Urban metabolism and water-energy-food nexus, new challenges for spatial planning

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Resource scarcity has been rising as an increasingly urgent matter in the last decades and particularly in the last years. A combination of factors such as climate change, population growth, rise of the middle class and deterioration of ecosystems contribute to increase the concern on present and future resource availability. Given the situation there is a need for new approaches to resource management in order to change the business as usual model and find sustainable and innovative solutions. To this end, the water energy- food nexus (hereafter nexus) approach received particular attention in the policy and academic arenas. The rationale behind the nexus is to acknowledge and take in account relationships, synergies and trade-offs between water, energy and food sectors with the aim of finding sustainable and common solutions for the management of these resources (Hoff, 2011). Connections between water, energy and food undoubtedly exist in any circumstances and they occur more or less explicitly. Depending on how these connections are taken into account, they can become opportunities (best-case scenario), or if not considered they can become missed opportunities or develop in unexpected conflicts and problems (worst-case scenario). The nexus approach is still an immature and not well-defined concept (Allouche, 2015), but even so, researches from different academic fields and disciplines increasingly focus on it. Authors discussing on the nexus generally put water at the center of the debate and focusing on agriculture considering water and energy as inputs for the food production. Other researches argue on conflicts that rise for the use of water for agriculture and other purposes. Furthermore, research and analysis on the nexus are typically carried out on global, national, regional or river basin scale. In this panorama, where main focus is on agriculture and large scales, cities and their role on water, energy and food management have been neglected, which is quite bizarre considering the close connection between cities development and resources and the huge amount of energy and materials needed to sustain cities metabolism. Exploring an urban perspective on the nexus is even more important considering that more than a half of the global population is living now in urban areas and this percentage is bound to increase in the coming decades (UNPD, 2011). Developing of cities have been strongly linked to local resource availability for centuries, but this relationship between potential urban settings development and amount of resources available on site has weakened due to a series of events such as industrial revolution, green revolution, technological innovation and globalization (to mention most recent examples). This set of developments have enabled the development of larger urban areas that depend less and less on the local availability of resources such as water, energy and food. In this paper, we propose a path to follow in order to understand where the nexus of water, energy and food lays is in cities and which role it can have in turning cities in more resilient and sustainable systems. In doing so, simplified supply chains of water, energy and food are considered and decomposed in sequential steps to facilitate the identification of connection points between systems. This has the objective of making clearer which are the nexus aspects that more likely fall within urban areas, which is the domain of urban policies and urban planning.
Book of proceedings: Annual AESOP Congress, Spaces of Dialog for Places of Dignity, Lisbon, 11-14th July, 2017
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