively to avoid paying.

Irrigation schemes that provide year round irrigation water to allow for double or triple cropping should result in sufficient resources to maintain the schemes properly. This is normally not the case for irrigation schemes which only allow farmers to supplement rain during the wet season. Most schemes that use reservoirs fall in this category.

Given the prevailing view among farmers, that irrigation is a public good and that any fees imposed are a tax, the management committees that oversee the irrigation systems, called Farmer Water User Committees (FWUCs), find it difficult to take strong action to operate and maintain the schemes. Indeed, it is hard to find fully functional FWUCs within Cambodia.

Market Development Principles Applied to Irrigation and Water Management

The current situation in Cambodia where there is, on the one hand, sufficient water availability and good opportunities for sustainable irrigation schemes to be effective and, on the other hand, only a few examples of well-functioning schemes calls for an alternative approach to promotion of irrigation.

What is required is not a technical approach to the rehabilitation of dysfunctional schemes but rather an approach that puts sustainability at the forefront of program design. To be sustainable maintenance of irrigation schemes has to take place and farmers must be willing and able to pay. Irrigation scheme management committees or FWUC must be able to collect enough fees and manage the schemes effectively. Irrigation schemes must of course be technically sound to function. To be sustainable however, they also need to be commercially viable and well-managed. The development principles and techniques that CAVAC employs to improve markets are also a suitable mechanism to address these sustainability issues.

CAVAC’s expertise lies in examining complex socio-economic systems. CAVAC analyses historical and cultural norms and habits, roles and responsibilities, incentives, group dynamics, legal environments, constraints and opportunities and then assesses viabilities of investments looking at all their uncertainties. It assesses what innovations are needed and how to introduce these in an effective manner within the context. With this knowledge CAVAC judges the likelihood of sustainability, risks and potential value for money of possible investments. CAVAC also assesses where additional capacity is required, where innovations need to be introduced, and where players need incentives to change the way they operate.

By applying these principles to irrigation, sustainability becomes a key criteria for effective implementation. Sustainable irrigation can work best if seen as a private good but also with a clear role for the government in development and management. Therefore, farmers should “own” the schemes and feel responsible for collecting maintenance and operation fees rather than looking to the government to do so. When applied on technically and commercially viable irrigation schemes, the development challenge of sustainable irrigation can then be reduced to an organizational issue.

In this ‘private good’ model of irrigation management there is a role to play for all involved including farmers, FWUCs and water sellers but also the provincial and national government. There may be less of a role for the provincial and national government in operation and maintenance however, water used for these schemes will take away from water in other systems and drainage will be absorbed somewhere else. A decision to construct an irrigation scheme creates obligations for rural infrastructure planning and requires coordination of potential issues such as land ownership and ensuring environmental safeguards are in place. These are typically ‘public’ roles that only the government can and should fulfill.

Cambodia has the potential to construct many commercially viable schemes and if we consider operation and maintenance of schemes as a private good then an obvious question would be: why should a government or a donor government then pay for the construction of these schemes? In an ideal world, farmers or companies should be able to construct and pay for irrigation schemes. However, like all investments that CAVAC supports, donor funded irrigation schemes are needed because Cambodia’s reality is still far from this ideal. The question therefore should not be: Who should support the promotion of irrigation and water management in Cambodia?; but: How is Australian tax payer funded support best placed to reduce poverty both now and into the future?

Well designed and constructed irrigation schemes can offer thousands of poor households a way out of poverty. Money invested in irrigation is well spent. In the Cambodian context it is not yet possible for companies to invest securely in irrigation schemes for smallholder farmers. The laws and regulations that govern scheme ownership and that allow investors to enforce fee contributions are not strong enough to promote innovation and investment. This is partly because irrigation is still seen as a public good.

As evidenced by the examples above, CAVAC approaches implementation of irrigation activities in the same way as it approaches partnering with companies working across the agricultural sector. The tools used to assess investments and design activities are similar and the same principals are used throughout activity implementation.

In close collaboration with Provincial Government departments, CAVAC first assesses if investments make sense from an engineering and agricultural point of view. If a scheme is assessed as commercially viable, CAVAC then identifies the possible stakeholders in each scheme and outlines what their roles and responsibilities will be and what incentives and commitments they have to fulfill. A cost sharing and commitment arrangement is then established with the farmers and the relevant local government departments. CAVAC pays for the construction of the scheme and farmers voluntarily contribute the land required for construction and in many cases may also construct secondary canals. In some cases CAVAC may even go a step further by sharing the costs for the construction of the canals with local stakeholder. Cost sharing is an important element of the local ownership for the scheme and helps change the perception that irrigation is a public good. Cost sharing is a first step towards solving the organisational issues which pervade irrigation and water management within rural Cambodian communities.

During the process of developing irrigation infrastructure, CAVAC works closely with all concerned including farmers, local government institutions, local businessmen and the Provincial Department for Water Resources and Meteorology (PDWRAM). CAVAC has a team of ten Technical Experts employed to design and supervise construction and establish systems for operation and maintenance of between four and six schemes each year. Although most of the CAVAC team working on irrigation are engineers, with an internationally recognized academic degree, there are also three organisational experts that work closely with the communities within the CAVAC team.

CAVAC Irrigation Schemes From Start to Finish

All initial steps in the process outlined below have a stop-go function which means that if specified conditions are not met, construction will not go ahead. After construction, CAVAC has a commitment to ensure that schemes work well both now and into the future.


  1. Each year, the PDWRAM suggest a number of schemes for which CAVAC does a quick initial assessment.
  2. In parallel, CAVAC conducts feasibility studies that assess technical, agricultural and economic issues with assistance from both Provincial Departments of Agriculture (PDA) and PDWRAM
  3. CAVAC engages with the local community to ensure interests are captured in scheme designs. CAVAC requires commitment from the communities to ensure support during construction and for ownership afterwards.
  4. CAVAC conducts Environmental Impact Assessments and commissions Environmental Management Plans (EMP) (see the environment section of the website for further information).
  5. The PDWRAMs conduct studies of the sites (topographical surveys) and develop a design for the schemes, assisted by CAVAC engineers as required.
  6. The local commune councils and village chiefs discuss the consequences of the design with the farmers and request farmers to contribute land for irrigation system construction as required. Contribution of land for canal construction has to be done on a purely voluntary basis which is later checked by CAVAC staff to ensure all contributors are happy and aware of the obligations of all parties.
  7. When all requirements are met and the potential return on investment is favourable, CAVAC makes a priority list and submits it to the National Steering Committee (NSC) for approval.

Tendering and construction

  1. Once approval for the selection of schemes has been provided by the NSC, CAVAC starts the tendering process for construction, based on the PDWRAM designs. Construction tenders are jointly evaluated by CAVAC, MOWRAM and the respective PDWRAM representative.
  1. A final check is done to determine if all requirements for design and commitments from farmers and the community are met. If suitable bids are received, that fall within the National Steering Committee (NSC) approved budget, a contract is awarded.
  2. During construction, the PDWRAM, CAVAC and the local community jointly monitor the construction activities and address issues when they arise.
  3. CAVAC monitors implementation of the environmental plan and water safety requirements and makes changes as required to mitigate potential negative impacts.
  4. With support from CAVAC, FWUC specialists from the PDWRAM help the farmers to set up a FWUC and provide capacity building training as needed.
  5. FWUCs are then supported in their new role as managers of their scheme. This process often requires support provided over a number of years in order to ensure sustainability.
  6. It is rare that construction is finished within one dry season and, in most cases, modifications are needed and conducted after consultations with the PDWRAMs and the local communities.

After construction

  1. Schemes are complex systems affecting thousands of people. It is extremely unlikely that everything is perfect after one year. Both technical and organisational issues will be monitored and action is taken to resolve any issues if needed.
  2. Implementation of the Environmental Management Plan requires monitoring of changes and in many cases taking active steps to mitigate potential negative impacts.
  3. When schemes are delivering sufficient water to all users and are well managed and operated, they will be handed over to the Royal Government of Cambodia.

Continuing Focus for CAVAC Support

Although the use of irrigation in agriculture has a long history within Cambodia, experience constructing modern irrigation schemes is limited. There are many stakeholders involved who all have their own views and responsibilities on effective water management within the Cambodian context, of which CAVAC is only one actor. The first years of implementation have been a steep learning curve for CAVAC and its partners. Some initial choices were not as successful as they could have been and have led CAVAC and its partners to implement lessons learnt to activity designs and management approaches. Some of the initial schemes that CAVAC has supported still need fine tuning and CAVAC is committed to continuing to work on these schemes to ensure the best outcome for rural communities.

An example of how CAVAC has continued to change and fine-tune the approach is in the construction of secondary canals. In some areas local entrepreneurs have taken the initiative to construct secondary canals, linking to a CAVAC constructed main canal. These secondary canals offer a sustainable way to increase and widen the area of crops under irrigation for local communities. However, in other areas the development secondary canals has not been taken up by local stakeholders. CAVAC and its partners are still looking for the optimal way to assure construction of secondary canals which will enable greater access to irrigation for more farmers but also sustainability of schemes.

The real challenge lies in the organisational aspect of irrigation schemes. Dealing with so many stakeholders all with different expectations, incentives and interests will remain the main focus for the CAVAC irrigation and water management component until the end of the program. CAVAC is very committed to ensuring that this is done effectively to maintain CAVAC irrigation investments now and into the future.


Table One: List of CAVAC canals as per June 2014


Year of construction

Main canal lenght in km

1 Krapum Chouk canal Takeo 2010 5.5
2 Kveng Tayi canal Takeo 2011 5.2
3 Tumnub Lork canal Takeo 2011/12/13 14.8
4 Prey Rumdeng canal Takeo 2012 6.9
5 So Hang canal Takeo 2011/2012 8.7
6 Rokar Chhouk canal Takeo 2013/2014 2.3
7 Wat Thmey pump Takeo 2014 7.0
1 Prey Tonle canal Kampot 2010 3.2
2 O'Kak canal Kampot 2011/12/14 2.9
3 Sbov Andeth canal Kampot 2011/14 6.8
4 Thnoat canal Kampot 2011/14 6.8
5 Spean Touch canal Kampot 2012/13 6.6
6 Prey Leu canal Kampot 2012 3.9
7 Hay Saun canal Kampot 2013 3.8
8 Chamlong Chray pump Kampot 2013/14 1.7
9 Reservoir 77 reservoir Kampot 2013/14 1.5
10 Hay Saun extension 1 pump Kampot 2014 1.4
11 Hay Saun extension 2 canal Kampot 2014 2.9
1 Thnoat Chum canal Kg. Thom 2011 7.3
  Thnoat Chum impr. canal Kg. Thom 2014  
2 Angko + extension canal Kg. Thom 2011/12 3.5
  Angko improvement pump Kg. Thom 2014 5.1
3 Boeung Leas pump Kg. Thom 2013/14 0.5
4 6 January SC2 canal Kg. Thom 2013/14 4.6
5 6 January SC3 canal Kg. Thom 2013/14 4.1
6 6 January SC1 canal Kg. Thom 2014 1.7
23 TOTAL 116.8