Food aid is a critical component of the global food system, particularly when emergency situations arise. For the first time, we evaluate the water footprint of food aid. To do this, we draw on food aid data from theWorld Food Programme and virtual water content estimates from WaterStat. We find that the total water footprint of food aid was 10 km3 in 2005, which represents approximately 0.5% of the water footprint of food trade and 2.0% of the water footprint of land grabbing (i.e., water appropriation associated with large agricultural land deals). The United States is by far the largest food aid donor and contributes 82% of the water footprint of food aid. The countries that receive the most water embodied in aid are Ethiopia, Sudan, North Korea, Bangladesh and Afghanistan. Notably, we find that there is significant overlap between countries that receive food aid and those that have their land grabbed. Multivariate regression results indicate that donor water footprints are driven by political and environmental variables, whereas recipient water footprints are driven by land grabbing and food indicators.

The emerging and least developed countries are expected to absorb virtually all the increase in the world's population. With fast-growing population and ongoing urbanization, population density with reference to cultivated land is increasing significantly. In the emerging countries the increasing standard of living and to a certain extent biofuel production are adding more pressure on the already stressed land and water resources. Currently, most hungry people live in these countries and their number has been increasing for a few years. The least developed countries especially are regular food aid recipients. The future outlook is not promising: 80-90% of the required increase in food production will need to come from existing cultivated land. However, at present only 22% of the cultivated land in emerging and 11% in the least developed countries have irrigation facilities. Drainage development is almost non-existent. Better use of already cultivated land and water resources to ensure the required food production can be the key. The role of effective water management thus is crucial to achieve the objective of food security. This paper substantiates that the improvements in agricultural water management are closely linked to global food production.

The argument that economies that face acute water scarcity problems can and should meet their water demand for food through cereal imports from water-rich countries; and that virtual water trade can be used to achieve water securities has become dominant in global water discussions. Analysis of country level data on renewable freshwater availability and net virtual water trade of 146 nations across the world shows that a country's virtual water trade is not determined by its water situation. Some countries have the advantage of high "economic efficiency" in food production and have surplus water, but resort to food import, whereas some water scarce countries achieve high virtual water trade balances. Further analysis with a set of 131 countries showed that virtual water trade increased with increase in gross cropped area. This is because of two reasons: First, when access to arable land increases, the ability to utilize available blue water for irrigation increases. Second, increasing access to arable land improves the access to water held in the soil profile as "free good", a factor not taken into account in assessing water availability. Hence, many of the humid, water-rich countries will not be in a position to produce surplus food and feed the water scarce nations; and virtual water often flows out of water-poor, land rich countries to land-poor water-rich countries. This means that "distribution of scarcity" and "global water use efficiency", are goals that are difficult to achieve through virtual water trade in a practical sense. For a water-poor, but land rich country, virtual water import offer little scope as a sound water management strategy as what is often achieved through virtual water trade is improved "global land use efficiency". The important policy inferences emerging from the analyses are two: First, assessing the food security challenges posed to nations in future purely from a water resource perspective provides a distorted view of the food security scenario. National policies on food security should take into account "access to arable land" apart from water availability. Second, analysis of water challenges posed by nations purely from the point of view of renewable water availability and aggregate demands will be dangerous. Access to water in the soil profile, which is determined by access to arable land, would be an important determinant of effective water availability.

Water, energy, food, and environment are highly interconnected, with intricate dependencies and multiple uncertainties involved in agricultural system. This paper presents a novel water-energy-food-environment nexus (WEFEN) optimization model for sustainable development of agriculture. The developed model incorporates stochastic multi-objective programming, triangular fuzzy numbers, fuzzy credibility-constrained programming, mixed-integer programming, non-linear programming, and Stewart model into a general optimization framework. The model is capable of (1) balancing the tradeoffs among socio-economic, resources, and environmental concerns; (2) generating valid WEFEN management solutions achieving the targets of maximum net economic benefit, maximum renewable energy production, minimum water footprint, and minimum carbon footprint simultaneously; (3) dealing with complexities and uncertainties existed in agricultural WEFEN systems. The model was applied to the Zhanghe irrigation district to give policy-makers insights into what efforts should be made towards sustainable agricultural management. Flexible alternatives were generated under different scenarios and sensitivity analyses were conducted. Results highlighted the significance of improvement of internal water storage capacity, reasonable farmland management, and compromise decision preferences. The proposed methodology is applicable for other agriculture-centered regions suffering from multifold resources and environment crisis.

The North China Plain (NCP) is a major food producing region in China. Overexploitation of groundwater for irrigation and overapplication of nitrogen (N) fertilizer have contributed to increased food production but have also resulted in water shortages and groundwater contamination. This paper reviews potential conflicts between strategies that ensure water security, food security, and water pollution reduction in the NCP. It outlines some agriculture-related strategies for resolving water shortages. Besides water saving and N saving technologies, policies such as fallow tillage, a water transfer project accounting for the recovery of groundwater level, and N management limiting N input in farmland are discussed. In particular, there are conflicts between the strategies for recovering shallow groundwater and releasing N from the unsaturated zone to the aquifer in the piedmont plain because a large amount of N is stored in the thick unsaturated zone. A transition from food-oriented strategies to sustainable development management of resources and the environment is necessary. To benefit from synergies and avoid tradeoffs between water security, food security, and clean water in the NCP, we must combine water and N management, groundwater level and water quantity control, socioeconomic issues, and climate change.

China’s water resources are under increasing pressure from socioeconomic development, diet shifts, and climate change. Agriculture still concentrates most of the national water withdrawal. Moreover, a spatial mismatch in water and arable land availability—with abundant agricultural land and little water resources in the north—increases water scarcity and results in virtual water transfers from drier to wetter regions through agricultural trade. We use a general equilibrium welfare model and linear programming optimization to model interprovincial food trade in China. We combine these trade flows with province-level estimates of commodities’ virtual water content to build China’s domestic and foreign virtual water trade network. We observe large variations in agricultural water-use efficiency among provinces. In addition, some provinces particularly rely on irrigation vs. rainwater. We analyze the virtual water flow patterns and the corresponding water savings. We find that this interprovincial network is highly connected and the flow distribution is relatively homogeneous. A significant share of water flows is from international imports (20%), which are dominated by soy (93%). We find that China’s domestic food trade is efficient in terms of rainwater but inefficient regarding irrigation, meaning that dry, irrigation-intensive provinces tend to export to wetter, less irrigation-intensive ones. Importantly, when incorporating foreign imports, China’s soy trade switches from an inefficient system to a particularly efficient one for saving water resources (20 km ³/y irrigation water savings, 41 km ³/y total). Finally, we identify specific provinces (e.g., Inner Mongolia) and products (e.g., corn) that show high potential for irrigation productivity improvements.

Allocation and management of agricultural land is of emergent concern due to land scarcity, diminishing supply of energy and water, and the increasing demand of food globally. To achieve social, economic and environmental goals in a specific agricultural land area, people and society must make decisions subject to the demand and supply of food, energy and water (FEW). Interdependence among these three elements, the Food-Energy-Water Nexus (FEW-N), requires that they be addressed concertedly. Despite global efforts on data, models and techniques, studies navigating the multi-faceted FEW-N space, identifying opportunities for synergistic benefits, and exploring interactions and trade-offs in agricultural land use system are still limited. Taking an experimental station in China as a model system, we present the foundations of a systematic engineering framework and quantitative decision-making tools for the trade-off analysis and optimization of stressed interconnected FEW-N networks. The framework combines data analytics and mixed-integer nonlinear modeling and optimization methods establishing the interdependencies and potentially competing interests among the FEW elements in the system, along with policy, sustainability, and feedback from various stakeholders. A multi-objective optimization strategy is followed for the trade-off analysis empowered by the introduction of composite FEW-N metrics as means to facilitate decision-making and compare alternative process and technological options. We found the framework works effectively to balance multiple objectives and benchmark the competitions for systematic decisions. The optimal solutions tend to promote the food production with reduced consumption of water and energy, and have a robust performance with alternative pathways under different climate scenarios.

While past strategies for agricultural water management have focused on irrigation (use of blue water), this paper demonstrates the dominance of green water in food production. A global, yet spatially disaggregated, green-blue analysis of water availability and requirement, using the LPJmL dynamic vegetation and water balance model, indicates that many countries currently assessed as severely water short are able to produce enough food for their populations if green water is considered and is managed well. The need to integrate green and blue water management is highlighted in a future scenario of water availability under climate change and population growth (HadCM2 A2). For 2050, the scenario indicates that 59% of the world population will face blue water shortage, and 36% will face green and blue water shortage. Even under climate change, good options to build water resilience exist without further expansion of cropland, particularly through management of local green water resources that reduces risks for dry spells and agricultural droughts.

Water rights transfer is significantly required for alleviating the ever-intensive water crisis, particularly for arid watersheds with abundant farmland and fossil fuels. However, focusing solely on the re-allocation of water rights and disregarding agricultural water saving potential imperil the security of Water-Energy-Food (WEF) nexus. Furthermore, randomness in water availability leads to water shortage risks and subsequent impact on the whole system. In this study, a risk-based optimization model (RWEF) was proposed to promote inter-sectoral water rights transfer through encouraging energy sector to invest in agricultural water-saving works and get paid back in water rights. Chance-constrained programming is incorporated to analyze the trade-offs between system benefits and water-shortage risks. The developed model was applied to the Inner Mongolia section of the Yellow River Basin, China to verify its effectiveness, considering different development levels of food and energy industries. Results indicated that 488 million m³ of water could be transformed from agriculture to energy, without compromising agricultural production. The main recipients of transferred water rights would be traditional coal-based industries, while it would be difficult for thermal power and most modern coal chemical industries to participate. The construction of water-saving works would help safeguard agricultural production under risks. Compared against two alternative models without water rights transfer mechanism, the average benefit acquired from RWEF under varied water-shortage risks would be at least 68% higher. Particularly, when confronted with extreme water-shortage risk and increased production demands, RWEF would still be able to support agricultural and energy production, while the alternative models being incapable.

The escalating human demand for food, water, energy, fibres and minerals have resulted in increasing commercial pressures on land and water resources, which are partly reflected by the recent increase in transnational land investments. Studies have shown that many of the land-water issues associated with land acquisitions are directly related to the areas of energy and food production. This paper explores the land-water-energy-food nexus in relation to large-scale farmland investments pursued by investors from European countries. The analysis is based on a “resource assessment approach” which evaluates the linkages between land acquisitions for agricultural (including both energy and food production) and forestry purposes, and the availability of land and water in the target countries. To that end, the water appropriated by agricultural and forestry productions is quantitatively assessed and its impact on water resource availability is analysed. The analysis is meant to provide useful information to investors from EU countries and policy makers on aspects of resource acquisition, scarcity, and access to promote responsible land investments in the target countries.