Sustainable use and management of nutrients is an important issue for food, energy and water systems. The close connections between the three systems, reflected by the “nexus” concept, warrant an integrated approach to nutrients management across the nexus. In this paper, dynamic modelling of nutrient flows in a local food-energy-water system is presented and applied to a simplified case study. The model was used to simulate several scenarios affecting nitrogen flows and stocks to assess the impact of a) the level of local wheat production, b) the selection of energy generation technology, and c) the management of available nutrient resources (digestate and straws). The simulation results showed that varying the proportion of locally produced wheat significantly affects the surface runoff and the nitrogen content in a local water body, with the latter increasing by nearly 70% in 50 years if about half of the wheat consumed is produced locally as opposed to being 100% imported. The introduction of anaerobic digestion as an energy generation option helps to supply more electricity, reduce the imported fertiliser, and also significantly reduce the landfilled nitrogen nutrient by up to 60 times, due to the reuse of the anaerobic digestate. On the other hand, a balanced consideration should be given between using the straw as fertiliser and as feedstock for energy generation. This work offers a first analysis of the food-energy-water nexus with a focus on nutrient flows and stocks. The modelling approach has the potential to inform holistic decision making with respect to nutrient usage, efficiency and the related environmental impact in the design of a local system for meeting the demand for food, energy and water.

Increasing pressure from population growth and climate change has placed various challenges to urban systems concerning the sustainable supply and use of food, energy and water. To achieve the synergistic and sustainable management of food, energy and water demand, the inter-linkages between the three subsystems should be explored. Taking Beijing as the case study reproducible in a like manner for other urban systems, this research aims to develop a household Food-Energy-Water (FEW) nexus dynamic model to explore the influence of various factors on the end-uses. Three main innovation points are included in this research. Firstly, long-term simulations from 2010 to 2050 can be provided in this model to quantitatively estimate climate change potential under possible management strategies. Secondly, three different levels of influencing factors of household resource consumption are included in this model at the same time, including individual level (behaviors), household level (appliances) and government level (resource prices). Thirdly, multiple scenarios combinations are analyzed in this research. The results demonstrate the complex interconnections among the household food-energy-water uses. What’ more, short-term effects, lag effects as well as lock-in effects can influence the policy effectiveness, so that policy combinations or complements are needed to enhance the effects.

The water-energy-food (WEF) nexus concept highlights the importance of integrative solutions that secure resource supplies and meet demands sustainably. There is a need for translating the nexus concept into clear frameworks and tools that can be applied to decision making. A simulation and analytics framework, and a concomitant Nexus Simulation System (NexSym) is presented here. NexSym advances the state-of-the-art in nexus tools by explicit dynamic modelling of local techno-ecological interactions relevant to WEF operations. The modular tool integrates models for ecosystems, WEF production and consumption components and allows the user to build, simulate and analyse a “flowsheet” of a local system. This enables elucidation of critical interactions and gaining knowledge and understanding that supports innovative solutions by balancing resource supply and demand and increasing synergies between components, while maintaining ecosystems. NexSym allowed assessment of the synergistic design of a local nexus system in a UK eco-town. The design improved local nutrient balance and meets 100% of electricity demand, while achieving higher carbon capture and biomass provisioning, higher water reuse and food production, however with a remarkable impact on land use.

This book, which contains 13 separately authored chapters, has been developed from the ADAPT Project, focusing on the development of regional adaptation strategies to climate change and climate variability for water, food and the environment in river basins across the world. Chapter 1 describes a generic methodology for river basins (called the Adaptation Methodology for River Basins, AMR). Chapter 2 discusses the use of climate change scenarios as provided by the Intergovernmental Panel on Climate Change and, more specifically, how these scenarios can be used for regional studies. Chapters 3 and 4 describe in more detail the possible consequences of climate change and climate variability for food security and environmental quality. The application of the generic AMR methodology to 7 basin case studies in contrasting geographical areas of the world is presented in Chapters 5-11: Syr Darya (Kyrgyzstan, Uzbekistan, Tajikistan and Kazakhstan), Zayandeh (Iran), Rhine (Germany, Netherlands and France), Mekong (Yunnan (China), Myanmar, Laos, Thailand, Cambodia and Vietnam), Volta (Ghana), Walawe (Sri Lanka), and Sacramento (California, USA), respectively. Chapter 12 integrates the findings of the basin studies and compares these findings with global trends in climate change related to food security. Finally, Chapter 13 gives a summary of the experiences encountered during the ADAPT project, and provides key findings that should be addressed in new regional adaptation studies. This book will be of interest to researchers in climatology, geography, ecology, agriculture, environmental studies and related disciplines. | Gift

Understanding the complexity and feedbacks among food, energy, and water (FEW) systems is key to making informed decisions about sustainable development. This paper presents qualitative representation and quantitative system dynamics simulation of the water resources system in the Qazvin Plain, Iran, taking into account the energy intensity of water supply and interconnected water use sectors (e.g., urban, industrial, and agricultural). Qazvin Plain faces water resources challenges that are common to arid/semi-arid areas, including frequent droughts, declining surface water and groundwater, and increased urban and agricultural water demand. A system dynamics model is developed using historical data (2006–2016) to investigate the effects of anticipated dynamics of integrated water and energy sectors in the next two decades. The results of policy scenarios (2020–2039) demonstrate that the continuation of the existing management policies will cause severe damage to the water and energy sectors, pushing the system towards water resources limits to growth. An annual groundwater table decline of nearly 1 m is anticipated, indicating significant overshoot of the plain's natural recharge capacity, which may lead to the depletion of recoverable groundwater in the plain within the next three decades. The groundwater table decline will cause energy consumption of water supply to increase by about 32% (i.e., 380 GWh) to maintain irrigated agriculture. It is critical to implement a combination of water demand and supply management policies (e.g., net agricultural water savings and recycling treated wastewater) to delay the problem of water limits to growth in the region.

Water resources and food are the most important and basic resources for human beings and society. In recent decades, due to the growth of global population and economy, water resources and food shortages have become a global resource problem. Under this background, the significance of exploring the relationship between water-food in ecosystem services becomes more and more prominent. In view of this, this study used the SWAT model and the spatialized food production model to quantitatively evaluate the supply, demand, and supply-demand ratio of water and food production in the Jinghe River Basin in 2020, and built a system dynamics model of the watershed ecosystem services to simulate the coupling of water and food. According to the socio-economic conditions, nine different population economic development scenarios were set up to simulate the development of the water-food relationship between the ecosystem services of the river basin in 2030. The results showed that ① the spatial differences in water supply-demand ratio and food self-sufficiency rate in Jinghe River Basin in 2020 were obvious, and the supply-demand ratio in the upper reaches of the basin was significantly higher than that in the lower reaches. ② Through model simulations of three water supply-demand ratios and three food self-sufficiency rates, it was found that the water supply-demand ratios and food self-sufficiency rates showed obvious synergistic relationships both in time and in spatial distribution. ③ Under nine economic and demographic development scenarios, the optimal simulation effect was achieved under scenario E1P3 for both water-food supply and demand in the Jinghe River Basin in 2030. That was, when the economy and population develop in opposite directions, the supply-demand ratio of the two achieved the best simulation effect. The results provided a scientific basis for the sustainable development of water-food relationship in Jinghe River Basin in the future.

A nexus approach can support the transition to sustainability by addressing trade-offs and pursuing synergies to improve water, energy, and food security. In this paper, a participatory system dynamics model was developed to identify and assess the key interlinkages between water, food, and energy in Andalusia (Spain). A panel of relevant stakeholders contributed to all stages of the model’s development. Further, by calibrating the model to CAPRI-Water projections until 2050, the evolution of the system under a plausible climate scenario, as well as effects of water prices changes, was evaluated. The results revealed a close link between water cost, irrigation water use, energy consumption, and the economic development of agriculture in the region. Large variability was observed in the effects of water pricing policies across crops. This paper concludes that a participatory system dynamics model can help in understanding the nexus synergies and can support the design of more coherent sustainability strategies in the region.

Urban areas often face versatile stressors (e.g., food security, congestion, energy shortage, water pollution, water scarcity, waste management, and storm and flooding), requiring better resilient and sustainable infrastructure systems. A system dynamics model (SDM), explored for the urban region of Orlando, Florida, acts as a multi-agent model for portraying material and energy flows across the food, energy, water, and waste (FEWW) sectors to account for urban sustainability transitions. The interlinkages between the FEWW sectors in the SDM are formulated with multiple layers of dependencies and interconnections of the available resources and their external climatic, environmental, and socioeconomic drivers through four case studies (scenarios). The vital components in the integrated FEWW infrastructure system include urban agriculture associated with the East End Market Urban Farm; energy from the fuel-diverse Curtis H. Stanton Energy Center; reclaimed wastewater treated by the Eastern Water Reclamation Facility, the Water Conserv II Water Reclamation Facility, and stormwater reuse; and solid waste management and biogas generation from the Orange County Landfill. The four scenarios evaluated climate change impacts, policy instruments, and land use teleconnection for waste management in the FEWW nexus, demonstrating regional synergies among these components. The use of multicriteria decision-making coupled with cost-benefit-risk tradeoff analysis supported the selection of case 4 as the most appropriate option as it provided greater renewable energy production and stormwater reuse. The SDM graphic user interface aids in the visualization of the dynamics of the FEWW nexus framework, demonstrating the specific role of renewable energy harvesting for sustainably transitioning Orlando into a circular economy.

This study examines a green building retrofit plan through a system dynamics model (SDM) creating symbiosis embedded in a building-scale food-energy-water (FEW) nexus. An indicator approach was employed to exploit cross-domain seams via the use of carbon, water, and ecological footprints for sustainability, as well as food security and energy supply reliability ratio for resilience. The SDM was formulated to demonstrate a continuous stormwater treatment outflow model for rooftop farming with stormwater reuse for irrigation, nutrient cycling via the use of green sorption media, and green energy harvesting in support of rooftop farming. We prove that green energy use, stormwater reuse, and rooftop farming can lower carbon, water, and ecological footprints, avoid CO₂ emissions via carbon sequestration in rooftop farming, and improve energy supply reliability and food security. Case 1 (Base Case) includes no retrofit (current condition), Case 2 includes rooftop farming and stormwater reuse, and Case 3 incorporates additional green energy harvesting for sustaining rooftop farming. All three scenarios were assessed using a life cycle assessment (LCA) to generate water and carbon footprints. Case 3 exhibited a 2.24% reduction of total building energy demand from the utility grid due to renewable energy harvesting, while the preservation of nitrogen and phosphorus via the use of green sorption media for crop growth promoted nutrient cycling by maintaining 82% of nitrogen and 42% of phosphorus on site. The ecological footprints for the three case studies were 0.134 ha, 0.542 ha, 6.50 ha, respectively. Case 3 was selected as the best green building retrofit option through a multicriteria decision analysis.

To ensure food, energy, and water (FEW) security in urban areas with high-density populations and concentrated social economic activities, it is imperative to build a better understanding of the dynamics of urban FEW systems. Using the STELLA platform, a system dynamics model named the BJ-FEW was developed by incorporating both the production and consumption sides of FEW systems into a single system-of-system model that considered the interactions between the FEW sectors within and beyond the urban economic system. This model was run for the megacity of Beijing over the period from 2000 to 2050 to simulate changes in the FEW demand and supply. Results showed that Beijing City will face an increasing challenge of FEW resource security with regard to the enlarging gap between the total demands and the local provision capability. Under the baseline scenario without policy intervention, the total demand for food, energy, and water in Beijing will incredibly reach 10 Mt, 129 Mtce, and 6.4 Bm³ in 2050. In such case, it was estimated that 75% of food, 88% of energy, and 48% of water will depend on trans-boundary imports. The implement of Xiong'an New Area Plan will be the indispensable development pathway to alleviate resource pressure in Beijing. The scenario analysis verified the positive effect of such program, which will improve the status of the resource system by reducing 15%, 29%, and 34% of the supply-demand gap for food, energy, and water. The results highlighted the necessity of a regional coordinated management strategy to build a more resilient FEW provision system.