Trabajo presentado en el 12th Dahlia Greidinger Memorial Symposium (Water-Soil-Nutrients: Integrated Solutions for Assuring Global Food and Water Security), celebrado en Haifa (Israel) del 29 de febrero al 2 de marzo de 2016. | No

The expected worldwide demand for agriculture, energy, and manufactured products will result in a supply chain that is increasingly dependent on exported rural products (e.g., livestock, cereal grains, fossil fuel, and biofuel). Rural areas such as the northern Great Plains are net exporters of food and energy, essentially “mining” valuable water and nutrient resources to do so. Rural areas are the foundation of supply chains; thus, to achieve sustainability, one must begin focusing at the source of the supply chain– with the farm, ranch, mine, or well. There are many knowledge gaps within the food–energy–water nexus in rural areas that shroud regional sustainability thresholds. Research and legislation are needed to address these critical issues.

CGIAR Research Program on Policies, Institutions, and Markets (PIM) | Yang Y. C. Ethan et al., 'Modeling the Agricultural Water–Energy–Food Nexus in the Indus River Basin, Pakistan', Journal of Water Resources Planning and Management 142, IFPRI, 2016

PR | IFPRI3; ISI; PSSP; CRP2; E Building Resilience | EPTD; PIM | CGIAR Research Program on Policies, Institutions, and Markets (PIM)

Sub-Saharan Africa (SSA) faces high incidence of food and nutrition insecurity. Consequently, increasing agricultural productivity has always featured prominently on regional agenda. The Comprehensive Africa Agriculture Development Programme’s (CAADP) set a target to expand the area under irrigation by at least 5 million ha by 2025. This review assessed the current status of irrigated agriculture in SSA from a water–energy–food nexus perspective, focusing on southern Africa. Gaps and opportunities for improving irrigated agriculture were also assessed in terms of the feasible limits to which they can be exploited. Sub-Saharan Africa faces water scarcity and projections show that countries in SSA will face increased physical and / or economic water scarcity by 2025. However, with agriculture already accounting for more than 60% of water withdrawals, increasing area under irrigation could worsen the problem of water scarcity. Recurrent droughts experienced across SSA reaffirm the sensitive issue of food insecurity and water scarcity. The region also faces energy insecurity with most countries experiencing chronic power outages. Increasing area under irrigation will place additional demand on the already strained energy grids. Projections of an increasing population within SSA indicate increased food and energy demand; a growing middle class also adds to increasing food demand. This poses the question - is increasing irrigated agriculture a solution to water scarcity, food insecurity and energy shortages? This review recommends that, whilst there are prospects for increasing area under irrigation and subsequent agricultural productivity, technical planning should adopt a water–energy–food nexus approach to setting targets. Improving water productivity in irrigated agriculture could reduce water and energy use while increasing yield output.

Centralised production of essential products and services based on fossil fuels and large scale distribution infrastructures has contributed to a plethora of issues such as deterioration of ecosystems, social-economic injustice and depletion of resources. The establishment of local production systems that deliver various products for local consumption (e.g. food, energy and water) by making the best use of locally available renewable resources can potentially alleviate unsustainable resource consumption. The main objective of this work is to develop process systems engineering tools combined with the concept of resource accounting using exergy for the design of such local production systems. A general design framework comprising an optional preliminary design stage followed by a simultaneous design stage based on mathematical optimisation is proposed. The preliminary design stage considers each supply subsystem individually and allows insights into the potential interactions between them. The simultaneous design stage yields an optimal design of the local production system and has the capacity to include all design integration possibilities between the subsystems and generate a truly integrated design solution. The proposed methodology, which reflects generalised principles for designing local production systems, has been illustrated through a case study on the integrated design of the food-energy-water nexus for a designated eco-town in UK. It demonstrates the advantages of an integrated design of a system making use of local resources to meet its demands over a system relying on centralised supplies and a design without considering integration opportunities between subsystems.

PURPOSE: Consuming 375–500 ml of water 30 min before a meal has been shown to reduce energy intake in older, but not younger adults. This study investigated the effects of ingesting a water preload immediately pre-meal (<1 min before eating) on within-meal ad libitum energy intake in non-obese young males. METHODS: Fourteen healthy males [mean (SD) age 27 (3) years, height 1.83 (0.05) m, body weight 80.47 (9.89) kg, body fat 17.5 (4.0) %, body mass index 24.0 (2.5) kg/m²] completed a familiarisation trial and two experimental trials in randomised counterbalanced order. Subjects arrived at the laboratory overnight fasted and consumed an ad libitum porridge breakfast. Immediately prior to the meal, subjects consumed either a 568 ml (1 pint) water preload (preload trial) or no preload (control trial). Visual analogue scale questionnaires to assess hunger, fullness and satisfaction were completed before and after the meal in both trials, as well as after the water preload. RESULTS: Ad libitum energy intake was greater (P < 0.001) during control [2551 (562) kJ] than preload [1967 (454) kJ]. Ad libitum water intake was also greater (P < 0.001) during control [318 (226–975) ml] than preload [116 (0–581) ml]. The water preload increased fullness and satisfaction and decreased hunger compared to pre-trial (P < 0.001) and the control trial (P < 0.001). CONCLUSION: This study demonstrates that consumption of a 568 ml water preload immediately before a meal reduces energy intake in non-obese young males. This might therefore be an effective strategy to suppress energy intake in this population and possibly assist with weight management.

The sufficient supply of food and energy requires large amounts of fresh water. Mainly required for irrigation, but also processing and cooling purposes, water is one of the essential resources in both sectors. Rising global population numbers and economic development could likely cause an increase in natural resource demand over the coming decades, while at the same time climate change might lead to lower overall water availability. The result could be an increased competition for water resources mainly in water-stressed regions of the world in the future. In this study we explore a set of possible changes in consumption patterns in the agricultural and energy sector that could be primarily motivated by other goals than water conservation measures—for example personal health and climate change mitigation targets, and estimate the indirect effect such trends would have on global water requirements until 2050. Looking at five world regions, we investigated three possible changes regarding future food preferences, and two possible changes in future resource preferences for electricity and transport fuels. We find that while an increase in food supply as a result of higher protein demand would lead to an increase in water demand as well, this trend could be counteracted by other potential dietary shifts such as a reduction in grains and sugars. In the energy sector we find that an increasing water demand can be limited through specific resource and technology choices, while a significant growth of first-generation biofuels would lead to a drastic rise in water demand, potentially exceeding the water requirements for food supply. Looking at the two sectors together, we conclude that an overall increase in water demand for both food and energy is not inevitable and that changes in food and energy preferences could indeed lead to an alleviation of water resource use despite rising population numbers.