Changing precipitation patterns and shortages of surface and groundwater in important cropping regions pose a serious threat to China’s future food security. This paper presents a comprehensive analysis of water used for food production over the period 1998–2010 with a view to identifying pathways for achieving the national target of 580 million tons of grain output by 2020. The analysis was based on modelling of agricultural water use coupled with national and provincial statistics. The present situation was defined by (a) a slow declining trend in national precipitation and internally renewable water resources, (b) 12 out of the 13 so-called breadbasket provinces (which currently produce 74 % of national grain output) already facing water shortages and increasing competition for water from non-agricultural sectors, (c) national crop water productivity (CWP) increases of 19.5 % over the 13 years to 2010, and (d) a widening gap in CWP between breadbasket and non-breadbasket provinces. By 2020 an estimated 510 to 680 km³ of water will be required for food production depending upon future gains in CWP. A concern is that in many of the breadbasket provinces, recent CWP gains have already been substantial and additional large gains may prove difficult especially considering current environmental concerns related to agricultural intensification in China. That said, the historic efficiency gains give reason for optimism provided that there is continued investment in genetic improvement and innovation of farming systems.

The kinetics of water uptake by food powders (animal and vegetable proteins and starch materials) were studied, and a mathematical relationship developed to describe the results. The water uptake rate was found to be proportional to the square of the amount of water still needing to be absorbed to reach equilibrium. The amount of water uptake was a function of the total water uptake at equilibrium and the time required to absorb half of the total uptake. A specific rate constant for the uptake was determined. (wz)

Optimal allocation of the food, energy and water (FEW) resources is of emergent concern owing to depleting supply of the natural resources. Increasing demand for the FEW resources is attributable to growing population, migration, economic development, technological advancements and climate change. The FEW nexus (FEW-N) is an intricate system that requires robust quantitative decision-making tools to investigate the links between the various system components and sustainability. This study proposes a meta-model-based FEW-N system for addressing the issue of natural resource allocation for food and energy security. It incorporated an integrated model consisting of the Techno-Economic and Input/Output models in an Optimisation framework with maximum economic benefit as its objective function. The COINOR Branch and Cut (CBC) and CPLEX solvers in the Advanced Interactive Multidimensional Modelling System (AIMMs) were used to formulate and solve the optimisation problems. To validate the developed framework, the scenario analysis was performed on three cases in South Africa. First, it was found that using FEW resources for food production in dryland open fields, undercover greenhouses, and irrigated open fields was more profitable than for production of electrical energy from bioenergy, solar/wind-based hybrid renewable energy, and hydropower production systems. Second, the revenue of the sub-sector determined the percentage use of the FEW resources and the percentage contribution of technology options to food and energy security. Third, open fields, greenhouses, and irrigated open fields contributed significantly to food security. The holistic framework developed provided enhanced understanding of the FEW-N system. Resource security has significantly improved due to the ability of various technologies in each subsector to meet the food and energy demands of the specific population. Besides providing scientific support for national decisions regarding food, energy, and water policy, the proposed framework will also contribute to sustainable development at the subnational level.

There is a growing recognition of the interdependencies among the supply systems that rely upon food, water and energy. Billions of people lack safe and sufficient access to these systems, coupled with a rapidly growing global demand and increasing resource constraints. Modeling frameworks are considered one of the few means available to understand the complex interrelationships among the sectors, however development of nexus related frameworks has been limited. We describe three open-source models well known in their respective domains (i.e. TerrSysMP, WOFOST and SWAT) where components of each if combined could help decision-makers address the nexus issue. We propose as a first step the development of simple workflows utilizing essential variables and addressing components of the above-mentioned models which can act as building-blocks to be used ultimately in a comprehensive nexus model framework. The outputs of the workflows and the model framework are designed to address the SDGs.

We present a network model of interstate food trade and report comprehensive estimates of embodied irrigation energy and greenhouse gas (GHG) emissions in virtual water trade for the United States (U.S.). We consider trade of 29 food commodities including 14 grains and livestock products between 51 states. A total of 643 million tons of food with a corresponding 322 billion m³ of virtual water, 584 billion MJ of embodied irrigation energy, and 42 billion kg CO₂-equivalent GHG emissions were traded across the U.S. in 2012. The estimated embodied GHG emissions in irrigation water are similar to CO₂ emissions from the U.S. cement industry, highlighting the importance of reducing environmental impacts of irrigation. While animal-based commodities represented 12% of food trade, they accounted for 38% of the embodied energy and GHG emissions from virtual irrigation water transfers due to the high irrigation embodied energy and emissions intensity of animal-based products. From a network perspective, the food trade network is a robust, well-connected network with the majority of states participating in food trade. When the magnitude of embodied energy and GHG emissions associated with virtual water are considered, a few key states emerge controlling high throughput in the network.

Water and food are facing increased demands from larger and more affluent populations thus necessitating a coordinated and effective management of limited natural resources. In this study, we present an optimization model developed for optimal resource allocation towards sustainable water and food security under nutritional, socio-economic, agricultural, environmental, and natural resource constraints. The core objective of this model is to maximize the composite water-food security status by defining an optimal water and agricultural policy that ensures nutritional guidelines while still maintaining food-preferences. This policy transforms optimum food demands into optimum cropping options given the water and land footprints of each crop or agricultural product. The model performance is evaluated with a hypothetical regional case study testing a wide spectrum of cases from the water-stressed to the land-stressed extremes thus showing the model's ability to suggest fundamentally different policy approaches. Results demonstrated the sensitivity of adopted water and food security definitions in shaping water and agricultural policies, thus reinforcing the need for agreements amongst the wide range of stakeholders at global scale.

The current study introduces a conceptual socio-hydrological-based framework for the water-energy-food (WEF) nexus. The proposed conceptual framework aims to investigate how farmers' dynamic agricultural activities under different socio-economic conditions affect the WEF systems. The WEF nexus model has been integrated with an Agent-Based Model, reflecting the farmers’ agricultural activities. Furthermore, the agent-based model benefits from Association Rule Mining to define farmer agents’ agricultural decision-making in various conditions. The processes within the WEF nexus are simultaneously physical, socio-economic, ecological, and political. Indeed, there are interrelated interactions among the mentioned processes in ways that have not yet been properly delineated and mapped. Thus, to obtain sustainable outcomes, the current study investigates trade-offs among natural resources and social systems in the WEF nexus approach. The proposed socio-hydrological WEF nexus framework may provide more in-depth future insights for policy-makers through capturing bidirectional feedbacks among farmers and WEF systems. In other words, the proposed framework can help policymakers to capture the dynamic impacts of agricultural activities by farmers on the WEF nexus, which may vary due to different socio-economic conditions.

Researchers and practitioners have developed many tools to study the water-energy-food nexus at a variety of scales and perspectives in order to aid decision-making. However, there is a recognised lack of tools that consider these interdependent and complex interactions in an integrated fashion. Whether to connect and federate wellestablished modelling systems and approaches, which may be challenging, or to design truly integrated tools for holistic consideration of the nexus issues, is also debated. This paper discusses four distinctly different approaches which appear to have wide-scale applicability, although demonstration of these approaches in multiple cases (besides the Polestar model which is already regional/ global) is yet to be applied. Sustainable implementation of any tools will require greater accessibility such that they may be more widely deployed by practitioners. Harmonisation of results and insights between different scales, so that decision-makers may consider global-local impacts, also remains a challenge.