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The Nexus: efficient approaches

The Nexus: efficient approaches


The Sim4nexus and Magic consortia outlines how detailed understanding of the Nexus – water, land, energy, food, climate – can facilitate decision making. 

Even though the concept of the integrated management of natural resources such as water, energy, food and land has been in use for years, the complex interlinkages and interdependencies amongst these individual resources have not been given due importance in the development and implementation of this concept. As a result, responding to a challenge in the management of one resource often creates challenges for the management of others. According to the perspective of UNU Flores (, the collective and integrated management of these resources using a Nexus approach should be used to increase resource-use efficiency and minimise environmental risks and ecological degradation.

The EU ambition to become a more inclusive, sustainable and competitive economy is expressed in the ‘EU 2020 vision of smart, sustainable and inclusive growth’ through a series of narratives such as ‘low-carbon economy’, ‘circular economy’ and ‘efficiency increase’. In order to achieve these goals, it is essential that an effective Nexus approach is used to reinforce the cycle from research to implementation, thus focusing on governance. The Nexus approach also necessitates a better understanding of the factors that determine the entanglement of flows in the supply and demand of water, energy, food and other materials in our economy, as well as of the role that the interlinkage over these flows plays in the stabilisation of socioeconomic and ecological processes across different scales.

Nexus complexity

Present in the sustainable development discourse for nearly three decades, the Nexus concept has only gained traction among scientific, policy and political circles over the last ten years, especially including the interactions across the Water-Energy-Food domains which face the pressure of population growth and climate change. Lately, the list of domains covered by the Nexus has been expanding to also include land use, climate, economy, ecosystems, health and others, making the Nexus even more multi-dimensional and interdisciplinary; similar to the evolution of the UN Sustainable Development Goals.

Green economy, resource efficiency and sustainability issues are at the centre of the Nexus. As resources are tightly interlinked and the use of one requires the presence of the other (e.g. the production of energy requires water and the production of food requires water and energy), resource use entails complex interactions and potential conflicts among Nexus dimensions.

Depending on the context of the term, the Nexus takes up different perspectives:

(i)        A biophysical perspective, related to trends in resource use and the system capacity to meet resource demands and deal with threats of depletion, especially under climate change;

(ii)       A governance perspective, related to the need for better co-ordination and improved capacity to manage trade-offs and synergies across policy domains, thus overcoming fragmented thinking and ‘silo’ vision;

(iii)      A knowledge perspective, related to the high complexity and uncertainty that biophysical, socioeconomic and policy interactions within the Nexus introduce, requiring trans-disciplinary, integrated, multi-perspective and multi-actor approaches, across scales and sectors.

As communities deal with resource scarcity, high urbanisation rates, population growth and extreme events associated with climate change, national and international institutions that aim for secure and resilient societies are faced with difficult decisions and trade-offs. The Nexus approach provides a framework for designing and implementing policies that are coherent in their goals among all Nexus dimensions.

EU policies performance

Any policy addressing the resources relevant for the Nexus – water, land, energy, food, climate – may have unintended positive or negative consequences across different sectors. This means decisions taken in these sectors or, for example, on economic investments, trade, development, biodiversity protection, innovation and research may have the effect of either reinforcing or counteracting impacts on other sectors. Consequently, ‘policy coherence’ is important, and refers to the systematic effort to reduce conflict, manage trade-offs and promote synergy between policies within and across the nexus.

A recent investigation (Munaretto and Witmer, 2017) on 33 European policy objectives for water, land, energy, food and climate revealed that, on paper, EU policies along the Nexus are largely coherent. For example, when considering high-level overarching objectives, such as ‘improving natural resources quality and quantity to all human and ecosystem uses’, positive effects in all Nexus sectors are evident. However, when these policy objectives are articulated in specific objectives such as ‘increase biofuel production’, ‘increase hydroelectricity generation’ and ‘improve the competitiveness of the agricultural sector’ conflicts emerge, depending on how these objectives are interpreted and achieved. Such conflicts are only partly addressed in the EU policies.

For example, the increase of biofuel production is a particularly problematic objective as it has many potentially negative interactions in the Nexus. The current EU proposal for a revised Renewable Energy Directive envisages a gradual phasing out of the use of food and feed crop for energy generation. Nevertheless, these crops will still be grown in the years to come with potentially negative impacts, especially on land and water. The Directive proposal addresses these impacts with strict rules for land use but not for water use. However, the expansion and intensification of energy crops may affect water quality and quantity, the hydrological cycle, as well as local microclimate. The large-scale cultivation of maize and rape in the Czech Republic, for example, has changed the regional hydrology, leading to local weather extremes, such as heat waves, droughts and local floods (Pokorny et al. 2010).

Overall, EU policy documents addressing the Nexus essentially acknowledge the interconnectedness of sectors within and across the Nexus proposing a range of measures with different degrees of stringency. Yet, problems may arise when the overarching objectives and measures are articulated and implemented in practice.

Making Nexus operational

The current big challenge is to understand the Nexus not only in its qualitative links, but also to map and use quantitative relationships so as to facilitate decision making. SIM4NEXUS and MAGIC explore these in different ways.

SIM4NEXUS addresses Nexus challenges by developing a ‘Serious Game’; a cloud-based, integrated resource-use and policy assessment tool that will bridge the Nexus knowledge gap effectively, by providing an immersive experience to the user. It is designed to be used primarily by authorities and policymakers at all levels (regional, national, continental and global) and will allow them to identify critical areas of the Nexus, to evaluate and quantify the effects of new policies and subsidies, of climate change and mitigation practices, of the implementation of technological and social innovations, of adopting low-carbon options, of new investments and interventions, etc. on resource levels. It is based on well-established, scientifically sound and widely used models (E3ME-FTT, CAPRI, MAGNET, IMAGE/GLOBIO, OSeMOSYS, SWIM, MAGPIE-LPJmL).

Using complexity science principles, methodologies and tools (System Dynamics Modelling-SDM), SIM4NEXUS integrates its outputs in a single high-level simulation model as a framework, in which all sectors of the Nexus are brought together, and the complex web of their interlinkages is quantified. The models will provide results for 2010 (Base Line), 2020, 2030 2040 and 2050 and will run under the new scenario framework for climate change research, meaning the combination of SSPs (shared socioeconomic pathways) and RCPs (representative concentration pathways).

The SIM4NEXUS Serious Game is showcased in a series of 12 geographically, economically, climatically, and politically diverse case studies that span all levels, from regional, national to continental and global, covering also transboundary issues. Artificial intelligence principles are used to ‘educate’ the ‘brain’ of the Serious Game, the Knowledge Elicitation Engine (KEE), which runs tirelessly in the background and feeds off the SDMs, getting smarter with time by recording every ‘player’ action or decision taken in the case studies along with their corresponding impacts. This way, the KEE implements a top-down learning approach, based on the decisions of the ‘players’ and a bottom-up approach based on classical KEE methodologies applied to the data, both of them realised in an holistic manner.

All learning (user decisions and reactions) and relevant knowledge generated for the Nexus is stored in a semantic repository, supported by a cross-domain ontology which is, in turn, linked to other existing ontologies. This simplifies information exchange among different Nexus components, fosters better understanding of Nexus interactions, and facilitates future research initiatives that can exploit the semantic technologies built within SIM4NEXUS that standardise knowledge representation, contextualisation, and interpretation.

The Serious Game also acts as a visualisation tool, providing an immersive experience to decision- and policymakers and assisting them in better understanding and visualising highly complex systems and policies at various geographical and spatial resolutions, achieving a better scientific understanding of the Nexus.

MAGIC uses Quantitative Storytelling (QST) to structure the perception (qualitative) and representation (quantitative) of the Nexus. QST recognises that within the Nexus there is irreducible scientific uncertainty and value plurality in decision making. By providing an alternative set of tools and processes, QST seeks to promote progressive thinking about Nexus/sustainability issues by:

(i)        Recognising the ‘evidence trap’ whereby an absence of scientific certainty is used as a justification for inaction, or controversial claims of scientific certainty are used as a justification for action.  Value plurality permeates Nexus issues, shaping both what is considered evidence and how that evidence is interpreted; and

(ii)       Recognising that the role of science is to adequately understand and explain the nature of conflicts, and not to resolve such conflicts.

The QST process is characterised by six iterative steps (see Figure 1) (Matthews et al. 2017):

1)        Summarising narratives of interest to policy makers and other stakeholders;

2)        Agreeing Aspects to Explore – deciding the specific aspects of systems that have to be represented – i.e. system boundaries, scales of analysis, functional and structural elements, and useful indicators;

3)        Design and build the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) application as analytical framework;

4)        Run Multi-Scale Analysis – populating the application with quantitative data and using it to test narratives about the current state (diagnostic mode) and possible alternatives (anticipation mode);

5)        Generate Benchmark Metrics – assessing the feasibility (within ecosystem limits), viability (within socioeconomic limits) and desirability (within institutional limits); and

6)        Interpret the Outputs – deliberating with stakeholders the interpretation of the outputs and the shaping of any further stages – either with new narratives or with alternative cases.

QST aspires to check the robustness, the usefulness and the fairness of the narratives used to discuss and select policies and innovations. It will be applied to five policy areas, namely energy policy, the Common Agricultural Policy, the circular economy, the Water Framework Directive and environmental policy, and to innovations and policy solutions with regard to alternative water sources, biofuels and biorefineries, green bonds, shale gas extraction, water-saving irrigation, and electric vehicles. The QST process will draw from a database of the state-of-the-play at NUTS1 and 2 level, using the MuSIASEM (Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism) approach.

Irrigation in Andalusia

Andalusia is one of the regional case studies of SIM4NEXUS, led by the Technical University of Madrid (UPM). In Andalusia, 64% of agricultural production is derived from irrigation, which generates 67% of farm income, and accounts for 63% of agricultural employment. The water-agriculture linkage is thus the most crucial Nexus component in Andalusia. Moreover, energy cost has turned into a limiting factor in irrigated agriculture because of increases in energy demand and energy prices.

All SIM4NEXUS case studies are guided through an iterative stakeholder involvement process aimed at engaging the local public institutions, private companies, associations or research communities. In Andalusia, stakeholders were identified through an online investigation and snowball sampling. Preliminary interviews with fourteen key stakeholders helped identify the stakes relevant to the region.

The coherence among sector-specific policies is being analysed in order to identify room for improvement, leading to more Nexus-compliant policies. Conflicting policies are apparently present in the water, agriculture, and energy domain. To better understand the Nexus in Andalusia, two models are used: CAPRI, to analyse food-water links (irrigation and livestock) and agriculture-energy links (biofuel markets) and E3ME to analyse the energy-food links (energy use in agriculture and biomass production) and the energy-water links. Baseline scenarios are already available, and the outcomes of both models will feed into the SDM developed for the Andalusian case study.

A first stakeholders’ workshop organised in October 2017 helped to identify the main interlinkages and challenges in the Nexus, as well as potential policy scenarios, through the use of diverse participatory methodologies. The workshop allowed for the corroboration that the key challenges consist of: (1) major pressures on water and land as a result of farming intensification and urbanisation; (2) over-allocation of water resources; (3) inadequate consideration of the linkages between water saving technologies and energy use; and (4) economic development closely linked to greater use of resources. Consequently, emphasis will be placed on integrating agricultural and environmental policies to cope with pressures on land and water, so as to promote economic development with a more sustainable use of resources.

More workshops with stakeholders are planned in the project’s lifetime to evaluate the conceptual framework, to discuss the modelling results, and to test the Serious Game. The overarching goal is to address the major Nexus challenges through improved policies and policy making processes.

Desalination in Gran Canaria

MAGIC’s approach to the water-energy-food Nexus assessment is illustrated with the application of MuSIASEM to a case study at the local level in the island of Gran Canaria, Spain, where desalination powered by wind energy is used to irrigate crops. Gran Canaria is an island with limited energy, water and food resources depending heavily on food and energy imports. Desalination offers an interesting possibility to tackle water scarcity, but it is highly energy-intensive. A system that combines wind turbines with desalination looks like a promising solution for a territory that aims at producing food locally. To assess the sustainability of this local WEF system, important questions must be addressed: how much net energy, water and food are being produced? Is this WEF system self-sufficient/autarkic? What are the possible external and internal constraints? What is the economic viability of this system? Is it possible to reproduce this model in other areas?

The MuSIASEM approach analyses the Nexus-using processors (data array organisation of inputs and outputs describing the characteristics of structural and functional elements) and relational analysis of the structural and functional elements (energy, water and food providers) with each other and with the surrounding system (e.g. food to the markets, electricity to the grid, water from the aquifers). The characterisation of inputs and outputs can also be done in monetary terms to get an assessment of the economic viability of the system.

The results of the analysis reveal that the wind turbines supply electricity both to the desalination plant and the electric grid, and the desalination plant uses electricity both from the wind farm and the grid. Because of intermittency of wind, the desalination plant cannot depend on the wind turbines alone for all of its energy requirement. Additionally, the water supplied by the desalination plant does not cover all the water demand from the farms. As a consequence, the water-energy-food system under analysis is still dependent on conventional inputs, both for electricity and for water.

Moreover, fresh local farm products are only a small part of the food required by the population, and the water produced by desalination has a price higher than other sources and therefore requires subsidies. This analysis shows that the water-energy-food Nexus system analysed cannot be considered as a silver bullet guaranteeing self-sufficiency in the Canary Islands per se, but rather one of several possible solutions contributing to a more sustainable production of food. The integrated characterisation provided by MuSIASEM allows us to identify the relevant attributes of performance that need to be considered when integrating different solutions.

Improved policy support

The inherent complexity of the Nexus demands novel approaches, to policy making and to the methodological and theoretical improvement in the science that informs policy. The Horizon 2020 programme has responded to this need and is currently funding major research projects such as SIM4NEXUS and MAGIC. In this way, the EU is accomplishing a step beyond naïve conceptions of Science ‘speaking Truth to Power’ and towards a science that integrates knowledge of the physical dimension of the Nexus with a deep understanding of the complexity of the decision-making context.

SIM4NEXUS and MAGIC test the Nexus approach in real conditions by exploring new ways of handling quantitative analysis that combine different types of disciplinary knowledge. Preliminary findings confirm that in order to guarantee the quality of the process of production and use of scientific information for governance it is essential to establish a two-way dialogue through: (i) an interactive exchange of information across different social actors (reflecting the existence of different values); (ii) inclusion of different dimensions of analysis (reflecting the different pre-analytical choices of narratives); and (iii) consideration of different perceptions (reflecting the co-existence of different scales/horizons of analysis).

MAGIC and SIM4NEXUS are ready to share their findings with policymakers, practitioners and concerned social actors, and invite those interested in following up or getting involved to contact us.


Matthews KB, Blackstock KL, Rivington M, Waylen K, Miller DG, Wardell-Johnson D, Kovacic Z, Renner A, Ripa M, and Giampietro M. (2017 in press). Delivering more than the “Sum of the Parts”: using Quantitative Storytelling to address the challenges of conducting science for policy in the EU land, water and energy nexus.  In: G Syme, D MacDonald and J Piantadosi, Managing cumulative risks through model-based processes, 22nd International Congress on Modelling and Simulation (MODSIM2017), Hobart, Australia, 3-8 December 2017

Munaretto S, Witmer M. (2017) ‘Water-land-energy-food-climate nexus: policies and policy coherence at European and international scales’. SIM4NEXUS project report. Netherlands Environmental Assessment Agency (PBL), Den Haag, The Netherlands

Pokorny J, Brom J, Cermak J, and Hesslerova P. (2010). Solar energy dissipation and temperature control by water and plants. Int. J. Water 5(4): 311-336



Floor Brouwer (WUR, Co-ordinator of SIM4NEXUS,, Mario Giampietro (UAB, Co-ordinator of MAGIC,, Gabriel Anzaldi (EUT), Maria Blanco (UPM), Sandra Bukkens (UAB), Bente Castro (UPM), Xavier Domingo (EUT), Maïté Fournier (ACTeon), Silvio Funtowicz (UiB), Zora Kovacic (UAB), Chrysi Laspidou (UTH), Pilar Martínez (UPM), Keith Matthews (HUTTON), Stefania Munaretto (PBL), Linda Romanovska (FT), Guido Schmidt (FT), Tarik Serrano (UAB), Roger Strand (UiB), Lydia Vamvakeridou-Lyroudia (UNEXE), and Maria Witmer (PBL)

This article will appear in Pan European Networks: Science & Technology issue 25, which will be published in December, 2017

Pan European Networks Ltd