Sokhem Pech and Kengo Sunada Population Growth and Natural-Resources Pressures in the Mekong River Basin The Mekong River Basin possesses the region’s largest potential water source and related resources, which support ongoing economic development and basin com- munity livelihoods. It is currently witnessing a major demographic transition that is creating both opportunities and challenges. An analysis of the complex relationship between demographic changes and impacts on the natural-resource base confirms that resource exploitation is occurring not only to meet growing domestic needs but also for other vested interests. Population, together with other major drivers, such as institutions, markets, and technology, will have a very strong bearing on the way in which the rich resources of the Mekong River Basin are developed and distributed in the present and future. The Mekong River Basin’s rich resources, and the benefits derived from them, are unevenly distributed both in time and geographically. Moreover, since the causes and impacts do not respect political boundaries, the Mekong countries need to jointly develop alternative management strategies to meet projected demands within the sustain- able capacity of the Mekong River Basin natural-resource base. INTRODUCTION The Mekong countries have a complex, but interesting, mosaic of demographic attributes and trends. The population of the Mekong region—whole of Yunnan Province of China, Myan- mar, Laos, Thailand, Cambodia, and Vietnam—is nearly 300 million, and over 70 million people live in the Mekong River Basin (1). The Mekong Basin possesses the region’s largest potential water source and related resources. These resources are fundamental to ongoing economic development in terms of irrigation and agricultural production, fisheries and aquacul- ture, energy and forest products, navigation and other modes of transport, domestic and industrial water supply, and tourism (2). Levels of dependency on the river’s water and related resources are very high, particularly among the rural poor, who rely on subsistence livelihoods and moral economy (3). Rec ent socioeconomic development has begun to slow population growth rates in China, Thailand, and Myanmar, while Cambodia, Laos and Vietnam are expected to experience further positive growth well beyond 2050 (4). It is also true that the population growth rates vary considerably across th e Mekong River Basin, within and between the basin countries (2). For example, Yunnan population density has doubled since the 1950s, reaching the current level of 103 people km À2 , but in the Lancang/Mekong part, the population density is only 62 people km À2 due to the rugged and inhospitable landform (5). On the other hand, Yunnan population growth rate has declined slower than other parts of China (present level of 1.3% y À1 compared to less than 0.7% annually for all of China) (5). Accordingly, the overall Mekong populations are projected to increase well beyond 2050. The population growth and expected demographic changes in these countries create both opportunities and challenges. Population size and its composition have significant impli- cations for pressures on natural resources. Growing populations require more or different food, which typically requires land and water or other forms of production (6). This paper examines population growth and its likely impacts on food demand and land and water resources in the Mekong River Basin in a systematic and integrated manner. As a first step, we present a clear overview of demographic trends in the Mekong River Basin. Next, we conduct a comprehensive analysis to explore the complex relationship between demographic change and impacts on the natural-resource base in the Mekong River Basin. Purpose and Methodology The main purpose of this paper is to stimulate policy debate over the current national focus on food self-sufficiency and a broader national and regional development agenda in the Mekong River Basin. We provide the context, empirical evidence, and an analysis of the demand (real or perceived) associated with population growth. We also present a compar- ison of demand forecasts with the sustainable potential of the natural-resources base of the Mekong River Basin in order to contribute to a better understanding of this immense and complex Mekong River Basin environment. Population growth, food and water demands, and their impacts on water resources in both the Mekong River Basin and other river basins around the world have been discussed in a number of studies (e.g., 6–10). While the approaches used and information provided by these studies give a good indication of annual food and water demands, they generally do not provide information about water and other related resources necessary for meeting food demand at finer timescales, such as during critical dry-season months, or at more specific geographical scales. This paper reviews conditions and trends in the Mekong River Basin through both quantitative and qualitative analysis. It examines both underlying opportunities for and threats to sustainable water-resources management in the Mekong River Basin at critical time periods and at key locations along the Mekong main stem as shown in Figure 1. To this end, the study makes use of a systematic assessment framework that allows for identification of both key issues and appropriate management responses to balance environmental and socioeconomic devel- opment objectives. The study tests the hypothesis of a complex multidimensional relationship among key demographic attri- butes and other intervening factors, such as institutions, policy, technology, culture, and the natural environment. DEMOGRAPHIC TRENDS IN THE MEKONG RIVER BASIN Overcoming Different Population Growth Rates The Mekong River Basin population is over 70 million and is expected to increase rapidly (1). Projections of population growth in the Mekong River Basin differ widely as a result of both different methods of enumeration and poor reporting (1, 8, 10). To address this problem, this study derives the Mekong Ambio Vol. 37, No. 3, May 2008 219Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se River Basin population growth rate from the national population growth rates of each country represented in the Mekong River Basin adjusted to the specific conditions of the Mekong River Basin. United Nations (UN) data (4) on key population statistics for China, Laos, Myanmar, Thailand, Cambodia, and Vietnam were analyzed. The rate of natural increase was estimated for each country from 1970 to 2050 as the birth rate less the death rate, assuming that the rate of net migration is zero. Population growth in the basin over a 50 y period is projected based on two scenarios: scenario A—where the natural population increase rate changes over time as estimated above; and scenario B—where the rate of natural increase is kept constant at year 2000 levels as estimated by the Mekong River Commission (MRC) (1). Discussion of Population Growth Outlook The projections estimated by the present study show that the Mekong River Basin population grew from 63 million in 1995 to over 72 million in 2005. This is in good agreement with the observed/estimated data (1). Under scenario A, by 2050, the Mekong River Basin population is expected to grow by another 60%, while under scenario B—constant growth—it will double its 2005 values. Empirical evidence suggests that future population growth in the Mekong Basin is likely to follow the trends projected under scenario A (4). While these figures are only indicative, they do point to the complexity associated with policy debate around population growth as metajustification for natural-resources exploitation in Mekong River Basin. Most, if not all, Mekong countries have argued that to fulfill the resource requirements (perceived or real) of a growing population, some form of water and/or land- use change will be required to support increasing human numbers (1, 11, 12, 13). FOOD DEMAND GROWTH PROJECTION IN THE MEKONG RIVER BASIN Selecting a Method for Projecting Food Demand Total food demand projections usually depend on three crucial factors: i) population size; ii) increase in per capita consump- tion and life style; and iii) changes in the composition of diet (10). Data on the Mekong River Basin population size is available (as shown previously), and changes in per capita consumption can be estimated from Food and Agriculture Organization (FAO) food balance sheets (14). An analysis of the data on the composition of average daily diet (1990, 1995, and 2000) of all six Mekong countries shows that more than 65% of the daily calorie supply is provided by cereals (rice and wheat), both directly as cereal products and indirectly through animal products (14). It is therefore assumed in this study that such a change in lifestyle would be minimal over the next 40 y, and that cereal products and rice will remain the major staple foods in the Mekong River Basin in the coming decades. Some early Mekong River Basin studies applied a method for calculating food demand that built on an assumption of per capita demand of 300 kg y À1 of paddy or equivalent across all Mekong countries (see, e.g., 9). An analysis of the FAO food balance sheets (14) (1990, 1995, and 2000) shows that method was overgeneralized because food composition and availability differ from country to country. The food balance sheets also provide information about average per capita food supplies, which can be used to measure long-term trends in national food demand and diet composition. In this study, domestic food demand is considered as the sum of a country’s demand for food and other uses from available supplies, such as seed use, livestock feed, food manufacturing, and farm and market waste (postharvesting, transport, and retail losses). Discussing Food Demand Estimates Year 2000 cereal (rice, maize, and wheat) demand in the Mekong River Basin was estimated to be around 20.65 million t. Based on the constant population growth in scenario B, total cereal demand in the basin will more than double to around 44.1 million t by 2050. Under scenario A, cereal demand is projected to increase by nearly 60% (roughly 11 million t more than 2000 values), as shown in Figure 2. Comparing this demand with the 2000 paddy rice production of 30.64 million t in the Lower Mekong Basin (15), and assuming no changes in paddy production levels or farming practices, the Mekong River Basin is likely to produce enough rice to feed its basin community until 2030 or 2040 (see Fig. 3). Northeast Thailand and the Vietnamese Delta—major rice producers and exporters—are likely to produce rice surplus even after 2050. However, malnutrition remains in many of the least-developed parts of t he basin—Myanmar, Laos, and Cambodia (2). This is mainly due to problems of distribution Figure 1. Mekong River key monitoring stations (27). 220 Ambio Vol. 37, No. 3, May 2008Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se and nonaffordability by some low-income groups, rather than of an absolute lack of food (1). As far as the expansion of food production in the future is concerned, the Mekong countries have different potentials and constraints. These are discussed in the next section. THE RELATIONSHIP BETWEEN POPULATION GROWTH AND AGRICULTURAL LAND EXPANSION IN MEKONG COUNTRIES An analysis of long-term population (4) and cropping-area changes in all countries in the Mekong region during the past four decades (1960–2004) (16) does not produce a uniform relationship between population growth and land-use change. All Mekong countries except for Myanmar experienced cropping land area increases in proportion to the increase of population until 1995, whereafter agricultural land expansion has been much slower than population growth. This result suggests that although population s ize is an important determinant of agricultural land-use change, its form and the intensity of change in the Mekong River Basin in a particular locale are influenced by other factors, including land-tenure policies, international markets for forest and agricultural products, land resource availability and the level of competition for it, technological factors, and development impacts (16). Food Demand Growth and Impacts on Land Use Numerous studies have highlighted the major influence of land and water productivity on overall food production (e.g. 16, 17). This study applies a Crop Area Production Model to evaluate crop-area demands by taking into account not only food demand and population change, but also land and water productivity levels (16). For this study, the year 2000 yield was assumed to grow at the rate observed between 1987 and 1997. Figure 3 shows the increase in the crop-area demand in the whole Mekong River Basin projected by this study as compared against the 2000 observed paddy area data in the Mekong parts of Yunnan, Laos, Thailand, Cambodia, and Vietnam (16, 17). In a moderate scenario (A), the harvested area demand is likely to increase to 9 million ha (i.e., an increase of 2 million ha from 2000 values). Similar trends are found at each individual Mekong River Basin country level. If w e compare crop production area demand with the 2000 paddy areas (roughly 7 424 000 ha or 11 597 000 ha, if double- and triple-cropping areas are counted), the projected paddy crop-area demand would exceed existing paddy crop areas by 2020 or 2045, respectively (16, 17). Given these findings, crop-area expansion appears to be inevitable in the Mekong River Basin. This leads to the question about whether there is any more room for this expansion. This is discussed next. Any More Room for Agricultural Land Expansion in the Mekong River Basin? At first glance, the future crop-area demand seems to be less than the land area available. However, out of the Mekong River Basin total catchment area of over 795 000 km 2 (795 million ha), only about 227.5 million ha is classified as Class A—land areas suitable for upland or irrigation agriculture (18). Furthermore, much less than half of this is available due to Figure 2. Mekong Basin cereal demand projections comparing with 2000 cereal production (option A: population growth rate declining; option B: population growth constant). Is a human being an aquatic or terrestrial species? This question occasionally comes to the mind in the Mekong context. Floating settlements on the shores of the Bassac River in Phnom Penh, Cambodia (Photo: O. Varis). Figure 3. Mekong River Basin growth in crop-area demand vs. 2000 harvested crop area (option A: population growth rate declining; option B: population growth constant) (land-use data source: 16). Ambio Vol. 37, No. 3, May 2008 221Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se high levels of degradation, remoteness, poor soil quality, land- tenure issues, lack of access to water, and competition with forestry, human settlements, industrial uses, and infrastructure development, as shown in Table 1 (16, 19). Vietnam and Thailand use their arable land in the Mekong River Basin almost to its full extent for producing paddy rice and other crops for both domestic consumption and export (16, 17). To meet growing needs beyond 2015, Cambodia and Laos will have to increase the paddy production or develop an alternative food-security strategy with clear actions and appropriate mechanisms for implementing it. While these countries still have potential for paddy area expansion, they need substantial investment in irrigation systems, transport infrastructure, and market access (15). ASSESSMENT OF POPULATION GROWTH AND WATER AVAILABILITY ISSUES Long-Term Per Capita Water Availability Trends in the Mekong River Basin According to the World Resource Institute, a basin reaches ‘‘water stress’’ when per capita water supply is less than 1700 m 3 y À1 (20). Compared to other river basins across the world in term of actual renewable water resources per capita, the Mekong Basin is not yet considered to be water-stressed. An average M ekong river flow of 474 932 MCM each year theoretically can service the irrigation requirements of all Mekong Basin countries many times (17). However, the region still faces a series of water issues, including floods and drought in many parts of the basin at different times of the year, degradation of many key fish species and other important habitats, and intensification of sectoral competition within and among the Mekong countries (2). These water issues are closely related to the unequal geographical and temporal distribution of flow. Furthermore, these issues are likely to intensify further as a result of future population increases, changes in flow regimes due to built structures and irrigation diversions, and climate-induced change. Assessing Hydrological Impacts Due to Irrigation It is understood that a series of large-scale economic activities in the Mekong subregion are at various stages of planning and development (3, 13, 21). The main source of major future impacts, both positive and negative, on the communities and natural resources of the Mekong River Basin is the development and operation of major hydropower schemes, other large infrastructure projects, and increased irrigation water diversion in different parts of the basin (22). Water abstraction from the Mekong is limited during the wet season when flow levels are high and rainwater is available. However, there are many constraints on water utilization during the dry season, especially in drought years (23, 24). The dry seasons pose the most water challenges. Therefore, we studied the changes to the minimum daily flows due to the expansion of irrigated paddy areas to the maximum potential of arable land in the Lower Mekong Basin parts of Laos, Thailand, Cambodia, and Vietnam (15). In examining the hydrological impacts of irrigation, for the purposes of this study, crop types were assumed to remain the same, and therefore existing proportions between different crop types within an irrigation area were retained. The scenario limited the analysis to those crops associated with an increase in total water demand as a result of additional dry-sea son irrigation areas. The paddy area of 2000 (in thousands of ha) and percentage assumed increase, crop irrigation lifetime and cropping calendar, the crop water unit requirement of irrigation water per hectare, and the return flow fraction are presented in Tables 2 and 3. We estimated the flow changes at Pakse and the Cambodia- Vietnam border (see Fig. 1 for locations) and compared the Table 1. Summary of Agricultural Potential and Constraints of the Mekong River Basin. Basin area Areas for upland agriculture Area used (%) Area suitable for irrigation (ha) Area used (%) Irrigation ratio Constraints Cambodia 2 941 300 5 11 242 700 31 7%–10% Management and low inputs; poor access to market and high loss; landmine and small landholding; and low irrigation efficiency. Laos 3 051 400 25 2 317 100 35 7%–10% Poor access to market; high operation cost and low return; and low irrigation efficiency. Vietnam Highlands 1 131 300 51 360 900 36 12% Vietnam Delta 10 100 68 3 256 200 88* 60% Water shortage, salinity, acid sulfate soil; low irrigation efficiency; and high postharvest losses. Thai NE 3 600 500 75 12 156 600 95 12% High labor cost; low-quality soil; salinity; and low irrigation efficiency. Yunnan 233 333  n.a. 566 366 z n.a. n.a. Flat and gentle slope area is about 6%, and irrigation potential is marginal; 41.8 is high slope greater than 258; and high erosion. * Around 300 000 ha grow three crops of rice each year; 1 080 000 ha are double cropped (source: 16).  Pasture land. z Farmland: 93% for single-rice cropping and 3% for double-rice cropping. Table 2. Paddy area of 2000 and percentage of assumed increase (in thousands of ha), crop irrigation lifetime, and cropping calendar. Basin country Dry season, 3.5 mo, Feb–May Recession, 4 mo, Jan–Apr Spring/summer, 4 mo, Apr–Jul Winter/spring, 4 mo, Dec–Mar 2000 2040 2000 2040 2000 2040 2000 2040 Cambodia 55 þ 150% 137.5 200 þ 150% 500 Vietnam Delta 1500 1879 1237 1581 Thailand 155.9 * 10% 171.5 0 0 0 0 0 0 Laos 131.8 * 250% 461.3 0 0 0 0 0 0 (Data source: 16) 222 Ambio Vol. 37, No. 3, May 2008Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se impacts of irrigation expansion on the Mekong Delta at low flow to 1996–2000 average monthly flow volumes at Pakse and Cambodia-Vietnam border, as estimated by the World Bank (23). Above Kratie, the total dry-season irrigation withdrawal is projected to remain lower (in term of percentage) than the areas below Kratie and in Vietnam’s Mekong Delta. The 2000 estimated irrigation water demand in the Mekong River Basin parts of Thailand and Laos was only 30% of the total average flow volume at Pakse. However, with an increase in irrigated areas to 250% and 10% in Laos and Thailand, respectively, the total irrigation demand would be close to 80% of total average flow volume during the critical months of February and March. The dry-season flow change would be even more remarkable with the projected increase of the dry-season irrigation in the area further downstream of Kratie (Fig. 1). It will further exacerbate an issue of competing demands from other uses, including in-stream environmental uses and critical habitat maintenance for endangered species, which are known to require water of a certain depth. The comparison of the irrigation volumes of 2000 with average flow volumes in April and May shows that the irrigation demand constituted 76%–81% of the flow availability. The results of irrigation volume estimates for downstream of Kratie and in the Mekong Delta during the dry-season period from December to July show an increase of 47% from the 2000 value of 32 096 MCM. The average value and the actual flow volumes may be higher or lower, since the baseline standard deviation of wet and dry years is estimated to be around 23% on average (24). This incident of dry-season shortage is confirmed by the report of severe incidence of seawater intrusion in the Mekong Delta area of Vietnam in very dry years. With a projected growth in irrigation water use, the critical dry-season months—April and May—will face more serious water short- ages and more competition among water users, as irrigation demand alone will surpass flow availability (21). DISCUSSION AND CONCLUSION Population, together with other major dr ivers, such as institutions and organizations, markets, and technology, will have a very strong bearing on the way in which the rich resources of the Mekong River Basin are developed and distributed, both at present and in the future. Levels of dependency of people on the river’s water and related resources are very high, particularly among the rural poor, who depend heavily on subsistence livelihoods. However, the rich resources and the benefits derived from them are unevenly distributed both in time and space (3). They are exploited not only for meeting growing domestic needs but also for export demands, further demonstrating the high level of dependency on the rich natural resources of the Mekong River Basin as a source of economic growth. The Mekong leaders maintain that the requirements of a growing population ultimately require some form of land-use change to provide for the expansion of food production, or to develop the infrastructure necessary to support increasing human numbers (1, 13, 14). At first glance, the projected crop-area demands appear to be lower than the land available in the basin. However, in reality, much less than half of this land is available due to high levels of degradation, remoteness, poor soil quality, land-tenure issues, lack of access to water and markets, and competition with other land-use activities, e.g., forestry, human settlement, industry, and infrastructures. Some cash-trapped riparian countries need to carefully assess land suitability, address irrigation viability (cost, access, and effectiveness), and market prices and access. Furthermore, for these countries, securing and allocating substantial investment in irrigation systems, transport infra- structure, and market access is often very challenging. Water abstraction from the Mekong River Basin is limited during the wet season when flow levels are high and rainwater is available; however, there are many constraints on water utilization during the dry season, especially in drier years. It is true that good water-resource management practices can increase the availability of water during critical periods, and that integrated planning that optimizes the benefits derived from waters can clearly increase the overall productivity of a river system. Major (joint or several) development, such as the construction of dams and major abstractions for irrigation, presents special challenges due to the need to assess options and trade-offs and to apply environmental and social safeguards effectively and equitably across inter national borders and jurisdictions. The results of this study suggest that, in order to satisfy the requirement for further irrigation expansion in the Lower Mekong Basin and to prevent seawater intrusion into the Mekong Delta, a dry-season flow needs to be generated during the critical dry months, either from the points above Kratie or from Tonle Sap Great Lake (25, 26). Modeling results generated by the MRC (2004) show that the development of Chinese dams (two existing dams and two larger planned dams) and six dams on Laotian tributaries will have the effect of reducing flows beyond even the standard deviation of wet and dry years (estimated to be around 23%) at Kratie (which is used as a control point to monitor flow patterns and flow distribution in Table 3. Estimated crop irrigated-water requirement and return flow fraction. Activity Noncritical period, May–Jan (m 3 ha À1 mo À1 ) Crop irrigation life (mo) Critical period, Feb–Apr (m 3 ha À1 ) Return fraction Lowland rice 2074 3.5 7258 0.3 Upland crops 1555 4 6221 0.3 Fruit trees 1037 4 4147 0.0 Coffee 1100 4 4400 Recession rice 1037 3 3110 0.3 (Source: adapted from 16) Figure 4. Total irrigation demand and average monthly flow volume at Pakse and Cambodia-Vietnam border. Ambio Vol. 37, No. 3, May 2008 223Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se Cambodia’s floodplains and in Vietnam’s Mekong Delta) (23). The generation of a dditional flow with major structural measures in the Lower Mekong Basin floodplains is technically, financially, and even ecologically challenging (27). The issues described here are compounded by many factors, such as: – Each Mekong country tends to take an independent course of action, often ignoring external and indirect effects. This represents one of the largest challenges to overcome, since the asymmetry of causal responsibility, power/capacity, and distributional problems are highly prevalent in the subre- gion. – An effective and truly Mekong-wide institution for negoti- ating cooperative development is lacking, and there is no commonly accepted knowledge base or tools for impact assessment and monitoring. – There is a lack of reliable data and knowledge, which leads to a failure to fully understand and correctly evaluate impacts and identify the causa l mechan isms at work in large, dynamic systems, and to consider and integrate multiple risks and vulnerabilities. – Inadequate attention is given to the cumulative impact of activities. As the number of development projects in an area increases, the incidence and importance of cumulative impacts also increase. Better approaches, guidelines, and conventions for carrying out cumulative and cross-sectoral impact assessment and monitoring are needed. In summary, growing food demand requires one or more of i) further expansion of crop and irrigation areas; ii) increasing crop and land-use intensities, diversity, and productivity levels; iii) demand-side management, iv) a limit on irrigation abstractions, significant improvements in irrigation efficiency (i.e., adoption of a ‘‘more crop per drop’’ approach), or diversification of crop types toward those requiring less water; and v) virtual water trade. Vietnam presents an interesting case. Statistically, it has lowest ratio of water availability per person, but it has been successful in increasing food production for domestic consump- tion through high crop productivity and water- and land-use intensity. References and Notes 1. Mekong River Commission (MRC). 2006. The MRC Basin Development Plan: Completion Report for Phase 1. Mekong River Commission Secretariat, Vientiane, Laos PDR, 104 pp. 2. MRC. 2003. State of the Basin Report. Mekong River Commission Secretariat, Phnom Penh. 316 pp. 3. Sokhem, P. and Kengo, S. 2006. The governance of the Tonle Sap Lake, Cambodia: integration of local, national and international levels. Int. J. Wat. Res. Dev. 22, 299–416. 4. United Nations. 2005. World Population Prospects: The 2004 Revision. Population Division of the Department of Economic and Social Affairs of the United Nations Secretariat, United Nations, New York, dataset on CD-ROM. 5. Esa Puustjarvi. 1999. Review of Policies and Institutions Related to Management of Upper Watershed Catchments. Report of Greater Mekong Subregion Watershed Project (Phase II): Poverty Reduction and Environmental Management in Remote Greater Mekong Sub-region. Yunnan, China, 28 pp. 6. Boberg, J. 2005. Liquid Assets: How Demographic Changes and Water Management Policies Affect Freshwater Resources. RAND Corporation, Santa Monica, CA, 107 pp. 7. Molden, D., Amarasinghe, U. and Hussain, I. 2001. Water for Rural Development. Background paper on water for rural development. Working Paper 32. International Water Management Institute, Colombo, 91 pp. 8. Rosegrant, M.W., Cai, X. and Cline, S. 2002. World Water and Food to 2025: Dealing with Scarcity. International Food Policy Research Institute, Colombo, and International Water Management Institute, Sri Lanka. (http://www.ifpri.org/srstaff/rosegrantm.asp) 9. Hoanh, C.T., Guttman, H., Droogers, P. and Aerts, J. 2003. Water, Climate, Food, and Environment in the Mekong Basin in Southeast Asia. Final Report ADAPT Project. Adaptation Strategies to Changing Environment, Amsterdam, 52 pp. 10. Davis, T. (ed). 2003. Mekong River Basin and Yangtze River Basin. In: Water Use for Agriculture in Priority River Basins, Section 4. World Wide Fund for Nature Publication, Living Water Programme, Netherlands, 32 pp. 11. Asian Development Bank (ADB). 2002. Key Indicators 2002: Population and Human Resources Trends and Challenges. ADB, Manila. (http://www.adb.org) 12. GMS Summit Declaration. 2005. A Stronger GMS Partnership for Common Prosperity. 2nd Greater Mekong Sub-region Summit, Kunming, Yunnan, China, 4–5 July 2005. ADB, Manila, 5 pp. 13. World Bank and ADB. 2006. Future Directions for Water Resources Management in the Mekong River Basin. Joint Working Paper. World Bank and the Asian Development Bank, Vientiane, Lao PDR, 65 pp. 14. FAO. 2005. AQUASTAT Information System on Water and Agriculture. Online database. Food and Agriculture Organization of the United Nations (FAO), Land and Water Development Division, Rome. (http://www.fao.org/waicent/faoinfo/agricult/agl/ aglw/aquastat/dbase/index.stm) 15. Papademetrieu, M.K. (ed). 2000. Bridging the Rice Yield Gap in the Asia-Pacific Region. FAO RAP Publication, 219 pp. 16. BDP. 2002. Basin Development Planning Regional Sector Overview: Agriculture and Irrigation Report. MRC Secretariat, Basin Development Plan Programme, Phnom Penh, Cambodia, 32 pp. 17. BDP. 2003. Water Used for Agriculture in Lower Mekong Basin. Mekong River Commission Secretariat, Basin Development Plan Programme, Phnom Penh, Cambo- dia, 56 pp. 18. Molden, D., et al. 2007. Pathways for increasing agricultural water productivity. In: Water for Food, Water for Life. Molden, D. (ed). Earthscan, London, and International Water Management Institute, Colombo, 280 pp. 19. UNEP/GIWA. 2006. Global International Waters Assessment: Mekong River. GIWA Regional Assessment 55. University of Kalmar for United Nations Environment Programme, Bangkok, 75 pp. 20. Ravenga, C. 2000. Will There Be Enough Water? World Resources Institute. (http:// www.earthtrends.wri.org) 21. Ratner, B.D. 2003. The politics of regional governance in the Mekong River Basin. Glob. Change 15, 59–76. 22. Lazarus, K. 2003. Lancang-Mekong: A River of Controversy. Mekong Watch, Southeast Asia Rivers Network (SEARIN), and International Rivers Network (IRN), Chiang Mai, Thailand, 75 pp. 23. World Bank. 2004. Mekong Regional Water Resources Assistance Strategy: Modelled Observations on Development Scenarios in the Lower Mekong Basin. World Bank, Vientiane, Lao PDR, 126 pp. 24. Halcrow Group Ltd. 2004. Development of Basin Modelling Package and Knowledge Base (WUP-A). DSF 650 Technical Reference Report Appendix A 1–6. Halcrow Group Limited, for Mekong River Commission Secretariat, Phnom Penh, Cambodia, 260 pp. 25. SMEC. 1998. Water Utilization Programme Preparation Project. Final Report, SMEC/ MRC Secretariat, Bangkok, Thailand, 194 pp. 26. Daming, H. 1997. Sustainable development of Lancang-Mekong River Basin and integrated multi-objective utilization research of water resources. J. Chin. Geogr. 7, 9–21. 27. Sarkkula, J. and Koponen, J. 2003. Modelling Tonle Sap for Environmental Impact Assessment and Management Support. Final Report. Finnish Environmental Institute and EIA Ltd., Helsinki, 110 pp. Sokhem Pech is a senior international river basin governance specialist, Hatfield Group, Vancouver, Canada. He has broad and multidisciplinary experience in water law; water and natural-resources management; institutional and organization development with specific focus on the Mekong subregion; regional policy formulation and hydrodiplomacy; multistake- holder dialogue and consultation; water-resources strategic assessment; water dispute management; and development of intercountry data- and information-sharing mechanisms. His address: Natural Resources & Policy Researcher, 46DE0, 118 Street, Tuk La Ak I, Toul Kork District, Phnom Penh, Cambodia. E-mail: speech@hatfieldgroup.com. Kengo Sunada is a professor at the Department of Civil and Environmental Engineering, Interdisciplinary Graduate School of Medicine and Engineering. He is currently a leader of the Japan Science and Technology Agency’s research project ‘‘Sustainable Water Policy Scenario for River Basins with Rapidly Increasing Populations’’ and is developing counter- measure strategies to global hydrological variations in mon- soon Asia. His address: Civil and Environmental Engineering Department, University of Yamanashi, Takeda 4-3-11, Kofu, Yamanashi 400-8511, Japan. E-mail: sunda@yamanashi.ac.jp 224 Ambio Vol. 37, No. 3, May 2008Ó Royal Swedish Academy of Sciences 2008 http://www.ambio.kva.se . understanding of this immense and complex Mekong River Basin environment. Population growth, food and water demands, and their impacts on water resources in both the Mekong River Basin and other river. Sokhem Pech and Kengo Sunada Population Growth and Natural-Resources Pressures in the Mekong River Basin The Mekong River Basin possesses the region’s largest potential water source and related. 2008 http://www.ambio.kva.se River Basin population growth rate from the national population growth rates of each country represented in the Mekong River Basin adjusted to the specific conditions of the Mekong River Basin.