Table 1.
Various studies of the Nexus’ concepts (WEF, WE, WF, and EF), regarding countries and regions worldwide for the 2008–2022 period
| Study by | Journal/book chapter/technical report/conference/action plan | Study areas/approaches/objectives/methodologies/tools/results/suggestions/recommendations |
|---|---|---|
| Hellegers et al. (2008) and McCornick et al. (2008) | Water policy | Investigated the WEF-Environment synergies and trade-offs for India, Ethiopia, Jordon, and the USA. Presented the nature of trade-offs in various hydrological, energy, agricultural, and environmental contexts. Provided some anecdotal evidence and illustrative cases of policy options available to reduce conflicts, while maximizing the synergies amongst the Nexus subsystems (WEF) and the environment |
| Khan and Hanjra (2009) | Food policy | Investigated the WEF–Environment Nexus and recommended that the investments to enhance water usage and improve energy efficiency in crop production are two pathways to reduce environmental impacts, which can result, globally, in a good balance of the WEF–Environment Nexus |
| Mushtaq et al. (2009) | Energy Policy | Investigated the increasingly complex relationships between energy and agriculture, in terms of EF Nexus, and concluded that such relationships require an in-depth understanding of the water and energy trade-offs. Contributed to energy and food policies by analyzing complex water, energy, and economic dynamics across selected major rice-growing countries. Concluded that, of all the countries investigated, China has the highest water productivity due to its water-saving irrigation policies and practices |
| Hoff (2011) | International Conference | Provided initial evidence of how a Nexus’ approach can enhance water, energy, and food security by increasing efficiency, reducing trade-offs, building synergies, enhancing policies, and improving governance across the three sectors (WEF) |
| Scott et al. (2011) | Energy Policy | Advanced understanding of the water–energy Nexus by illustrating how these resources are coupled at multiple scales, and by revealing institutional opportunities and obstacles to the decision-making. Three interdependencies between water and energy were examined for different regions in the USA, whereas socioeconomic–environmental dimensions were taken into account |
| Hardy et al. (2012) | International Journal of Water Resources Development | Studied the water–energy Nexus in Spain and provided accounts for both the energy used in the water sector and the water required to operate the energy sector. Provided assessments of policy goals for biofuels and other renewable energy sources. Concluded that (1) approximately 6% of the total electricity demand in Spain is used in the water sector; (2) irrigated agriculture is one of the Spanish water sectors showing the greatest growth in energy requirements; and (3) search for more efficient ways to use farming water, urban treated wastewater, and desalinated water should include the energy component |
| Kumar et al. (2012) | Food Security | Studied the food security challenge that affects the food-land–water Nexus in India. Showed that the real challenge to food security and water management lays in the mismatch between water availability and agricultural water demands. Indicated that high water demands occur in water-scarce but agriculturally prosperous areas, and low water demands occur in areas that are naturally rich in water but agriculturally backward. To face this challenge, several strategies were recommended |
| Bizikova et al. (2014) | IISD (International Institute for Sustainable Development) Report | Presented a central concept that the rural poor (those who benefit most from investments in agricultural productivity) would be better off if the key environmental determinants of WEF Nexus’ security were protected and strengthened. Provided a practical, spatially clear, and ecosystem-based framework for designing and managing land investments that provide greater water, energy, and food security. Presented specific objectives, approaches, and tools, as well as illustrative examples of the key steps to implement a comprehensive process, to improve the WEF Nexus’ security |
| Keskinen et al. (2015) | Water | Investigated the WEF Nexus’ approach for the Tonle Sap Lake (TSL) region, Cambodia. Concluded that the WEF Nexus is closely related—both in the TSL and in the transboundary Lower Mekong River Basin (LMRB) in general. The current trend of large-scale hydropower threatens water and food security at the local and national levels. Hence, the WEF Nexus provides a suitable starting point for promoting sustainable development in TSL and LMRB. (Note: The LMRB is made up of the Northern Highlands, the Khorat Plateau, the Tonle Sap Basin, and the Mekong Delta, covering Thailand, Laos, Cambodia, and Viet Nam. The Upper Mekong River Basin (UMRB) comprises the Tibetan Plateau, the Three Rivers Area and the Lancang Basin in China and Myanmar.) |
| Kibaroglu and Gürsoy (2015) | Water International | Analyzed cross-border (transboundary) evolution of water resources management in the Euphrates and Tigris Rivers’ Basin (ETRB) with special reference to the interdependences (Nexus) of the water, energy, and food policies at the national (Turkey) level and the regional (Turkey, Iraq, and Syria) level. Explored how the WEF Nexus’ policy has changed at the highest level of decision-making, and how it has worked to produce synergies of cooperation between the three riparian countries of the ETRB |
| Hang et al. (2016) | Journal of Cleaner Production | Developed process system engineering tools along with resource accounting concept to design local production systems. Proposed a general design framework that includes an optional initial design phase followed by a concurrent design phase based on mathematical optimization. The initial design phase took into account each supply subsystem (water, energy, food) individually, which allowed insight into the potential interactions amongst the WEF Nexus’ subsystems. This approach was illustrated through a case study on the integrated design of the WEF Nexus for a designated eco-town in the UK |
| Gilmont et al. (2016), Gilmont et al. (2017), Gilmont et al. (2018a), Gilmont et al. (2018b), Gilmont et al. (2018 in Arabic); Gilmont et al. (2019) | International Conference; Book; Book Chapter; Book on a Special Issue; Book Chapter in Arabic; Book Chapter |
Carried out a regional joint project on water–agriculture decoupling concept, with the focus on water–food Nexus, in Jordan, Palestine, and Israel, which was led by the Oxford University and funded by the British Council, London, UK Demonstrated the relative ease with which economic and population growths can be decoupled from water resources’ needs, to mobilize the growing natural freshwater resources. This can be achieved through diversifying economies away from agriculture, importing more water-intensive food needs, and improving agricultural water productivity, developing non-natural water sources (including wastewater recycling and seawater desalination). Provided revised conceptual models, using water and agricultural implements. Explored examples of decoupling trends achieved through economic diversification and food trade in the regions studied (Israel, Palestine, and Jordan). The analysis and evaluation processes used economic growth data from the World Bank and food balance data from FAO. The project resulted in numerous polymorphic publications, including journal articles, chapters in books, books, and presentations given at international conferences |
| Jalilov et al. (2016) | Journal of Hydrology | Argued that it is impossible to project development strategies without taking into account the WEF Nexus’ elements or subsystems to meet the demands of a growing population. Studied two possible modes to operate the Rogun Dam on the Vakhsh River in southern Tajikistan, which are power mode (guaranteeing the hydroelectric needs) and irrigation mode (guaranteeing water for downstream agriculture). Concluded that societies should choose between, for example, using land, water, and fertilizers to produce food, bioenergy, or other kinds of renewable energy resources, and between using fresh water to produce energy and irrigate crops, whereas both choices can lead to the WEF Nexus’ approach |
| Smidt et al. (2016) | Science of The Total Environment | Analyzed the WEF Nexus over the High Plains’ Aquifer System in the USA, as a framework for isolating the major drivers that have shaped the history, and will guide the future, regarding water use in modern agriculture. Concluded that future water management strategies can benefit from (i) prioritizing farmers’ profits to encourage decision-making in line with strategic objectives; (ii) managing water as an input into the WEF Nexus, as interdependence and key incentive for farmers; (iii) adapting frameworks that enable farmers to achieve short-term and long-term agricultural goals; (iv) putting innovative strategies that fit within restrictive policy frameworks; (v) reducing production risks to help farmers make decisions; and (vi) increasing political willingness to preserve valuable water resources |
| EcoPeace Middle East and Konrad Adenauer Stiftung (2017) | Technical Report | Provided a preliminary feasibility study for a hydropower initiative’s exchange between Israel, Jordan, and Palestine (the Occupied Palestinian Territories—OPT) as a means of saltwater desalination and energy generation in an economically efficient and environmentally sound manner. The idea is that Israel and/or Palestine (OPT) can produce desalinated water and supply Jordan with it, while Jordan can generate solar energy and supply Palestine (OPT) and Israel with it. As such, all parties will gain from such a WE Nexus of the regionally integrated water and energy sectors. Presented a practical WE Nexus’ framework through (i) evaluating the various technological options to achieve a possible WE Nexus’ arrangement, considering the geopolitical disagreements, obstacles, and political conflicts amongst the peoples in the three countries; (ii) conducting a preliminary socioeconomic analysis of the project to be undertaken in the three countries; and (iii) determining the benefits and identifying political and geopolitical challenges of the project when will be implemented |
| Eftelioglu et al. (2017) | Book Chapter | Described a vision of the role of spatial computing in understanding the WEF Nexus from a spatial data life cycle perspective. Provided details of each of the spatial computing components (data collection, management, modeling, and visualization). Listed, for each of the WEF components, new technical challenges that likely to drive spatial computing research in the future, regarding the WEF Nexus’ approach |
| Endo et al. (2017) | Journal of Hydrology: Regional Studies | Selected 37 projects, through which 4 types of interrelated research have been identified, including WF-, WE-, WEF Nexus-, and climate-related. Amongst them, 6 projects (16%) are closely related to WF Nexus; 11 projects (30%) are closely related to WEF Nexus; 12 projects (32%) are closely related to WE Nexus; and 8 projects (22%) are closely related to climate issues. The regions investigated were divided into Asia, Europe, Oceania, North America, South America, the Middle East, and Africa. North America and Oceania tended to focus on a specific type of interdependence, including WE Nexus (46%) and climate issues (43%), while Africa had a lower focus on WE Nexus (7%). Recommended that it is essential to develop a unifying framework of Nexus’ research to share solution-oriented common goals amongst projects’ members and stakeholders, to develop methods to integrate results of research and to understand the WEF Nexus’ complexities. Also, recommended that the framework can be used within interdisciplinary and transdisciplinary approaches under the Future Earth Framework, and to encourage local-to-global connected Nexus’ systems. Concluded that such a framework will contribute to reducing trade-offs and increasing synergies of the use of the three elements or subsystems of the WEF Nexus |
| Engström et al. (2017) | Sustainable Cities and Society | Proposed a technology-independent “resource-to-service reference system” framework for the simultaneous assessment of water and energy subsystem interventions (WE Nexus) for the New York city, USA. Indicated that interventions, primarily driven by water management objectives, can significantly reduce energy use and contribute to mitigating greenhouse gas (GHG) emissions. Likewise, energy efficiency interventions can significantly reduce water use and GHG emissions. Recommended that more useful research should be conducted, and the existing analysis should be expanded to consider a broader range of resource interactions towards a full climate–land–energy–water (CLEW) Nexus’ approach. Concluded that evaluating the impacts, trade-offs, and co-benefits of the WE interventions can enhance resources’ (water and energy) efficiency through the integration of decision-making |
| Mohtar (2017) | Policy Brief | Based on the fact that climate change is already happening, and according to the Intergovernmental Panel on Climate Change (IPCC), the Earth has warmed faster in the past three decades than at any time since 1850. Ocean temperature has increased by about 0.11 °C per decade for the past 40 years. The rate of sea-level rise is now more than 3 mm per year since the 1990s (due to climate change and other aspects) (IPCC 2014). These and other changes in climate, such as precipitation, have severe effects on human systems. Accordingly, indicated that understanding the links amongst climate change, on the one hand, and water, energy, and food resources (in terms of WEF Nexus), on the other, is critical to developing effective strategies, in order to adapt to expected changes and to ensure adequate access to these resources for a growing global population. Identified some of the key factors and specific impacts of climate change on the WEF Nexus, and presented possible adaptation strategies |
| Peri et al. (2017) | Sustainability | Analyzed the fluctuations’ implications between the indexes that represent the financial component of the WEF Nexus. Used the Generalized Auto-Regressive Conditional Heteroskedasticity (GARCH) model with daily data, in which the water variable is a proxy for a stock index that represents the performance of the industry involved in the water business at the local and global levels. The findings highlighted a financial relationship amongst water, energy, and food (WEF Nexus) that was, particularly, exacerbated during the 2008 global economic crisis. Recommended the need to better investigate policy options that can be used to reduce price volatility in the context of the increasing importance of sustainability issues, with respect to the WEF Nexus. (Note: GARCH is a statistical modeling technique used to help predict the volatility of returns on financial assets.) |
| Ramaswami et al. (2017) | Environmental Research Letters | Developed a general framework to analyze the WEF Nexus, from an urban system perspective, that links interactions within and across borders. Identified the multiple environmental impacts at the community level for cities. Visualized the few supply chain risks that the environment poses to cities, taking into account the New Delhi city, India, as a case study. Found that more than 75% of the water use for food is devoted to urban agriculture and that over 76% of the energy used for food is generated from cooking fuels |
| Albrecht et al. (2018) | Environmental Research Letters | Pointed out that the Nexus’ approach aims to identify trade-offs and synergies amongst water, energy, and food subsystems. Evaluated social and environmental impacts and guided policy development across the three sectors. Indicated that, while the WEF Nexus offers a promising conceptual approach, the use of various methods and models, to systematically assess the WEF linkages and support the development of socially and politically relevant resource policies, have some limits. To help overcome these limits, four key features of the Nexus’ analysis tools and methods were obtained from the literature. These features, reflecting the interconnected thinking of the WEF Nexus, are innovation, context, collaboration, and implementation. Recommended that inter- and multi-disciplinary approaches that incorporate the social and political dimensions of water, energy, and food are needed, and also stakeholders and decision-makers should be engaged, to meet complex resource and development challenges that face the WEF Nexus |
| Brouwer et al. (2018) | Energy Strategy Reviews | Suggested that the Nexus’ is better defined as the interconnection amongst climate, land, energy, water, and food (CLEWF Nexus). Such interconnection enables trade-offs to be addressed and synergies sought. Accordingly, some models were used to support the design and testing of coherent strategies for sustainable development, regarding the CLEWF Nexus |
| Cai et al. (2018) | Advances in Water Resources | Stressed on the importance of current and continuing research needs within the water community, to understand the WEF Nexus (linkage processes and subsystems) and implement WEF solutions through innovations in technologies, infrastructures, and policies |
| Chandrasekharam (2018) | Water–Energy Nexus | Investigated the WEF Nexus’ potential in Saudi Arabia, and suggested that a renewable energy option can provide fresh water for the domestic and agricultural sectors and secure food and water in the country. Indicated that Saudi Arabia may appear as a leader in supporting the agricultural sector in all the GCC countries if the WEF Nexus would be implemented. Recommended that the most cost-effective way to obtain fresh water from the sea is to adopt technology based on solar photovoltaic (PV) or geothermal energy sources. Indicated that PV is not cost-effective, as it needs supporting facilities, while geothermal can provide base-load electricity and the system can operate with > 90% efficiency all year round at reasonable cost |
| Chen (2018) | Water (Special Issue) | Indicated that there is a growing policy focus and scientific emphasis on the relationship amongst water, energy, and food subsystems (WEF Nexus), as a framework for analyzing human and ecological systems at global and local levels, and for suggesting more sustainable pathways to a secure future. However, the issue of water quality in relevance is often a secondary consideration. Evaluating the role of water quality in the WEF Nexus, and discussed approaches to assessing water quality within the WEF Nexus, with case studies and at different levels. Covered the following topics: (i) case studies examining water quality and quantity in the WEF Nexus; (ii) regional/global analyses and models of water quality/quantity in the WEF Nexus; (iii) water quality/quantity monitoring and evaluation in the WEF Nexus, including current methods and new technologies; and (iv) water quality/quantity management approaches informed by the WEF Nexus |
| Dai et al. (2018) | Applied Energy | Based on a comprehensive survey of the recent scientific literature on the water–energy Nexus, 70 studies were identified and 35 were selected as comprehensive case studies for review. Categorized and evaluated the reviewed studies according to a clustering based on the geographical scale and Nexus’ scope. Found that fewer approaches were designed to support governance and implement technical solutions, which can be considered as a priority challenge for the scientific community if aimed at achieving greater impact on resources’ policy and management. Recommended that this requires a better use, more effectively, of the existing knowledge, and also requires putting of a greater emphasis on managing and implementing the WE Nexus |
| Hoolohan et al. (2018) | Sustainability Science | Identified four aspects of Nexus research, considering the value and potential challenges of interdisciplinary research regarding each of the four aspects. Focused on evaluating and visualizing Nexus subsystems; and understanding governance, capacity building, significance of scale, and implications for future changes and challenges. Described a new, multi-method approach that integrates stakeholders’ knowledge with insights from multiple disciplines |
| Kibler et al. (2018) | Waste Management | Characterized the waste generated from food in the WEF Nexus. Found that many food waste management options (such as waste prevention, landfilling, composting, anaerobic digestion, and incineration) offer variable pathways for WEF impacts and opportunities. Recommended that comprehensive sustainable management of food waste should involve different mechanisms and actors at multiple levels of governance and consumption. Proposed a “food-waste subsystems” approach within the WEF Nexus, to address the complex problem of food waste, and to protect and optimize resources |
| Chang et al. (2018); Uen et al. (2018) |
Geophysical Research Abstracts; Science of The Total Environment |
Within the scope of the Sustainable Urbanization’ Global Initiative: Inviting Food, Water, and Energy (SUGI-IFWE), promoted the green urban centers of tomorrow. That can be established by creating effective exchange mechanisms for the three subsystems (WEF) from sources to urban centers, and then improving WEF Nexus related to public health. Used the Artificial Intelligence Technique (AIT), big data, system dynamics, and scenario analysis to build optimal resource allocation models, to understand the interrelationship amongst the three subsystems. Provided feasible solutions that address the allocation and use of WFE resources. Indicated that during the wet year, water shortage rates can be reduced by 10% at most, food production rate can be improved by 45% at most, and annual revenue of hydropower can be increased to USD 9 million. Concluded that the proposed methodology could be a promising tool to increase the collaborative benefits of the WEF Nexus, in response to future urban’s water requirements. Also recommended that the methodology used can provide decision-makers with reference guidance for the sustainable management of water, energy, and food resources |
| White et al. (2018) | Applied Energy | Illustrated the mismatch amongst regional water, energy, and food availability, as well as final resources’ consumption and the lack of attention to environmental impacts in national economic growth strategies for East Asian countries. Concluded that resource-scarce countries, such as China, must incorporate, in their strategic regional development policies, trade-offs’ decisions related to pursuing national economic growth, eliminating environmental degradation, and having food security |
| Yang and Wi (2018) | Agricultural Water Management | Studied the water-intensive activities in the Usangu plains and Ruaha National Park in southern Tanzania, Africa, as these areas present a typical case of aquatic competition in the WEF Nexus. Found that the combination of improvements in irrigation efficiency, reductions in the proposed expansion of irrigated lands, and management of wetland areas, significantly reduce the number of the zero-flow days. This means increasing ecosystem function, which leads to positive impacts on the agricultural sector within the WEF Nexus’ approach |
| Zaidi et al. (2018) | Big Earth Data | Indicated that the Machine-Learning Technique (MLT) can help explain distinct patterns of the water–energy Nexus, with respect to water availability, transportation, power generation, fuel supply, and customer demand. Discussed ways in which statistical data and MLT can be applied to challenges facing the WE Nexus. Investigated MLT that can provide solutions to WE Nexus’ problems. Identified future research directions and opportunities for collaboration between MLT communities and the WE Nexus’ concept, which can lead to mutually synergistic advantages |
| Zhang et al. (2018) | Journal of Cleaner Production | Provided a review of concepts, research questions, and methodologies in the field of WEF Nexus. Discussed eight modeling approaches, in terms of their advantages, disadvantages, and applications. Provided guidance on choosing an appropriate modeling approach. Identified future research challenges, including WEF Nexus’ boundaries and limitations, data modeling and uncertainty, system performance’ evaluation, and the mechanisms of correlation issues. Addressed challenging questions, with respect to interconnected research and development of sustainable and resilient water, energy, and food subsystems within the WEF Nexus’ approach |
| Al-Saidi and Saliba (2019) | Water | Proposed a view of resource supply security, based on the characteristics of the systems under change and their ability to deal with risks and shocks, in terms of resilience. Presented internal and external risk factors for the WEF supply subsystems (WEF Nexus) in the GCC countries (Gulf region), and highlighted recent knowledge regarding those risks. Explained the vulnerability of WEF supply’s subsystems for risks related to growth, technology, market, and climate change. In light of these risks, highlighted the importance of investing in risk management and resilience policies in infrastructure planning. Recommended measures to respond to future risks, such as warehousing, knowledge, diversification of energy sources (fossil and renewables), and most importantly, promoting regional cooperation and synergies from joint infrastructure planning across the GCC countries, with respect to the WEF Nexus’ mechanisms |
| Araujo et al. (2019) | Current Opinion in Environmental Sustainability | Applied a collaborative research practice framework to the São Francisco River Basin, which is a hotspot of climate vulnerability in northeastern Brazil. Built cause-and-effect research on climate change from a WEF Nexus’ perspective, considering the added value of resilience and adaptability of the concept. Proposed an additional underpinning of the Nexus’ approach—namely socioecological security, which can be defined as a political–territorial dimension of the associated socioecological system. Recommended that the climate component should be included in the WEF Nexus to address social and environmental sustainability |
| Campana et al. (2019) | International Conference organized by the American Geophysical Union | Used the Artificial Intelligence Technique for the WEF Nexus’ management during drought in Sweden. Concluded that, unlike farming practices in southern European countries where irrigation is a well-known practice, Swedish farmers generally lack sufficient means and incentives to know water use of crops, actual irrigation applications, responses of crop yields to different water management practices, and current water efficiency levels on farms. Used grid climatic data, made available by the Swedish Meteorological and Hydrological Institute (SMHI), in order to develop a WEF Nexus’ model to estimate the effects of drought on the Swedish agricultural sector. In addition to SMHI data, used also a genetic algorithm for optimal allocation of natural resources (water, energy, and food), and long-term memory networks for seasonal predictions. The WEF Nexus’ model aimed at building a pioneering model to provide instant information, regarding management of irrigation water, crop yield conditions, and natural resources’ allocation in Sweden. Concluded that the WEF Nexus’ model, based on SMHI data and AIT, can serve as a demonstration of a future operational service, especially for farmers interested in crop growing conditions and irrigation guidelines, but also for agencies related to WEF Nexus’ management |
| Djehdian et al. (2019) | Sustainable Cities and Society | Developed a new measure of the WEF Nexus that quantifies and visualizes direct and indirect exposures to urban water scarcity in the USA. Improved understanding of vulnerability to water scarcity, with respect to food and bioenergy resources, enabling policy-makers to improve the reliability of WEF Nexus in urban US areas |
| Hong et al. (2019) | Sustainable Cities and Society | Integrated multi-regional input–output data analysis to investigate the WE Nexus in the construction industry at the provincial level through the entire industrial supply chain in China. Showed that the construction industry makes up approximately 9% and 27% of China's virtual water and embodied energy, respectively. Also showed that the western, eastern, and central areas of China are suffering from imbalance in the WE Nexus, with respect to the industrial activities, regarding inefficient usages of the water and energy resources |
| Nashashibi and Gal (2019) | Action Plan | Pointed out that only a comprehensive action plan led by the donor community, in cooperation with the Israeli and the Palestinian governments, along with local infrastructure institutions, can address the interrelated and interconnected problems of water, energy, and governance (WE-Governance Nexus) that affect the Gaza Strip in the Occupied Palestinian Territories. This is with the consideration of the extremely complicated political and socioeconomic conditions affecting the Gaza Strip’s population. Urged the donor community to take a proactive stance and lead the proposed action plan, to revitalize and lead the energy and water sectors towards financial sustainability |
| Noruzi and Yazdandoost (2019) | International Journal of Optimization in Civil Engineering | Investigated the WE Nexus’ approach for the Kashan city, Iran, as being an arid area and, thus, recommended unconventional water resources (e.g., desalinated saltwater and treated wastewater) to be considered as alternative water resources. Showed that alternative water resources must be exploited, while taking into account energy costs and environmental impacts. Used WEAP (Water Evaluation and Planning software program) to model the allocation of water demand and supply. Also used LEAP (Long-range Energy Alternatives Planning software program) to model the energy required to obtain water from unconventional resources. Accordingly, estimated the desired volume of unconventional water, using the optimization method |
| Simpson and Jewitt (2019a) | Current Opinion in Environmental Sustainability | Argued that the call for activating the Nexus’ concept has been publicized in several recent publications, and the common theme is that “Nexus’ Thinking” must evolve into “Nexus Action”. Indicated that Nexus’ policies were enabled at different spatial scales from regional and national levels to city level, and appropriate mechanisms and decision support tools were evolved to achieve integrated and coherent planning to practically implement the Nexus’ concept |
| Simpson and Jewitt (2019b) | Frontiers in Environmental Science | Examined the evolution of the WEF Nexus’ concept since its rise to prominence in policy and development discourses. Presented various interpretations of the Nexus’ concept, while considering its novelty. Examined the challenges of integrating and optimizing components of the Nexus’ concept, with case studies in South Africa and South Asia. Reviewed the WEF Nexus, as a contribution potential to the achievement of the United Nations’ Sustainable Development Goals (UN’s SDGs) |
| Zhang et al. (2019a) | Resources, Conservation and Recycling | Presented a comprehensive literature review to discuss current concepts and methods of the WEF Nexus at different levels, with the goal of developing a conceptual knowledge base framework for scientific analysis and policy-making associated with urban interdependence of the WEF Nexus. Concluded that, although the Nexus’ concept of correlative thinking has been widely accepted, a coherent and explicit realization of it is still lacking and, hence, a sophisticated, systematic modeling framework is urgently needed at various levels |
| Zhang et al. (2019b) | Journal of Cleaner Production | Investigated the WEF Nexus with particular end-demand-driven internal linkages of the Beijing city, China. This was at various points along the city’s supply chains, by combining structural path analysis with the China 2010 multiregional input–output WEF Nexus’ model, with the focus on the least developed regions and energy-related sectors in the city. Besides, critical supply chains showed divergent trends for the flows of the WEF Nexus, driven by the food supply, construction, and agricultural industries. Recommended that the results obtained are very useful for targeting the efforts to address the WEF Nexus’ problems of under-developed urban connectivity from both supply-side and demand-side perspectives |
| Abdi et al. (2020) | Inventions | Attempted to review some of the recent research on the WEF Nexus’ topic. First described some facts about the exponential growth of demand and consumption in the three areas (water, energy, and food) of the Nexus, focusing on their statistical dimensions. Next, the most important research works published in the field were reviewed. Also, the most important policy-making events of this emerging concept were discussed, including committees and conferences. Finally, some significant challenges and opportunities for implementation of the WEF Nexus, along with future visions, were presented |
| Abou Farhat et al. (2020) | Book Chapter | Attempted to help overcome energy sustainability challenges in Lebanon, while minimizing impacts on the country’s natural, economic, and value-added social resources, taking into account the climate, land, energy, and water (CLEW) Nexus. Proposed such a Nexus to increase the capacity of renewable electricity generation, as well as conventional power stations that run on imported fuels to ensure energy security. This is due to the fact that Lebanon has been facing long-standing energy challenges, resulting from the lack of comprehensive assessment of the decision-making. However, this approach does not necessarily take into account Lebanon’s most pressing energy challenges and potential impacts of selected technologies on Lebanon’s scarce land and water resources. Recommended that offshore wind, solar PV, natural gas, geothermal, nuclear, and hydropower technologies are the most desirable electricity generation options in Lebanon, based on the assumptions and values used |
| Avgoustaki and Xydis (2020) | Food Security | Carried out a comprehensive review of scientific papers of the WEF Nexus, to analyze the different applications of urban farming on the basis of three different dimensions, which are: (i) manufacturing techniques and equipment used to produce food; (ii) the energy required, energy distribution, and methods of energy-related cost reduction; and (iii) technological innovations applied to improve the possibilities of water consumption for urban farming |
| Connor et al. (2020) | Technical Report | Pointed out that water-use efficiency measures in agriculture can increase water availability and reduce the energy needed for pumping, and further reduce the water needed for energy production. This lower energy demand can also result in lower greenhouse gas emissions; thus mitigating the effects of climate change. This way of cross-benefits can lead to positive reinforcements. Also, increased use of renewable energy sources and technologies in agriculture and other sectors could increase energy efficiency and provide additional opportunities to reduce GHG emissions. Furthermore, in addition to energy savings and efficiency, improved approaches to wastewater treatment can provide a broader range of climate change’s mitigation measures. This report presented a better understanding of the WEF–Climate Nexus |
| Do et al. (2020) | Science of The Total Environment | Highlighted three major trade-offs that occur amongst hydropower and irrigation, hydropower and fisheries, and irrigation and fisheries, representing the WEF Nexus’ approach for the Lancang–Mekong River Basin, China. Quantified the effects of reservoir operation on hydroelectric generation, irrigated crop production, and fisheries productivity in the Tonle Sap Lake through a new basin-wide hydro-economic model. Indicated that trade-offs can be turned into synergistic opportunities. Concluded that this alternative narrative can enhance the dialogue, regarding fair and efficient water use amongst the Mekong River’s riparian countries |
| El Youssfi et al. (2020) | E3S Web of Conferences | Reviewed the WEF Nexus’ adoption in two typical African countries—namely Morocco and South Africa. Compared the water, energy, and food sectors and relevant national policies, plans, and frameworks in both countries. Explored the importance of technology-supported frameworks for the WEF Nexus, and also analyzed the risks facing the agriculture and food security in both countries. Data on the WEF Nexus revealed major difficulties, regarding WEF availability in both countries. Revealed policy differences, regarding the Nexus across the water, energy, and agriculture sectors |
| Endo et al. (2020) | Current Opinion in Environmental Science & Health | Reviewed published research to understand the current state of the WEF Nexus, focusing on methodologies and the process by which it expands the Nexus as an interdisciplinary and integrated approach, academically and geographically. Highlighted various indicators for evaluating the Nexus’ methods and tools. Also, discussed WEF Nexus’ initiatives that apply mixed methods for replicability and reproducibility of specific case studies, based on findings |
| Katz et al. (2020) | Water | Examined the growing importance of the WEF Nexus to critically evaluate the features necessary to identify it. Indicated that the WEF interdependent relationship differs from sector-focused natural resources or sustainability problems, in terms of complexity and challenges. Stimulated two new focus areas of research—namely the identification of low-dimensional indices of the state of the WEF Nexus, and the approaches to determining the WEF Nexus’ bounds |
| Kirchem et al. (2020) | Applied Energy | Discussed the wastewater treatment process as a single industrial end user within the energy–water Nexus, where the lack of appropriate modeling tools affects the accurate assessment of the potential of the demand response (DR) within energy systems. Indicated that case studies suggested the potential for wastewater treatment plants to provide DR, but no study recognized the homogeneity of energy prices that arise from the widespread use of DR. Proposed an integrated modeling approach that combines energy system optimization with the level of operational detail in process simulation models. Recommended that such approach can yield a higher level of accuracy, regarding the assessment of DR potential from a specific process, such as wastewater treatment |
| Mahlknecht et al. (2020) | Energy | Examined baseline and resource security trends, based on the concept of the WEF Nexus in Latin America and the Caribbean. Developed a performance indicator to assess progress in the WEF Nexus’ security in the regions studied. Also developed a correlation-based indicator to assess the interdependence of the three resources (WEF). Addressed issues and challenges that are critical to sustainable development. Showed that an unprecedented amount of infrastructure is needed to counteract the increasing energy consumption. Suggested that emphasis should be placed on the gradual replacement of high carbon sources of electricity with low carbon and clean energy production systems. Showed that the water scarcity will be exacerbated by the changing climatic conditions. Recommended that improvements are urgently needed in water management, water provision, and sanitation. Also recommended that it is important to promote new agricultural practices and sustainable food systems, by enhancing and implementing the WEF Nexus’ approach |
| Norouzi and Kalantari (2020) | Water–Energy Nexus | Pointed out that the WEF Nexus’ approach can bring about change and balance in various sectors, depending on the needs and participation of all stakeholders, taking into account the environmental and water crises that threaten Iran’s food and energy security. Developed a model of the WEF Nexus’ governance approach, using a multi-layered view of Iranian regions, regarding the water and food crises which the country is currently facing |
| Norouzi and Soori (2020) | Water–Energy Nexus | Investigated the criteria and standards for evaluating different buildings, considering green building as a primary goal. Indicated that evaluation methods and mechanisms rely on the energy, environment, water, and land-use Nexus’ approach, as one of the primary evaluation metrics. Compared the methods of obtaining sustainability assessment in three criteria dimensions—namely environmental, social, and economic |
| Putra et al. (2020) | Science of The Total Environment | Performed a systematic analysis of the WEF Nexus in South Asia, using open country-wide data sources. Statistically analyzed interactions amongst the WEF Nexus sectors. Identified positive and negative correlations between WEF safety indicators as synergies and trade-offs. Observed a greater share of trade-offs compared to synergies within the water and energy sectors, and a greater share of synergies compared to trade-offs amongst the WEF Nexus’ sectors. Encouraged the strategies related to promoting sustainable energy sources (renewables), and discouraged the use of fossil energy sources that can have negative overall effects on the WEF Nexus’ security. Provided evidence that WEF Nexus’ security is viewed as an integrated system rather than just a combination of the three different sectors (WEF) |
| Sadegh et al. (2020) | Sustainable Cities and Society | Pointed out that agricultural irrigation accounts for 84% of global fresh water consumption, the food supply chain requires up to 30% of global primary energy use, and nearly 80% of global electricity generation depends on water for cooling. Thus, suggested a better understanding of the complex interactions of the WEF Nexus, as top priority for human well-being, sustainable development, and policy-making. Presented an interactive analysis toolkit of the WEF Nexus that brings together available data to enable modeling, analysis, and interrelationships of the WEF resources at the local and global levels. The samples analyzed included country-specific estimates of the water resources required to produce energy and different types of food, the energy required per amount of water or agricultural product, and the equivalent GHG emissions associated with the provision of water and energy, within the WEF Nexus’ framework |
| Shannak and Vittorio (2020) | Book Chapter | Described a spatio-temporal decision support tool that analyzes the energy requirements of the food sector based on the water demand in Saudi Arabia. The tool can provide policy-makers with background information for assessing greater energy inputs into food production and the factors that may influence increased energy use over space and time. The tool was developed using a web-based Geographical Information System (GIS) application, in such a way that it allows the user to navigate through different spatial locations, select an important point to grow a certain amount of a particular crop, and calculate the land, water, and energy requirements, representing a land–water–energy–food Nexus’ approach |
| Sharma and Kumar (2020) | International Environmental Agreements: Politics, Law and Economics | Pointed out that, globally, 3 billion people do not have access to modern fuels or cooking/heating technologies; 900 million people lack safe drinking water; 2.6 billion people lack improved sanitation; 2 billion people lack intermittent food security; and more than 820 million people suffer from chronic hunger due to extreme poverty. Developed a model on the allocation and access of the WEF Nexus, based on the “Rawlsian Concept” of distributive justice for human security and the competing demands of WEF sources. Indicated that “policy coordination” amongst all actors that govern the WEF Nexus is a key to promoting fair allocation of, and access to, the WEF resources. Concluded that the findings can advance the objectives of mitigating trade-offs and enhancing synergies between WEF Nexus’ resources, as well as preserving the environment in the context of the UN’s SDGs. (Note: The Rawlsian Concept refers to John Rawls (1921–2002), who was an American political philosopher in the liberal tradition, and whose “Theory of Justice as Fairness” describes a society of free citizens holding equal basic rights and cooperating within an egalitarian economic system (SEP 2021) |
| Zhang et al. (2020) | Pointed out that the WEF Nexus’ security is a prerequisite for achieving the 2030 UN’s SDGs. Indicated that the increasing restrictions and conflicts around the world, due to water scarcity, energy shortages, and food insufficiency, have forced people, globally, to think about the security and interdependence of each of the WEF Nexus’ subsystems. Performed a bibliometric analysis of the literature on the WEF Nexus over the 1995–2018 period, and applied the CiteSpace technique for data visualization. Indicated that Nexus’ research has not become a stable and independent system and is still suffering from great uncertainties, in terms of the mechanisms and driving forces of multi-system interactions. Concluded that synthesis and trade-offs amongst water, food, and energy sectors must be analyzed more systematically to gain insights into sustainable development | |
| Al-Saidi and Hussein (2021) | Science of The Total Environment | Indicated that the COVID-19 pandemic provides an opportunity to study the effects of system-wide crises on key supply sectors, such as water, energy, and food (WEF Nexus). Highlighted the main long-term impact categories of medicalization/hygienization, (re)localization of production, and demand fluctuations. Indicated that analysis of the impacts of COVID-19 on the WEF Nexus reflects heterogeneous experiences of short-term adaptations and reassessment of the WF-Trade Nexus. Indicated that food adequacy can take advantage of green applications to reduce expected trade-offs. Regarding resource’ security issues in the WEF Nexus, concluded that the globally wide-spread of COVID-19 reinforces discussions of the adequacy of production value chains (e.g., contingency and storage, diversification, and self-sufficiency) and the value of cross-border integration (e.g., trade, globalization, aid, etc.) |
| Carmona-Moreno et al. (2021) | Book | Pointed out that the European Commission’s Joint Research Center (EC’ JRC) in partnership with the UNESCO’s Intergovernmental Hydrological Program (IHP) launched, in 2018, the Water–Energy–Food–Ecosystems Nexus’ (WEFE Nexus) project. The project, supported by the European Union Dialogue Program NEXUS and co-financed by the European Union (EU) and the German Federal Ministry for Economic Cooperation and Development, aimed to analyze security supply solutions. The project addresses the effective implementation of measures for sustainable growth by contributing to EU policy objectives and conducting analyses of the water, energy, and food security resilience of societies, without compromising ecosystem services. The project’s components are present in 14 of the 17 UN’s Sustainable Development Goals (UN’s SDGs), whereas those components are closely related to be implemented |
| European Commission (2021) | EU’s Research and Innovation Programme, Horizon 2020 (2014–2020) | Pointed out that water, energy, and food resources are essential to human well-being, poverty reduction, and sustainable development. Indicated that projections suggest that demand for fresh water, energy, and food will rise due to demographic changes, economic development, and international trade, amongst other things. Indicated that climate change imposes additional pressures on water availability and quality, and causes extreme events (floods/droughts) with severe social, economic, and environmental consequences. Suggested that mitigation and adaptation actions to climate change and variability can have powerful impacts on the surface water and groundwater systems and users. Also, changes in energy use and types of energy production (for example, fossil fuels replaced by hydroelectric or biofuels) can considerably affect water use and agricultural production. Concluded that the resulting conflicts in water distribution amongst the water, energy, and food sectors or subsystems cause additional concerns about the sustainable management of water resources, particularly transboundary water bodies, where a very large proportion of the world’s population lives. Within this framework, the EU’s Horizon 2020 Programme funded several projects to investigate the strong relationship amongst the water, energy, and food subsystems (WEF Nexus), in relation to the climate change impacts, as being essential mechanisms in achieving the goals of the European Green Deal. This deal aims to make the EU’s economy sustainable by making the WEF Nexus an effective tool in sustainable development, and by turning climate and environmental challenges into opportunities in all policy areas |
| Fontana et al. (2021) | Frontiers in Water | Presented “Five W Questions” (FWQ) as an iterative guide to the concept of WEF Nexus to encourage reflexivity and interdisciplinary dialogue, while aiming to produce actionable knowledge. The FWQ are: (i) ‘why’, in which the purpose of correlative research for actionable knowledge can be explored; (ii) ‘what’, in which the physical aspect of the interdependence and interactions amongst water, energy, and food subsystems (WEF Nexus) can be understood; (iii) ‘where’, in which issues of scale, interactions between scales, and the geographic context of the WEF Nexus or interdependence can be discussed; (iv) ‘when’, in which the temporal dimensions of interconnected research with a particular focus on intergenerational trade-offs can be considered; and (v) ‘who’ which focuses on relevant stakeholders and the importance of understanding justice and equity issues |
| Heal et al. (2021) | Hydrological Science Journal | Pointed out that the role of water quality and, in particular, its impact on health, the environment, and the broader well-being of the water–energy–food (WEF) Nexus, is rarely acknowledged. Demonstrated the necessity of including water quality in the water dimension of the WEF Nexus, to address the complex and multidisciplinary challenges facing humanity. Explained the impact of water quality on the energy and food dimensions of the WEF Nexus and vice versa at multiple scales, from households to cities, regions, and transboundary basins. Used examples to show how including water quality would increase and improve the WEF analyses and applications. Encouraged hydrologists and other scientists to promote relevant water quality research to address the associated challenges of the WEF Nexus. To make tangible progress, suggested that analyses of water quality interactions initially focus on interconnected WEF “hotspots,” such as cities, semi-arid regions, and regions dependent on groundwater or meltwater threatened by climate change |
| Kondash et al. 2021 | Environmental Science & Policy | Explored the state of WEF Nexus research in Guatemala to highlight progress, while also noting future research needs. Found that only a limited number of studies have inducted the correlation amongst WEF subsystems; 26% of articles (36 out of 138) focused on two aspects of the WEF, while 20% (27 out of 138) focused on all three aspects (WEF). Found that water issues were the most common to study, with drinking water, hydropower, and wastewater management frequently discussed. Pointed out that WEF Nexus in Guatemala revolves primarily around three separate but related areas: clean water and sanitation, climate change and renewable energy, and urbanization and modernization. Concluded that the interrelated roles of the WEF Nexus can improve the resilience of natural resources and reduce the multi-dimensional poverty in the country |
| Purwanto et al. (2021) | Sustainability | Presented knowledge gaps and criticisms, regarding the relationship amongst water, energy, and food (WEF Nexus) that have emerged since the WEF Nexus’ concept was proposed by the World Economic Forum at the 2011 Bonn Conference. Analyzed current innovations around the WEF Nexus’ concept and its applications and implications during 2012–2020. Proposed improvements to the interconnected frameworks that have been identified to narrow the gaps and put the WEF Nexus’ concept into practices of management and governance. Proposed four principles and the ‘local-to- global’ perspective for development of a future WEF Nexus’ framework to ensure sustainable water, energy, and food resources’ security, which can improve the impacts of national and global ambitions regarding the WEF Nexus’ security |
| Tayal and Singh (2021) | Book Chapter | Indicated that the recent outbreak of COVID-19 has created a widespread impact on the economy, and disrupted the normal livelihoods of people around the world. Also indicated that COVID-19 has provided an opportunity for the integrated management of already stressed natural resources, such as water, energy, and food. Reviewed various aspects of the WEF city-wide interdependence with reference to two major cities in India (Navi Mumbai (Maharashtra) and Gurugram Haryana), under both pre-COVID-19 and in current scenarios. Examined the possibility of implementing mitigation measures integrated to ensure optimal WEF consumption levels and sustainable environmental benefits. Recommended that it is necessary to resume economic activities, but an integrated approach around the management of WEF resources has the potential to ensure sustainability from the environmental benefits achieved during COVID-19 |
| Wang et al. (2021) | Renewable and Sustainable Energy Reviews | Explored the extended links amongst the water, energy, and food resources, such as GHG emissions, waste, pollution, land, etc. from a relationship and practical perspectives in mitigating challenges towards the environment-related UN’s SDGs. Recommended that the term “Nexus” is generally more attractive to replace specific expressions, such as multi-criteria optimization, trade-offs, correlation, relationship, input–output evaluation, material flow analysis, and integrated design. Indicated that methodologies, such as input–output analysis and life-cycle assessment, necessitate the need to adequately integrate the WEF Nexus’ diversity. Recommended that necessary assessment of resource flows in multiple regions and sectors, as well as the associated environmental and socioeconomic impacts, should be taken into account within the WEF Nexus |
| Yuan et al. (2021) | Science of The Total Environment | Used a qualitative approach to form priority strategies in four selected cities—namely Amsterdam and Eindhoven (The Netherlands), and Taipei and Tainan (Taiwan), in order to study the WEF Nexus. Developed a system of indicators to guide implementation and improve urban sustainability, to illustrate the policy mechanisms and heterogeneity of sustainability issues related to the WEF Nexus at the city level. Concluded that renewable energy plays a fundamental role in the WEF Nexus’ framework, while future Nexus’ work should focus on technological innovation. Suggested that the unique combination of factors affecting water, energy, and food Nexus’ sustainability provides a comprehensive view of the broad and complex challenges that cities face due to resource constraints, which can help guide future practices of governance |
| Yue et al. (2021) | Journal of Hydrology | Proposed an imprecise optimization’s approach from the perspective of a new Nexus that links water–food–energy–climate change–land (WORLD), which has the potential to promote socioeconomic development, ensure livelihood security, and achieve a low-carbon target. Pointed out that WORLD subsystems are closely intertwined, and play notable roles in the regional and global resource management’s systems. Recommended that there is a need to quantify the connections, synergies, and trade-offs across the WORLD subsystems in a more integrated and holistic manner, which is a challenging approach due to the complexities and uncertainties involved amongst the WORLD components |
| D’Amore et al. (2022) | Sustainability | Analyzed the role of Artificial Intelligence Technique in the WEF Nexus under the perspective of enterprise and stakeholder’s theories and innovation. Particularly focused on AIT as a technology that companies adopt to promote sustainable development, with respect to the UN’s SDGs. Developed an in-depth review of the literature that discusses the investigated main issues. Highlighted the importance of AIT in relation to the WEF Nexus’ industries and the UN’s SDGs, and concluded that the WEF Nexus and AIT are still needed to be deeply researched and investigated. Also concluded that it is highly important that AIT and other digital technologies should play a remarkable role in addressing the interconnected challenges of the WEF Nexus |
| Feng et al. (2022) | Frontiers in Environmental Science, Frontiers in Ecology and Evolution, and Frontiers in Earth Science | Indicated that the booming development of advanced Artificial Intelligence Technique’ methods could provide new possibilities for dealing with many practical engineering problems. Indicated that using well-designed mathematical models and a block of desired datasets, AIT methods can offer the advantages of high response speed, strong generalization’s ability, and high data processing’s ability. Pointed out that AIT is beneficial in promoting applied sciences involved in the linkages amongst water, energy, and food (WEF Nexus), as well as the environment, and, thus, contributing to the implementation of sound policies and sustainable solutions under a rapidly changing global environment |
| Yuan and Lo (2022) | Renewable and Sustainable Energy Reviews | Developed three special themes, which are assessment, awareness, and accessibility, regarding the WEF Nexus. Described interconnected governance that promotes integrated evaluation into cross-sectional and sectoral coherence of the WEF Nexus. The framework of the WEF Nexus governance is based on a cohesive set of nine principles, including: connectivity, innovation, equitability, participation, coordination, sharing, legitimacy, empowerment, and strategy. Taking Taiwan as an example, the results showed that effective Nexus’ management requires a range of combined integration options |