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1. Impacts of irrigated agriculture on food–energy–water–CO2 nexus across metacoupled systems

   https://doi.org/10.1038/s41467-020-19520-3  

   Xu, Zhenci; Chen, Xiuzhi; Liu, Jianguo; Zhang, Yu; Chau, Sophia; Bhattarai, Nishan; Wang, Ye; Li, Yingjie; Connor, Thomas; Li, Yunkai (December 2020, Nature Communications)

   null (Ed.)

   Abstract Irrigated agriculture has important implications for achieving the United Nations Sustainable Development Goals. However, there is a lack of systematic and quantitative analyses of its impacts on food–energy–water–CO 2 nexus. Here we studied impacts of irrigated agriculture on food–energy–water–CO 2 nexus across food sending systems (the North China Plain (NCP)), food receiving systems (the rest of China) and spillover systems (Hubei Province, affected by interactions between sending and receiving systems), using life cycle assessment, model scenarios, and the framework of metacoupling (socioeconomic-environmental interactions within and across borders). Results indicated that food supply from the NCP promoted food sustainability in the rest of China, but the NCP consumed over four times more water than its total annual renewable water, with large variations in food–energy–water–CO 2 nexus across counties. Although Hubei Province was seldom directly involved in the food trade, it experienced substantial losses in water and land due to the construction of the South-to-North Water Transfer Project which aims to alleviate water shortages in the NCP. This study suggests the need to understand impacts of agriculture on food–energy–water–CO 2 nexus in other parts of the world to achieve global sustainability. 

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2. Food flows between counties in the United States from 2007 to 2017

   https://doi.org/10.1088/1748-9326/ac5270  

   Karakoc, Deniz Berfin; Wang, Junren; Konar, Megan (February 2022, Environmental Research Letters)

   Abstract Food supply chains are essential for distributing goods from production to consumption points. These complex supply chains are important for food security and availability. Recent research has developed novel methods to estimate food flows with high spatial resolution, but we do not currently understand how fine-grained food supply chains vary in time. In this study, we use an improved version of the Food Flow Model to estimate food flows (kg) between all county pairs across all food commodity groups for the years 2007, 2012, and 2017 (which requires estimating 206.3 million links). We then determine the core counties to the US food flow networks through time with a multi-criteria decision analysis technique. Our estimates of county-to-county food flows in time are freely available with this paper and could be useful for future research, policy, and decision-making. 

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3. Estimating geographic spillover effects of COVID-19 policies from large-scale mobility networks

   Chang, Serina; Vrabac, Damir; Leskovec, Jure; Ugander, Johan (January 2023, AAAI)

   Many policies in the US are determined locally, e.g., at the county-level. Local policy regimes provide flexibility between regions, but may become less effective in the presence of geographic spillovers, where populations circumvent local restrictions by traveling to less restricted regions nearby. Due to the endogenous nature of policymaking, there have been few opportunities to reliably estimate causal spillover effects or evaluate their impact on local policies. In this work, we identify a novel setting and develop a suitable methodology that allow us to make unconfounded estimates of spillover effects of local policies. Focusing on California’s Blueprint for a Safer Economy, we leverage how county-level mobility restrictions were deterministically set by public COVID-19 severity statistics, enabling a regression discontinuity design framework to estimate spillovers between counties. We estimate these effects using a mobility network with billions of timestamped edges and find significant spillover movement, with larger effects in retail, eating places, and gyms. Contrasting local and global policy regimes, our spillover estimates suggest that county-level restrictions are only 54% as effective as statewide restrictions at reducing mobility. However, an intermediate strategy of macro-county restrictions—where we optimize county partitions by solving a minimum k-cut problem on a graph weighted by our spillover estimates— can recover over 90% of statewide mobility reductions, while maintaining substantial flexibility between counties. 

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4. Network centrality in perishable food distribution networks in the United States

   https://doi.org/10.1088/2976-601X/add01c  

   Miller, Michelle; Konar, Megan; Hanawa_Peterson, Hikaru; Court, Christa; Shakya, Sumadhur; Stevens, Andrew (May 2025, Environmental Research: Food Systems)

   Abstract This analysis quantifies the network dynamics, geographic concentration, and disparities in perishable food supply networks for temperature-controlled food shipments in the United States. The United States forms the core of global food systems and produces more high-quality data for network analysis than most other countries. We use the 2017 US Census Commodity Flow Survey and other publicly available data to derive empirical results from the Food Flow Model for perishable meats and perishable prepared foods. We identify the top ten counties for perishable food distribution and find that the Los Angeles and Chicago regions support the greatest volumes of perishable food movements. States that largely exist outside national perishable food networks are Arizona, Michigan, Montana, North Dakota, Texas, and West Virginia. Our analysis of US data highlights the importance of certain counties, states, and regions in perishable food networks and illustrates how data and logistics optimization models shape the geography of food. Findings suggest areas where interventions could improve systems’ functions by reducing reliance on core areas, increasing access to markets for farmers, and improving access to food for under-served communities, especially those in rural regions. 

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5. Growing pains in local food systems: a longitudinal social network analysis on local food marketing in Baltimore County, Maryland and Chester County, Pennsylvania

   https://doi.org/10.1007/s10460-021-10199-w  

   Brinkley, Catherine; Manser, Gwyneth M.; Pesci, Sasha (January 2021, Agriculture and Human Values)

   null (Ed.)

   Abstract Local food systems are growing, and little is known about how the constellation of farms and markets change over time. We trace the evolution of two local food systems (Baltimore County, Maryland and Chester County, Pennsylvania) over six years, including a dataset of over 2690 market connections (edges) between 1520 locations (nodes). Longitudinal social network analysis reveals how the architecture, actor network centrality, magnitude, and spatiality of these supply chains shifted during the 2012–2018 time period. Our findings demonstrate that, despite growth in the number of farmers’ markets, grocery stores, farms and restaurants in both counties, each local food system also experienced high turnover rates. Over 80% of the market connections changed during the study period. Farms, farmers’ markets, and grocery stores showed a 40–50% ‘survival’ rate, indicating their role in sustaining local food systems over longer time periods. Other actors, such as restaurants, had a much higher turnover rate within the network. Both food systems became more close-knit and consolidated as the center of gravity for both local food systems pulled away from urban areas toward rural farmland. Evidence of both growth and decay within local food systems provides a new understanding of the social networks behind local food markets. 

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