Irrigation for Food Security, Poverty Alleviation and Rural Development in the LMB
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Irrigation for Food Security, Poverty Alleviation and Rural Development in the LMB June 2014 Agriculture and Irrigation Programme Mekong River Commission Authors: Barry Hall, Itaru Minami, Prasong Jantakad, Cong Nguyen Dinh Table of Contents 1. Introduction .......................................................................................................................................... 5 2. Development Trends in the LMB .......................................................................................................... 6 3. Magnitude and Distribution of Irrigation ............................................................................................ 11 4. Irrigation Variety and Variation .......................................................................................................... 14 5. Roles in Water Balance ....................................................................................................................... 18 6. Drought and Flood Mitigation ............................................................................................................ 24 7. Economic Value and Trade ................................................................................................................. 31 8. Food security ....................................................................................................................................... 34 9. Poverty Reduction ............................................................................................................................... 37 10. Climate Change ............................................................................................................................... 40 11. Environment .................................................................................................................................... 43 12. Plans and Trends: ............................................................................................................................ 43 13. Suggestions for Future Irrigation Development ............................................................................. 48 14. Glossary ........................................................................................................................................... 50 15. References ...................................................................................................................................... 51 2 List of Figures and Tables Figure 1: Agricultural Contribution to Economic Activity in four countries of the LMB…………………………..8 Figure 2: World Milled Rice Price Projections to 2022 (US$/ton)…………………………………………………………...9 Figure 3: Total Rice Production by Province…………………………………………………………………………………………..10 Figure 4: Actual (1990‐2012) and Projected Average Rice Yields in the LMB…………………………………………11 Figure 5: Total Cultivable Land and Land Used for Paddy Cultivation in the LMB………………………………….13 Figure 6: Percentage of Cultivable Land that is Irrigated in the Wet Season………………………………………….14 Figure 7: Annual Irrigated Areas in the LMB (ha)……………………………………………………………………………………15 Figure 8: Irrigation Canal in Thailand……………………………………………………………………………………………………..16 Figure 9: Floating Pump in Lao PDR……………………………………………………………………………………………………….16 Figure 10: Wooden Weir in Lao PDR………………………………………………………………………………………………………17 Figure 11: Colmatage in Cambodia………………………………………………………………………………………………………..17 Figure 12: Tnup in Cambodia…………………………………………………………………………………………………………………18 Figure 13: Dike and Sluice Gate in the Delta………………………………………………………………………………………….18 Figure 14: Production of Selected Non‐Rice Crops (000 tonnes)…………………………………………………………..19 Figure 15: Simulation of average daily flow at Kratie……………………………………………………………………………20 Figure 16: Estimated Annual Irrigation Water Use in the LMB by Country…………………………………………...20 Figure 17: Monthly Net Water Use for Irrigation in LMB Countries (Million m3)………………………………….21 Figure 18: Khong‐Loei‐Chi‐Mun Water Transfer Project……………………………………………………………………….22 Figure 19: Water Yield Minus Existing Irrigation Demand……………………………………………………………………..23 Figure 20: Groundwater Table in Prey Veng in the Wet Season…………………………………………………………….24 Figure 21: Groundwater Table in Prey Veng in the Dry Season…………………………………………………………….25 Figure 22: Existing Irrigation Projects with Flood Risk Areas……………………..............................................27 Figure 23: Drought Risk Classification………………………………………………………………………………………………….29 Figure 24: Water Balance in October…………………………………………………………………………………………………..32 3 Figure 25: Financial Returns from Rain Fed and Irrigated Rice in Studied Sites……………......................34 Figure 26: Comparison of Average Financial Returns for Rice and Non‐Rice Crops in a Pilot Study……34 Figure 27: Water Productivity Comparison in an MRC Pilot Study ($/m3)………………………………………….35 Figure 28: Rice Balance of Each Province…………………………………………………………………………………………..38 Figure 29: Poverty Incidence and Water Poverty Hotspots…………………………………………………………………41 Figure 30: Projected Irrigation Demand under a Climate Change Scenario…………………….....................44 Figure 31: Planned Irrigation Area Expansion in the LMB (ha)……………………………………………………………46 Figure 32: Total Existing and Planned Irrigation Area in the LMB (ha)……………………………………………….46 Figure 33: Irrigation Projects in Savannakhet and Khamouane Provinces in Lao PDR……………………….49 Table 1: Arable and Irrigated Rice Areas…………………………………………………………………………………………….12 Table 2: Projected Average Rice Yield under Climate Change……………………………………………………………43 4 1. Introduction Irrigation is the largest water user in the Lower Mekong Basin (LMB) but it only uses 12% of the average annual flow. All the countries of the Basin have policies and plans to expand irrigation areas to increase rice production and exports, diversify food production, respond to food security needs or address rural poverty. Various scenarios of current and planned developments suggest that future flows in the mainstream will accommodate the expansions of irrigation areas planned by all countries. But one study (Kirby et al. 2009) suggests that water deficits may emerge in certain sub‐basins and tributaries. Irrigation can be expected to reduce the risk of crop damage from water shortages in the wet season and expand cropping area in the dry season. But conditions are changing. Climate change will increase the intensity and duration of droughts as well as the frequency of extreme floods. In general, this has an effect of exacerbating saline intrusion in the Delta1and storm surges, thereby threatening crop yields, damaging infrastructure, increasing crop demand for water and raising irrigation pumping costs. This will put a premium on efficient water management. Since climate change is altering the pattern of water availability and sea levels, farmers in some areas are diversifying with aquaculture and non‐rice crop cultivation as part of the adaptation process to the natural as well as technical and economic environments. Irrigation has played a major role in increasing rice yields and consequently also in food security in large areas of the Basin. There is no doubt that irrigation has contributed to the impressive LMB record in increased rice production and export. It must have contributed to reducing the incidence of poverty, but between 13 and 28% of households in LMB countries still live on less than US$1.15/day and extreme poverty still occurs in some areas where food security is fragile. Irrigated rice production generates higher returns than rain fed rice, but some systems are more accessible to wealthier households than poorer households. Irrigated paddy fields generate positive and negative environmental externalities including non‐ commodity benefits such as flood protection, groundwater recharge, aquatic ecosystem nurturing and restoration, and soil productivity improvement and conservation but they can also produce negative externalities such as soil erosion, nutrient runoff and leaching. Irrigation has increased yields and marketable surpluses and staple food security is no longer considered a national problem in the LMB countries. However, rice deficit areas still exist in certain areas and in others the margin of security is very modest. Also, with increasing irrigation and intensive crop production, the important rice‐fish relationship for nutritional food security and livelihoods is at risk. Scenario assessments have suggested that planned irrigation expansions can be achieved without negatively affecting water quality significantly. However, various recent studies have cautioned that the often‐associated increased use of fertilisers and chemicals threatens the common property of fisheries and other aquatic resources, endangering the income and food supply of poorer households (Lorenzen et al. 2007) . 1 In this document, the term “Delta” is used for the Mekong Delta or Cuu Long Delta in the territory of Viet Nam. 5 Canal systems properly located, designed, maintained and correctly used can effectively enhance farmer’s access to water during different seasons, and in many cases allow more than one crop to be grown during the year and improve yields. About 20% of the arable land in the Basin is under irrigation but inappropriate location, poor design, limited attention to maintenance and inefficient operation has reduced efficiency and effectiveness of irrigation services and created the need for extensive rehabilitation investments. Irrigation expansions are planned throughout the Basin, but some plans in southern Cambodia and in