event 04 May 2020

Publication // Systems thinking on the resource nexus: Modeling and visualisation tools to identify critical interlinkages for resilient and sustainable societies and institutions

By Laspidou, C. S., Mellios, N. K., Spyropoulou, A. E., Kofinas, D. T., & Papadopoulou, M. P. (2020). This paper shows up the development of a system-dynamics model of the water-energy-food-climate nexus in Greece. The model aims to reveal strong resource interlinkages and Nexus hotspots by implementation of illustrative chord plots. The work described in this paper has been conducted within the project SIM4NEXUS (https://www.sim4nexus.eu/).

Sim4nexus greek

The United Nations, the European Commission and the FAO (Flammini et al., 2014) have all acknowledged the importance of dealing with the nexus between resources in an integrated manner. Hoff (2011) described the process illustrating that the “nexus” concept provides a new way of thinking that is not limited to just the Water, Energy and Food sectors while the World Economic Forum launched a report entitled “Water Security: The Water - Energy - Food - Climate Nexus”, marking the emergence of the nexus as we know it today.

A recent literature review by Galaitsi et al. (2018) revealed that the WEF nexus is closely interlinked with governance, economic forces and socio-physical factors. Thus, economic considerations might be those that create and enhance some of the interlinkages within the nexus and include economic incentives for managing resources and promoting innovations, variable pricing schemes to curb demand, fossil fuel taxation, mechanisms for ecosystem service payments, etc. Sustainable development and efficient resource use necessitate the decoupling of economic growth and resource depletion, thus bringing the economy at the heart of resource nexus management schemes. The global community can promote a multisector integrated approach to complex trade-offs and challenges in order to strengthen resource security by developing governance processes that engage stakeholders from the nexus arena and empower them in analyses and management decisions, using appropriate tools. Such tools need to tackle the complexity of the system, introducing enough detail to capture the important trends, but also providing the data needed to enable informed decisions and quantified nexus analysis.

In this article, a comprehensive SDM is presented that establishes and quantifies interlinkages among resources and Nexus components by mapping data and incorporating outputs from well-established models, thus producing a modeling platform that can incorporate various data sets and modeling outputs in order to run scenarios and produce forecasted trends for future decades. The modeling platform can be used as a testing bed for newly introduced policies, subsidies and incentives and can capture cross-sectoral implications of policies that are not obvious at first. The multitude of modeling results and complex interlinkages make the need for an innovative visualisation tool quite urgent. Nexus Directional Chord plots are presented in this article to address this need and their use in depicting complex interlinkages in a compact form is showcased. This results in raising awareness on the nexus among stakeholders and actors in governance systems. Modeling results and visualization tools are presented for the case of Greece, which is developed both at a national scale, but also at a River Basin District (RBD) scale. Finally, the resource nexus is presented for 2030 and 2050 for Greece, using the baseline EU Reference Scenario.

Key messages

An analysis of the directional Nexus chord plot for the national case of Greece shows that:

  • A large part of Water goes towards Food Production, which includes irrigation and livestock water, while a small part goes towards (or is consumed by) the BE (household, commercial use, tourism, industry, etc.). An even smaller part goes towards the Energy sector—this is the cooling water used to operate thermal power plants.
  • Incoming arrows in the Water sector are small: Energy (this is pumping and desalination energy) and Climate (GHG emissions associated with wastewater treatment).
  • Almost all Energy is consumed by the BE, while agriculture (Food) consumes only a small part of the overall national energy
  • A thick arrow from Climate to Energy signifies the massive GHG emissions associated with energy production (power generation); this is expected for Greece that relies heavily on coal and other fossil fuels for power. A part of Natural Land (forest and biomass) is used for energy production and a small part of Food (waste) is used as well, shown by the green arrow from Food to Energy.
  • The arrow leaving the Food sector goes almost exclusively to BE, since it is assumed to be consumed or exported and has a few incoming arrows signifying the fact that food production requires Water, Energy, Natural Land and has relatively significant GHG emissions associated with livestock and managed agricultural soils. A tiny arrow from Food goes back to Food—this is reuse by the Food industry.

As resource scarcity increases and societies and institutions are getting stressed, especially under the pressure of climate change, abandoning silo-thinking and institutional fragmentation becomes even more urgent. Nexus-coherent policies are at the core of achieving the SDGs and securing resources; even though this fact is widely recognised, governments still have a lot of progress to make in that direction, with lack of suitable information, that is easy to comprehend and appreciate probably playing an important role. In this direction, a methodology for analysing and assessing the Nexus for a national case study is presented. The Nexus modeling platform, the Nexus SDM, showcases how data-intensive the process of making the Nexus operational for policymakers and stakeholders is and how it can help identify Nexus hotspots, i.e. areas where the security of one sector (e.g. energy) relies on the availability of another (e.g. water). The complexity of a highly-interlinked Nexus system, the plethora of data to be considered and the importance of scale make it challenging to communicate modeling outcomes to stakeholders. To this end, the development of advanced visualisation diagrams, the Directional Nexus Chord plots that can present the complex Nexus data coming from robust modeling analysis to stakeholders in a comprehendible way is an important innovation. The Nexus plots are presented for the national case of Greece for 2010 and forecasted plots for 2030 and 2050 are shown, implementing the baseline, European Commission Reference Scenario. In order to support sustainable development at a national level, it is imperative to recognise the need to implement greener solutions in power generation that include reduction of coal use and enhancement of renewables. At the same time, the BE can improve with more sustainable resource use, while the excessive amount of water required for food production results in a threatened food security under the pressure of climate change and water scarcity. Policies that recognize the trade-offs between saving energy and water, reducing GHG emissions and intensifying food production would be the ones with the most sustainable outcomes.


February 2020


© The authors.


Laspidou, C. S., Mellios, N. K., Spyropoulou, A. E., Kofinas, D. T., & Papadopoulou, M. P. (2020). Systems thinking on the resource nexus: Modeling and visualisation tools to identify critical interlinkages for resilient and sustainable societies and institutions.

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