The importance of the nexus
Emergence and rise of the “nexus” concept
Governments are often organized along sectoral lines, resulting in siloed management of environmental resources. This being the case, policy fragmentation remains a key challenge to overcome. While a given administration might lack established procedures and structures for working across sectors, disparate elements of the “real world” are strongly interwoven. From a water-focused perspective, several factors have impacts on water resources that lie outside the strict domain of water management. One can approach water issues from any number of perspectives, including energy, food, climate and waste. One guiding principle, however, remains constant: any one sector is influenced by several outside factors.
The interlinkages between water, energy and food have gained significant attention in recent years. Figure 1 shows some examples of how the three sectors are interlinked. The attention brought by the concept of the water-energy-food nexus can help reduce trade-offs and boost synergies between sectors, resulting in greater policy coherence and better resource-use efficiency. Holger Hoff lucidly describes the process in a background paper for the 2011 Bonn Nexus Conference(1).
The “nexus” concept provides a new way of thinking that is not limited to just the water, energy and food sectors. Other approaches have been described in recent years as well, such as the water-soil-waste nexus or the water-food-energy- ecosystems nexus, both developed in the frameworks of United Nations entities.
As of 2012, the “Water-food-energy-ecosystems nexus in transboundary basins” is a defined area of work under the Water Convention with a strong focus on transboundary aspects. Waters that flow across national borders are often the connecting resource for food and energy, while international food trade and regional markets for electricity and energy carriers traverse state borders.
While research and discussion on the nexus have gathered great momentum in the past decade, the concept originated several years earlier when the United Nations University (UNU) launched its Food-Energy Nexus Programme in the early 1980s. In 2002, the World Summit on Sustainable Development in Johannesburg implicitly recognized the nexus by listing water and sanitation, agricultural productivity and energy among its priority areas. Shortly afterwards, the concept of “virtual water” and the assertion that increasing scarcity of water, food and energy would result in “the perfect storm” by 2030 catalysed further thought and discussion on the nexus. The 2008 launch of the World Economic Forum's report "Water Security: The Water-Energy-Food-Climate Nexus" and Hoff's background document for the Bonn Nexus Conference marked the emergence of the nexus as we know it today. Following these early landmark publications, scientists have continued to advance the understanding about the interaction of different resource systems, while also dealing with scale and other related issues.
A large body of academic research on the nexus concept with variable scoping of the nexus is available: some are more conceptual, while others focus on quantitative analysis, but a thorough overview is beyond the scope of this brief introduction. Liu and others (2017)(2) and Brouwer and co-authors (2018)(3) provide recent reviews and references on nexus research from the technical perspectives of water and energy, respectively, while Weitz and others (2017)(4) discuss governance across sectors.
From a more critical angle, Galaitsi and co-authors (2018) have called for evidence to support claims that nexus approaches have a positive impact on resources management, finding there to be little to show so far.(5)
Figure 2A presents key milestones in the development of the nexus concept, while figure 2B offers a general timeline of nexus activities under the Water Convention(6)
(1)Holger Hoff. Understanding the Nexus – Background Paper for the Bonn 2011 Conference:
The Water, Energy and Food Security Nexus (Stockholm, Stockholm Environment Institute,
(2)Junguo Liu and others. Challenges in operationalizing the water-energy-food nexus.
Hydrological Sciences Journal, vol. 62, No. 11, 2017.
(3)Floor Brouwer and others. Energy modelling and the Nexus concept. Energy Strategy
Reviews, vol. 19, No. 1-6, 2018.
(4)Nina Weitz, Claudia Strambo, Eric Kemp-Benedict and Måns Nilsson. Closing the
governance gaps in the water-energy-food nexus: Insights from integrative governance
. Global Environmental Change, vol. 45, July 2017, pp. 165−173.
(5)Stephanie Galaitsi, Jason Veysey and Annette Huber-Lee. Where is the added value? A
review of the water-energy-food nexus literature. SEI working paper (Somerville, Stockholm
Environment Institute, 2018).
(6)ECE. Reconciling resource uses in transboundary basins: assessment of the water-food-
energy-ecosystems nexus (United Nations, New York and Geneva, 2015), pp. 2-4.
(7) Mario Roidt and Lucia de Strasser 2018 “Methodology for assessing the water-food-
energy-ecosystem nexus in transboundary basins and experiences from its application: