Synergistic evolution of water-energy-food system resilience and efficiency in urban agglomerations.

With increasing internal and external risks to the WEF system, a single emphasis on efficiency or a lopsided pursuit of resilience can lead to difficulties in adapting to complex changes and resource redundancy. Revealing the synergistic evolutionary characteristics between efficiency and resilience of the WEF system is an effective method to deal with systemic internal and external risks. However, the current study of the WEF system lacks a synergistic perspective on resilience and efficiency. Thus, taking Chengdu-Chongqing Economic Circle (CCEC) as the research object and its geospatial boundary as the system boundary, this paper adopted the entropy-topsis model to evaluate the WEF resilience, and applied the super-efficient SBM model to measure the WEF efficiency accurately, which fully considered the non-expected outputs in the process of resource utilization. Then, applying the development coordination degree model, the synergistic relationship between the two was measured. The results indicated that: the average value of WEF resilience in CCEC increased from 0.414 to 0.485 and showed spatial characteristics of west＞east＞central. The WEF efficiency interval was 0.79-0.93, and cities with average WEF efficiency reaching the effective production frontier accounted for only 37.5%. The clustered distribution of the synergy levels intensified. The number of cities with primary, medium, more advanced, and advanced levels was 6, 6, 1, and 3, respectively, with primary and medium synergy levels dominating. The findings suggest that cities should strengthen regional exchanges and formulate targeted measures based on their own situations. In addition, CCEC should possess a comprehensive understanding of the interdependencies and conflicts that arise between resilience and efficiency throughout the decision-making procedure.

Decoupling of water resources utilization and coordinated economic development in China's Hexi Corridor based on ecological water resource footprint.

The rapid growth of population and economy leads to a further increase in demand for water resources. The contradiction between supply and demand of water resources has become the main bottleneck restricting sustainable development of a regional social economy. Accurate measurement of regional water usage and the harmonious balance between water consumption (WC) and economic growth (EG) are the premise of regional high-quality development. Based on this premise, this paper studied the arid oasis region, Hexi Corridor, as the research object; utilized the theory of ecological footprint to calculate the ecological footprint (EFW) and ecological carrying capacity (ECCW) of water resources from 2005 to 2019; and quantitatively analyzed the water utilization situation in Hexi Corridor in the past 15 years. Then, combining with the coordinated development decoupling evaluation model, the connection between WC and EG was evaluated. The main results of this study were as follows: (1) During the study period, EFW has shown a fluctuating downward trend, decreasing from 1.745 in 2015 to 1.588 hm2/person in 2019. The average annual EFW per capita of 10,000 yuan of GDP decreased by 10.18%, which showed that the water resources utilization efficiency was gradually increasing. However, there was still a large water deficit. The average water ecological pressure index was 16.55; water resources were under great pressure. (2) From 2005 to 2019, the relationship between WC and EG experienced stages of strong decoupling-weak decoupling-weak negative decoupling-strong decoupling in Hexi Corridor, and the coordination between the two was gradually strengthened. (3) The decoupling status of the Hexi Corridor cities was gradually optimized. Zhangye was the best and in a stable decoupling state, followed by Wuwei and Jiuquan. The number of decoupling years accounted for 85.7% and 78.6% of the evaluation period, respectively. The cities with poor decoupling status were Jiayuguan and Jinchang, and the number of decoupling years accounted for 71.4% and 57.1%, respectively. This study provides some highlights for the formulation of arid oasis regional water strategy.

The gap of water supply-Demand and its driving factors: From water footprint view in Huaihe River Basin.

Climate change, population growth, the development of industrialization and urbanization are increasing the demand for water resources, but the water pollution is reducing the limited water supply. In recent years, the gap between water supply and demand which shows water scarcity situation is becoming more serious. Clear knowing this gap and its main driving factors could help us to put forward water protection measures correctly. We take the data of Huaihe River Basin from 2001 to 2016 as an example and use ecological water footprint to describe the demand, with the water carrying capacity representing the supply. We analyze the water supply-demand situation of Huaihe River Basin and its five provinces from footprint view in time and space. Then we apply the Logarithmic Mean Divisia Index model to analyze the driving factors of the ecological water footprint. The results show that: (1) the supply and demand balance of Huaihe River Basin was only achieved in year 2003 and 2005. There is also a large difference between Jiangsu province and other provinces in Huaihe River basin, most years in Jiangsu province per capital ecological footprint of water is more than 1 hm2/person except the years of 2003, 2015, and 2016. But other provinces are all less than 1 hm2/person. (2) Through the decomposition of water demand drivers, we concluded that economic development is the most important factor, with an annual contribution of more than 60%. Our study provides countermeasures and suggestions for the management and optimal allocation of water resources in Huaihe River Basin, and also provides reference for the formulation of water-saving policies in the world.

Optimization of a Capacitated Vehicle Routing Problem for Sustainable Municipal Solid Waste Collection Management Using the PSO-TS Algorithm.

Sustainable management of municipal solid waste (MSW) collection has been of increasing concern in terms of its economic, environmental, and social impacts in recent years. Current literature frequently studies economic and environmental dimensions, but rarely focuses on social aspects, let alone an analysis of the combination of the three abovementioned aspects. This paper considers the three benefits simultaneously, aiming at facilitating decision-making for a comprehensive solution to the capacitated vehicle routing problem in the MSW collection system, where the number and location of vehicles, depots, and disposal facilities are predetermined beforehand. Besides the traditional concerns of economic costs, this paper considers environmental issues correlated to the carbon emissions generated from burning fossil fuels, and evaluates social benefits by penalty costs which are derived from imbalanced trip assignments for disposal facilities. Then, the optimization model is proposed to minimize system costs composed of fixed costs of vehicles, fuel consumption costs, carbon emissions costs, and penalty costs. Two meta-heuristic algorithms, particle swarm optimization (PSO) and tabu search (TS), are adopted for a two-phase algorithm to obtain an efficient solution for the proposed model. A balanced solution is acquired and the results suggest a compromise between economic, environmental, and social benefits.

A Chance-Constrained Vehicle Routing Problem for Wet Waste Collection and Transportation Considering Carbon Emissions.

In order to solve the optimization problem of wet waste collection and transportation in Chinese cities, this paper constructs a chance-constrained low-carbon vehicle routing problem (CCLCVRP) model in waste management system and applies certain algorithms to solve the model. Considering the environmental protection point of view, the CCLCVRP model combines carbon emission costs with traditional waste management costs under the scenario of application of smart bins. Taking into the uncertainty of the waste generation rate, chance-constrained programming is applied to transform the uncertain model to a certain one. The initial optimal solution of this model is obtained by a proposed hybrid algorithm, that is, particle swarm optimization (PSO); and then the further optimized solution is obtained by simulated annealing (SA) algorithm, due to its global optimization capability. The effectiveness of PSOSA algorithm is verified by the classic database in a capacitated vehicle routing problem (CVRP). What's more, a case of waste collection and transportation is applied in the model for acquiring reliable conclusions, and the application of the model is tested by setting different waste fill levels (WFLs) and credibility levels. The results show that total costs rise with the increase of credibility level reflecting dispatcher's risk preference; the WFL value range between 0.65 and 0.75 can obtain the optimal solution under different credibility levels. Finally, according to these results, some constructive proposals are propounded for the government and the logistics organization dealing with waste collection and transportation.