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Background: Climate change is increasingly affecting the supply of resources such as water and food. From 2015 to 2018, Cape Town endured its most severe drought on record. Yet, resource management often occurs in isolation, which contrasts with the holistic perspective provided by the nexus concept that recognizes the interdependence of resource sectors. This study employs system dynamics modeling, to examine the City of Cape Town's (CoCT) water-food trade-offs and interactions using qualitative and quantitative approaches. It assesses various policies proposed by the CoCT, to improve system resilience and to boost future water supplies, examining their efficacy and potential drawbacks. These policies are tested against future scenarios including population growth and climate change predictions of different severities. Results: The simulation results show an increase in food demand, which is mainly linked to population growth and a significant decrease in water availability. Without intervention, the CoCT is expected to experience serious water shortages within the 40-year simulation period. Conclusions: The findings indicate that the CoCT's strategies will effectively secure adequate water for its expanding population. However, a major concern was found to be the proposed intensification of aquifer exploitation. The model predicts that such an approach could lead to overabstraction of some aquifers, compromising their sustainability. [ABSTRACT FROM AUTHOR]

Abstract Background Climate change is increasingly affecting the supply of resources such as water and food. From 2015 to 2018, Cape Town endured its most severe drought on record. Yet, resource management often occurs in isolation, which contrasts with the holistic perspective provided by the nexus concept that recognizes the interdependence of resource sectors. This study employs system dynamics modeling, to examine the City of Cape Town’s (CoCT) water-food trade-offs and interactions using qualitative and quantitative approaches. It assesses various policies proposed by the CoCT, to improve system resilience and to boost future water supplies, examining their efficacy and potential drawbacks. These policies are tested against future scenarios including population growth and climate change predictions of different severities. Results The simulation results show an increase in food demand, which is mainly linked to population growth and a significant decrease in water availability. Without intervention, the CoCT is expected to experience serious water shortages within the 40-year simulation period. Conclusions The findings indicate that the CoCT’s strategies will effectively secure adequate water for its expanding population. However, a major concern was found to be the proposed intensification of aquifer exploitation. The model predicts that such an approach could lead to overabstraction of some aquifers, compromising their sustainability.

Climate change has challenged water allocation for food production in water-scarce areas. This fact calls for water reallocation (RA) strategies in basins with dominant agriculture. This study develops a framework combining the SWAT model and water footprint (WF) to evaluate water resource sustainability and improve its indices by fair RA from agriculture. The Karkheh River Basin in Iran was chosen as a study area for verification. Deficit irrigation (DI) was a farm strategy to promote basin sustainability and maintain food security. DI was distributed according to the equality of resources, proposed by Ronald Dworkin, as a just allocation principle. It means irrigated water would be allocated based on an equal water ratio per hectare. Results showed that the basin is currently unsustainable regarding the groundwater (BkWS) and surface flow (BuWS). According to the SSP5-8.5 scenario, the BuWS in the basin increases from 1.12 to 1.22 (9%), and BkWS increases from 2 to 2.15 (7.5%), while GnWS remains relatively constant at 0.99. By Dworkin's principle, DI caused 21-48% reduction in water allocation among five provinces. RA improved the BuWS, GnWS, and BkWS and ensured environmental flow. Climate change reduces 3.5% of food production, with an extra 9% by RA. These reductions would not endanger food security. HIGHLIGHTS An integrated approach for water reallocation is proposed by considering hydrological modeling, climate change impacts, water footprint assessment, just water reallocation, food production yields, and security.; Water footprint and its sustainability indices modeled by the SWAT for climate change conditions.;

In the goals of the United Nations for the sustainable development of societies in the third millennium, the approach of water and food nexus is considered one of the important interdisciplinary perspectives in the direction of the dynamic balance of production and consumption of resources. Due to the consumption of more than 90% of the country's water resources in the agricultural sector, access to accurate statistics of this field is vitally important in creating a balance between water production and consumption in the water-food nexus approach. In such a way, the presentation of incorrect statistics or statistics with many errors, especially by official authorities, by entering into different models developed by researchers, will lead to distorted results, wrong decisions and ultimately economic and environmental damages and social tensions. In this research, with the approach of using the connections of ecosystems, water-food nexus was investigated; Thus, the correlation between the presented statistics of the production sector and the water consumption sector was analyzed by using water-food nexus with the method of uncomplicated calculations. Based on the information, the inconsisitency of the statistics provided by different departments is evident. According to the statistics of crop production in 2014-2015 and 2019-2020, the undercultivated area in the agricultural sector in 2019-2020 has grown by about 1% compared to 2014-2015, and in 13 provinces the undercultivated area has increased and in other provinces the undercultivated area in the agricultural sector has decreased. Water consumption in the agricultural sector has grown by about 10%, so that in 23 provinces, water consumption in the agricultural sector has increased and in 8 provinces, water consumption in the agricultural sector has decreased. This difference is due to the change in the cultivation pattern and the crop selected by farmers in the country. Also, according to the amount of programmable water that has been announced by the Ministry of Energy, in 12 provinces, the amount of programmable water is not enough to meet the Pure water consumption for crops, and even in some provinces, the amount of programmable water is only enough to supply garden products. This important and basic finding implies and emphasizes the need to solve the problems of statistics of different authorities of the country.

This study introduces the foundational principles behind the water footprint in water and food security for evaluating the managerial strategies of agricultural water management in arid areas. The role of green, grey, blue and white water footprints in yield production has been critically investigated to analyze the climate and economic risks. Therefore, a nonlinear hydro-economic framework, which integrates soil water content, food production and economics has been used for the semi-arid regions of China. Non-dimensional form of net benefit per drop was formulated to analyze the uncertainty of economic parameters. Root zone moisture was simulated to estimate crop yield, transpiration, evaporation, water required for irrigation and increase water quality. Five plants of potato, onion, tomato, eggplant and carrot were selected due to similarity in the plant growth season and market criteria. The results showed that the average effective rainfall contributed less than 15% to food production. The impact of the risk of economic fluctuations in achieving the expected net profit has been more than water. HIGHLIGHTS The impact of the water footprint on food security was considered to improve agricultural water management in arid areas.; A hydro-economic framework, which integrates soil water content, food production and economics has been used.; Non-dimensional form of net benefit per drop was formulated to analyze the uncertainty of economic parameters.;

Located in a semi-arid and arid zone, Iran is suffering from growing challenges of water scarcity. In the paradigm of a circular economy, the reuse of treated wastewater in agriculture is currently regarded as a possible solution for alleviating the issues of water scarcity and pollution. Accordingly, this research aims to assess the use of polluted water in the integrated management of water resources in Semnan. The research used the Water Evaluation and Planning System (WEAP) software package to model and analyze the water sector. Also, the Bayesian network method was used to assess the risk of using polluted water and its effects on humans and plants. The research explored two general scenarios for the study site of Semnan. The first scenario assumes the increase in population, crops (food), and industries, and the second has the same assumptions plus an increase in agricultural efficiency (food production). Based on the results, the agricultural, urban, and industrial water demands are 37, 0.06, and 0.01 million m3 in the base year, respectively. The water demand in the next years will be higher due to population growth. Finally, it is safer to use the wastewater of both treatment plants of the region (Mehdishahr and Semnan) in the industry than in other sectors. Additionally, the wastewater of the Mehdishahr Sewage Treatment Plant is more reliable than that of the Semnan Sewage Treatment Plant. HIGHLIGHTS Management of a smart city.; Critical assessment on Iran's water resources development.; A novel framework and multisectoral approach toward the implementation of IWRM and the W&F nexus in Iran, case study Semnan, is proposed.; Enhancing IWRM and W&F nexus may eradicate hunger as the agriculture sector is disconnected with water, by replacing water reuse.;

Food loss and waste (FLW) is an issue of great public concern, due to its major impact on food security and on the social, economic and environmental resources involved in food production, trade and consumption. In this work, we put the lens on water resources, as those lost in the different stages of FLW represent about a quarter of the total freshwater resources used in food crop production. To this end, we propose the NETFLOW model (Network-based Evaluation Tool for Food LOss and Waste) as an innovative tool capable of reconstructing, for each commodity, the complex global multi-layered network linking FLW at each stage of the value chain with the corresponding wasted water resources. Food re-exports, nested supply chains, telecoupling of food markets, and different levels of food transformation are taken into account. Focusing on the emblematic case of wheat and its derived food commodities (e.g. flour, bread, pasta), we show the complexity and extent of the FLW-linked water network. For example, in 2016, more than 100 countries used their water resources (almost 3 km ^3 ) to produce wheat which was ultimately lost or wasted along the food consumption value chain in Italy, with almost half of this amount being directly attributable to the bread value chain. On the supply side, we show that about 18.3 km ^3 of water resources in the U.S. were lost through wheat-related FLW in 144 countries, about 40% for flour, 27% for raw wheat (mainly used for feed), and 24% for bread. The NETFLOW model proves useful in unravelling the complex links between (i) product-specific global trade networks, (ii) primary and derived products, (iii) country- and stage-dependent FLW, and (iv) country- and product-specific virtual water content.

Saving fresh water is a big challenge for the next generation due to enhanced living standards and population growth. In addition, the expansion of agricultural and industrial activities is causing unmatched demands for fresh water supplies across Egypt. The Nile River is Egypt's main water resource, representing 69.4% of the total water resources, while rainwater, torrential water and groundwater, as well as recycled agricultural and sanitary drainage water and desalinated seawater, are estimated at about 30.6%. Smart drip irrigation systems are in great demand, especially in Upper Egypt. SDG's of the circular economy and the WEF nexus lead to full implementation of drip irrigation systems, achieving ~6.6 BM3/year of direct saving from fresh water and/or doubling the cultivated area. In addition to PV tubes and other utilities, renewable energy, e.g, photovoltaic panels, will posses an important role in low-energy driven drip irrigation systems, reducing fossil-uses, CO2 emissions and devolving more sustainable processes that are less dependent on conventional energy sources. The current research work is a case study of the substitution of flood with drip irrigation, and its positive advantages for the Egyptian agricultural economy and capital expenditures (capex), which depends on the country's infrastructure and availability of utilities. [ABSTRACT FROM AUTHOR]

The application of biochar in agriculture is a developing means to improve soil water retention, fertility, and crop yield. The present work focuses on biochar preparation from mixed vegetable and fruit wastes, using cauliflower, cabbage, banana peels, corn leaves, and corn cobs. The biochar produced at 400 °C was applied to the soil as an amendment to observe the qualitative changes of soil quality, plant growth, and water retention capacity of the soil based on screening in a previous study. Pot experiments were conducted at a laboratory scale having 0%, 2%, and 6% biochar mixed with sand. Each pot was sown with seeds of chickpeas (Cicer arietinum L.) and monitored over 60 days. Two biochar application rates improved soil quality by increasing soil porosity from 49.3 to ≥ 53.4%, more than doubling cation exchange capacity to ≥ 21.1 cmolc.kg−1, providing a small reduction in bulk density of approximately 10% and decreasing electrical conductivity of the extract by at least 40% in comparison to control condition. The biochar application also increased key soil nutrients K, Mn, S, and P by a factor of 2–9 times. Application of biochar at 2% and 6% improved water retention from 55 to 77 and 91 mL respectively over the study and, more importantly, more than doubled the biomass yield for the same water application. The lower biochar application rate of 2% led to more germinated seeds (p = 0.0001), leaves (p = 0.0001), flowers, and fruiting chickpeas than the control condition. The 6% biochar application rate slightly improved plant height (p = 0.01) and provided a small reduction in water loss compared with the 2% biochar. Both biochar loadings increased the root and shoot biomass (p = 0.005) and nutrient content of the shoot and root biomass, particularly K, P, and S (p = 0.0001). This study demonstrates that biochar application at 2–6% is an effective means to increase chickpea yield and reduce water stress. Given small differences in performance within this application range, 2% application is recommended. The study establishes valorization of cellulose rich food waste in the form of biochar as a potential method for positive soil management and increased agricultural productivity in arid environments. [ABSTRACT FROM AUTHOR]

This article examines the evolution and potential of the water agenda of BRICS. The members of this international association of major countries of South America, Eurasia, Asia and Africa are rich in water resources and population. The development of water resources extends beyond their borders to projects in other countries through the activities of a major development institution, the New Development Bank of BRICS. Such conditions suggest some anticipation of a global and comprehensive view on the part of BRICS on the issues relating to water resources. However, the hypothesis of this article is opposite: despite the unique potential of the BRICS water strategy, it remains non-specific, focused on the lower common denominators for the member countries such as cleanliness, sanitation and water management. To account for this, the authors take the position that the bureaucratic logic of basic common interest downgrades strategic vision. This is reflected in the growing gap between the multifaceted nature of the issues related to water resources in the world and the narrowly specialized approach of BRICS association which perceives water de facto without its resource and global function. To study this, the authors analyze the water portfolios of the BRICS member countries and compare the national water agendas based on an analysis of policy documents. They then systematize water initiatives under the auspices of the BRICS and, finally, calculate virtual water flows and their structure between the BRICS countries using agricultural products trade as an example. The conducted analysis allows the authors to identify a wide gap between the current and potential water agenda of the BRICS. The authors then propose a number of initiatives that can create added value for the BRICS as an association both for its member countries and for developing countries facing water resource challenges. The authors assert that such a new approach, based on a profound understanding of the resource function of water as a commodity with global value, has all the potential to be implemented by BRICS.

The water-food nexus literature examines the synergies and trade-offs of resource use but is dominated by large-scale analyses that do not sufficiently engage the local dimensions of resource management. The research presented here addresses this gap with a local-scale analysis of integrated water and food management in Burkina Faso. Specifically, we analyse the implementation of a national food security campaign (Opération Bondofa) to boost maize production in a subbasin that exhibits two important trends in Africa: a large increase in small-scale irrigators and the decentralisation of water management. As surface water levels dropped in the region, entities at different scales asserted increased control over water allocation, exposing the contested nature of new decentralised institutions, and powerful actors’ preference for local control. These scalar power struggles intersected with a lack of knowledge of small-scale irrigators’ cultural practices to produce an implementation and water allocation schedule that did match small-scale irrigator needs, resulting in low initial enthusiasm for the project. Increased attention from national governments to strengthen decentralised water management committees and spur greater knowledge of, and engagement with, small-scale irrigators can result in improved programme design to better incorporate small-scale irrigators into national food security campaigns.

To explore the bioaccumulation of the emerging contaminants in the freshwater bodies and food crops, and the possible implications, this study investigated the chromium-enriched industrial wastewater irrigation on Lablab purpureus with respect to the physical growth, photosynthetic pigments, proline content, and antioxidant defense responses. Chromium enrichment inhibited the elongation of roots and shoots by 68% and 76% respectively, as a function of chromium concentration. The total chlorophyll, chlorophyll- a , chlorophyll- b , and total carotenoids were severely retarded by 81%, 84%, 76%, and 63%, respectively, and excessive accumulation of proline was detected at 2.80 μmol/g fresh weight. The activities of ascorbate peroxidase, guaiacol peroxidase, and catalase were significantly altered, with a strong stimulation at the chromium concentration of 0.30 mM, predicting chromium-induced toxicity of the food crop. The findings provide insight into the interference of heavy metal–contaminated wastewater irrigation practice and its alarming implications for the sustainability of food safety, the dynamic equilibrium of ecosystems, and the water–food nexus. [ABSTRACT FROM AUTHOR]

In a globalizing and rapidly-developing world, reliable, sustainable access to water and food are inextricably linked to each other and basic human rights. Achieving security and sustainability in both requires recognition of these linkages, as well as continued innovations in both science and policy. We present case studies of how Earth observations are being used in applications at the nexus of water and food security: crop monitoring in support of G20 global market assessments, water stress early warning for USAID, soil moisture monitoring for USDA's Foreign Agricultural Service, and identifying food security vulnerabilities for climate change assessments for the UN and the UK international development agency. These case studies demonstrate that Earth observations are essential for providing the data and scalability to monitor relevant indicators across space and time, as well as understanding agriculture, the hydrological cycle, and the water-food nexus. The described projects follow the guidelines for co-developing useable knowledge for sustainable development policy. We show how working closely with stakeholders is essential for transforming NASA Earth observations into accurate, timely, and relevant information for water-food nexus decision support. We conclude with recommendations for continued efforts in using Earth observations for addressing the water-food nexus and the need to incorporate the role of energy for improved food and water security assessments.

Extensive research has evaluated virtual water trade, the water embodied in traded commodities. However, relatively little research has examined virtual water storage or the water embodied in stored commodities. Just as in physical hydrology, both flows and stocks of virtual water resources must be considered to obtain an accurate representation of the system. Here we address the following question: How much water can be virtually stored in grain storage in the United States? To address this question, we employ a data‐intensive approach, in which a variety of government databases on agricultural production and grain storage capacities are combined with modeled estimates of grain crop water use. We determine the virtual water storage capacity (VWSC) in grain silos, map the spatial distribution of VWSC, calculate contributions from irrigation and rainwater sources, and assess changes in VWSC over time. We find that 728 km3 of water could be stored as grain in the United States, with roughly 86% coming from precipitation. National VWSC capacities were 777 km3 in 2002, 681 km3 in 2007, and 728 km3 in 2012. This represents a 6% decline in VWSC over the full 10‐year period, mostly attributable to increased water productivity. VWSC represents 62% of U.S. dam storage and accounts for 75–97% of precipitation receipts to agricultural areas, depending on the year. This work enhances our understanding of the food‐water nexus, will enable virtual water trade models to incorporate temporal dynamics, and can be used to better understand the buffering capacity of infrastructure to climate shocks. Key Points: Just as in physical hydrology, both flows and stocks of virtual water resources must be consideredApproximately 728 km3 of water can be virtually stored as grain in the United States, with roughly 86% coming from precipitationVirtual water storage capacity represents roughly 62% of normal U.S. dam storage or 75‐97% of precipitation receipts [ABSTRACT FROM AUTHOR]

Abstract Food and water are inextricably linked. With the increase of water consumption in irrigation and food growth, water shortage has become an urgent issue. Irrational cross-regional transfer of water embodied in food exacerbates water scarcity and restrict China's sustainable development. Given that, a Virtual Water-Food Nexus Model is developed to quantify the inter-provincial transfer of water embodied in food and to identify the complicated interactions between different provinces. In detail, Environmental Input-Output Analysis is applied to quantitatively estimate the inter-provincial water transfer embodied in food trades. Based on the network constructed by interrelated nature of nexus, the mutual interactions, control situation, and the dominant and weak pathways are examined through the combination of Ecological Network Analysis and Principal Component Analysis. Two new indictors water consumption intensity and water supply capacity are first performed to measure the role of each province from the supply and consume side respectively. It is revealed that interregional food transactions failed to realize water resources dispatching management. Many water-deficient regions suffered from massive virtual water losses through food exports, but water-rich areas still import large quantities of food containing virtual water. Results show that exploitation and competition dominate the ecological relationships between provinces. Agricultural GDP ratio is the indicator which most affect water consumption intensity and water supply capacity. Network-based research contributes more insights into the recognition of water management responsibilities across provinces and municipalities. These findings will provide a scientific support to adjust unreasonable allocation of water resources in China in an attempt to addressing the contradiction between food demand and water shortages. Graphical abstract Unlabelled Image Highlights • A Virtual Water-Food Nexus Model (VWFN) from the Chinese perspective is developed. • Water consumption intensity and water supply capacity of each province are first identified. • A full picture of China's inter-provincial water transfer embodied in food trades is depicted. • China's water transfer embodied in food trades worsened the maldistribution of water resources. • Policy suggestions for various provinces are proposed based on local realities. [ABSTRACT FROM AUTHOR]

In order to achieve worldwide food security, there is a focus on sustainable intensification of crop production. This requires sustainable irrigation water use for irrigated croplands, as irrigation withdrawals are already resulting in groundwater exploitation and unmet ecosystem water requirements. Our study aims to quantify attainable wheat, maize, rice and soybean production on currently irrigated cropland under sustainable water use. Attainable production accounts for increases in nutrient application, while limiting irrigation withdrawals to renewable water availability and without compromising river ecosystem water requirements. Attainable production was quantified using a newly developed two-way coupled hydrological model and crop model. This model framework could comprehensively simulate biophysical processes related to water availability and crop growth under water and nutrient limitations. Our results indicate worldwide crop nitrogen uptake should increase by 20%, to achieve production gap closure. However, worldwide irrigation withdrawals should decrease by more than a third in order to ensure sustainable water use. Under these constraints, a total (all crops) production decrease of 5% was estimated, compared to currently achievable production. Moreover, achievable irrigated crop production in the extensively irrigated croplands of northeastern China, Pakistan and northwestern India would be reduced by up to a third. On the other hand, increases in achievable irrigated crop production may be possible in regions such as southern America, eastern Europe and central Africa. However, in these regions currently only a small fraction of crops is irrigated. Our results imply that intensification on currently irrigated croplands is at odds with sustainable water management, and further locally-oriented research is needed to assess suitable water management options and solutions.

The water-food nexus literature examines the synergies and trade-offs of resource use but is dominated by large-scale analyses that do not sufficiently engage the local dimensions of resource management. The research presented here addresses this gap with a local-scale analysis of integrated water and food management in Burkina Faso. Specifically, we analyse the implementation of a national food security campaign (Opération Bondofa) to boost maize production in a subbasin that exhibits two important trends in Africa: a large increase in small-scale irrigators and the decentralisation of water management. As surface water levels dropped in the region, entities at different scales asserted increased control over water allocation, exposing the contested nature of new decentralised institutions, and powerful actors' preference for local control. These scalar power struggles intersected with a lack of knowledge of small-scale irrigators' cultural practices to produce an implementation and water allocation schedule that did not match small-scale irrigator needs, resulting in low initial enthusiasm for the project. Increased attention from national governments to strengthen decentralised water management committees and spur greater knowledge of, and engagement with, small-scale irrigators can result in improved programme design to better incorporate small-scale irrigators into national food security campaigns. [ABSTRACT FROM AUTHOR]

Most research into the connections between water and energy, water and food, and food and energy has been scientific and technical; little research has examined the public’s understandings of these connections. This article studies these understandings and awareness of nexus issues using a 2015 national public opinion survey on the water–energy–food nexus. Responses from this representative sample of U.S. adults are used to create “awareness measures” for elements of the nexus—water and energy, water and food, and energy and food—which are then used as independent variables to investigate the extent to which awareness is associated with support for public policies designed to address these nexus interconnections. All three measures are significantly correlated to support for policy options. Results suggest that awareness of the water–energy–food nexus may represent conditions necessary for supporting policies and that building such awareness could represent an important pathway for increasing support for policy interventions. [ABSTRACT FROM AUTHOR]

Local-scale opportunities to address challenges of the water–food nexus in the developing world need to be embraced. Borehole-garden permaculture is advocated as one such opportunity that involves the sustainable use of groundwater spilt at hand-pump operated borehole supplies that is otherwise wasted. Spilt water may also pose health risks when accumulating as a stagnant pond. Rural village community use of this grey-water in permaculture projects to irrigate borehole gardens is proposed to primarily provide economic benefit whereby garden-produce revenue helps fund borehole water-point maintenance. Water-supply sustainability, increased food/nutrition security, health protection from malaria, and business opportunity benefits may also arise. Our goal has been to develop an, experience-based, framework for delivery of sustainable borehole-garden permaculture and associated benefits. This is based upon data collection and permaculture implementation across the rural Chikwawa District of Malawi during 2009–17. We use, stakeholder interviews to identify issues influencing uptake, gathering of stagnant pond occurrence data to estimate amelioration opportunity, quantification of permaculture profitability to validate economic potential, and critical assessment of recent permaculture uptake to identify continuing problems. Permaculture was implemented at 123 sites representing 6% of District water points, rising to 26% local area coverage. Most implementations were at, or near, newly drilled community-supply boreholes; hence, amelioration of prevalent stagnant ponds elsewhere remains a concern. The envisaged benefits of permaculture were manifest and early data affirm projected garden profitability and spin-off benefits of water-point banking and community micro-loan access. However, a diversity of technical, economic, social and governance issues were found to influence uptake and performance. Example issues include greater need for improved bespoke garden design input, on-going project performance assessment, and coordinated involvement of multi-sector governmental-development bodies to underpin the integrated natural-resource management required. The developed framework aims to manage the identified issues and requires the concerted action of all stakeholders. Based on the probable ubiquity of underlying issues, the framework is expected to be generalizable to the wider developing world. However, this particular application of permaculture represents a fraction of its greater potential opportunity for rural communities that should be explored. [ABSTRACT FROM AUTHOR]

Abstract: The United States is the largest producer of goods and services in the world. Rainfall, surface water supplies, and groundwater aquifers represent a fundamental input to economic production. Despite the importance of water resources to economic activity, we do not have consistent information on water use for specific locations and economic sectors. A national, spatially detailed database of water use by sector would provide insight into U.S. utilization and dependence on water resources for economic production. To this end, we calculate the water footprint of over 500 food, energy, mining, services, and manufacturing industries and goods produced in the United States. To do this, we employ a data intensive approach that integrates water footprint and input‐output techniques into a novel methodological framework. This approach enables us to present the most detailed and comprehensive water footprint analysis of any country to date. This study broadly contributes to our understanding of water in the U.S. economy, enables supply chain managers to assess direct and indirect water dependencies, and provides opportunities to reduce water use through benchmarking. In fact, we find that 94% of U.S. industries could reduce their total water footprint more by sourcing from more water‐efficient suppliers in their supply chain than they could by converting their own operations to be more water‐efficient. [ABSTRACT FROM AUTHOR]

• The physical water in watershed was connected to virtual water flow as new transboundary water management. • The urban area as food consumers could be considered as main stakeholder of water management in rural area. • Physical-virtual water flow was highly influenced by the self-supply of local food. This study aimed to analyze the interaction among watershed, food-producing, and food-demanding areas through the connected system of physical-virtual water flows and local food networks in terms of the transboundary water-food nexus, even though they might not be geographically connected. Here, we analyzed the potential food network of local rice among 47 prefectures in Japan using the gravity model and estimated the physical-virtual water flows (PVWFs) by lining the physical water flow in food-producing areas and virtual water flow embedded in the food network. Through in-and out-degree centralities of the food network, we found that the results of degree centrality revealed which prefecture was more influenced by the changes in self-supply ratios (SSRs) of local rice. As all prefectures intended to increase consumption of local rice that was produced in their area, the scale of the food network was reduced, as shown by the decrease in in-and out-degree centralities. Based on the food network, we analyzed the dependency of food-demanding areas on each watershed based on a connected system of PVWFs. In a case study of the Kansai region, the northern watershed directly affected Hyogo, which was also indirectly influenced by Osaka in terms of PVWFs. In the food network with 20% SSR, the PVWF was estimated to be 189.17 × 106 m3·yr−1 from the northern watershed to Osaka in the food-producing area of the northern watershed, showing higher interaction of Osaka with the northern watershed than with other watersheds. [ABSTRACT FROM AUTHOR]

Enhancing local production is key to promoting food security, especially in rural households of low-income countries, but may conflict with limited natural resources and ecosystems preservation. We propose a framework integrating the water-food nexus and a sustainable livelihoods perspective to assess small-scale food production in water-poor regions. We demonstrate it by assessing alternative production scenarios in the Gaza Strip at different spatial scales. At the scale of a single farm, there is a clear conflict among objectives: while cash crops ensure good incomes but contribute scarcely to domestic protein supply, crops performing well from the nutritional and environmental viewpoint are among the worst from the economic one. At the regional scale, domestic production might cover an important fraction of nutritional needs while contributing to household income, but water scarcity impairs the satisfaction of food demand by domestic production alone. Pursuing food security under multiple constraints thus requires a holistic perspective: we discuss how a multidimensional approach can promote the engagement of different stakeholders and allow the exploration of trade-offs between food security, sustainable exploitation of natural resources and economic viability. [ABSTRACT FROM AUTHOR]

Population growth, socio-economic development and climate changes are placing increasing pressure on water resources. Crop water footprint is a key indicator in the quantification of such pressure. It is determined by crop evapotranspiration and crop yield, which can be highly variable in space and time. While the spatial variability of crop water footprint has been the objective of several investigations, the temporal variability remains poorly studied. In particular, some studies approached this issue by associating the time variability of crop water footprint only to yield changes, while considering evapotranspiration patterns as marginal. Validation of this Fast Track approach has yet to be provided. In this Letter we demonstrate its feasibility through a comprehensive validation, an assessment of its uncertainty, and an example of application. Our results show that the water footprint changes are mainly driven by yield trends, while evapotranspiration plays a minor role. The error due to considering constant evapotranspiration is three times smaller than the uncertainty of the model used to compute the crop water footprint. These results confirm the suitability of the Fast Track approach and enable a simple, yet appropriate, evaluation of time-varying crop water footprint.

Global waterbodies are experiencing increased risk of eutrophication and harmful algal blooms due to excess nutrients including phosphorus and nitrogen discharged from human activity on the landscape and as a result of climate change. Despite modeling that suggests the efficacy of best management practices in agricultural systems to be sufficient to address the problem, adoption by farmers remains far below the levels needed to achieve significant water quality improvements and new approaches to encourage and sustain adoption are urgently needed. In this work, we apply a modified transtheoretical model (TTM) of behavior change to a longitudinal dataset (N = 584) of farmers' adoption decisions and stated intentions to use cover crops, collected in the Maumee Basin of Lake Erie, USA in 2016 and 2018. The TTM posits that behavior changes over time and is influenced by different social-psychological processes at each stage of change. Our findings confirm past research into the importance of many of the factors investigated, while providing new insight into their role in specific stages of the change process with potential implications for the design of interventions for farmers in different stages. Several factors investigated (mean environmental concern, education, information from conservation groups and off-farm income) were uniquely important to a particular stage. Other factors (response efficacy at the field level, total farm size and risks of spring planting interference) were important at both an earlier and later stage, but less important in predicting middle stages of change. A third set of factors (self-efficacy, proportion rented, no-till adoption and uncertain long-term paybacks) were statistically important across each stage of the TTM model. In applying the TTM longitudinally, we found evidence that farmers in a more advanced stage of cover crop adoption, in the first wave of data collection (2016) were more likely to have adopted cover crops in the second wave (2018), a result not predicted by individual factors alone. We report findings for cover crops but see the potential for the transtheoretical model of behavior change to be applied to other best management practice adoption decisions and to diverse populations of farmers to generate similarly novel insight and utility for intervention design and targeting. • Behavior change takes place over time and is a multi-stage process. • We investigate farmer adoption of cover crops, a water quality best management practice. • Farmers in different stages have different characteristics and barriers to adoption. • Farmers in later stages of change are more likely to adopt cover crops. • Interventions must target farmers' stage of change for sustained adoption. [ABSTRACT FROM AUTHOR]

There is increasing interest in the water–food nexus, especially the restrictive effect of water on food production in hot spots where irrigation stress is growing. However, little is known about the larger-scale implications of future irrigation shortfalls for global trade and economic welfare, as well as of the potential buffering impacts of international trade on the local impacts of irrigation shortage. In this paper, we utilize a recently developed model, GTAP-BIO-W, to study the economic effects of changes in irrigation outlook for 126 river basins, globally by 2030. Projected irrigation availability is obtained from the IMPACT-WATER model, and imposed upon the present-day economy. Irrigation availability in 2030 is expected to drop by 30–60% in several key rivers basins, including: Hai He, Indus, Luni, and the Eastern Mediterranean basin, leading to significant output declines in China, South Asia, and the Middle East. We find that the regional production impacts of future irrigation water shortages are quite heterogeneous, depending on the size of the shortfall, the irrigation intensity of crop production, the possibility of expanding rainfed areas, as well as the crop mix. These changes in regional output significantly alter the geography of international trade. To compensate for the loss of productivity caused by the irrigation constraint, an estimated 7.6 million hectares of cropland expansion is needed to meet the demand for food. In spite of the remarkable reduction of irrigation in some basins, the resulting welfare impact is relatively modest as a result of the buffering capacity of global markets. The global welfare loss amounts to $3.7 billion (2001 prices) and results from a combination of the reduction in irrigation availability as well as the interplay with agricultural support policies. [ABSTRACT FROM AUTHOR]

In face of the interdependencies between policy areas in the management of common pool resources, studying nexus challenges is insightful for the exploration of new governance strategies. This includes the co-occurrence of and the interaction between different governance modes. We put forward the argument that a promising approach to explore these dynamics over time is the method of discourse network analysis. By conducting a discourse network analysis of German agricultural and water policy in a region with intensive livestock farming and large surpluses of manure that exert pressure on water and soil resources, we analyse the development of discourses within and across policy areas. We show that the analysis of public discourses contributes to the understanding of coordination between actors. • The separation of policy areas presents a major challenge to the sustainable management of common pool resources. • The analysis of public discourses enables a new perspective on governance types beyond the trichotomy of cooperation, competition and coercion. • Hybrid governance strategies going beyond the analytical distinction between government, market and community have proven successful for sustainable environmental management. • External pressure leads to the rapprochement of discourse coalitions. [ABSTRACT FROM AUTHOR]

Cities are complex and evolving systems with various factors playing key roles, e.g., population increase, the migration of population, the availability of resources, and the flexibility of policies. Consumers' socioeconomic status is also an important aspect that needs to be studied in the context of a self-reliant urban city in its resource consumption. In this regard, the association between water–food and socio-economic attributes was analyzed based on the consumer-centric approach for the Hyderabad Metro Development Authority (HMDA) region, India. In this study, the embedded water content in food consumption was estimated and analyzed for nine food groups and twelve economic classes of the HMDA region. The middle economic classes were found to correspond to ~80% of embedded water content in the HMDA region, followed by the upper and lower economic classes. Except for cereals, per capita, the water consumption of all food groups increased with the spending power of the economic class. The green, blue, and grey consumption water footprints (WFs) suggested that much of the water that is being consumed in the HMDA region is precipitation-driven, followed by surface and groundwater resources. Limited water resources, water resource variability, climate change consequences including future climate projections, uncertainty in data, WF estimates, and region's future growth imply a detailed study in drafting policies to become a self-reliant region. [ABSTRACT FROM AUTHOR]

• The agricultural water consumption is identified to have the most significant effect on reducing the lake volume. • A Monte Carlo system dynamics model is developed to evaluate different restoration policies for the Urmia Lake. • The novel prey predator model is developed to simulate the nexus between food security and environmental. • The lake could be restored if the all four scenarios are implemented together. In recent decades, population growth, agricultural development and climate change have caused environmental problems in the world, especially in the arid and semi-arid regions such as Iran. Urmia Lake, one of the unique biosphere reserves of the world, has suffered from these problems in the last 20 years. Although many studies conducted to the negative impacts of human-induced activities, especially agricultural expansion on the lake, few studies focused on providing restoration plans for that. This study uses a system dynamics method for modelling the restorations scenarios of Urmia Lake based on the prey-predator approach. This method is helpful to simplify the complicated feedbacks and interactions among human-environment. The Monte Carlo simulation is used to explore the effect of uncertain parameters on the lake level. Based on the results of this study, the agricultural water consumption (as predator) has the most significant effect on reducing the lake volume (prey). The results indicated that decreasing the area of irrigated lands by 40%, improving irrigation efficiency, reducing the lake area itself, and inter-basin water transfer will lead to increase in the lake water level by 2.54 m, 2.04 m, 1.19 m and 1.19 m, respectively. By applying all the suggested scenarios, the lake water level will reach to its ecological level (1274 MSL) in 2023. The recent positive restoration signals of the lake have coincidence with the findings of current research and bring more hope to the future of the lake. [ABSTRACT FROM AUTHOR]

Successful adaptation to global climate change and enhancement of agricultural watersheds' resilience requires widespread use of Nutrient Best Management Practices (NBMPs) by farms of all sizes. In the US, adoption of many NBMP practices is voluntary and insufficient to achieve local and downstream conservation objectives. Despite evidence that both social-psychological factors and socio-economic factors influence farmer decision-making, very few studies of farmers' decision-making related to NBMP adoption combine these two factor groups in a theoretically rigorous way. To better understand farmers' management decisions, we test the social-psychological Theory of Planned Behavior (TPB) to determine the relative influence of attitudes, perceived social norms, and perceived behavioral control on adoption of nine NBMPs. A survey was designed by the research team and implemented by the U.S. Department of Agriculture-National Agricultural Statistics Service (USDA-NASS) in 2013, and replicated in 2016, on a stratified sample of 129 farmers (including panel data on 56 farmers). Farmers were located in the Missisquoi, and Lamoille River watersheds of the Lake Champlain Basin in the Northeast region of the United States. Survey responses revealed variation in past adoption of NBMPs was sensitive to practice type and farm size. We developed nine weighted structural equation models to test endogenous (social-psychological) and exogenous (policy, economic and demographic) predictors of farmer intention to adopt NBMPs. We found that perceived behavioral control had the largest effect size and strongest statistical significance on the farmers' expressed intentions to adopt NBMPs in the future. For a subset of NBMPs, perceived social norms and farmer attitudes toward these NBMPs were each also significant drivers of intention to adopt individual practices. Among the exogenous variables, we found that large farm size, college education, and having a conservation easement all had a positive influence on farmers' intention to adopt NBMPs. This study suggests that for widespread adoption of NBMPs, environmental managers, policy makers, and program developers should be attentive to farmers' perceived behavioral control, and support the design and execution of outreach and technical assistance programs that build on drivers of farmers' decision making. • Self-assessed ability to adopt new practices is most important for all practices. • Previous land conservation action significant indicator of self-assessed ability. • Higher intent to adopt nutrient best practices with large farm and college education. • Programs to encourage adoption should include human behavior and demographic insights. [ABSTRACT FROM AUTHOR]

China's Belt and Road Initiative (BRI) needs little introduction; the infrastructure investment will reconfigure development in Central Asia. As its origin story and initial encounter, Central Asia offers a prismatic lens to delve into the vital impacts and significant changes wrought by the BRI. In the dryland region, the BRI impact on watersheds and agriculture is a critical challenge with direct implications for food security. Framed by diverse research sources, we utilized spatial datasets from the European Space Agency Climate Change Initiative and the World Bank to explore the intersection of food production, water and development. Investigation evaluates the possible trade-offs that Chinese infrastructure investment can have on the communities and environment of Central Asia. The findings identify more than 15,000 km of rail and 20,000 km of roads linked to the BRI crisscrossing the region in 2018. Whilst these transport corridors have improved connectivity, many of these rails and roads traverse important agricultural and water zones, creating undetermined risks and opportunities. Land use change was examined within a 10-km buffer around BRI roads and rails from 2008 to 2018. Railways increased by 23% during this time, yet irrigated and rainfed agriculture decreased whilst urban areas markedly expanded. Contextual research identifies how Chinese policies may encourage agribusiness investment for food exports as possible disruptions to national and regional food supply. However, to date Central Asia provides <1% of Chinese agricultural imports. In fact, Afghanistan is the region's dominant export market, tripling agricultural imports >300% in this time. Similarly, five times more livestock are traded within the region than to China. Evaluating infrastructure change is essential to understand BRI impacts on environments and societies, with the food-water nexus a particular concern in Central Asia. Limited Chinese imports of Central Asian agriculture suggests the region's food security will not be significantly altered by the Belt and Road Initiative. [ABSTRACT FROM AUTHOR]

International agricultural trade triggers inter-dependency among distant countries, not only in economic terms but also under an environmental perspective. Agricultural trade has been shown to drive environmental threats pertaining to biodiversity loss and depletion and pollution of freshwater resources. Meanwhile, trade can also encourage production where it is most efficient, hence minimizing the use of natural resources required by agriculture. In this study, we provide a country-level assessment of the future international trade for 6 primary crops and 3 animal products composing 70% of the human diet caloric content. We set up four variegate socio-economic scenarios with different level of economic developments, diets habits, population growth dynamics, and levels of market liberalization. Results show that the demand of agricultural goods and the correspondent trade flow will increase with respect to current levels by 10–50% and 74–178% by 2050, respectively. The largest increase in the amount of traded goods is expected under the Economic Optimism scenario that will see an average trade flow of 2830 kcal/cap/day (i.e., nearly doubling the current per-capita flow). Most of the increase will be driven by the trade of crops for animal feeding, particularly maize will be the most traded crop. The trade networks architecture in 2050 and 2080 will be very different from the one we actually know, with a clear shift of the trade pole from the Western toward the Eastern economies. The dramatic changes of global food-sources and trade patterns will jeopardize the water resources of new regions while exacerbating the pressure in those areas that will continue serving food also in the future. In spite of this, trade may annually save around 40–60 m3 of water per person, compared to a situation where countries are self-sufficient. Unlabelled Image • There will be a transition of the food trade core from Western toward Eastern economies by 2050. • Half of the future projected agricultural demand will be met by international trade. • International trade will save 40–60 m3 of water per person, despite an increase of the total trade flow. • Increased market openness may enlarge impacts on water sources by 3 times with respect to 2016 levels. [ABSTRACT FROM AUTHOR]