Water resources management and irrigation work operatton in Cambodia

The national water resource system of Cambodia consists of a number of river basins, most of them tributaries of the Tonle Sap Lake and Mekong river systems, and a few river basins in the Southwestern part which drain directly to the coast. All of the river basins experience a set of common challenges, while those in the environmentally delicate Tonle Sap Lake region share a unique set of issues and challenges.The Royal Government of Cambodia (RGC) is to develop its water resources, mainly for irrigation and hydropower, by rehabilitating old defunct irrigation systems, and by planning dams for hydropower generation, irrigation and flood control. Cambodia faces many water-related issues, especially floods and droughts. Floods occur during the rainy season throughout the country when rainfall is above average from August to November. Water shortages in the dry season, exacerbated by occasional droughts, makes the people dependent on wells and rainwater for their basic water needs in the upper catchments. Irrigation development have a rich history in Cambodia and can be trace back to the Angkor period, especially from the 11-14 century. During the Khmer rouge regime period from 1975 to 1978, forced labors were used to build several hundred irrigation schemes across Cambodia within a 3 years period. Cambodia, currently there are more than 2,000 irrigation schemes that can provide water resources potential for irrigating about 59% of cultivated areas. Thus, there is a need for water storage reservoir to store water from the wet season for use during the dry season. Also, water shortages during the short spells of “small dry seasons” during the wet season, can also adversely affect irrigated agriculture if there are no water storage reservoirs. The low water use efficiency and productivity in irrigated agriculture has also resulted in excessive water use and low irrigation productivity. Also, there is underutilization of the irrigation potential in the Cambodian part of the Mekong delta.

In August 2010, the Cambodian government has set the goal of exporting milled rice of up to a million tons by 2015. To achieve this goal many strategies have been developed and implemented. One of them is to expand the construction and rehabilitation of irrigation systems across the country, so that rice production can be carried out the whole year round, instead of being dependent on rainwater.

1. Country Context

1.1. Cambodia has an area of 181,035 km2

1.2. Estimated population of Cambodia in 2018 is 16.2 million people of which approximately 80% live in the rural areas and 20% in urban areas.

1.3. Cambodia’s economy has undergone three major phases of reform and development since 1989

1.4. Poverty incidence has fallen from 47.8% in 2007 to 18.9% in 20121

2. Status of Water Resources and Irrigation

2.1. Cambodia is the country located in South East Asia

2.2. The Mekong River basin

2.3. The Mekong flows

2.4. However, current development of water and related resources in the Mekong Basin is limited relative to other international river basins

2.5. Much of the Mekong Basin remains among the world’s poorest areas

2.6. Rainfall is extremely variable across the 39 river basins and 5 River Basin Groups (RBG) in Cambodia within and between years

2.7. Annually, Cambodia has abundant amount of water but also extreme water shortage due to the lack of water storages and opportunities to store water and access to available water

2.8. Extensive flooding, flash flood, and drought are annual that have significant economic, social, and environmental impact.

2.9. Climate change is likely to intensify storms and extend the number of consecutive dry days during both dry and wet seasons

2.10. Continuing upstream hydropower development in the mainstream of Mekong River and its tributaries in the People’s Republic of China (PRC), Lao PDR, and Viet Nam are already leading to significant alterations of the natural water flow regime and sediment movement, obstruction of fish movement, and degradation on aquatic ecosystems

2.11. Surface water is mostly good quality for the Mekong mainstream and the Tonle Sap Lake

2.12. Groundwater is primary used for drinking and for subsistence farming and is not yet monitored (quantity or quality)

2.13. Cambodia has about 2,500 irrigation schemes of which 1,926 schemes are in a condition that have potential to be fully rehabilitated 4

2.14. Significant potential to expand irrigated agriculture command area and production in Cambodia.

3. Finding and Issues for National Water Status

3.1. Cambodia is facing many challenges regarding water resources management and establishment of sustainable irrigation which are explained below and summarized in Table 1.

3.2. Making sure that the water sector, among the other three priorities, contributes to the development and rehabilitation of the country

4. Water Resources

4.1. Cambodia is heavily dependent on water inflows from other counties, receiving 70% its water this way

4.2 IWRM is not ongoing applied as required by the Water Law- Cambodia is still very much in a water development phase

4.3. Groundwater is a vital resource in many areas, but is poorly understood and is not being managed

4.4. Cambodia’s water resources assessment and monitoring are totally inadequate for management

4.5. Future water quality assessment must factor in the result of the MRC’s BDP Scenario analysis

4.6. Water catchments-are not being identified and protected

5. Agriculture

5.1. Lack of financing for irrigation O&M is not economically sound

5.2. Irrigation management capacity needs strengthening

5.3. The use of both chemical fertilisers and pesticides is not according to the standards

5.4. The fisheries sub-sector, already vulnerable faces a growing number of threats from inside and outside the country

6. Aquaculture

7. Industry

8. Hydropower

9. The hydropower development potential of the plants to be built in Cambodia in the near future is high.

10. Rural water supply and sanitation

11. Policy and Implementation Framework

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H.E. Mey LyHuoth, H.E.Chhea Bunrith

International conference water resources research on water resources security,
disaster prevention and climate change adaptation