Important role of water resources in the Mekong River Delta’s agriculture by Le Anh Tuan

8/6/2019 Important role of water resources in the Mekong River Deltas agriculture by Le Anh Tuan

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International workshop on Mekong Environment and Livelihood: The Changing Situation and Trans-boundary Implications, Can Tho, Vietnam, 3 4 February, 2010============================================================================

Important role of water resourcesin the Mekong River Deltas agriculture

Le Anh Tuan1

1College of Environment and Natural Resources, Can Tho University, VietnamE-mail: [email protected]

Abstract

The Mekong River Delta (MD), the most downstream part of the Mekong river, isknown as the biggest "rice basket" of Vietnam. The MD is 4 million hectares in sizeand hosts 18 million inhabitants. Currently, 2.4 million ha are used for agriculture. Inthe MD, agriculture and aquaculture has been developed quickly during last twodecades and distributed greatly to the national economic. Each year, the deltasupplies more than 50 percent of the nations staple rice and crop food, 65 percent ofthe total fish production, and 70 percent of tree fruits for domestic and export.

Presently water-abstractions from the Mekong River are mainly used to irrigate therice and upland crops, curb salinity intrusion and leave acid sulfate soil layers withsufficient wetness. The combination of the hydrological regime, sea, soil-type andpollution poses original water resources management problems for irrigation. Currentseasonal limitation of water irrigation, the impacts of climate change and sea levelrise as well as the potential trans-boundary effects on the Mekong Deltasagricultural production are discussed in this paper.

Key words:the Mekong River Delta, rice production, water resources, threats.

========================================================================== 1Important role of water resources in the Mekong River Deltas agricultureLe Anh Tuan, College of Environment and Natural Resources, Can Tho University, Vietnam.
mailto:[email protected]:[email protected]


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I. THE MEKONG RIVER DELTA IN VIETNAM IN GENERALThe Mekong River Delta (MD) in Vietnam, located in the tropical monsoon zone, isan alluvial plain stretching from the border between Cambodia and Vietnam to thesea (Figure 1). The total area of the MD is approximately 28,734 km2 (NEDECO,1993). About 2.4 million ha of the delta are used for agriculture. Rice cultivation

lands take almost 90% of the agricultural land (Tuan et al., 2004). In 2003, therewere 600,000 ha of water surface in the MD used for aquaculture (Can Tho StatisticsDepartment, 2003). The Delta is very low and flat, with an average land elevation ofabout 1.00 1.50 meters above mean sea level The Mekong river section inVietnam is 255 km long and accounts for 5.17% the total length of the main river(Tuan, 2000). The delta has 18 million inhabitants in 2009, in which 8 millions oflabors are counted. More than 70% labors in the MD are farmers. Historically andpractically, the people of the Delta have settled and cultivated the land along theriver and canal banks. Human life, agriculture and aquaculture production, anddomestic water supplies in the Delta depend highly on the river water regime. TheMekong River water is basic of life for millions of people to whom water provides

directly or indirectly the source of livelihood. The Mekong immense water resourcesare one of the key factors for social and economic development in the region (Marko,2004). Annually, the MD supplies more than 50% total rice production, 70% of fruit,and 80% of fish production for the whole country (De, 2006). The MD is a reallybiggest wetland area of Vietnam and is important for biodiversity conservationMekong basin (Tuan and Guido, 2007).

Fig.1. Map of the Mekong River Basin and the MD in Vietnam



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The average monthly temperature of the MD varies from 25C - 28C. There are onlytwo distinct seasons in the Delta: rainy season (from May to October) and dryseason (the rest months of the year). The mean annual rainfall is about 1,600 mm.More than 90% the rainfall amount occupies in the rainy season. Part of the Delta isflooded during the rainy season. Salt intrusion along the 600 km-coast has degraded

soil and water quality, compromising the agricultural productivity and livelihoods ofcoastal communities. In addition, an area of 2-million ha is covered by acid sulfatesoils. The MD is particularly vulnerable to climate change. The objectives of thispaper are to express the important role of water resources for agriculture, to presentthe projected threats and to analyze the impacts to the rice production of the Delta.

II. THE IMPORTANT ROLE OF WATER RESOURCES FOR AGRICULTURERice and fish are the major food not only for Vietnamese but also for many people inthe world. Since the end of the decade of 1980s up to present, Vietnam has knownas one of the biggest agriculture and aquaculture export countries. In average, about

3 3.5 million tons of rice and 600,000 - 700,000 tons of fishes are yearly exportedfrom Vietnam to the rest of the world. In 1999, 4.5 million tons of exported rice hasrecorded. It is planned that, total aquaculture production in the MD can reach thetarget of 1.5 million tons in 2010 and 2 million tons in 2020. This increase in fishproduction and processing will also generate more jobs for local workers, with thenumber of workers involved in this sector estimated to increase from 200,000 in2010 to 250,000 in 2020(Vietnam News Agency, 2008).

Almost rice and fish productivity and export in Vietnam come from the Mekong Delta.Agricultural and fishery products are considered as highest water demand fields. Theagricultural production currently consumes 85 - 90% of the total natural surfacewater sources approximately. In some areas, paddy rice always occupies not belowthan 95% of total irrigation water. Almost fresh water resources in the MD aresupplied by the Mekong River system and the local rainfall. To produce one kilogramof rice requires 3,000 - 5,000 liters of water, depending on the rice variety and typeof irrigation used (MRC, 2004). Moreover, the aquaculture areas are increasing withan annual rate of 4.1% (General Statistical Office, 2000) due they are being highpotential products for export on the world market as compared with the rice price.The areas of rice cultivation have increased more than 100,000 ha yearly during theperiod 1995 -1999 that has brought about high irrigation water demands.

In the dry season, about 1.8 million hectares of rice fields request to be irrigated asroughly 1.1 to 1.2 liter per second per hectare. Otherwise, nearly 200.000 hectaresof perennial fruit trees and industrial crops in the delta need to be watered until thesoils reaches field wet capacity. Water use in the Mekong delta is approximately haftpart in a total water volume used by the whole Vietnam. As a result from theirrigation systems extension and high-yielding rice varieties technical application,agricultural areas increased by approximately 20% last two decades, however, totalproduction doubled. The rice yield of the Delta in 1996 from 12.8 million ton has risenup to 17.5 million to in 2003 playing an important role in the contribution to thenational food security. In general, depending on the water supply capacity and land



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use patterns, there are three major rice cropping systems in the MD, i.e. Winter-Spring crop, Summer-Autumn crop, and Autumn-Winter crop. The specific waterrequirement of these different rice crop regimes is shown in Table 1.

Table 1: Estimated water productivity of rice production in the MD.

Rice cropsParametersWinter-Spring Summer-Autumn Autumn-Winter

Total water requirement (m3 /ha) 8080 7520 6500Rain water available (m3 /ha) 160 4000 7000Irrigation requirement (m3 /ha) 7920 3520 -500Average yields of rice (tons/ha) 6.0 4.3 4.0Water productivity (kg rice/ m3 water) 0.8 1.2 -

(Source: Nhan et. al., 2008, reproduced from Sam, 1997)

For serving the goals of the food security policy of the Vietnam Government, manywater resources projects have been established and implemented during last 3

decades. More than 3,300 billion VND (nearly 210 million USD) was invested in 105irrigation projects in the Mekong River Delta in the 1996-2003 period, of which 60 outof 105 projects were completed (Vietnam News Agency, 2003). At the present, thedelta has a dense river and canal system (Figure 2) that estimated over 7,000 kmlength of main channels, 4,000 km on-farm irrigation systems, more than 20,000 kmof protection dikes to prevent early flood (Ministry of Agriculture and RuralDevelopment - MARD, 2003). In average, the canal density are about 2-3 m/ha forthe main canals, 5-10 m/ha for secondary canals and 2-5 m for tertiary canals.These canal systems are not commonly used for irrigation, drainage but also forwater supply, fishery, and local water transport. These water systems are serving formore than 2 million ha of paddy fields, keeping the average yield of 4.5 5.5

tons/ha.

Since last ten years from 1995 to 2005, the aquaculture area in the Delta hasincreased more than 2.37 times and its production has jumped up more than 3.68times. However, this outbreak growing has put the water bodies on the threats ofpollution due to the asymmetry of water resources planning strategy in the present.The aquaculture is releasing approximately 3 million tons of sludge yearly to waterenvironment in the form of untreated composting organic matters (Tuan, 2008). It isestimated that in 2010 about 30,600 tons of nitrogen would be flushed intosurrounding rivers through pond water exchange (Nhan et. al., 2008). There were5000 ha of fish ponds in 2005. These water bodies need to exchange 80 90% oftheir water capacities weekly for keeping a good fishery water habitat.



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Figure 2: Water resources map of the MD(Source: MARD, 2003)

III. LIMITATION AND THREATS OF THE WATER RESOURCESEXPLOITATION FOR AGRICULTURAL PRODUCTIONThere are three water quality problems and two water quantity problems that are theprincipal limit factors of agricultural production in the Delta (Tuan et al., 2004, 2008) :

(i) The salinity intrusion: There are more or less 2.1 million hectares of the MDcoastal areas (50%) affected by salinity during the dry season fromDecember to May.

(ii) The acid sulfate soils (ASS): Large areas of Long Xuyen Quadrangleand Plain of Reeds and other scattered lands, cover 1.6 million hectares(40%) of the MD are holding the soil with high iron sulfide content.

(iii) The polluted water: The Mekong river is facing more and more waterpollution by agricultural and industrial chemicals and domestic untreatedwastewater. In some places, this situation is threatening seriously the publichealth and socio-economic development.

(iv) The shortage of fresh water: In the dry season, the average discharge of theMekong river is lower than 2,500 m3 /s down to 1,700 m3 /s. In addition



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the groundwater table lowers by 2 to 3 m. This water amount is not enough toirrigate nearly 1.5 million hectares of cultivable lands in the dry season. Theshortage of freshwater leads to increasing salinity intrusion throughout the MDcoastal provinces.

(v) The floods: Discharge of the Mekong River during the wet season averages of

39,000 m3

/sec. About 1.2 1.9 million of hectares of the southwestern part ofthe Delta can be flooded where farming becomes impossible.

Many scientists and international organizations have classified Vietnam, especiallythe Vietnamese MD, as highly vulnerable to climate change and sea level rise (Peterand Greet, 2008; Dasgupta el al., 2009; IPCC, 2007; UNDP, 2007; WB, 2007; ADB,1994). If the sea level rises 1 meter, the Mekong Delta may lose 15,000 20,000km2 of land, and about 3.5 to 5.0 million of people will be affected (IPCC 2007). Acombination of higher temperatures, lower rainfall, more extensive flooding and arise in sea level will impact significantly on agricultural activities in general and onrice production in particular, adding more pressure to the livelihoods of people in the

delta area (TTK & SEA START RC, 2009). The solutions for climate changemitigation such as watering to the dry lands in the upstream countries may lead moresalinity intrusion impacts to the MD in the low-flow months.

Another threat to the water regime of the delta is the existing and planneddevelopment upstream dams, both in the main flow and tributaries in the MekongRiver Basin. A dam-reservoir-hydropower series will alter water flow regimes in thedownstream leading a strongly effect the present cropping patterns, reduce thesediment source, block the fish migration and change seriously the ecosystemswhere millions people culture rice and fish for their livelihoods. Industrialdevelopment in the upstream countries may release the chemical pollutants forriparian communities. In addition, if China and Thailand transfer Mekong water toother basins, it will be a real warning to Vietnams agricultural production.

IV. DISCUSSION AND RECOMMENDATIONConcerning agriculture production and water resources in the MD, it can be foreseenthat in the future (Figure 3):

The rice and fish production, as well as other crops, will be reduced bothcultivation area and yield by serious droughts and floods in the future. A fall oftotal production will threat the food security of the nation.

Farmers in the Delta have to pay more money to pump water due to theshortage water in their fields. That means their income from agricultureproduction will be reduced.

Rice farmers, fish and shrimp farmers, salt farmers and small agriculturalbusinessmen will be significantly impacted due to the lack of essential nutrientsources, land ownership, financial sources and information assessment foradaptation the water regime change. As a consequence, resources areas offorest, land, water, wildlife, natural minerals will be encroached, overexploited and damaged.



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CLIMATE CHANGEAND SEA LEVEL RISE

TRAN-SBOUNDARY WATERISSUES


Fig. 3: Foreseen impact chain from climate change and trans-boundary water issueson agricultural production and socio-ecological systems in the MD

There is an urgent need for research on climate change and trans-boundary watercooperation and environmental problems, rather than only technical problems. Thisis a critical issue that regional and national planners, policy makers, academicscientists, businessmen, local officers and people in the Mekong River Basin have tobe aware of. There must be policy on information sharing and measures to adjustnational decisions.

AcknowledgementThe author wishes to acknowledge Can Tho Peoples Committee, Can ThoUniversity (CTU), Vietnam River Network (VRN), Towards Ecological Recovery andRegional Alliance/Foundation for Ecological Recovery (TERRA/FER), Thailand,Save the Mekong (StM) Coalition and Oxfam Australia for their support to organizethe International Workshop on Mekong Environment and Livelihood: The ChangingSituation and Trans-boundary Implications in Can Tho University on 2-3 February,2010.

UPSTREAM DAMS

MEKONG DELTAWATER RESOURCES EFFECTS

INDUSTRIAL GROWTH

DEFORESTATION

WATER TRANSFERWATER

QUANTITYWATER

QUALITYWATER

DYNAMIC

POVERTY AND UNSTABLEINCREASES

NATIONAL FOODSECURITY THREATS

AGRICULTURAL LAND ANDPRODUCT REDUCTION

ENVIRONMENTAL & NATURALRESOURCES DEGRADATION

DIRECT/ INDIRECT


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References

ADB (Asian Development Bank), 1994. Climate Change in Asia: Vietnam CountryReport, p.27.

Can Tho Province Statistics Department, 2003. Can Tho Statistical Yearbook. Can

Tho City, Vietnam.Dasgupta Susmita, Benoit Laplante, Craig Meisner, David Wheeler, and Jianping

Yan, 2007. The Impact of Sea Level Rise on Developing Countries: AComparative Analysis. World Bank Policy Research, Working Paper 4136,February 2007.

De, Nguyen Ngoc, 2006. Farmers, Agriculture and Rural Development in theMekong Delta of Vietnam. Education Publishing House, HCMC, Vietnam

General Statistical Office, 2000. Statistical Yearbook 2000. Statistical PublishingHouse, Hanoi, Vietnam

MARD (Ministry of Agriculture and Rural Development), 2003. Atlas of SomeSelected Hydraulic Works of Vietnam. Ha Noi, Vietnam.

Marko Keskinen (2004). The Lake with Floating villages: A socio-economic analysisof the villages around the Tonle Sap Lake, Proceeding of the Workshop onIntegrated Water Resources Management on Tonle Sap Lake, 1-2 February2004, Phnom Penh, Cambodia.

Nhan, Dang Kieu, Nguyen Van Be, Nguyen Hieu Trung, 2008. Water Use andCompetition in the Mekong Delta. In: Challenges to sustainable Developmentin the Mekong Delta: Regional and National Policy Issues and ResearchNeeds, T.T. Be, B.T. Sinh and Fiona M. (Eds). The Sustainable MekongResearch Network (Sumernet)'s publication, Stockholm, Sweden.

IPCC (Intergovernmental Panel on Climate Change), 2007. Fourth AssessmentReport, Working Group II report. Impacts, Adaptation and Vulnerability.

TTK & SEA START RC, 2009. Water and Climate Change in the Lower MekongBasin: Diagnosis & recommendations for adaptation, Water andDevelopment Research Group, Helsinky University of Technology (TTK), andSoutheast Asia START Regional Center (SEA START RC), ChulalongkornUniversity, Water & Development Publications, Helsinky University ofTechnology, Espoo, Finland

Tuan. Le Anh, 2000. Hydrological Regime Characteristics of the Mekong RiverDelta. (c im Ch Thy vn vng ng bng sng Cu Long).Lecture Notes on Hydrological Engineering. Can Tho University, Vietnam (inVietnamese).

Tuan, L.A, Wyseure, G.C.L, Viet, L.H., 2004. Sustainable Water Management forRural Development in the Mekong River Delta, Vietnam. The secondInternational Symposium on Southeast Asian Water Environment Hanoi,Vietnam, 1-3 December, 2004.

Tuan, L.A, Wyseure, G.C.L, Viet, L.H., Haest, P.J., 2005. Water QualityManagement for Irrigation in the Mekong River Delta, Vietnam. AgEng2004Leuven, Belgium. International Conference on Agricultural Engineering,12-16September, 2004.

Tuan. Le Anh and Guido Wyseure, 2007. Action Plan for the Multi-levelConservation of Forest Wetlands in the Mekong River Delta, Vietnam.



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International Congress on Development, Environment and NaturalResources: Multi-level and Multi-scale Sustainability. Cochabamba, Bolivia.

Tuan, Le Anh, Chu Thai Hoanh, Fiona Miller, and Bach Tan Sinh, 2008. Floods andSalinity Management in the Mekong Delta, Vietnam. In: Challenges tosustainable Development in the Mekong Delta: Regional and National Policy

Issues and Research Needs, T.T. Be, B.T. Sinh and Fiona M. (Eds). TheSustainable Mekong Research Network (Sumernet)'s publication, Stockholm,Sweden.

Tuan, Le Anh. 2008. Water for aquaculture in multi-purpose water resources planning strategy in the Mekong Delta, Vietnam. CTU Scientific Journals2008(2):205-209.

Peter Chaudhry and Greet Ruysschaert, 2008. Climate Change & HumanDevelopment in Vietnam: A case study for the Human Development Report2007/2008. Oxfam and UNDP.

NEDECO (Netherlands Engineering Consultants), 1993. Master Plan for theMekong Delta in Vietnam. Summary Report. Government of Vietnam, World

Bank and UNDP.UNDP (United Nations Development Program), 2007. Human Development Report

2007/8, Fighting Climate Change: Human Solidarity in a Divided World.Palgrave MacMillan, New York.

Vietnam News Agency, 2003. 3,300 billion VND for Irrigation Network in MekongDelta. News dated 27 April, 2003. Vietnam

Vietnam News Agency, 2008. Plan to develop tra catfish industry in Mekong Delta.News dated 11 November 2008. Vietnam


Important role of water resources in the Mekong River Delta’s agriculture by Le Anh Tuan

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