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The Rouse formula and its variants have been widely used to calculate the steady-state vertical concentration distribution for suspended sediment in steady sediment-laden flows, where the diffusive flux is assumed to be Fickian. Turbulent flow, however, exhibits fractal properties, leading to non-Fickian diffusive flux for sediment particles. To characterize non-Fickian dynamics of suspended sediment, the current study proposes a Hausdorff fractal derivative based advection-dispersion equation (HADE) model, where the Fickian diffusive flux in the Rouse model is replaced by a fractal derivative re-scaled using a constant diffusivity. The order of the Hausdorff fractal derivative is designed to characterize the influence of the multi-fractal turbulence structure on sediment diffusion. Applications show that the HADE model, with the analytical solution expressed using a stretched exponential function, can accurately describe the observed vertical concentration profiles for suspended sediment with different sizes. This improvement well captures the non-exponential decay of the vertical sediment concentration in turbulent flow. Further analyses of measured sediment concentration profiles reveal that the Hausdorff fractal order decreases with the Rouse parameter, which describes the stronger impact of turbulent flow and a more uniform sediment concentration profile for smaller particles. Model comparisons also show that the HADE model provides better performance in describing the sediment concentration profiles than the improved Rouse formula and the standard fractional derivative advection-dispersion equation (FADE), which either under- or over-estimates vertical displacement of sediment particles, likely due to coherent turbulent structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • The AHP-EWM-ICT method was proposed to assess wetland degradation risk. • Incorporating AHP-EWM in catastrophe theory reduces the uncertainty of normalized calculation results. • The assessment result based on the power function fitting approach is more intuitive than that of the conventional catastrophe theory. • Wetland degradation risk in Xiong'an New Area showed a fluctuating upward with an overall from 2000 to 2020. Increased groundwater exploitation can cause severe groundwater depletion and may trigger geological hazards such as wetland degradation. The Xiong'an New Area is an important deployment of the national strategy to promote the coordinated development of the Beijing-Tianjin-Hebei region. The protection of wetlands will play an important ecological role in the socio-economic development of the Xiong'an New Area. This paper proposes an improved catastrophe theory (ICT) combined it with the analytic hierarchy process (AHP) and the entropy weight method (EWM), labelled AHP-EWM-ICT method. This method was applied to evaluate the evolutionary trend of the wetland degradation risk in Xiong'an New Area from 2000 to 2020. Results showed that, first, the wetlands degradation risk in the Xiong'an New Area was fluctuating upward, with an increase of 80.17% in 2020 compared to 2000. The risk level increased from 'Very low' in 2000 to 'Medium' in 2020, and most years at 'Medium' level during 21 years. Second, Rongcheng County, which has the higher intensity of groundwater extraction as well as the higher per capita GDP compared with Xiong County and Anxin County, contributed most to wetland degradation. The stress degree values progressed from northwest to southeast. Third, due to the implementation of ecological recharge, the degradation risk of Baiyangdian wetland has shown a trend of first increasing and then decreasing. Fourth, the risk of wetland degradation in Xiong'an New Area may be more severe than in other wetlands in northern China. In addition to implementing ecological replenishment projects, the government should also pay more attention to the functional restoration of wetlands and the reduction of risk sources in areas surrounding wetlands. [ABSTRACT FROM AUTHOR]

Resilience and efficiency are the core concepts of sustainable management of agricultural water resources system. This study constructed an evaluation system of the efficiency and resilience of agricultural water resources system (E AWRS , R AWRS) in the Yellow River Basin by comprehensively applying the analytic hierarchy process (AHP), entropy method (EVM), SBM-DEA model, and the development coordination model. The results showed that: (1) From 2005–2019, the E AWRS and R AWRS showed a fluctuating upward trend. The E AWRS increased significantly, especially the Baihe, Heihe, Luohe and Wudinghe river basins grew at a faster rate. However, the overall efficiency levels were still not high, and all the 72 prefecture-level administrative units were inefficient areas. The R AWRS was at a relatively low level, in which the Huangshui, Taohe and Qingshuihe river basins had rapid growth in resilience. (2) From the perspective of spatial differentiation characteristics, the E AWRS in Sichuan, Qinghai, Inner Mongolia, Shaanxi, Henan, and Shandong was relatively high, while that in Gansu, Shanxi and Ningxia was relatively low. The prefecture-level administrative units of the upstream river source area, Hetao Irrigation District, Fenwei Plain and Huanghuaihai Plain had a relatively high E AWRS. The R AWRS in the lower reaches was significantly better than that in the upper and middle reaches. (3) The development degree of the agricultural water resources system has gone through a process of rapid rise (2005–2013) - fluctuating growth (2014–2017) - rise (2018–2019), showing an "upstream-midstream-downstream" stepwise increasing pattern. The coordination degree of the agricultural water resources system showed a downward trend, and the decrease showed an "upstream-downstream-midstream" increasing pattern. (4) The three clusters divided by the average value of the development degree and coordination degree of the agricultural water resources system showed the changes from concentration to dispersion, in contrast, the coordination degree was gradually decreased. • Agricultural water efficiency and resilience evaluation was completed. • Spatial–temporal characteristics of agricultural water efficiency and resilience was presented. • The influencing factors of agricultural water efficiency and resilience were discussed. • Policy implications linked to the agricultural water resources management were proposed. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from the industrial sector are rapidly increasing in China. As the largest producer of magnesia-refractory raw materials in the world, the production of magnesia-refractory raw materials in Dashiqiao city causes severe environmental problems, such as greenhouse gas emissions, air pollution and high energy consumption. As Dashiqiao's pillar industry, the production of magnesia refractory raw materials has become a serious obstacle to its sustainable development. At present, most studies are mainly focused on the greenhouse gas emissions from magnesium production and the emissions from magnesia refractory raw material production have not been thoroughly investigated. This research addresses this important information gap. This study focuses on the carbon emissions from the production of five kinds of magnesia refractory raw material products. The results demonstrate that the estimated greenhouse gas emissions are 2.7 t CO 2 eq/t of caustic calcined magnesia, 3.1 t CO 2 eq/t of general dead-burned magnesia, 4.7 t CO 2 eq/t of middle grade dead-burned magnesia, 4.7 t CO 2 eq/t of single-phase process fused magnesia, and 7.8 t CO 2 eq/t of two-phase process fused magnesia. In 2014, the five production chains of the main magnesia refractory raw materials in Dashiqiao released 13.76 million t GHGs, in which the single-phase process fused magnesia accounted for 24%, while the caustic calcined magnesia and the middle grade dead-burned magnesia for 23% and 23%, respectively. As one of the most important magnesia producer and supplier, the magnesia related industry in Dashiqiao has emitted large amounts of GHGs during the past 90 years, resulting in a significant contribution to global warming potential and negative impacts on urban sustainable development. Therefore, the city needs the magnesia industry to make structural adjustments and technical improvements. [ABSTRACT FROM AUTHOR]

A laboratory experimental method has been developed to obtain the hydraulic head loss of either the closed fractures or conduits based on balance of energy. It was found that the linearity between hydraulic head loss and flow velocity decreases as the aperture increases, based on which a possible division of fractures and conduits is proposed. The results of the division show that a closed flow structure with less than 1.4635 mm aperture can be defined as a fracture whilst a closed flow structure with more than 1.8375 mm aperture can be defined as a conduit. The flow structure with an aperture of 1.6000 mm is in the transitional area of fractures and conduits. In addition, the Cubic law could not exactly describe the relationship between hydraulic head loss and velocity when applied to closed fractures in these investigations. The effects of deviations from ideal conditions when applying the Cubic law caused an apparent reduction in hydraulic head loss and may be incorporated into the Cubic law by adding the effects of both the width of the fracture and the ratio of the width to the aperture. The coefficient n was introduced to indicate the influence of the ratio of the width to the aperture on hydraulic head loss. [ABSTRACT FROM AUTHOR]

Emissions from road transport have significant impacts on climate change and air quality. However, few studies focused on long-term emission changes, long-range passenger transport of air pollutants, especially, neglecting how those cities with larger urban agglomeration area interact with each other. This article fills the gap to evaluate interacting emissions from inter-city passenger transport and related PM 2.5 health impacts, also to assess possible development in passenger transport sector in long-term post fossil period. Shenyang Metropolitan Area is chosen as a case in which include eight neighboring cities, covering 23.6 million inhabitants. Results show that total air pollutants and greenhouse gases (GHGs) emissions from urban agglomeration area passenger transport reached 265 kt and 17 kt in 2012, respectively, and may result in about 170 deaths per year. Importantly, the interacting emissions are closely related with the local economic development of destination city, meaning that interactions between each city in an urban agglomeration area are mostly based on economic cooperation. In order to mitigate and adapt to such emissions, different scenarios were set up for policy making and implementing. Comparing with business-as-usual scenario, optimal scenarios with the promotion of hybrid vehicles, plug-in electric vehicles and ethanol vehicles can lead to less air pollutants and GHGs. Finally, appropriate policies for supporting the application of the optimal scenario were raised and discussed so that policy-makers can seek an innovative pathway to both mitigate and adapt to climate change and improve air quality in transport sector of an urban agglomeration area. [ABSTRACT FROM AUTHOR]

Energy and resource consumption has been expanding quickly with the rapid growth of Asian cities, which has resulted in increased greenhouse gas emission and waste generation. The promotion of low-carbon industries is an urgent global issue that extends to Asia as well. To reduce carbon dioxide emission substantially, industries must not only introduce energy-saving technologies but also use low-carbon raw materials and fuel, such as recyclable wastes and carbon-neutral biomass. This paper presents the concept of a “hybrid industry,” that is, an industry whose processes utilize not only fossil resources but also recycled and renewable resources as much as possible. This study examines the feasibility of hybrid industries through the promotion of urban symbiosis in cities in three Asian countries with different circumstances: Kawasaki in Japan, Ulsan in Korea, and Shenyang in China. Asian cities are in the midst of shifting from dumping wastes to incineration. However, in view of the carbon reduction effect of recycling as well as the cost for recycling and appropriate treatment of wastes, the potential of hybrid industries that use combustible municipal wastes as input should be considered. In this study, the potential for carbon dioxide reduction as well as the costs of promoting hybrid industries are evaluated. The results highlight that promoting hybrid industries generates significant environmental benefits for the three cities, and there are important factors that affect the cost-effectiveness of hybrid industries, including the spatial density of waste generation, composition of wastes, relative labor cost for collection and pre-treatment of wastes compared with construction cost of an incinerator and avoided costs through product and fossil resource substitution, and the willingness of citizens to separate wastes. Finally, key drivers for promoting hybrid industries through urban symbiosis in Asian cities are discussed. [ABSTRACT FROM AUTHOR]