Irrigation in Vietnam

Although it is a country of high annual rainfall, irrigation in Vietnam is widespread. The reason is the uneven distribution of rainwater in space and in time. Irrigation management is mainly dominated by the state whereas there have been certain reforms leading to change during the last years. Awareness rising concerning environmental issues is starting to reach the people in Vietnam as well. Different strategies have been developed within the last decade to deal with environmental problems and mitigate possible impacts of climate change. With the implementation of different management structures taking into account the people's local needs, Vietnam is starting to follow Integrated Water Resources Management principles.

History of the irrigation sector

Agricultural land under irrigation; past and present trends Vietnam is one of the largest rice exporter since the late 1980s and early 1990s. Previous to the Doi Moi reforms initiated in 1986, the country was dependent on net imports of rice. After having changed the policies and opened the market, Vietnam was finally able to earn foreign exchange within these years and hence gain financial power. The domestic economy grew rapidly. Nowadays, irrigated agriculture is by far the largest water user and although the country is developing very fast, agriculture which is predicted to grow moderately remains to be an important employer in Vietnam.

Irrigation infrastructure Due to the shift of agriculture from self-supporting production to highly intensified cropland systems there has been a total investment of the Vietnamese Government of ~125 trillion VND in irrigation infrastructure during the last four decades. The constructions built during that time include approximately 100 large to medium scale hydraulic works. Furthermore, there are more than 8000 other irrigation systems (e.g. reservoirs, weirs, irrigation and drainage gates and pumping stations). The main irrigation form used is paddy field irrigation. Whereas gravity irrigation is widely distributed in the Mekong region, in the Central North and coastal regions (3/5 of total irrigation schemes). Irrigation utilizing pumps (electric or with oil engines) is mainly located in the delta regions (~2/3 of total). The other irrigation forms are informal (non-governmental) systems like small private pumps or small gravity diversions. Other investments are made by foreign donors; both foreign and internal investments tend to concentrate on the upgrading and rehabilitation of irrigation and drainage schemes. External Investment Proposals 1995-2000

Source: World Bank et al, Viet Nam Water Resources Sector Review 1996

Institutional development As irrigation in Vietnam is an essential component for the farmers to achieve middle income status, its development is based on institutional reforms and settings. The Vietnamese government still has the major institutional predominance. Nevertheless, in the beginning of the 21st century the policy of irrigation management transfer led to the establishment of water user associations (WUAs) and the development of participatory irrigation management (PIM). In the process of decentralization, the WUAs gain responsibilities for commune and inter-commune branch canals and structures while the PIM has been introduced in 15-20 provinces only supported by international donors. Irrigation service fees were collected until 2008 and abolished afterwards dispossessing a high amount of the financial basis for the local Irrigation and Drainage Management Companies (IDMCs) and WUAs.

Environmental aspects

Linkages with water resources Vietnam counts as one of the highest rainfall countries in the world with an annual precipitation of 1940 mm making a total volume of 640 billion m3 per year. Although the amount of water is comparably high, the distribution is uneven in time and in space. The rainy season lasts 4–5 months and during this time 75-85% of the total volume of precipitation occurs. The water availability in Vietnam is supposed to be 830-840 billion m3 annually from which approximately 37% is generated on Vietnamese territory. More than 2,000 rivers (with a length >10 km) and more than 100 main rivers belong to Vietnam. 13 of these rivers have a basin area of more than 10,000 km2 with 10 being international ones. Nine rivers count as major ones accounting for ~93% of the total basin area; these are the Red River, Thái Bình River, Bằng Giang-Kỳ Cùng rivers, Ma River, Cả River, Vu Gia-Thu Bồn rivers, Đà Rằng River, Đồng Nai River and Cửu Long River. Beneath an uncountable number of lakes, ponds, lagoons and pools, there are water reservoirs with a total capacity of 26 billion cubic metres (21,000,000 acre-feet). The main purpose of the reservoirs is to generate hydropower. Six of them have a capacity of more than 1 billion cubic metres (810,000 acre-feet); Thác Bà (2.94 billion cubic metres (2,380,000 acre-feet)), Hòa Bình (9.45 billion cubic metres (7,660,000 acre-feet)), Trị An (2.76 billion cubic metres (2,240,000 acre-feet)), Thác Mơ (1.31 billion cubic metres (1,060,000 acre-feet)), Yaly (1.04 billion cubic metres (840,000 acre-feet)) and Dau Tieng (1.45 billion cubic metres (1,180,000 acre-feet)). Water reservoirs for irrigation in general have a capacity <10 million m3. Groundwater resources include yielding aquifers mainly located in the North and South of Vietnam. However, ground water is not yet well exploited. The following figure shows how the uneven distribution of water leads to water shortages both regionally and seasonally. Both indicators (annual water availability and dry season water availability indicator show the discharge of the river basin divided by the population of this basin).

Environmental impacts of irrigation The environmental impacts of irrigation in Vietnam are mainly:

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