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Water quality data represent a critical resource for evaluation of the well-being of aquatic ecosystems and assurance of clean water sources for human populations. While the availability of water quality datasets is growing, the absence of a publicly accessible national water quality dataset for both inland and the ocean in China has been notable. To address this issue, we utilized R and Python programming languages to collect, tidy, reorganize, curate, and compile three publicly available datasets, thereby creating an extensive spatiotemporal repository of surface water quality data for China. Distinguished as the most expansive, clean, and easily accessible water quality dataset in China to date, this repository comprised over 330 000 observations encompassing daily (3588), weekly (217 751), and monthly (114 954) records of surface water quality covering the period from 1980 to 2022. It spanned 18 distinct indicators, meticulously gathered at 2384 monitoring sites, which were further categorized as daily (244 sites), weekly (149 sites), and monthly (1991 sites), ranging from inland locations to coastal and oceanic areas. This dataset will support studies relevant to the assessment, modeling, and projection of water quality, ocean biomass, and biodiversity in China, and therefore make substantial contributions to both national and global water resources management. This water quality dataset and supplementary metadata are available for download from the figshare repository at 10.6084/m9.figshare.22584742 (Lin et al., 2023b). [ABSTRACT FROM AUTHOR]

Reservoir operation policies affect sediment methane (CH4) production and pathways through complex influence on hydrodynamic and biogeochemical processes in reservoir water and sediment. However, the underlying influencing mechanisms, especially the impact of operations on sediment CH4 production and pathways, remain poorly understood. This study combines a physical‐biogeochemical model with a reservoir operation model to evaluate operation impacts on spatiotemporal sediment CH4 production and release dynamics and to analyze affiliated processes and driving factors. Three typical operation policies (i.e., standard, hedging, eco‐friendly) are selected to create the operation scenarios, and a coupled physical‐biogeochemical model is adopted to simulate and compare sediment CH4 production, consumption, diffusion, and ebullition under these scenarios. The methods are applied in the second largest reservoir in China (i.e., Danjiangkou Reservoir) as a case study. Results show that annual total sediment CH4 production among the scenarios ranges from 285.9 to 298.3 Gg C year−1, while operation scenario outcomes significantly differ. Specifically, a significant CH4 percentage (34%–39%) is oxidized in surface sediment while the remaining escapes sediment through diffusion and ebullition. Although diffusion accounts for >60% of the annual sediment CH4 release, sediment ebullition ultimately dominates atmospheric CH4 emissions. Annual total atmospheric CH4 emissions range from 42.8 to 71.1 Gg C year−1 and account for 14%–25% of the annual total sediment production among the three scenarios. The differences demonstrate that reservoir operations significantly impact CH4 pathways and atmospheric emissions. This study provides implications for reservoir managers to coordinate socioeconomic and ecological protection while mitigating CH4 emission targets. Key Points: CH4 dynamics are affected by hydrological, hydrodynamic, and water quality factorsEbullient fluxes in shallow‐water and drawdown zones dominate atmospheric emissionOperations impact sediment CH4 consumption, ebullition, and atmospheric emission [ABSTRACT FROM AUTHOR]

Neonicotinoid insecticides (NEOs) are commonly used to prevent unwanted insects in urban fields. Degradation processes have been one of the important environmental behaviors of NEOs in an aquatic environment. In this research, hydrolysis, biodegradation, and photolysis processes of four typical NEOs (i.e., thiacloprid (THA), clothianidin (CLO), acetamiprid (ACE), and imidacloprid (IMI)) were examined through the adoption of response surface methodology–central composite design (RSM-CCD) for an urban tidal stream in South China. The influences of multiple environmental parameters and concentration levels on the three degradation processes of these NEOs were then evaluated. The results indicated that the three degradation processes of the typical NEOs followed a pseudo-first-order reaction kinetics model. The primary degradation process of the NEOs were hydrolysis and photolysis processes in the urban stream. The hydrolysis degradation rate of THA was the highest (1.97 × 10−5 s−1), and that of CLO was the lowest (1.28 × 10−5 s−1). The temperature of water samples was the main environmental factor influencing the degradation processes of these NEOs in the urban tidal stream. Salinity and humic acids could inhibit the degradation processes of the NEOs. Under the influence of extreme climate events, the biodegradation processes of these typical NEOs could be suppressed, and other degradation processes could be further accelerated. In addition, extreme climate events could pose severe challenges to the migration and degradation process simulation of NEOs. [ABSTRACT FROM AUTHOR]

Water and land are crucial natural resources for agricultural development. It is necessary to allocate water and land resources effectively in order to achieve the maximum economic profits and the minimum environmental costs. In this research, an inexact two-stage fractional programming model was developed for the allocation of water and land resources, which is integrated interval-parameters (IPP), two-stage stochastic programming (TSP), fractional programming (FP). This model could optimally allocate water and land resources at the same time under the scenario of the maximum economic profit and the minimum environmental cost; it was proved to be beneficial in (1) dealing with the conflicts between economic development and environmental protection and give insights in trade-off among the agricultural system; (2) allocating water and land resources for five crops under multiple flow level simultaneously; and (3) describing the uncertain inputs as interval-parameters to reduce model uncertainties. The developed model was applied to the northeast region of China. The optimal allocation schemes of water and land resources, the maximum economic profits, and the minimum environmental costs were obtained. The results showed that economic profits in the agricultural system in the northeast region of China would not definitely be connected with the allocation of water and land resources, and solid waste pollution would bear the largest environmental cost. The developed model could help decision-makers to get a deeper understanding of the agricultural system and manage water and land resources in an efficient and environment-friendly way. [ABSTRACT FROM AUTHOR]

Hydrological simulation in areas with complex topography and pronounced climatic heterogeneity has a certain degree of uncertainty, and how precipitation data from multiple types of sources influence hydrological simulation remains unclear. Performances of precipitation datasets based on multiple interpolation methods (i.e., inverse distance weighted [IDW], cokriging, and ANUSPLIN) and satellite remote sensing datasets (i.e., tropical rainfall measuring mission multi‐satellite precipitation analysis 3B42 version7 [TRMM 3B42V7], precipitation estimation from remote sensing information using artificial neural networks–climate data record [PERSIANN‐CDR], climate predication centre morphing technique, and sian precipitation–highly resolved observational data integration towards evaluation of water resources [APHRODITE]) were obtained for comparison. Hydrological responses from these precipitation datasets were evaluated through distributed hydrological model variable infiltration capacity. The Yalong river basin (YRB), located in the Hengduan Mountains region and characterized by the significant heterogeneity of precipitation in China, was focused. Four sub‐regions (i.e., sub‐region I to IV) were divided. The results indicated that: (a) TRMM 3B42V7 and APHRODITE data were superior in detection capability from daily to annual measurement than other satellite precipitation data sets generally; (b) under the scale of gauges, TRMM 3B42V7, APHRODITE, and cokriging performed well in sub‐regions I, II, and IV, respectively. In sub‐region III, performance of the interpolation methods was better than that of TRMM 3B42V7; (c) the interpolation datasets exhibited a poor capability to simulate peak runoff. The combination dataset COM could improve the overall runoff simulation in flood periods; and (d) the interpolation method has the problem of excessive smoothness. Whatever the interpolation dataset is, hydrological simulation tends to result in smaller runoff, which was related to that the measurements from meteorological stations in mountainous valleys are not necessarily representative of the entire region. In this paper, the applicability of multi‐source precipitation data in the hydrological simulation process of YRB was comprehensively analysed, which could provide effective references for improving the accuracy of precipitation data and the applicability of hydrological simulation. [ABSTRACT FROM AUTHOR]

Plastic waste management, deeply intertwined with our economy, presents a global challenge. Plastic pollution pervades both aquatic and terrestrial ecosystems worldwide. In a vast country like China, establishing a comprehensive plastic flow regime that accounts for socioeconomic disparities between urban and rural areas is essential for effectively reducing s plastic waste. This study aims to map the life-cycle of China's plastic flows from 2001 to 2040, distinguishing between urban and rural sources, through integrating dynamic probabilistic material flow analysis with scenario analysis. The results indicate that from 2001 to 2020, cumulative plastic waste generation was 1001 ± 14.6 million tonnes (Mt), with a higher proportion originating from urban areas (706 ± 10.3 Mt) compared to rural areas (218 ± 3.2 Mt). The rate of increase in mismanaged plastic wastes (MPWs) in rural areas outpaced that in urban areas, peaking in 2016, five years after the peak in urban areas. Consequently, the cumulative total of rural MPWs, including littering (103.5 ± 2.0 Mt) and open dumping (74.8 ± 1.5 Mt), was higher than that in urban areas (littering: 83.0 ± 4.0 Mt; open dumping: 70.3 ± 1.4 Mt). The scenario analysis forecasts a reduction of 96.5 ± 0.4 % and an 83.0 ± 2.1 % in MPW generations in urban and rural areas by 2040, respectively, if all interventions are implemented. However, strategies like reuse&recycling and reduce&substitute are less effective in rural areas compared to urban areas. Therefore, we recommend establishing a collection system with both penalties and incentives to reduce rural MPWs. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • A comprehensive model for quantifying PET flows is developed. • The disposal methods of waste PET changed from 2000 to 2018. • Fibers and bottles manufacturing industries are the largest PET in-use stocks. • The treatment of waste PET would be a challenge in the future. Polyethylene terephthalate (PET) is a widely used plastic material that may cause significant environmental pollution. China is a major global producer and consumer of PET. Previous studies have focused on the effects of toxic elements from PET (e.g., antimony leached from PET products) on the environment. However, detailed information about PET, particularly about the PET production, trade, use, and recycling in China, is limited. This study developed a network model of PET flows in China, including the production, market trade, manufacturing and use, and waste management and recycling stages. Based on this network model, the characteristics of PET flows during three periods of development for the PET industry were analyzed. The results show that the fiber and bottle manufacturing industries are the industries with the largest PET in-use stocks. The PET flows showed different characteristics in the terms of waste import, recycling, and disposal (mechanical recycling, chemical recycling, incineration, landfill, and discarding) in the different periods of PET industrial development. Notably, the amount of discarded PET was significant, and the treatment of waste PET would probably be a challenge in the future. Policies for improving the PET cycling system were provided on the basis of the study results to promote the management and sustainable utilization of PET materials. [ABSTRACT FROM AUTHOR]

Land use classification is fundamental both for monitoring and predicting regional development patterns and for planning and regulating land use. This research proposed a joint probability-based classifier for land use classification of multispectral remote sensing data and applied it to the Lake Baiyangdian region of North China. This classifier, based on the vine copula method, was suitable for dealing with the uncertainties of land classification and its random variables that did not necessarily obey predefined distributions. Comparison of the results obtained using the proposed classifier with those derived using the widely used maximum likelihood classifier indicated that the accuracy of land use classification of multispectral remote sensing data was higher with the proposed classifier. Compared with the contingency matrix of the maximum likelihood classifier, that of the vine copula classifier showed an increase in the producer's (user's) accuracy of rural land (shallow water) of 29.4% (30.0%). The proposed classifier increased the shallow water area and significantly reduced the area of rural land. The main reason was the maximum likelihood classifier had poor classification performance, misclassifying pixels of shallow water as rural land. The findings of this study demonstrated that the vine copula classifier performs better than the traditional maximum likelihood classifier and that its application could promote full utilization of remotely sensed data. [ABSTRACT FROM AUTHOR]

Flood disasters are one of the most destructive hazards faced across the globe, and thus flood hazard analysis is an essential factor for flood management. Due to the randomness and fuzziness of flood hazard, a series of possibilities is required for a certain flood level rather than just one exact probability. As a method for fuzzy hazard analysis derived from the information diffusion theory, the Interior-Outer-Set Model (IOSM) has the potential to reflect the randomness and fuzziness of flood hazard, however, the controlling intervals might have no sample points particularly when there are extraordinarily large flood peak flows or the flood samples concentrate. Based on this, the current study proposes a new framework for flood hazard analysis. First, flood samples are extracted from daily observed peak flow data. Second, the traditional IOSM is improved using design peak flows from flood frequency analysis (FFA) as the controlling points. From this, probability and floods hazard values are estimated via the FFA based IOSM (FFA-IOSM).The proposed framework is applied using data from the Dongjiang River, South China. Results demonstrate that the estimated flood probability was able to more effectively reflect the randomness and fuzziness of flood hazard compared to the traditional IOSM. This study provides a basis for reasonable flood engineering practices and supports the government with effective guidance on flood risk management, particularly under the increasing frequencies of the extreme precipitation events. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spatiotemporally contiguous precipitation events are tracked through FiT algorithm. • Contiguous precipitation events exhibit different Spatiotemporal characteristics in different geographical locations. • Role of atmospheric rivers and tropical cyclones in heavy precipitation are explored. • Heavy events associated with TCs (ARs) mainly occur in southern (central and southern) China. • Heavy events associated with TCs (ARs) normally have higher maximum intensity (longer duration). Precipitation events exhibit a spatiotemporal continuity since they move across both space and time, however, the joint spatiotemporal characteristics of precipitation events are often neglected, and the role of Atmospheric rivers (ARs) and tropical cyclones (TCs) in the events has not been systematically explored. To solve these problems, this study seeks to detect and characterize the three-dimensional (latitude + longitude + time) structures of spatiotemporally contiguous precipitation events, distinguish the heavy events associated with ARs or TCs, and systematically explore the different roles of these events. We do so by combining Forward-in-Time algorithm, an object-based physical event detecting algorithm, with TMPA precipitation estimates to detect spatiotemporally contiguous precipitation events over China, and an AR detection technique considering a combination of fixed lower limit and Integrated Water Vapor Transport percentile threshold is adopted to identify ARs. The heavy events are defined to analyze the differences of the events associated with TCs and ARs as a function of precipitation total, duration, and intensity. Results show that approximately half or more of precipitation events are shorter than 6-hour, and the precipitation total of each event is strongly correlated with maximum intensity and average intensity across China. The heavy events normally occur in southern, center, northern, and southwestern regions, where have approximately 10 to 40 heavy events at each grid. The fraction of heavy events associated with TCs generally increase for events with larger precipitation totals and for events with higher maximum intensity, until all of events are associated with TCs. The percentages of events associated with ARs as well normally increase as precipitation totals and maximum intensity increase up to around 150 mm and 30 mm/h, respectively. Our findings show that the events associated with TCs or ARs exhibit distinct different characteristics, and suggest that the different spatiotemporal dynamics should be sufficient considered in contiguous events analyses in different regions. [ABSTRACT FROM AUTHOR]

• Probability of slight drought was higher than moderate drought. • Range of single probability of slight drought was 26.15 to 41.06% • Range of joint probability of droughts in moderately was 3.76 to 31.32% Documenting the joint probability of meteorological-hydrological, meteorological-agricultural, and hydrological-agricultural drought can be invaluable for understanding drought evolution under climate change in a high-diversity watershed of south China. Through constructing the edge and joint distribution functions of multi drought indices (SPEI, SPI, SSI, and SWI) based on SWAT and copula methods, we explored the evolution of multi droughts under climate change in the East River basin. During 1997–2017 and 2023–2099, we used logistic, generalized pareto, and normal distributions to construct edge distribution functions of SPEI, SPI, SWI, and SSI. For the four indices, the probability of slight drought increased with rcp2.6, 4.5, 6.0, and 8.5, and it was higher than moderate drought. Also, Clayton, Frank, Gumbel, and Gaussian copula functions were used to construct joint distribution functions of SPEI and SSI, SPEI and SWI, SSI and SWI to quantify their interactions. During 1997–2017, the probability of slight drought was 26.15 to 41.06 %, and the return period changed from 3.8 to 2.4 years. The joint probability of meteorological-hydrological, meteorological-agricultural, and hydrological-agricultural drought in slightly was 24.4 to 31.32 %, 14.95 to 22.63 %, and 6.18 to 22.05 %, respectively. During 2023–2099, the joint probability of droughts in moderately was 3.76 to 14.19 %, and the return period was 7 to 26.6 years. Our results provide a quantitative assessment of single and joint probability of meteorological, hydrological and agricultural drought, which could be used to support watershed water resource management. [ABSTRACT FROM AUTHOR]

A simulation-based interval stochastic bi-level multi-objective programming (SISBLMOP) model was proposed in this research, through integrating the global nutrient export from watersheds model, interval parameter programming and stochastic chance-constrained programming into a general bi-level multi-objective programming framework. The SISBLMOP model can handle multiple uncertainties expressed as discrete intervals and probability density functions in both the simulation and optimization processes. System complexities, including the hierarchy structure of upper- and lower-level decision makers, can also be addressed in the model. The proposed model is applied to a real-world case study of the Xinfengjiang Reservoir Watershed in South China to identify the satisfactory implementation levels of multiple best management practices (BMPs). The model results show that multiple BMP schemes for water quality management can be obtained under different upper- and lower-level decision-making and risk-violation scenarios, reflecting the cooperation and gaming results of the two-level decision makers. Consequently, the corresponding BMP implementation costs are acceptable to both the upper- and lower-level decision makers. The model is widely applicable and can be effectively used for water quality management under multiple uncertainties and complexities. • A simulation-based interval stochastic bi-level programming model was developed. • System hierarchical structure and multi-objective characteristics were considered. • The stochastic characteristics of nutrient export can be reflected. • The model can reflect uncertainties in both simulation and optimization processes. • The model can support watershed water quality management. [ABSTRACT FROM AUTHOR]

Climatic variation within a typical dry-valley area located in the southern Hengduan Mountains of China is studied, and the potential regional climate influences of large reservoirs in the area are discussed. Six meteorological stations near a reservoir are identified and classified into two categories (dry and non-dry valleys) to compare their level of climate change. Temperatures tended to increase since 1990 with a precipitation shift toward the dry season in both dry and non-dry valleys. Wavelet analysis shows that temperature and precipitation have significant variation with periods of 3.6 and 16.5 years, respectively. The standardized precipitation evapotranspiration index (SPEI) shows that dry valleys have multiple drought trends. Temperature in non-dry valleys changed more than that in dry valleys, but the variations of other indices in the two categories of valleys are not statistically different. The climatic variation of one station is in accordance with the reservoir filling, which is related to the orientation of the reservoir in the prevailing wind direction especially during summer. This study provides a profile of the climate change of dry valleys and documents the influence of large artificial reservoirs on regional climate. [ABSTRACT FROM AUTHOR]

• A high-resolution integrated assessment framework for estimating future watershed ecosystem services was proposed under the latest SSP-RCP scenarios; • The spatial–temporal dynamics on water-related ESs of the PRB were projected under the SSP-RCP scenarios; • The main driving factors affecting the spatial–temporal heterogeneity of water-related ESs of the PRB were identified under the SSP-RCP scenarios. The projection of future ecosystem service (ES) dynamics under SSP-RCP scenarios would be beneficial for the development of effective climate mitigation strategies for policymakers. However, current projection frameworks generally neglect the downscaling of high-resolution climate and land use data, leading to uncertainties in the simulation of ESs under the SSP-RCP scenarios. To address this issue, this study proposes an integrated analysis framework to downscale climate and land use data. We first identified areas of high risk in terms of inadequate water-related ESs in the Pearl River Basin (PRB) of China. Subsequently, we analyzed key socio-environmental factors driving the dynamics of water-related ESs under future SSP-RCP scenarios. The results indicate that 1) water-related ESs in the PRB are expected to show an overall increasing trend, 2) the sub-watersheds located in the downstream is at a higher risk of experiencing insufficient supply capacity for water-related ESs, and 3) under the coupling effects of climate change, land use change, and socio-economic development, drastic changes in future land use are expected to have a stronger impact on watershed ESs than the climate (i.e., global warming). Our work provides valuable insights for policymakers and managers regarding future water and land resource planning. The proposed framework can be integrated with other hydrological or land surface models to project the spatial–temporal evolution characteristics of future watershed ESs with finer temporal resolution. [ABSTRACT FROM AUTHOR]

• Stimulate the BW and GW variation dynamics. • Examine the sensitivity of BW and GW to land use change. • Measure the effects of land use change on both BW and GW. • Assess the potential impact of land use change on various water security indicators. • Quantify the interaction of BW and GW based on the Copula function. land use change had a considerable impact on the regional water cycle throughout the past century, leading to an influence on water security. Bluewater (BW) and Greenwater (GW) concepts have found broad application in evaluating the water accessibility of both socioeconomic and ecological systems. However, regarding the interactions between BW and GW systems and their coupled risk under land use change, there has been limited research in this area. This study aims to address this gap by developing an integrated Hydrology and Water Security Modeling Framework (HWSMF) that combines a hydrological model (Soil and Water Assessment Tool), a copula-coupled risk model, and a water security assessment model to assess the impact of land use change on regional water security. As an example, the methodology was utilized in the East River basin (ERB) located in China's Pearl River Delta. Results showed that the sensitivity of GW to forest land change was significant. In general, land use change had a notable impact on the GW coefficient at a rate of more than 4% of change and in certain areas, it was over 8%. Due to land use change the freshwater availability per individual in each city of this basin decreased. When the probability of coupled risk is defined, the BW required is greater than the GW required in this basin. Land use change can lead to fluctuations in the coupled risk of the regional Bluewater- Greenwater nexus system (BGN), which implies that appropriate land use management could be promising for regional water system risk mitigation. The results of this study will be valuable for policymakers and managers of watersheds in their endeavors to manage water resources sustainably amidst evolving land use patterns. [ABSTRACT FROM AUTHOR]

Conserving and restoring ecosystem services in urban areas is an efficient measure to deal with increasing ecological challenges for cities while enhancing urban ecological resilience. However, rising inequalities threaten to improve critical environmental justice, public health and urban ecological resilience. This study proposed a non-monetary framework for accounting for urban ecosystem services and explored the inequality of ecosystem services using the Gini coefficient. Further, a regression-based decomposition method was used to identify primary socioeconomic factors that contributed to inequality. The results showed that the total ecosystem service in the urban areas presented a trend of first growing rapidly and then fluctuating steadily from 6.78 × 1022 sej in 1985 to 1.14 × 1023 sej in 2020 the percentage of existing services in the total ecosystem services was over 50%. The Gini coefficient of 1985 was more extensive than that of other years, which is 0.461. The runoff regulation service and the temperature mitigation service were the primary contributors for the inequality. Meanwhile, such income per capita, nonfarm rate and industrial production provided over 70% contribution rate to the inequality. This study assessed the inequality of urban ecosystem services and analyzed the driving factors, emphasizing the importance of reducing inequality, and providing a specific reference basis and theoretical support for decision-makers in urban planning and development strategies. • Establishing a framework to calculate urban ecosystem services. • Analyzing the inequality of ecosystem service inequality. • Pointing out the contributions of the related ecosystem services to the inequality. • Identifying certain socioeconomic factors that are affecting the inequality and these contributions. [ABSTRACT FROM AUTHOR]

In this research, an integrated simulation-optimization modeling approach (ISOMA) was developed for supporting agricultural N2O emission mitigation at the watershed scale. This approach can successfully combine soil N2O emission simulation and the consequential mitigation management within a general modeling framework. Also, uncertainties associated with the key soil parameter can be effectively reflected and addressed through adoption of Monte Carlo analysis for the simulation results. The Monte Carlo simulated results were then used to generate fuzzy membership functions that can be consequentially used for emission mitigation management, reflecting the combined uncertainties for N2O emission simulation and mitigation management. The developed ISOMA was then applied to a reservoir watershed in Miyun county of Beijing municipality. In the studying watershed, the simulation model was calibrated and verified. Then, N2O emission from multiple agricultural land-use patterns were predicted. The amounts of N2O emission of four land use patterns (i.e., cash tree, orchard, cropland, and natural forest) were (536.9, 590.8, 653.1), (237.7, 254.4, 275.9), (79.5, 100.7, 105.1), (33.0, 47.3, 61.1) kg CO2 eq ha−1 year−1, respectively. Two scenarios (i.e., G1 and G2) were set up according to development priorities of local economy and society. Meanwhile, multiple credibility levels were considered according to the risk of N2O emission. The land use patterns could be adjusted according to solutions of ISOMA. The developed methods could help regional manager choose various production patterns with cost-effective agriculture N2O emission management schemes in the Miyun reservoir watershed. The manager also can obtain deeply insights into the tradeoffs between agricultural benefits and system reliabilities. [ABSTRACT FROM AUTHOR]

With the rapid economic growth and social development in China, conflicts over water resources between human and nature are continuously increasing which is attracting the attention of researchers. At the same time, discharge of water pollutants and exploitation of water resources pose a daunting challenge to the sustainable development of economy and society. China consists of 34 provincial administrative regions having similar or different characteristics in the levels of economic development, water resource endowment, water environmental capacity and water environmental pressure. Among these, it is meaningful to analyze spatial similarities and variations in water environmental carrying capacity (WECC), which contributes to carrying out different and scientific strategies for the management of water environment and for sustainable economic and social development in China. An index system is established to quantify WECC from the perspectives of carrying capacity, environmental pressure, vulnerability of water environment and exploitation and utilization potential. The k-means clustering method is applied to conduct the similarity combination based on the quantification of 4 integrated indicators using catastrophe progression method. The silhouette coefficient is introduced to measure the quality of clustering and to determine the optimal clustering number. The obtained results indicate that carrying condition of water environment becomes more and more better and exploitation and utilization potential of WECC is decreasing gradually from the east to the west in China, and there are more overload in the north provinces and less in the south. In addition, water environmental vulnerability in the west is higher than that of central and eastern provinces in China. The optimal clustering number is 4 obtained by calculating the silhouette coefficient. Also, 31 provinces are categorized into 4 sub-areas i.e. key protected area, controlled development area, optimized development area and prioritized development area. The suggestions on the corresponding bidirectional regulation to different sub-areas are also put forward to provide a scientific reference to rational distribution of economic development, elaborate management of water environment as well as regional sustainable development in the future. [ABSTRACT FROM AUTHOR]

Due to frequent and serious waterlog and environmental pollution in cities in recent years, urban stormwater management (USM) has become an essential issue of urban sustainable development in China. Low Impact Development (LID) technologies are effective and popular measures of USM, and can be used to reduce urban waterlog and the associated environmental pollution. In this paper, in order to identify an optimal strategy of LID technologies based on economic efficiencies and environmental performances, the construction costs and environmental benefits of the four LID technologies (including grass swales, bioretention cells, green roofs, and permeable pavement) were analyzed. Then, due to the uncertain feature of rainfall, concentration of pollutants and many social-economic factors, an inexact fuzzy chance-constrained programming (IFCCP) model was developed. Multiple uncertainties that can be expressed as interval parameters, fuzzy sets, and stochastic distribution can be addressed effectively and incorporated directly into the modeling process. Based on the analysis of the precipitation probability distribution and land use data, the developed model was applied to a university campus with relatively high building density and plot ratio in Beijing. Then, optimal solutions of multiple precipitation probabilities ( p m ) under varying USM goals were obtained. The four LID technologies were chosen to meet multiple USM goals based on multiple p m values. When   p m = 0.1 , 0.05 , 0.02 and   0.015 , the total construction investments would be 1.46 to 4.66, 1.46 to 5.25, 2.31 to 8.54 and 3.95 to 12.7 million yuan, respectively. The relationship between construction costs and p m represented the relationship between economic benefit and system risk. The results indicated that USM was influenced by the rainfall capacity, construction costs would increase with the increase of precipitation, and the risks of constraint violation would decrease as the construction costs increase. When considering the four LID technologies during the planning stage of USM, the preferred selection order would be bioretention cells, permeable pavements, grass swales and green roofs. Therefore, the solutions under each p m level could provide the references for desired USM plans. [ABSTRACT FROM AUTHOR]

• Establishing a comprehensive index to identify urban ecological sources. • The synthesis framework to evaluate the urban ecological resilience based on balance of robustness and redundancy. • The dynamics change of ENs resilience with the existence of risk and disturbance from external shocks. The resilience of the urban ecological network is an indispensable aspect of reflecting the recovery capacity after the external risk shock. Improving the resilience of the ecological network is conducive to enhancing the ecological benefits. However, the current studies are lack of resilience evaluation from a comprehensive perspective. Thus, in this study, taking three typical urban agglomerations as cases, a comprehensive evaluation framework was proposed to assess ecological network resilience. First, we selected the comprehensive reserve as ecological sources and combined them with ecological corridors to construct the ecological network. Then we evaluated the resilience of ecological networks from the perspectives of robustness and redundancy. Finally, we analyzed the resilience of the network under different importance nodes failed. The results showed that (1) the average values of the comprehensive reserve value (CRV) in three urban agglomerations were over than 0.8. (2) the resilience of ecological networks in three urban agglomerations was blow the optimal value throughout during the period from 1985 to 2020. (3) the resilience change trends of multiple urban agglomerations were significant differences after removing certain important nodes, indicating the current ecological network is redundant. The research will help to improve the evaluation of urban ecological resilience and enhance the improvement of sustainable urban management and ecological restoration. [ABSTRACT FROM AUTHOR]

• The flow model and framework for PE, PP, and PET plastics are established. • The waste amount of PET was the largest, followed by PE waste. • Untreated waste cannot be ignored, and its proportion exceeded that of incineration. • Under the scenario of multiple measures, the total waste will reduce by 69.12 Tg. Plastic pollution is a global threat. China's plastic limit order has the most significant impact on plastic pollution. However, under the plastic limit order, the change characteristics of flows and waste for polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) (the most widely used plastics in China) are unknown. Therefore, this study explored the flow characteristics of PE, PP, and PET based on material flow analysis, then considered the impact of the plastic limit order on them, and obtained the most effective strategies for mitigating plastic pollution. The study found that if plastic waste is not controlled, the total amount will reach 128.84 Tg, an increase of 116% over 2017. The PET waste was the largest, followed by PE waste. Moreover, the waste reduction under multiple strategies would be the most significant, and the waste of PE, PP, and PET would reduce by 23.32, 16.84, and 28.96 Tg respectively, and the total would reduce by 69.12 Tg, 54% less than the "business as usual (BAU)" in 2030. The second is the alternative strategies, which is 33% less than BAU (reducing by 42.11 Tg), followed by strategies of prohibition (reducing by 24.29 Tg) and standardizing waste management. Notably, PE waste from packaging and agriculture is reduced most significantly under the prohibition strategy. This study expounds on the reduction potential and strategies of PE, PP, and PET waste under plastic limit order, which will provide a scientific basis for promoting the sustainable consumption of plastics and realizing the waste reduction goal. [ABSTRACT FROM AUTHOR]

Understanding the changes in hydrological process is a key subject for water resource management of a high-diversity watershed. In this paper, through an establishment of a SWAT-based model, the effects of climate change and its induced vegetation change on hydrological process were analyzed in the East River Basin. The model could well simulate the hydrological processes of the basin including surface runoff (SURQ), groundwater (GWQ), lateral flow (LATQ), total water yield (WYLD), actual evapotranspiration (ET), and groundwater recharge (PERC). Under the vegetation change induced by temperature increase, the effects of the vegetation change on hydrological process were larger than that of the temperature change. Under the vegetation change caused by the increase of temperature and precipitation, the vegetation change enhanced the effects of climate change on annual SURQ, LATQ, GWQ, WYLD, and PERC of the basin. Under spatial scale, when the temperature and precipitation changed simultaneously, the increase of precipitation could promote the increase of annual ET in sub-watersheds. Also, the annual SURQ, WYLD, GWQ and ET in western sub-watersheds were more sensitive to the cumulative changes of vegetation and climate. This work can provide useful information to decision makers in water resource management of watersheds. • A SWAT-based model was established for a multi-level simulation. • Response of hydrological process to a climate-driven vegetation change was explored. • Effect of climate and vegetation changes on hydrological process was quantified. [ABSTRACT FROM AUTHOR]

Traditional blue water resources assessment and management may not meet the needs of sustainable water resource utilization; ignoring the number of green water resources will underestimate the availability of water resources. To rationally allocate and scientifically manage the limited water resources, it is necessary to divide the rich and poor flow situation of blue water and green water. The MIKE SHE-MIKE HYDRO integrated coupled model was selected and used in the Yalong River basin to ascertain the blue and green water in the hydrological cycle. The model was calibrated by matching simulated discharge against observed streamflow discharge at the Tongziling Station. At the same time, the research analyzed the component of green water and the total amount of blue water or green water on a temporal scale. The set pair analysis (SPA) was introduced to classify blue water and green water, which can not only understand the amount and distribution characteristics of water resources in the Yalong River Basin but also rationally allocate the total of water resources in the basin from the perspective of the regional water cycle. Furthermore, according to the situation of blue water and green water in the basin, the related policies are formulated to realize the efficient utilization of water resources in the Yalong River basin. • A high-resolution hydrological model of the Yalong river basin is bulit. • The MIKE SHE system as the modeling platform is used to obtain the variation of Bluewater and Greenwater. • The set pair analysis (SPA) was introduced to study the variation of rich and poor Bluewater and Greenwater. • Table Captions. [ABSTRACT FROM AUTHOR]

• The interactions of drivers on takeaway packaging waste generation in China were explored. • The nighttime economy has the largest driving effects. • The interaction between education level and millennial has inhibitory effects. • The interaction of driving factors should be considered in waste management. The growing food delivery industry has led to the emergence of takeaway packaging waste generation (TPWG) as a pressing environmental issue, particularly in China. Regional heterogeneity in socioeconomic development, population size, and geographical location results in large differences in the regional TPWG in China. This study explored the socioeconomic and environmental drivers of TPWG in 2018 and their interactions based on the geographical detector model. The results showed that socioeconomic factors (i.e., nighttime economy) had significant exacerbating effects, and their interactions further amplified the impacts on TPWG. The one-way effect of environmental factors was minimal; however, the effects were enhanced upon their interactions with socioeconomic factors (i.e., urbanization and gross domestic product (GDP) per capita). The interactions between education level and socioeconomic factors (i.e., percentage of millennial) reduced TPWG. By combining the spatial statistical analysis, this study provided a way of thought in exploring interactions (i.e., direction, strength, nonlinearity) between driving factors of TPWG. Results could provide decision-making basis for localized and targeted municipal waste management and packaging waste reduction. Inhibitory drivers and their decreasing interactions should be better taken into account in policymaking to provide novel insights for effective takeaway packaging waste management in China and other countries with fast-growing food delivery industries. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a hybrid method integrated unbiased grey model (UGM) and artificial neural network (ANN) into an interval two-stage fuzzy credibility-constrained programming (ITFCP) framework is proposed for water resources allocation of the Yalong River research area. Through the grey correlation analysis and the eXtreme Gradient Boosting (XGboost) algorithm, the economic and social indicators are related to the water demands of different water sectors in different regions can be obtained for building water demand prediction model. According to the unbiased grey prediction of the socio-economic development data of each region in the Yalong River Basin (YRB), water demand prediction models are constructed by using neural network. The establishment of a hybrid two-stage interval fuzzy credibility-constrained programming model can analyze the uncertainties existing in the process of water resources allocation. Taking 2020, 2025, and 2030 as the planning years, the developed model studies and reveals the system benefits at different credibility levels, the water shortage of each user in sub-regions and the water resources allocation situation to provide suggestion for managers to optimize the allocation of water resources. Compared to the previous methods, this integrated model can help decision-makers set management policies more sustainably and profitably. • A simulation-optimization method was developed. • The method represents a combination of unbiased grey model (UGM) and artificial neural network (ANN). • Interval two-stage fuzzy credibility-constrained programming was used as a general framework. • The developed method was applied to support water management in Yalong River Basin, China. [ABSTRACT FROM AUTHOR]

In this research, a hybrid nonlinear grey-prediction and quota allocation model (HNGP-QAM) was developed for supporting optimal planning of China's carbon intensity reduction at both departmental and provincial levels in 2020. At such dual levels, HNGP-QAM can not only help forecast carbon intensity and its fluctuations over the concerned period, but also facilitate the identification of China's carbon intensity reduction target in 2020 and the corresponding quotas for minimizing the total abatement cost. Two scenarios were developed based on multiple governmental policies and allocation schemes among provinces and departments. The results showed that the total abatement cost would be 92.07 and 98.93 × 10 9 , as well as 180.57 and 194.19 × 10 9 RMB (It is another shortname for China Yuan) for provincial and departmental allocation schemes under the reduction ratios of 40 and 45%, respectively. Furthermore, the west, the east, and the central China would be allocated the emission assignments that would be accounting for 48.53, 28.26, and 23.21% of the total national emission reduction, respectively. The obtained results were particularly useful for multi-level governments in providing information to identify the carbon intensity reduction target, conducting emission reduction assignments among provinces and departments, as well as supporting relevant policy-making. The results also suggested that the developed HNGP-QAM be applicable to similar engineering and planning problems. [ABSTRACT FROM AUTHOR]

• A model for quantifying life-cycle GHG emissions of PS, PVC, and ABS was developed. • The P stage of PS, PVC, and ABS is the main source of GHG emissions in 2007-2017. • The key paths of GHG emissions are the PM process of PS, PVC, ABS STP&C and PVC film. • Under optimal mitigation strategies, the carbon peak would be achieved before 2030. The plastic industry is a high carbon emission industry in China. Previous studies mainly focused on the flows and stocks of polystyrene (PS), polyvinyl chloride (PVC), and acrylonitrile-butadiene-styrene (ABS) plastics. However, there is limited detailed information on the GHG emissions of PS, PVC, and ABS in China and the key paths of carbon peak in 2030. Therefore, we established the GHG accounting model of PS, PVC, and ABS based on dynamic material flow analysis and life cycle assessment, and further analyzed the carbon peak path and strategy in 2030. The results show that the main source of GHG is the production and manufacturing stages. Notably, the key paths of GHG emissions are the manufacturing process of PS STP&C and foam plastics, PVC film and STP&C, and ABS STP&C. Moreover, the cumulative GHG emissions of these plastics reached 230.34, 677.43, 143.12 Tg CO 2 e in 2007-2017, respectively. From 2007 to 2017, the trends of GHG emissions from the PS, PVC, and ABS had their characteristics. PVC had the largest GHG emissions. Different from PVC and ABS, GHG emissions from PS showed a trend of slow rise and then slow decline in this period. According to the current trend, the life-cycle GHG emissions of PS, PVC, and ABS would not reach the carbon peak in 2030. Under some mitigation strategies, the carbon peak would be achieved before 2030. This study clarifies the main sources of life-cycle GHG emissions of these plastics, and reveals the path and strategy of carbon peak in 2030. [Display omitted] [ABSTRACT FROM AUTHOR]

To facilitate regional water resources allocation, an integrated bi-level multi-objective programming (IBMP) model with dual random fuzzy variables was developed in this research The proposed model was derived through incorporating dual random fuzzy variables, multi-objective programming, and interval parameter programming within a bi-level optimization framework. This approach improved upon the previous bi-level programming methods and had two advantages. Firstly, it was capable of reflecting tradeoffs among multiple conflict preferences for water related bi-level hierarchical decision-making processes. Secondly, random fuzzy variables were used to tackle the dual uncertainties in both sides of the constraints, which were characterize as probability density functions and discrete intervals. Then, a real-world water resources planning problem was employed for illustrating feasibility of the application of IBMP model in Dongjiang river watershed of south China. Results reflected the alternative decisions for water allocation schemes under a set of probability levels and fuzzy α - cut levels, which can support in-depth analysis of tradeoffs among multiple levels and objective values. Moreover, modeling comparison analysis was undertaken to illustrate the performances of the proposed model. [Display omitted] • Dual-randomness bi-level interval multi-objective programming was developed; • Multi-objective, chance-constrained, and interval parameter programming approaches were used; • Interactions between multiple decision-makers can be addressed through hierarchical strategies; • Uncertain information can be expressed as interval and probability density functions; • Water allocation schemes under multiple constraint-violated levels can be handled. [ABSTRACT FROM AUTHOR]

In the upper reach of the Yangtze River Basin in China, changes of the runoff and sediment yield in the middle reach of the Jinsha River Basin have been given close attentions because of their declination trends over recent years. Then, the impact factors for the variations of runoff and sediment yield were urgent need to be investigated through a distributed hydrological modelling under multi spatiotemporal scales. The results showed that climate change had a significant impact on runoff and sediment yield of the basin before the operation of cascade reservoirs. The contribution rate of the reservoirs operation to the reduction of the annual runoff and sediment yield in the watershed was 48.90% and 28.75% respectively. The Ludila reservoir played an important role in reducing annual runoff and sediment yield of the basin. The location of reservoirs with the sequence of Ludila, Longkaikou, Jin'anqiao, and Ahai from upstream to downstream had the greatest effect on the annual sediment yield of the basin. The function of multiple reservoirs on the monthly runoff and sediment yield of the basin was not the superposition of a single one. Under the simultaneous change of temperature and precipitation, the precipitation had a greater impact on runoff and sediment yield of the basin than temperature. Spatially, the annual runoff and sediment yield in the middle and upper reaches of the basin were sensitive to changes of temperature and precipitation. This research provides scientific support for management of water and sediment resources in watersheds with cascade reservoirs. • The response of runoff and sediment yield (RSY) was assessed under multi scales. • The impact of reservoir scale on RSY was not superimposed. • The impact of temperature and precipitation on annual RSY was spatially different. [ABSTRACT FROM AUTHOR]

• The influence mechanism of discharge variation on NEP was explored in the PRE. • Low GPP and high ER caused lowest NEP rate at Humen with largest discharge. • Restriction of discharge increase on NEP exceeded stimulation of seasonal factors. • High discharge intensified low NEP, hypoxia and acidification at three outlets. Clarifying the influence of hydrological variations on ecological function is a topic of considerable interest in watershed ecological flow assessment and water resource management. Net ecosystem productivity (NEP) is a useful composite indicator of ecosystem function, reflecting material cycling and energy flow. However, the effects of hydrological variations on NEP, especially the influence mechanism, remain unclear due to the complex environmental characteristics in estuaries. We analysed the spatial–temporal variability of the aquatic environment and NEP through in-situ monitoring and field sampling from December 2018 to January 2020 at three outlets (Humen, Jiaomen, and Hongqimen) with different hydrological conditions in the Pearl River Estuary (PRE), China, and explored the influence mechanism of hydrological variation on NEP. The 155 groups of effective metabolism values were estimated using Odum's open-water method. The daily ecosystem respiration (ER) was higher than the gross primary production (GPP); therefore, water bodies were dominated by net heterotrophy at the three outlets. The daily NEP (–4.34 ± 1.40 mg O 2 L–1d–1), O 2 concentration (5.2 ± 1.02 mg L–1), and pH (7.53±0.24) were lowest at Humen, which also had the largest discharge and tide volume, deepest water depth, and widest channel. Seasonally, the NEP in the summer (–3.30 ± 1.39 mg O 2 L–1d–1) and autumn (–3.19 ± 1.60 mg O 2 L–1d–1) was lower than those in the spring (–1.56 ± 1.92 mg O 2 L–1d–1) and winter (–2.17 ± 1.50 mg O 2 L–1d–1). The inhibitory effect of increased discharge on the metabolic rate exceeded the stimulation provided by seasonal factors, such as increased temperature and solar radiation. The scour and dilution effect caused by discharge increase reduced chlorophyll a concentration; meanwhile, the increase in turbidity resulted in a decrease in the photosynthetic rate and GPP. ER was stimulated by heterotrophic microorganisms and high total suspended solids, resulting in a decrease in O 2 and endogenous organics, thus causing the low NEP, hypoxia, and acidification phenomenon. Our results suggest that lengthening the discharge pulse period in summer and autumn will further decrease NEP and increase the area of hypoxia and acidification at the three outlets in the PRE. [Display omitted] [ABSTRACT FROM AUTHOR]

Cities consume most of the global energy and account for approximately 75% of global CO 2 emissions. Moreover, resource-based cities tend to consume higher amounts of fossil fuel and produce higher carbon emissions than other cities, whereas there are still insufficiencies about energy carbon reduction in resource-based cities in developed urban agglomerations. Therefore, it is necessary to explore the energy planning of such cities to achieve carbon peaking and carbon neutrality, and this is crucial for achieving carbon neutrality in urban agglomerations. This study aims to apply a scenario-based analysis approach to a resource-based heavy industrial city in China, Tangshan, based on the Long-range Energy Alternative Planning model, to explore Tangshan's future energy consumption, generation, and associated carbon emissions from 2010 to 2050. The impacts of different energy policies are analyzed for the Tangshan energy system by considering four scenarios. Under each scenario, energy consumption increased steadily by 2050, but the growth rate is different. The business as usual scenario is the fastest, and the low-carbon scenario is the slowest. In the comprehensive and integrated low-carbon transition scenarios, CO 2 is expected to peak at 298.34 million tons (Mt) in 2028. The main industrial sectors of Tangshan with high output value, high energy consumption, and high carbon emissions include smelting and pressing of ferrous metals, petroleum processing and coking, raw chemical materials and chemical products, etc. Combining Tangshan's coal resource endowment, the development of renewable energy, and introducing advanced technology can effectively reduce carbon emissions and increase the diversity of energy supply. We analyzed the cost-benefit of the energy system and found that the implementation of carbon capture and storage technology could effectively reduce carbon emissions by 219.62 Mt and increased costs by 563.12 billion yuan. The research could provide a scientific basis for the medium and long-term energy sustainable transformation of resource-based cities, especially for resource-based cities in urban agglomerations. [ABSTRACT FROM AUTHOR]

• An integrated modeling approach is developed. • Multiple modeling methods were combined. • The approach is applied in a City Cluster of China. • Coordination for WEF and economy is analyzed under multiple scenarios. In this research, an integrated approach is developed through the incorporation of systems dynamics (SD), catastrophe progression (CP), and coupled coordination degree (CCD) analysis within a general modelling framework. The developed SD-CP-CCD is then employed to simulate and evaluate relationships among the water-energy-food (WEF) and the economic systems. It will improve traditional methods for WEF nexus analysis through a) incorporating urban WEF connections and changes into the cross-system coupling analysis framework, b) evaluating its coordination with economic growth and a multi-scale and regional disparity, and c) promoting policy recommendations to ensure the guarantee of urban WEF under economic growth. The approach is then verified through WEF nexus system of Urban Agglomerations of Pearl River Delta City Cluster (PRDCC) in China. Temporal and spatial characteristics of CCD in the region were analyzed. The results revealed their performance in cities with multiple economic backgrounds. Also, the fragile factors of each city were reflected by multi-scale exploration. Regional inequality and spatial agglomeration effects were considered. The results showed that CCD has noticeable temporal and spatial differences. Geographically, CCD varied from uncoordinated to high-level coordination. The eastern cities were much better coordinated than the western cities. Due to the increasing pressure of population and economic growth in the future, the upward trend of CCD would occur in most cities. The vulnerability factors of each city were explored. Simultaneously, apparent spatial inequality and agglomeration patterns were observed, with a downward trend over time. The temporal and spatial patterns of CCD revealed in this study indicated that PRDCC policymakers should formulate policies that suit the characteristics of cities and reduce the targeted regional imbalances. [ABSTRACT FROM AUTHOR]

Climate and land use changes have substantially affected hydrologic cycles and increased the risk of drought. Reservoirs are one of the important means to provide resilience against hydrologic variability and achieve sustainable water management. Therefore, adaptive reservoir operating rules are needed to mitigate their adverse effects. In this study, the Hanjiang River Basin in southeast China was selected as the study area. Future climate and land use projections were produced by the Delta method and CA-Markov model, respectively. Future climate forcings and land use patterns were then incorporated into a distributed hydrologic model to evaluate river flow regime shifts. Results revealed that climate and land use changes may lead to severe drought conditions in the future. Lower flows are shown to be more sensitive to environmental changes and a decline of monthly flows could reach up to nearly 30% in the dry season. To address the threat of increasing drought uncertainties in the water supply system, the aggregation-decomposition method incorporated with hedging rules was applied to guide the multi-reservoir operation. Parameters of optimal hedging rules were obtained by a multi-objective optimization algorithm. The performance of hedging rules was evaluated by comparison to standard operating policies and conventional operating rules with respect to reliability, resiliency, vulnerability, and sustainability indices. Results showed that the multi-reservoir system guided by hedging rules can be more adaptive to the environmental changes. [ABSTRACT FROM AUTHOR]

• Groundwater supply and effective hydraulic conductivity in channel had synergistic effects on streamflow with the highest weight among the parameter combination. • Baseflow recession factor was relatively at the center of parameter network, indicating wider relationships with other parameters. • The most commonly modified SCS-CN curve method related parameter was less applicable to YLRB with adequate available surface water. • SUFI-2 and PSO could achieve better fitting and uncertainty efficiency than GLUE algorithm. Semi-distributed model based on spatial information is effective for simulating hydrologic cycle. However, it cannot completely simulate all relevant natural processes. Uncertainty analysis is necessary for achieving high accuracy of hydrological modelling. In this study, optimization algorithms and weighted network analysis techniques were adopted to explore hydrological parameter combination characteristics as well as hydrological simulating uncertainties in Yalong River Basin (YLRB) of southwestern China based on Sequential Uncertainty Fitting version 2 (SUFI-2), Generalized Likelihood Uncertainty Estimation (GLUE) and Particle Swarm Optimization (PSO). The results indicated that: a) groundwater recession factor, effective hydraulic conductivity in channel and saturated hydraulic conductivity could significantly affect streamflow in the studying basin, b) complex parameter combination responded diversely under aforementioned three optimization algorithms. Comparatively, GLUE brought out higher autocorrelation parameter network and c) SUFI-2 and PSO performed better in terms of effective uncertainty analysis and fitting values than those of GLUE. This work could provide references and insights for sensitive parameter modification and prediction uncertainty reduction of streamflow simulation, furthermore contributing to an optimal water resource management. [ABSTRACT FROM AUTHOR]

Modern agriculture calls for efficient and environmental-friendly agricultural water and land management practice. Agricultural water and land utilization mode has a great impact on the amount of carbon emissions, and thus the aim of this work is to propose an optimal modeling approach for generating efficient agricultural water and land management alternatives and reducing carbon emission in agricultural water-energy-food nexus system. This study presents a novel approach consisting of carbon footprint lifecycle assessment method and bi-level multi-objective stochastic programming model. The proposed approach has contributions in following aspects: (1) the environmental impact of different resource allocation strategies can be measured in optimization (2) the spatial variability of spatial data (e.g., ET 0 and precipitation); can be fully reflected via remote sensing information; (3) tradeoffs among two decision-making levels and their conflicting objectives under randomness of surface water availability can be addressed. The proposed approach was applied to the middle reaches of the Heihe River basin, northwest China. After solving the proposed model, the optimal water and land use alternatives under different hydrological years can be generated. Decision makers can plan agricultural production strategy according to optimization schemes, and reduce carbon emission through increasing vegetable cultivation and surface water utilization. Furthermore, the performance comparison of different models indicated that fierce conflicts exist between income fairness and economic benefits. The comprehensive evaluation value of bi-level multi-objective stochastic programming model is 0.7036, which is highest among single- and multi-objective models, showing that such model has obvious advantage in dealing with multiple decision-making levels and conflicting objectives. This approach can help decision makers of similar regions manage the agricultural production system in a more efficient and environment-friendly way. [Display omitted] • Lifecycle assessment of carbon footprint was used for measuring environmental impacts. • Spatial data (e.g. ET 0 and precipitation) were collected and processed with the help of remote sensing information. • Vegetable cultivation increasing and groundwater use decreasing can help reduce carbon emission in agricultural production. • BLMOSP model has obvious advantage among single- and multi-objective models for addressing such problems. [ABSTRACT FROM AUTHOR]

The pursuit of the sustainable agriculture often ignores to consider the ecological benefits. To achieve this goal, it is necessary to evaluate the ecological impacts related to the sustainable development. Therefore, to assess the overall ecological impact of crop production in 31 provinces in China, this study proposes to set up a non-monetary framework and indicators based on Emergy theory. Further analysis focuses on sustainable ecosystem under three different planting scenarios to identify the driving factors. The results demonstrated that the ecosystem disservice of crop production processes is greater than the services. The total emergy inputs, fertilizers used and R%, all of these can affect the ecological benefits. Furthermore, simply changing the cultivation pattern cannot achieve a balance between ecology and economy, there is no doubt that other method needed are needed. These findings provide valuable insights for developing appropriate policies for decision makers. • Establishing a framework to calculate the agri-ecosystem services and dis-services. • Analyzing the ecological benefits of crop system in the three different scenarios. • Building three emergy-based ecosystem service indicators to assess the crop system. • Proposing some feasible advices from ecological benefits perspective. [ABSTRACT FROM AUTHOR]

• Study area was representative of the hilly and gully region of the Loess Plateau. • InVEST model and logistic regression model were jointly used. • Spatially explicit methods to study the relationship of ESS were developed. • Hotspots and coldspots were determined by overlaying and summing maps of each ESS. • Win-win areas were identified by the balanced water yield and sediment retention. Although the quantification and evaluation of ecosystem services has been discussed on the Loess Plateau of China, few studies have specifically focused on quantifying the ecosystem services of trade-off and finding win-win areas. Based on previous studies about the evaluation of ecosystem services, we proposed a comprehensive spatial analysis method based on the InVEST and CASA models to analyse the spatial interaction between the four ecosystem services of water yield, sediment retention, NPP and habitat quality in the study area. The results showed that soil retention, NPP, and habitat quality gradually increased from 2000 to 2010 as water yield increased. Relationships among sediment retention, NPP and habitat quality were synergistic, but trade-off occurred between those three ecosystem services and water yield. Hotspots accounted for 3.27% of the basin, and these areas were mainly located in the downstream area of the basin and coincided with the forest and grassland areas. Coldspots accounted for 3.64% of the basin and were mainly in line with the upstream area and the urban road area in the basin. Win-win areas only accounted for 1.6% of the basin. The existence of win-win zones was positively correlated with soil silt content and was negatively correlated with distance to grassland, distance to forest, soil erodibility and slope. This research may be helpful for managing water resources and the sustainable development of the basin on the Loess Plateau of China. [ABSTRACT FROM AUTHOR]

In this research, a dual-randomness bi-level interval multi-objective programming (DR-BIMP) model was developed for supporting water resources management among multiple water sectors under complexities and uncertainties. Techniques of bi-level multi-objective programming (BMOP), double-sided stochastic chance-constrained programming (DSCCP), and interval parameter programming (IPP) were incorporated into an integrated modeling framework to achieve comprehensive consideration of the complexities and uncertainties of water resources management systems. The DR-BIMP model can not only effectively deal with the interactive effects between multiple decision-makers in complex water management systems through the bi-level hierarchical strategies, but also can characterize the multiple uncertainties information expressed as interval format and probability density functions. It could thus improve upon the existing bi-level multi-objective programming through addressing discrete interval parameters and dual-randomness problems in optimization processes simultaneously. Then, the developed model was applied to a real-world case to optimally allocate water resources among three different water sectors in five sub-regions in the Dongjiang River basin, south China. The results of the model include determining values, interval values, and stochastic distribution information, which can assist bi-level decision-makers to plan future resources effectively to some extent. After comparing the variations of results, it is found that an increasing probability level can lead to higher system benefits, which is increased from [20,786.00, 26,425.92] × 108 CNY to [22,290.84, 27,492.57] × 108 CNY, while the Gini value is reduced from [0.365, 0.446] to [0.345, 0.405]. A set of increased probability levels gives rise to the lower-level objectives. Furthermore, the advantages of the DR-BIMP model were highlighted by comparing with the other models originated from the developed model. The comparison results indicated that the DR-BIMP model was a valuable tool for generating a range of decision alternatives and thus assists the bi-level decision-makers to identify the desired water resources allocation schemes under multiple scenarios. [Display omitted] • A dual-randomness bi-level interval multi-objective programming model was developed; • Interactions between multiple decision-makers can be addressed through bi-level hierarchical strategies; • Uncertain information associated with water can be expressed as interval and probability density functions; • Water resource allocation schemes under multiple constraint violated probability levels can be handled. [ABSTRACT FROM AUTHOR]

Carbon-reduction policy affects socio-economy and Water-Energy-Food (WEF) nexus contained therein. Existing studies concentrated on policy performances on resource consumption, but cannot quantify the impacts on resource utilization efficiency. To fulfill such gap, this study developed an integrated evaluation method through integrating computable general equilibrium model with data envelopment analysis to explore the impact of carbon tax on WEF environmental efficiency of China. Results show that increasing carbon taxes would improve the energy structure and reduce carbon emissions. While the increased cost of fossil fuels would have negative but limited impacts on economic output of water supply and food sectors through economic activity connections. Synergistic effect of WEF resource conservation could be observed in most production sectors, expect for clean energy sectors. Carbon tax would improve the WEF environmental efficiency expressed as the trade-offs between economic and carbon emission outputs and WEF resource inputs. There are significant differences in WEF efficiency and its growth rate among production sectors, with food sectors experiencing the most significant improvement in WEF efficiency at a carbon tax of 70 yuan/ton. The evaluation results raised the awareness of the performance of carbon tax on WEF nexus and provide a new perspective for promoting WEF nexus efficiency. • An integrated evaluation approach is developed with the combination of CGE and DEA models. • This method can assess the impacts of carbon tax policy on WEF environmental efficiency. • Carbon tax improves energy structure, but negatively affects water and food sectors' economic output. • Synergistic effects of WEF resource conservation exist in most production sectors. • Carbon tax would improve both the national and the sectoral WEF environmental efficiency. [ABSTRACT FROM AUTHOR]

• We calculate the effect of an impounded reservoir in China on evapotranspiration and the evaporative ratio. • The dam has increased evapotranspiration and the evaporative ratio in the smallest subbasin holding the reservoir. • This increase cannot be explained by other changes in land use or vegetation. • Our hydrological basin-constrained approach estimates the water footprint of the hydroelectric project to be 16.5 m3/GJ. Water management by the impoundment of reservoirs has been found to influence evapotranspiration not only locally but also at the basin scale. Highly regulated hydrological basins generally show the effect of a net increase in evapotranspiration accompanying the successive impoundment of reservoirs. However, understanding and isolating the effect from a particular single impounded reservoir remains a challenge due to the lack of long-term observation data required and the existence of many other drivers present at the basin scale. Focusing on the hydrological basin having the largest hydropower potential in China, we isolated in time and space and quantified the effects of a single impounded reservoir on evapotranspiration and the evaporative ratio (i.e., the ratio of actual evapotranspiration to precipitation) before and after the construction of the Ertan Dam in 1998. We find that the dam has increased evapotranspiration in the smallest subbasin by 46±15 mm/yr and the evaporative ratio by 0.05±0.015, from the period before impoundment (1983-1997) to that after impoundment (2000-2012). This increase is found only within the smallest differential subbasin holding the impounded reservoir and cannot be explained by other changes in land use or vegetation. We use this result from our hydrological basin-constrained approach to calculate the water footprint of the hydroelectric project as 16.5 m3/GJ, which accounts for additional hydroclimatic effects of the impoundment of the reservoir beyond the water surface. Hence, this study finds that when runoff data is available, the water consumption and the water footprint of hydropower projects can be calculated by water mass balance at the scale of their hydrological basins. [ABSTRACT FROM AUTHOR]

• An interval two-stage fuzzy credibility constraint programming (ITSFCCP) method was proposed. • Multiple uncertainties can be tackled for the social and natural complexities of the water resources system. • The model was demonstrated in the city of China and Myanmar. • The research scope and research factors (water environmental pollution factors) need to further expanded. In this paper, an interval two-stage fuzzy credibility constraint programming (ITSFCCP) method is proposed to deal with multiple uncertainties that can be expressed as fuzzy sets, discrete intervals and probability distributions, which can be used for effectively reflect natural and social complexities of relevant decision-making processes. Lincang city of Yunnan province, which is located in the southwest border of China, is employed as the demonstrative case. It is a frontier window and an important channel for China to face the "radiation center" of Southeast and South Asia. Also, it is the intersection of the Tropic of Cancer and the Geographic Water Distribution Line between the Pacific and Indian Oceans. The city's water resources system is particularly unique due to its connection with Myanmar. Considering multiple uncertainties and complexities of the existing water resources system in the city, ITSFCCP is developed to optimize the allocation of water resources. The objective function of the model is the maximization of economic benefits of the water resources system. Fuzzy sets, discrete intervals and probability distribution were introduced to represent the multiple uncertainties associated with the natural and social complexities. Credibility levels were adopted to solve the complexity of multi-ethnic human society in Lincang. The results showed that the model could effectively deal with the uncertainties and complexities of Lincang's water resources system, and reflect the trade-offs between the system benefits and risks. [ABSTRACT FROM AUTHOR]

• We investigate the impacts of interregional trade on improved GWF in China. • Compared with traditional GWF, improved GWF of Chinese regions decreases by 19-35%. • Up to 35% of China's improved GWF is embodied in interregional trade. • Beijing-Tianjin and coastal regions outsource GWF to central and northern regions. • This study provides more accurate results for water resource conservation in China. Grey water footprint (GWF) is an essential indicator describing the effects of aquatic pollutants on water quantity, which is significantly influenced by interregional trade. Existing studies on the impacts of interregional trade on GWF in China have deviations. That is, traditional GWF is determined by the pollutant with the highest pollutant-specific GWF, but overlooks the influences of coexisting compounds. Coexisting compounds have large influences on GWF quantification. However, the impacts of interregional trade on the improved GWF in China have not been well characterized. This study integrates the multi-regional input-output analysis and an improved GWF quantification method considering multiple pollutants, to investigate the impacts of interregional trade on the GWF in China. Compared with traditional GWF, the improved GWF of Chinese regions decreases by 19-35%. Up to 35% of China's improved GWF is related to commodities that are produced outside of regions where they are finally consumed. Beijing-Tianjin and coastal regions outsource GWF to the central and northern regions. Sectors contributing the most to GWF outsourcing include corn, cattle, swine, poultry, and other animal husbandry. This study provides more accurate region-specific and sector-specific results for policy decisions on water resource conservation in China. [ABSTRACT FROM AUTHOR]

The relationship between climate and forest is critical to understanding the influence of future climate change on terrestrial ecosystems. Research on trees at high elevations has uncovered the relationship in the Hengduan Mountains region, a critical biodiversity hotspot area in southwestern China. The relationship for the area at low elevations below 2800 m a.s.l. in the region remains unclear. In this study, we developed tree ring width chronologies of Pinus yunnanensis Franch. at five sites with elevations of 1170–1725 m in this area. Monthly precipitation, relative humidity, maximum/mean/minimum air temperature and the standardized precipitation evapotranspiration index (SPEI), a drought indicator with a multi-timescale, were used to investigate the radial growth-climate relationship. Results show that the growth of P. yunnanensis at different sites has a similar response pattern to climate variation. Relative humidity, precipitation, and air temperature in the dry season, especially in its last month (May), are critical to the radial growth of trees. Supplemental precipitation amounts and reduced mean or maximum air temperature can promote tree growth. The high correlations between chronologies and SPEI indicate that the radial growth of trees at the low elevations of the region is significantly limited by the moisture availability. Precipitation in the last month of the previous wet season determines the drought regime in the following dry seasons. In spite of some differences in the magnitudes of correlations in the low-elevation area of the Hengduan Mountains region, chronologies generally matched well with each other at different elevations, and the differences are not evident with the change in elevation. [ABSTRACT FROM AUTHOR]

• An integrated model was developed for identifying cost-effective strategies. • Effectiveness and costs of multiple pollution mitigation measures can be optimized. • The model has advantages in tackling practical problems with computational efficiency. • The developed model was used in Shiwuli River basin, Hefei city, south China. In water pollution control of urban river basins, one major issue is to reduce water pollutants at the least costs. In this research, an integrated hydrodynamic-water quality simulation-based multi-response surface method was proposed to help optimize mitigation measures on water quality rehabilitation in Shiwuli River basin of Hefei City, China. Initially, multi-response surface method (MRSM) with two-levels and two responses, i.e., cost-effectiveness ratio (CER) and water quality standard-reaching rate (WQSR) were designed where the factors of interests include the point source reducing rate (i.e., Factor A), the non-point source reducing rate (i.e., Factor B) and water transfer (i.e., Factor C). Then a hydrodynamic-water quality model was developed to predict water quality effects of the proposed combined factors. At the same time, the cost functions were established to estimate economic costs of the combined factors. Lastly, the analysis of variance (ANOVA) and multiple regression analysis (MRA) were employed to help gain some new cognition in the statistically significant way. The obtained model revealed that Factor A and B were significant for both CER and WQSR. This means that in the study area, pollution source reduction is more important than water transfer. Though the optimal minimal CER was obtainable with 0.1493 (M$ per percentage) when the pointing source reducing rate is 77.9%, the non-point source reducing rate is 40% and the water transfer was controlled at a low level, respectively, with water quality standard-reaching rate 70.7%. It fails to achieve water quality objectives (WQSR ≥ 90.0%). Moreover, In order to meet water quality target, simultaneous optimization of two objective functions: minimal CER and maximal WQSR was achievable with the optimum value of 90% for WQSR and 0.1810 (M$ per percentage) for CER ,respectively, with the pointing source reducing rate (90.0%), the non-point source reducing rate (57.2%) and the water transfer at a low level. It provided an alternative simulation–optimization method for decision of water pollution control which had the advantages in reflecting the real water environment system and simplifying the algorithm compared to the conventional mathematical programming at the watershed scale. [ABSTRACT FROM AUTHOR]

Multiple correlated risks caused by uncertain information pose great challenges to the coordinated regulation of water-energy-food nexus (WEFN). In this study, a Copula-based radial interval chance-constrained programming (CRICP) was developed. CRICP can not only quantify composite risk induced by multiple risks with nonlinear correlations, but also tackle dual uncertainty expressed as redial intervals with adjustable protection levels. CRICP was applied to an irrigated agricultural management problem constrained by water, energy, and land resource in Bayan Nur City in northern China. Results indicate that system benefit would increase with the incline of composite risk or the decline of protection level. Monte Carlo simulation verified that the different definitions of composite risk could lead to significant differences in the combination of subsystem risks. The composite risk induced by the simultaneous shortage of multiple resources would have greater impacts on system benefits compared against composite risk caused by shortage of at least one resources, with an increase of [24.65%, 25.95%] in the minimum value of system benefits. Comparisons against two alternative models further verified that CRICP outweighs previous methods by modeling the correlation structure of multiple risks and tackling dual uncertainties without distribution information. • The complex interactions and inherent uncertainty affect the security of Water-Energy-Food Nexus. • A Copula-based radial interval chance-constrained programming method was developed. • It can tackle composite risk induced by random variables with unknown correlations. • It can also address dual uncertainties without detailed distributions. • The bias in decision making process triggered different composite risks were clarified. [ABSTRACT FROM AUTHOR]

As alternatives for legacy brominated flame retardants, novel brominated flame retardants (NBFRs) have a wide array of applications in the electronic and electrical fields. The shift of recycling modes of electronic and electrical waste (e-waste) from informal recycling family workshop to formal recycling facilities might come with the change the chemical landscape emitted including NBFRs, however, little information is known about this topic. This study investigated the occurrence characteristics, distribution, and exposure profiles of eight common NBFRs and their derivatives in an e-waste recycling industrial park in central China and illustrated the differences in various functional zones in the recycling park. The highest level of ΣNBFRs in dust samples was found in e-waste storage area at median concentration of 27,400 ng/g, followed by e-waste dismantling workshops (23,300 ng/g), workshop outdoor area (7770 ng/g), and residential area outdoor (536 ng/g). In the e-waste dismantling associated dust samples, tetrabromobisphenol A bis(2,3-dibromopropyl ether) (TBBPA-BDBPE), tetrabromobisphenol A (TBBPA) and 2,4,6-tris(2,4,6-tribromophenoxy)-1,3,5-triazine (TTBP-TAZ) were the predominant components. This paper presented the first evidence regarding the occurrence characteristic and distribution of tetrabromobisphenol S (TBBPS), tetrabromobisphenol A bismethyl ether (TBBPA-BME) and tetrabromobisphenol S bis(2,3-dibromopropyl ether) (TBBPS-BDBPE) in the e-waste associated dust samples. By comparing with previous studies performed in China, this paper also noticed the significant decrease of TBBPA concentrations in the dust probably due to the shift of e-wastes sources and recycling modes. We further assessed the risk of occupational workers exposure to NBFRs. The median E DI (estimated daily intake) value of ΣNBFRs among e-waste dismantling workers was 9.71 ng/kg BW/d with the maximum E DI value being 19.6 ng/kg BW/d, hundreds of times higher than those exposed by general population. The study raises great concern for the health risk of occupational exposure to NBFRs in the e-waste recycling industrial park. • TBBPA-BDBPE, TBBPA, and TTBP-TAZ were detected at high levels in the dust from various functional zones in the e-waste recycling industrial park. • TBBPS, TBBPA-BME and TBBPS-BDBPE were also found in the dust samples from the e-waste recycling industrial park. • The risk of occupational and general dust exposure to the eight NBFRs were assessed. • Exposure doses of occupational workers to NBFRs were significantly higher than general population. [ABSTRACT FROM AUTHOR]

Highlights • A hybrid game theory and mathematical programming model was developed; • Initial rights of water and pollutant discharge among jurisdictions can be allocated; • The developed approach was used to solve real-world trans-boundary water conflicts; • The studying case is Guanting reservoir basin of Beijing, north China. Abstract In this research, a hybrid game theory and mathematical programming model (HGT-MPM) is proposed for solving trans-boundary water conflicts in Guanting reservoir basin (GRB) between two cities (i.e., Zhangjiakou and Beijing) in north China. A water allocation model, which considers both water quality and quantity, is developed for optimizing water use and pollutant discharge in the two cities, maximizing the net aggregate benefits from these activities and reducing the costs for water supply and pollution removal. The initial rights of water use and pollutant discharge are allocated to the cities of Beijing and Zhangjiakou, as two players based on the incorporation of a negotiation method for ill-defined water rights within the watershed. At this stage, equal treatment of every player's benefit claim can be addressed. The strategy spaces of the two players are delineated through solving the proposed HGT-MPM with mutual benefit claim constraints. The Rubinstein bargaining solution method is employed to identify the equilibrium of bargaining. To achieve maximal benefits for the two players, starting from allocating the results of the second step, the concepts of Core and Nash solutions of cooperative games are used to generate stable basin-wide cooperative solutions. Both players find it beneficial to cooperate with side payment from the downstream to upstream. At this stage, the principle of maximum economic benefits is mainly considered. The results indicate that unclear initial water rights and pollutant discharge rights can be fairly defined through bilateral negotiations between upstream and downstream. Without side payment, the initial water rights and pollutant discharge allocation will be the final outcome, which is suboptimal, although it is better than the status quo in term of both total and individual benefits. Full cooperation with side payment leads to the greatest total net benefits and the greatest benefits to each individual city. The results not only provide a basis to allocate trans-jurisdictional water rights and pollutant discharge rights in an equal and efficient way but also provide certain inspirations for management policy improvement, such as establishing a water right trading system. [ABSTRACT FROM AUTHOR]

Reservoir operation policies affect reservoir nitrogen (N) cycling and budgets through complex influences on physical and biogeochemical processes in water and sediment. However, the underlying influencing mechanisms, especially the impact of operations on sediment processes, remain unclear. This study combines a coupled hydrodynamic-eutrophication-sediment model and a reservoir operation model to clarify reservoir operation impact on N cycling processes in water and sediment as well as impact on stored and discharged water quality. Three typical reservoir operation policies (i.e., standard, hedging, and eco-friendly) were selected to create operation scenarios. The hydrodynamic-eutrophication-sediment model was used to simulate N cycling processes and N concentrations in stored and discharged water under each scenario. Using China's Danjiangkou Reservoir as a case study, results revealed that reservoir operation policies significantly affected spatiotemporal dynamics of N cycling processes and water quality. Specifically, reservoir sediment acted as a N source, contributing to annual net release of 9.5–16.1 Gg N. Higher water levels promoted sediment ammonium release through effects on reservoir submerged area and sediment temperature. Moreover, denitrification processes in water and sediment collectively contributed to annual N removal of 14.0–16.9 Gg N. Annual N removal was greater in the higher water level scenario despite its lower denitrification rate per unit area. Additionally, these processes and hydrodynamic conditions combine to affect N forms and concentrations. The N concentration in the lower water level scenario was generally higher, risking algal bloom outbreaks in the shallow-water zone. This study is intended to help guide reservoir operation policymaking to account for N management while also coordinating water quantity and quality targets. • Spatiotemporal dynamics in N cycling processes and water quality are assessed. • Higher storage levels can promote sediment ammonia release in deep reservoirs. • Denitrification in water and sediment significantly contributes to N removal. • Tradeoffs exist between the quantity and quality of water released to downstream. [ABSTRACT FROM AUTHOR]