Learning from integrated management approaches to implement the Nexus

A review on food subsystem simulation models for the water-food-energy nexus: development perspective

Agricultural crops are the primary food source because livestock and poultry products also indirectly depend on crops. A significant obstacle to adopting the water, food, and energy (WFE) nexus is the lack of a comprehensive and easy-to-use simulation model for the food subsystem focusing on crops. By reviewing the articles in Scopus and Google Scholar databases, WFE nexus studies can be divided into two categories: simulation-based and conceptual-based studies of WFE nexus. Based on the developmental perspective on food subsystem modeling in the WFE nexus, the conceptual studies were excluded, and the modeling studies were reviewed. Two points of view can be used for WFE nexus modeling: 1. hard-link modeling and 2. soft-link modeling. Comparing these two types of modeling showed that hard-link modeling cannot model the interrelations of the food subsystem, and this shortcoming is of great importance. This study reviewed the crop growth models (CGMs) used in the WFE nexus system from the development perspective. The technical characteristics of the CGMs have been evaluated according to the requirements of the CGMs. Finally, a checklist based on the criteria defined for the nexus system has been provided, which can guide researchers in choosing the appropriate CGMs for the food subsystem with the nexus approach. The analysis revealed that none of the CGMs studied alone were sufficient to develop a simulation model for the food subsystem with the WFE nexus. However, the AquaCrop model met more criteria.

The water-energy-food nexus in biodiversity conservation: A systematic review around sustainability transitions of agricultural systems

The Water Energy Food nexus is a powerful topic in agricultural systems to elucidate threats to biodiversity conservation and culture. This paper aimed to recapitulate nexus thinking research, focusing on social-ecological transitions of agriculture systems and biodiversity management within the Water-Energy-Food nexus. We developed a systematic review and a bibliometric analysis derived from 529 documents in the Scopus database. The ToS method identified a total of 81 relevant information in the sample of documents (529) categorised into roots (10), trunks (9) and leaves (62). This review paper situates types, focus, and highlights regarding biodiversity and prevalent thematic research areas such as "Food Nexus", "Environmental Flows", "Sustainability", "Transitions", and "Governance". Our results suggest that future research should focus on the nexus of "Water-Energy-Food-Biodiversity" and propose a transdisciplinary approach to elucidate the state of sustainability transitions in the agricultural systems at the landscape level. It could increase stakeholder interest in conservation, and sustainability management, to reverse biodiversity losses in ecosystems.

Addressing diffuse water pollution from agriculture: Do governance structures matter for the nature of measures taken?

Nutrient pollution of freshwaters from agriculture is a key barrier to achieving the water quality goals of the European Water Framework Directive (WFD). Governance research suggests that governance structures can support the planning of water quality measures. However, it is widely unclear how specific governance structures affect the actual nature of practical measures taken for addressing the "wicked problem" of diffuse nutrient pollution. This study analyses how the extent of consensual policy styles, organizational and program integration, participatory governance, and the capacities of public authorities are related to the substance of practical measures taken (effect-vs. source-based measures) and the choice of policy instruments (e.g., sermons, carrots, sticks). Based on a comparative case study design including six country cases, document analyses, and expert interviews, we find no clear-cut relationships between the country's governance structures and the types of measures chosen or any trend of a combined effect. This suggests that, in the case of the WFD, governance structures are less important than expected or that different governance structures compensate for the effects on the level of practical measures taken and policy instruments chosen. These results question the dominant assumption that these governance structures matter (a lot) in wicked problem solving and may hint to additional context factors these governance structures are embedded in.

Dual risk-aversion programming for regional industrial structure adjustment with water-energy nexus: A case study of Tianjin, China

The water-energy nexus (WEN) system is a large-scale complex system that comes with diverse forms of risks owing to many challenges in the process of maintaining economic-resource-environmental sustainability. First, the rapidly increasing demand for water and energy subjects many regions to the high risk of water and energy shortages. Second, decision makers face difficulties in weighing system benefits and loss risks under a series of stricter water-energy policies. To handle the aforementioned dual risks of WEN, in this study we propose copula-based stochastic downside risk-aversion programming (CSDP) for regional water-energy management. CSDP integrates the superiority of the copula analysis method and downside risk-aversion programming into a framework, which can not only reveal the risk interactions between water resources and energy demand by using copula functions under different probability distributions, even previously unknown correlations, but also control economic risk, tackle systemic uncertainties, and provide an effective linkage between system stability and conflicting economic benefits. The proposed model was applied to a water-energy system case study in Tianjin City, China. Optimal solutions for various water resources and energy demand copulas associated with different scenarios and hierarchical risk levels were examined in the CSDP model. The results showed that water resources have a greater influence than energy on industrial structure adjustment in Tianjin, with consequent effects on system benefits, optimal output value schemes, and environmental protection strategies. In addition, the tertiary industry provides a new opportunity for economic growth based on a large amount of water-energy consumption, and its potential resources and water-air pollution risks also deserve extensive attention.

A fixed-mix stochastic fractional programming method for optimizing agricultural irrigation and hydropower generation in Central Asia

In this study, a fixed-mix stochastic fractional programming (FSFP) method is developed for balancing the water-allocation conflict between upstream hydropower generation and downstream agricultural irrigation. FSFP has advantages in dealing with ratio-objective problem under uncertainty, reflecting the dynamic and stochastic characteristics over a long-term planning context, as well as analyzing interrelationships between system efficiency and violation risk of water-allocation target. Then, FSFP is firstly applied to Tuyamuyun reservoir in the lower reach of Amu Darya River basin (Central Asia), where multiple scenarios based on different hydropower-generation targets and inflow levels are examined for identifying the complex relationship between hydropower generation and crop irrigation. Major findings and managerial insights can be summarized as: (i) with the reduction of reservoir inflow, water allocation for downstream agricultural irrigation would decrease by 30.4% once the minimum demand is satisfied, and hydropower generation should be higher priority for pursuing higher marginal benefit; (ii) with the shrinking water supply and rising hydropower-generation target, cotton planting should be firstly restrained due to its high water demand and grape planting is encouraged; (iii) under extreme water scarcity (i.e., low and very-low inflow levels), low-level hydropower generation target (i.e., α = 0.45) is desired for meeting the food requirement in the study basin; (iv) for alleviating the water shortage during dry seasons, it is recommended that water storage should be conducted in autumn and winter, and water release for crop irrigation should be implemented during spring and summer. These findings can help managers identify sustainable water-allocation schemes for agricultural irrigation and hydropower generation against water shortage, environmental destruction and energy insecurity in arid regions.

Current solid waste management strategies and energy recovery in developing countries - State of art review

Solid waste generation has rapidly increased due to the worldwide population, urbanization, and industrialization. Solid waste management (SWM) is a significant challenge for a society that arises local issues with global consequences. Thus, solid waste management strategies to recycle waste products are promising practices that positively impact sustainable goals. Several developed countries possess excellent solid waste management strategies to recycle waste products. Developing countries face many challenges, such as municipal solid waste (MSW) sorting and handling due to high population density and economic instability. This mismanagement could further expedite harmful environmental and socioeconomic concerns. This review discusses the current solid waste management and energy recovery production in developing countries; with statistics, this review provides a comprehensive revision on energy recovery technologies such as the thermochemical and biochemical conversion of waste with economic considerations. Furthermore, the paper discusses the challenges of SWM in developing countries, including several immediate actions and future policy recommendations for improving the current status of SWM via harnessing technology. This review has the potential of helping municipalities, government authorities, researchers, and stakeholders working on MSW management to make effective decisions for improved SWM for achieving sustainable development.

Approach to Assess the Performance of Waste Management Systems towards a Circular Economy: Waste Management System Development Stage Concept (WMS-DSC)

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A holistic approach to assess waste management systems’ performance is presented.

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A benchmarking tool to estimate the circular economy (CE) evolvement in cities.

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Usable for cities both in the Global North and South to identify CE potentials.

In this paper a novel holistic approach to assess the performance of waste management systems (WMSs) is presented. The so called WMS development stage concept (WMS-DSC) can be used by practitioners or decision makers to assess primarily the WMS at the municipal level. The WMS categorization into development stages notably enables a clear identification of symptoms, the causes of possible waste mismanagement and potential measures for improvement. The concept can be used to (i) assess the status quo of a WMS and, based on this, identify possible measures for implementation; (ii) check whether relevant system conditions to implement a specific measure are met; (iii) monitor the progress of a WMS; and (iv) compare the WMSs of different cities. The concept consists of five development stages: stage 1 – absence or lack of essential elements of waste management; stage 2 – reliable collection and improved landfill sites; stage 3 – separate collection and sorting; stage 4 – expansion of the recycling industry; and stage 5 – circular economy (CE), waste as a resource. While stage 1 describes the absence of or a very immature and malfunctioning WMS, stage 5 stands for a fully implemented CE. By equating the highest stage to the objectives that have evolved today globally for a sustainable CE, this concept can be used to identify targets and the most suitable steps for an individual WMS towards a future best practice of CE.•

A holistic approach to assess waste management systems’ performance is presented.

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A benchmarking tool to estimate the circular economy (CE) evolvement in cities.

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Usable for cities both in the Global North and South to identify CE potentials.

Water-related challenges in nexus governance for sustainable development: Insights from the city of Arequipa, Peru

Peru has one of the fastest-growing economies in Latin America, but there are concerns regarding how long this can be sustained. Negative environmental impacts are increasing due to the pressures of a growing urban population and competition for natural resources. This study explores stakeholder perceptions linked to nexus governance in the context of integrated management of natural resources, particularly water, and the environmental, socio-economic and governance challenges constraining the achievement of UN Sustainable Development Goals (SDGs). Our analysis focused on the urban and rural areas associated with the city of Arequipa, an economically dynamic region subject to extreme levels of water stress. Face-to-face interviews with key informants were conducted to identify mechanisms that have enhanced successful multi-sectoral collaboration, and to assess challenges in promoting sustainable economic development. A workshop prioritised the identified challenges and an online survey was then used to assess stakeholder interest in and influence over nexus governance of water with other natural resources. Stakeholder mapping revealed a complex network of actors involved in nexus governance, where successful collaboration could be promoted through formal and informal mechanisms, including exemplar policies and initiatives across sectors and actors. Shared visions between stakeholders were identified as well as contradictory priorities relating to the sustainable management of natural resources. A key finding that emerged was the need to promote adaptation in water and land management (SDG 6) due to perceived impacts of extreme climate events (SDG 13), urban population growth (SDG 11), and increased sectoral water demands. This situation in combination with poor governance and lack of planning has exposed the vulnerability of Arequipa water supply system to future shocks. Urgent action will be needed to raise stakeholder awareness, strengthen governance and enforcement, and agree on a collective vision for integrated land and water planning if the SDGs are to be achieved.

Sustainability Considerations in Water–Energy–Food Nexus Research in Irrigated Agriculture

Irrigated agriculture is essential to satisfying the globally increasing demand for food and bio-based products. Yet, in water scarce regions, water-use for irrigation aggravates the competition for the use of water for other purposes, such as energy production, drinking water and sanitation. Solutions for sustainable food production through irrigated agriculture require a systemic approach to assess benefits and trade-offs across sectors. Here, the water–energy–food (WEF) nexus has become an important concept in natural resource management. It has been conceptualized to analyze linkages and trade-offs between the three sectors, across temporal and spatial scales. However, the concept has so far mainly been conceptual, with little empirical evidence or proof of concept in real world cases. The objective of this paper was to take stock of the rapidly advancing literature on the WEF nexus in irrigated agriculture, and to analyze how the concept was actually implemented in research studies, and how the nexus between water, food and energy was actually dealt with. The study period ranges from 2011 to 2019, and includes 194 articles. Results showed that the WEF nexus is indeed very relevant in irrigated agriculture, and the respective literature makes up one third of all WEF nexus papers. Modeling and empirical research have caught up with conceptual synthesis studies during the last four years, thereby indicating that the WEF nexus concept is indeed increasingly operationalized. However, most studies addressed the WEF nexus from a perspective of either socioeconomic, technological or environmental categories, and they place one of the dimensions of water, food or energy into the foreground. To address sustainable development, there is a need to fully integrate across research disciplines and thematic dimensions. Such studies are only starting to emerge. These findings are an important evidence-base for future WEF nexus research on irrigated agriculture, in support of sustainable solutions for water scarce regions, especially in settings undergoing transformations.