The missing link between cross-sectoral resource management and full-scale adoption of the water-energy-food (WEF) nexus has been the lack of analytical tools that provide evidence for policy and decision-making. This study defined WEF nexus sustainability indicators, from where an analytical model was developed to manage WEF resources in an integrated manner using the Analytic Hierarchy Process (AHP). The model established quantitative relationships among WEF sectors, simplifying the intricate interlinkages among resources, using South Africa as a case study. A spider graph was used to illustrate sector performance as related to others, whose management is viewed either as sustainable or unsustainable. The model was then applied to assess progress towards the Sustainable Development Goals in South Africa. The estimated integrated indices of 0.155 and 0.203 for 2015 and 2018, respectively, classify South Africa’s management of resources as marginally sustainable. The model is a decision support tool that highlights priority areas for intervention.

In order to promote the efficient use of resources and the sustainable development of the economy in Jiangsu Province, it is particularly important to ease the contradiction between water supply and demand on the basis of realizing the coordinated development of the water–energy–food (WEF) nexus. With the aim of a dynamic balance of water resources, this paper used system dynamics (SD) to build a WEF nexus SD model that focused on studying the specific supply-and-demand mechanism of water resources in each subsystem. Then, Jiangsu Province was taken as an example to perform simulation research on the regional water dynamic balance to explore effective policies for increasing water supply and decreasing water demand. The results showed that the imbalance of water resources will remain severe in the next few years. To relieve the imbalance, it will be helpful to promote the energy utilization of straw, improve the irrigation efficiency, adjust the crop planting structure, and require residents to strictly follow the water quota. An important advancement in this study is the simulation of the water resources supply-and-demand mechanism in each subsystem from the perspective of the WEF nexus.

The Pacific lamprey is an iconic native fish of great importance to the ecosystem and indigenous cultures in the U.S. Pacific Northwest. Pacific lamprey populations have declined in abundance from historic levels, and conservation aquaculture has been proposed as a technique to restore these populations. The present research focused on expanding the culture methods for larval lamprey. The larvae filter feed and cohabitate with juvenile salmonids in the wild, therefore the effluent water from rearing salmonids may be a viable source of water and food for culturing lamprey. This approach could be a sustainable method for raising lamprey at existing salmonid hatcheries. A nine week trial investigated the effects of rearing in effluent water from salmonid culture on the growth, survival, proximate composition, and fatty acid profile of larval lamprey. This trial also explored the potential of this rearing strategy to improve the water quality by removing nutrients from the effluent. The trial included three treatments testing the use of the effluent from steelhead trout (Oncorhynchus mykiss), a conventional lamprey diet (control diet), or both combined as a means for rearing lamprey. A fourth treatment where lamprey were excluded served as a water quality control to test the effect of lamprey presence on effluent quality. Lamprey survival was not affected by treatment. Lamprey reared solely on the effluent waste matched the survival and growth of fish fed the conventional diet. Lamprey fed the combination treatment grew faster than the conventional diet fed fish. Whole body lipid levels were elevated in lamprey from the combination treatment relative to the conventional diet fed lamprey. Crude protein in the whole bodies of effluent fed lamprey was low compared to fish from either of the treatments where the conventional diet was fed. Lamprey offered the effluent nutrients were high in saturated fats relative to the control fed fish, which reflected the lipid profile of this diet. However, lamprey from the combination treatment were lower in long chain polyunsaturated fatty acids relative to the control or the effluent treatment lamprey. There was no measureable improvement in water quality due to the presence of lamprey, though lamprey were able to sequester approximately 1.3% of the effluent dry matter as lamprey biomass. Overall, it appears the larval stage of lamprey can be effectively reared on salmonid effluent, and this method provides superior growth when used in combination with a conventional lamprey diet.

In order to promote the efficient use of resources and the sustainable development of the economy in Jiangsu Province, it is particularly important to ease the contradiction between water supply and demand on the basis of realizing the coordinated development of the water–energy–food (WEF) nexus. With the aim of a dynamic balance of water resources, this paper used system dynamics (SD) to build a WEF nexus SD model that focused on studying the specific supply-and-demand mechanism of water resources in each subsystem. Then, Jiangsu Province was taken as an example to perform simulation research on the regional water dynamic balance to explore effective policies for increasing water supply and decreasing water demand. The results showed that the imbalance of water resources will remain severe in the next few years. To relieve the imbalance, it will be helpful to promote the energy utilization of straw, improve the irrigation efficiency, adjust the crop planting structure, and require residents to strictly follow the water quota. An important advancement in this study is the simulation of the water resources supply-and-demand mechanism in each subsystem from the perspective of the WEF nexus.

To find a sustainable way of supplying food, energy, and water (FEW) while simultaneously protecting the ecosystem services, it is imperative to build greater understanding on interconnections, feedback, and dependencies in FEW systems. The FEW nexus has developed as a field of study to provide frameworks for such pursuits. Building upon previous work in this paper, we analyze FEW resources through the development of a virtual water trade network using the US network of food and energy flows and their associated virtual water contents. Our main objective is to provide a quantitative estimation of the virtual water embodied in the internal US food and energy transfers and analyze the associated interdependencies of these connections. Three methodological advancements demonstrate the novelty of this work. First, unlike existing FEW virtual water modeling studies, our work separates corn into both food and energy resources accounting for the significant use of corn for ethanol in the United States. Second, we apply recently published water consumption values for energy commodities confirming the variation between previous water footprint studies and these more accurate accounting procedures. Third, we examine network properties of the trade flows furthering FEW nexus literature and showcasing avenues for future research. Our results indicate that accounting for the transfer of corn from the food commodity network to the energy commodity network leads to a virtual water footprint decline of 11% for the cereal grain virtual water network. Additionally, the food trade network shows highly dense and connected properties compared to the energy trade network. Finally, our results indicate that transfers of water footprints between water scarce and water abundant states differ substantially between food and energy virtual water networks. A quantifiable understanding of the water footprint network embodied in the food and energy trade can help in developing policies for promoting conservation and efficiency in the context of the FEW nexus.

This study is an attempt to fill a knowledge gap in our understanding of WEF nexus, focusing on the effects of direct and indirect resource consumption with a life-cycle approach. In Taiwan, the food subsystem is water-intensive and energy-intensive, consuming 99% of water and energy resources directly to produce food. The water subsystem directly consumes 87.18% of its energy for water production, but indirectly consumes 12.82% for operations to prepare for water production and supply. However, the energy subsystem indirectly consumes 91% of the energy and 83% of the water from operations to prepare for energy generation. Consequently, direct resource consumption in the food subsystem and indirect operations in the energy subsystem cause more environmental impacts than those caused by others. The results highlight that environmental impacts derive from not only direct resource consumption but also preparation and production for resource generation (indirect consumption). There are approximately 28% of environmental impacts derived from indirect resource consumption in WEF nexus. Without considering the indirect resource consumption, we will underestimate the total resource depletion and environmental impacts. This study can help in developing policies for saving water and energy and in enforcing resource security.

Regions affected by resource scarcity, poverty, and land-use conflicts need to advocate the merits of practices strongly grounded in sustainable land management. This review paper provides an analysis of agroforestry as an integrated system embedded in complex relations between resource uses in the Water–Energy–Land–Food (WELF) nexus. Using the African Sahel region as a case study, the paper explains the need for understanding land management practices, such as agroforestry, through the lens of trade-offs and benefits inherent in the WELF nexus. Agroforestry practices are demonstrated to be valuable interventions leading to i) resilience to climate stresses, ii) water, energy, and food securities, iii) mitigation of resource-oriented harbingers of conflicts and iv) development opportunities. These goals can also yield valuable results in terms of promoting sustainable development, i.e. functional ecosystems, livelihoods, and human security. Two overarching sub-nexuses, namely agroforestry–food–energy and agroforestry–food–water–climate, are identified in the Sahelian context and conceptualized. Primarily, the trade-offs outlined within these sub-nexuses are fuelwood vs. crops, use of land for more forests vs. more cropping, and water availability for agroforestry vs. agroforestry impacts on the water cycle. Despite the positive outcomes and opportunities, agroforestry systems in the Sahel still face some challenges such as vague land use rights, inadequate capacities and lack of investments. Policy recommendations are synthesized at three levels. This synthesis involves remedies to lessen pressures at the interlinks of WELF resource use, overarching remedies in the two sub-nexuses, and remedies across all the sectors and issues for improving agroforestry outcomes. Optimal remedies stress the importance of choosing the right land, water and plant combinations as well as incorporating efficiency measures and alternative sources. A successful agroforestry system is characterized by a conducive environment at the farm level in terms of institutions, management, enhancing the farmer's capacity, and good infrastructure.

International audience | Based on the GRAFS method of biogeochemical accounting for nitrogen (N), phosphorus (P) and carbon (C) fluxes through crop, grassland, livestock and human consumption, a full description of the structure and main functioning features of the French agro-food system was obtained from 1850 to the present at the scale of 33 agricultural regions. For the period since 1970, this description was compared with the results of an agronomic reconstitution of the cropping systems of the Seine watershed based on agricultural census and detailed enquiries about farming practices at the scale of small agricultural regions (the ARSeine database), which were then used as input to an agronomical model (STICS) calculating yields, and the dynamics of N and C. STICS was then coupled with a hydrogeological model (MODCOU), so that the entire modelling chain can thus highlight the high temporal inertia of both soil organic matter pool and aquifers. GRAFS and ARSeine revealed that the agriculture of the North of France is currently characterised by a high degree of territorial openness, specialisation and disconnection between crop and livestock farming, food consumption and production. This situation is the result of a historical trajectory starting in the middle of the nineteenth century, when agricultural systems based on mixed crop and livestock farming with a high level of autonomy were dominant. The major transition occurred only after World War II and the implementation of the Common Agricultural Policy and led, within only a few decades, to a situation where industrial fertilisers largely replaced manure and where livestock farming activities were concentrated either in the Eastern margins of the watershed in residual mixed farming areas or in specialised animal production zones of the Great West. A second turning point occurred around the 1990s when regulatory measures were taken to partly correct the environmental damage caused by the preceding regime, yet without in-depth change of its logic of specialisation and intensification. Agricultural soil biogeochemistry (C sequestration, nitrate losses, P accumulation, etc.) responds, with a long delay, to these long-term structural changes. The same is true for the hydrosystem and most of its different compartments (vadose zone, aquifers, riparian zones), so that the relationship between the diffuse sources of nutrients (or pesticides) and the agricultural practices is not immediate and is strongly influenced by legacies from the past structure and practices of the agricultural system. This has strong implications regarding the possible futures of the Seine basin agriculture.