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Many studies have been conducted on environmental flow (e-flow) assessment and supply, but e-flow shortages remain common in many urban rivers. In addition to known reasons such as ever-increasing competition among water users and inadequate execution of designed e-flow supply plans, we propose that designing weir heights without explicitly considering e-flows is another major cause of this problem. In this paper, we suggest that the measures for satisfying e-flows be extended from the water supply stage to the river channel design stage. We establish a new weir height determination framework that would more effectively satisfy the required e-flows. The new framework differs from previous frameworks, in which flood control and water retention are the major concerns and the flow during floods is set as the inflow. In the new framework, e-flow provision and flow velocity maintenance are added concerns and the actual flows for e-flow supply are set as the inflow. As a case study of the new framework’s effectiveness, we applied it to the Shiwuli River, a typical channelized urban river in Hefei, China. The old framework specified too-high weir height to meet the e-flow requirements, whereas the new framework offered more reasonable heights that improved e-flow provision.

To achieve the Paris Agreement’s goals, many cities are building satellite cities to relieve the population and environment pressure of the central city. However, past experiences showed that long-term effects of such a solution were partially limited, due to limited attention on the effects of energy consumption and carbon emissions, depending on the dynamics of population and industrial development. This paper overcomes the previous limitations, applying a Long-range Energy Alternatives Planning model to the area of Xiong’an New District, an area extending from Hebei province (China) and nearby Beijing, is planned to support the development of Beijing. The proposed model was based on three different population migration, industrial and transposition scenarios to test their impacts on urban greenhouse gas (GHG) emissions. Results show that: (1) Increased population and building area will markedly increase GHG emissions from residential consumption in Hebei province, while slightly decrease GHG emissions in Beijing. (2) Green planning, including industrial structure changes, industrial transformation, will markedly decrease the GHG emissions in Hebei provinces and it can take down for the emissions increase due to the population migration. This paper proved the effectiveness of a multi-scalar, multi-dimensional, and multi-actor modeling approach for a satellite city and new town development planning, implying that a similar approach could be applied in planning and managing the development of future satellite cities.

Although groundwater (GW) potential zoning can be beneficial for water management, it is currently lacking in several places around the world, including Pakistan's Quetta Valley. Due to ever increasing population growth and industrial development, GW is being used indiscriminately all over the world. Recognizing the importance of GW potential for sustainable growth, this study used to 16 GW drive factors to evaluate their effectiveness by using six machine learning algorithms (MLA's) that include artificial neural networks (ANN), random forest (RF), support vector machine (SVM), K- Nearest Neighbor (KNN), Naïve Bayes (NB) and Extreme Gradient Boosting (XGBoost). The GW yield data were collected and divided into 70% for training and 30% for validation. The training data of GW yields were integrated into the MLA's along with the GW driver variables and the projected results were checked using the Receiver Operating Characteristic (ROC) curve and the validation data. Out of six ML algorithms, ROC curve showed that the XGBoost, RF and ANN models performed well with 98.3%, 96.8% and 93.5% accuracy respectively. In addition, the accuracy of the models was evaluated using the mean absolute error (MAE), root mean square error (RMSE), F-score and correlation-coefficient. Hydro-chemical data were evaluated, and the water quality index (WQI) was also calculated. The final GW productivity potential (GWPP) maps were created using the MLA's output and WQI as they identify the different classification zones that can be used by the government and other agenciesto locate new GW wells and provide a basis for water management in rocky terrain.

Assessing environmental flows (e-flows) for urban rivers is important for water resources planning and river protection. Many e-flow assessment methods have been established based on species’ habitat provision requirements and pollutant dilution requirements. To avoid flood risk, however, many urban rivers have been transformed into straight, trapezoidal-profiled concrete channels, leading to the disappearance of valuable species. With the construction of water pollution-control projects, pollutant inputs into rivers have been effectively controlled in some urban rivers. For these rivers, the e-flows determined by traditional methods will be very small, and will consequently lead to a low priority being given to river protection in future water resources allocation and management. To more effectively assess the e-flows of channelized urban rivers, we propose three e-flow degrees, according to longitudinal hydrological connectivity (high, medium, and low), in addition to the pollutant dilution water requirement determined by the mass-balance equation. In the high connectivity scenario, the intent is for the e-flows to maintain flow velocity, which can ensure the self-purification of rivers and reduce algal blooms; in the medium connectivity scenario, the intent is for the e-flows to permanently maintain the longitudinal hydrological connectivity of rivers that are isolated into several ponds by means of weirs, in order to ensure the exchange of material, energy, and information in rivers; and in the low connectivity scenario, the intent is for the e-flows to intermittently connect isolated ponds every few days (which is designed to further reduce e-flows). The proposed methods have been used in Shiwuli River, China, to demonstrate their effectiveness. The new methods can offer more precise and realistic e-flow results and can effectively direct the construction and management of e-flow supply projects. Keywords: Environmental flow, Urban river, Channelized rivers, River restoration

In order to provide effective measures for reclamation management and alleviate damages on ecosystems under multiple anthropologic interferences, quantification of coastal reclamation hydrodynamic disturbance (CRHD) and determination of the related threshold value of ecosystem are presented in this research. Eleven monitoring areas (approximately 1 km2 each) in Dongying Port of China are considered. Each monitoring areas were further divided into the affected and non-affected areas based on impact of coastal reclamation engineering by comparing the distribution of hydrodynamic disturbance. According to c the CRHD, which enhance quantification method in terms of (a) quantifying the CRHD for coastal environment under different types of coastal habitants, (b) developing the definition of hydrodynamic disturbance based on ecological threshold, and (c) prognosticating the distribution of IHD with the case study of Dongying port. As the results, IHD for most of affected area was 23.58% higher than that non-affected area in average. Also, CRHD was insensitive to sessile organisms’ growth, relatively sensitive to suspended organisms, and extremely sensitive to swimming organisms. The maximum ecological threshold value for sessile organisms was approximately 3.5, exceeding 45.32% and 38.83% actual intensity for the affected and non-affected areas, respectively. Also, the threshold value for suspended organisms was approximately 2.56, which was 3.55% less than that of the affected area. Comparatively, the threshold value for swimming organisms was approximately 2.05, which was 10.75% less than that of affected area. Therefore, it is not suitable to invest constructional project of coastal reclamation engineering at the northeast and northwest of Dongying port administrative regions. Overall, the quantitative modeling of CRHD is advantageous for policy maker to manage coastal reclamation engineering and protect aquatic biodiversity.

Scholars in environmental accounting have developed many methods, capable to transform raw environmental and socio-economic data into useful information, both to protect natural ecosystems and to define the most appropriate policy and planning options to meet the existing sustainable development goals. Due to the high number of existing research challenges and needs, Beijing Normal University organized a World Summit on Environmental Accounting and Management on “Designing A Prosperous and Sustainable Future”, which was held in Beijing on July 4–6, 2016. The main topic of the conference was the inclusion of system-wide effects into on-site environmental impacts, considering an integrated environmental accounting and management framework. The outcomes of this international summit, partially represented by the papers published in this Special Volume, provide an opportunity to assess the most recent progresses in biophysical and socioeconomic accounting, as well as in modelling the impacts of anthropogenic activities on environmental and socioeconomic systems. This SV includes cutting-edge papers, that focused on promoting the theories, ideas and practices involved in ecological accounting and management. All the works are aimed to develop broader perspectives, which can be applied to ecosystem protection, as well as on planning and policy-making in view of a transition toward more sustainable and equitable societies, as indicated through the Sustainable Development Goals.

The survival of waterbirds depends heavily on habitat, particularly aquatic plants. Previous studies usually focused on the use of hydrological management to achieve protection and restoration of aquatic plants. However, the hydrological processes in many lakes have been greatly changed and their ecological objectives usually cannot be achieved by hydrological management alone. This study proposes a new method to satisfy waterbird habitat requirements, by combining the management of hydrological processes and plant structure. In this study, the Hongze Lake National Wetland Nature Reserve was taken as the research area. Based on the water levels that different hydrophytes require for survival, and on waterbirds' needs for foraging and nesting area, we determined plantable area and plant structures under the current hydrological process. We then set three representative hydrological process scenarios and determined appropriate plantable area and plant structures under these hydrological processes. The results show that the current hydrological process of Hongze Lake is not conducive to the planting of the hydrophytes needed by waterbirds. A combination of hydrophyte planting and hydrological process management, however, can effectively expand the area of these aquatic plants. Within the constraints of flood control, the water level in March should be reduced, and the water level in July should be increased as much as possible. Therefore, a management method is provided for aquatic plant restoration and waterbird habitat protection in wetlands.

In water-deficient rivers, environmental flows (e-flows) are usually sustained via inter-basin water transfer projects from water-sufficient rivers, but these projects incur tremendous costs and may lead to many negative ecological effects, such as ecological invasion. This research proposed to transfer hydropower instead of water from water-sufficient rivers, because hydropower could substitute for water to promote economic development and reduce water withdrawal from water-deficient rivers. In this research, we established a computable general equilibrium model to analyze the substitution of hydropower for water in a water-deficient river basin, and determined the water withdrawal volume that could be reduced (conserved water). In addition, we adopted a range-of-variability approach to measure the effectiveness of e-flow provisions, and optimized the use of the conserved water to better maintain e-flows. The Luanhe River was adopted as a study case. The results showed that: the water-hydropower equivalent decreased as the transferred hydropower into the Luanhe River basin increased; a transferred hydropower amount of 22.46 kWh/s, equivalent to 18.30 m3/s conserved water, was optimal for the river basin; the conserved water should be distributed to the Luanhe River in the proportions of 0.55:0.1:0.35 during the wet, normal and dry seasons, respectively; the policy could transform the macro-economy toward a lower air-pollution pattern.

Macrophyte community diversity and composition respond to ecosystem conservation and local environmental factors. In this study, we developed a multidimensional diversity framework for macrophyte communities, including the taxonomic and functional alpha and beta diversity. We used the framework to explore the relationships among water level regimes and these diversity parameters in a case study of China’s Baiyangdian Lake. Analysis of indicators of hydrologic alteration divided the water level from 1959 to 2019 into four regimes (dry, 8.19 m). Alpha and beta diversity were significantly higher in the medium regime than in the low and high regimes. Redundancy analysis indicated that the maximum water depth significantly affected taxonomic alpha diversity, and total nitrogen (TN) and chemical oxygen demand (COD) concentration significantly affected functional alpha diversity, respectively. Mantel tests showed that TN, Secchi depth, and water depth in the high water level regime significantly increased the total beta diversity and turnover components. TN was the main factor that increased total taxonomic beta diversity. Interspecific competition decreased with the decreasing range (variation) of TN values and differed opposite with the variation of COD values in response to increasing water level, and reached its maximum in the medium regime. Ecosystem stability was promoted by maintaining high species richness and evenness and high differences among communities, and by reducing competition. Based on our results, the water level should be maintained between the medium and high water level regimes to promote restoration of the macrophyte community and improve ecosystem stability.

Reservoirs change the environment upstream of dams from lotic to lentic and alter hydrodynamic migration cues, thereby forming barriers to upstream fish migration. Increasing reservoir capa...

Inter-basin water transfer (IBWT) projects offer us a long-term means to minimize the mismatch between water demand and water availability. Climate change may impose significant vulnerability to IBWT projects through perturbations in water availability. However, previous studies of climate change’s impacts on IBWT’s vulnerability are mainly based on a top-down framework, i.e. forecasting the climate change via a wide range of GCMs, which may underestimate the uncertainty of climate change. In order to address this problem, a bottom-up vulnerability assessment framework is developed to evaluate the vulnerability of IBWT. In this framework, an IBWT vulnerability indicator is proposed based on three dimensions of vulnerability including exposure, sensitivity and adaptive capacity. The framework also highlights the deep uncertainty of climate change by adopting a probabilistic Budyko model, which can estimate the water availability over a broad range of climate futures. The South-to-North Water Transfer Project (SNWTP) in China is adopted as a case study to illustrate the effectiveness of the proposed framework. It shows that the framework is a useful tool for identifying the detrimental climate condition scope for the IBWT’s vulnerability, and is valuable to guide long-term water resources management and planning for policymakers.

There have been significant regime shifts in the ecosystem structure and function in a large number of lakes worldwide due to the increasing human disturbance and climate change in recent decades. It has become a critical issue in lake conservation and management to identify the characteristics of regime shifts in lakes and explore potential early-warning signals prior to regime shifts. However, research on identifying and predicting regime shifts in lakes is still a difficult task since recent modelling approaches cannot fully grasp the non-linear processes among multiple ecosystem components and the ecological time series data are too scarce to support the detection in most lakes. In this study, multi-proxy paleolimnological records were used to obtain long time-series ecological data and determine the inflection points of regime shifts in the Baiyangdian Lake, northern China. First, the sediment chronology was established, and macrophyte pollen as well as nutrient conditions in each dated sediment layer were identified. Then the heuristic segmentation algorithm and Pettitt test were used to determine the most significant inflection points of regime shifts. Additionally, multiple early-warning indicators including variance, autocorrelation and skewness were used to test their ability to forecast the major ecosystem regime shift. Results show that the most important abrupt change in the Baiyangdian Lake occurred in the early 1960s. The increasing variance coupled with decreasing autocorrelation and skewness started in 1–16 years before this regime shift, which is consistent with a flickering phenomenon rather than critical slowing down. The detection results of regime shifts and early-warning signals can provide valuable reference information for the lake management and aquatic ecosystem conservation.

Ecosystem state changes are actively engaged in the theory and practice of shallow lake restoration and management. Previous research focus on the occurrence and driving mechanisms of abrupt state shifts (regime shifts). However, the regulation effects of potential measures on the process of ecosystem state changes remain relatively unknown. The study employed a mechanism-driven, mathematical model to simulate the dynamics of ecosystem state changes in a shallow lake. Parameters for building regulatory scenarios were selected from the parameter sensitivity analysis outcomes. The convenience of use of the measures in real lake management was taken into consideration. Finally, regulation effects on the process of ecosystem state changes have been analyzed with scenarios. Lake Baiyangdian in north China plain was taken as a case study for this research. Results demonstrated that the process of ecosystem state changes could be regulated by reducing total phosphorous concentration in incoming water (inflows). The ecosystem will have better performance toward the clear state when reducing total phosphorous concentration in inflows below 0.23 g m−3. The ecosystem will experience periodical oscillation of states within a narrow range of vegetation coverage once total phosphorus concentration in inflows is reduced to 0.18 g m−3.

High flow events (including both the high flow pulses and floods) exert many critical ecological functions in riverine ecosystems and their elimination will lead to severe ecological degradation. However, common hydropower operations are only required to legally maintain the minimum environmental flows (e-flows). The extra release of high flow events will result in revenue loss of hydropower producers. In this research, we propose an approach to assessing the eco-compensation standard which is necessary to compensate the loss of hydropower producers and promote the release of high flows to downstream rivers. The scenario tree approach is adopted for the generation of possible scenarios of flows and electricity prices to deal with the uncertainties of the two factors in deregulated electricity markets. A stochastic linear programming method is proposed to determine the maximum mean annual revenues under two e-flow provision scenarios, i.e., only sustaining the minimum e-flows (scenario 1) and sustaining both the minimum e-flows and a specified number of high flow events (scenario 2). The revenue difference under the two e-flow scenarios is set as the eco-compensation standard. A case study in the Wangkuai reservoir, China, demonstrates that the eco-compensation standard is obviously influenced by the installed hydropower generation capacity (IHGC) and the number of high flow events planned to be released. Moreover, the greatest standards may be not corresponding to a very large IHGC.

One of the most challenging steps in implementing analysis of virtual water content (VWC) of agricultural crops is how to properly assess the volume of consumptive water use (CWU) for crop production. In practice, CWU is usually considered equivalent to the crop evapotranspiration (ET c ). Following the crop coefficient method, the ET c from crops grown under standard or non-standard conditions can be estimated by multiplying the reference evapotranspiration (ET 0 ) by one or a few coefficients. However, when current crop growing conditions deviate from standard conditions, accurately determining the coefficients under non-standard conditions will be a complicated process and requires lots of field experimental data. Based on regional surface water-energy balance, this research integrates the Budyko framework into the traditional crop coefficient approach to simplify the coefficients determination. This new method enables us to assess the volume of agricultural VWC only based on some hydrometeorological data and agricultural statistic data in regional scale. To demonstrate the new method, we apply it to the Shijiazhuang Plain, which is an agricultural irrigation area in the North China Plain. The VWC of winter wheat and summer maize is calculated and we further subdivide VWC into blue and green water components. Compared with previous studies in this study area, VWC calculated by the Budyko-based crop coefficient approach uses less data and agrees well with some of the previous research. It shows that this new method may serve as a more convenient tool for assessing VWC.

Parameter uncertainty inherent in reservoir operation affects operation model robustness and has been considered in conventional operation focusing on improving hydropower generation. With more attention paid to ecological environment protection recently, riverine ecosystem protection requires environmental flow (e-flow) management to sustain a near-natural flow regime. Whether there is e-flow management in reservoir operation has an impact on the uncertainty of reservoir operation, but parameter uncertainty was rarely considered in reservoir operation with e-flow management. In this study, a framework is proposed for performing parameter uncertainty analysis in reservoir operation associated with e-flow management. Both e-flow requirements and hydropower generation are considered in reservoir operation to sustain the harmonious development between ecological environment and human society. To compare the effect of different e-flow managements on the uncertainty of reservoir operation, three e-flow management scenarios are set. The Metropolis-Hastings algorithm of Markov Chain Monte Carlo (MCMC) sampling approach was applied for parameter estimation and uncertainty quantification. We used this framework in a case study of Nuozhadu hydropower station on the Lancang River in southern China to test its effectiveness. The results demonstrated that parameter uncertainty greatly affects the robustness of reservoir operation model. The comparison of reservoir operation under different e-flow management scenarios shows that more detailed e-flow management can effectively reduce uncertainty in reservoir operation and sustain the near-natural flow regime in a river.

Flow regimes have been severely altered by climate change and human activities in recent decades, which has led to ecological degradation in rivers. This study proposes an analogy analysis-based fr...

The virtual water content (VWC), which quantified the water consumption per unit of a food product, serves as a critical variable to the virtual water study. Because of the climate-dependent nature of VWC and its vulnerability to human influence, we still have little knowledge to interpret VWC variation regarding the contribution of climate change and human activities. This study aims to address this gap by proposing a VWC contribution analysis framework. In this framework, we applied the hydrological sensitivity method to a newly developed crop VWC calculation formula. We firstly separated the study period into baseline and change periods to calculate the change of VWC over time (ΔVWC). Based on the VWC calculation formula, the partial derivatives of VWC to precipitation (P) and potential evapotranspiration (PET) are mathematically derived. These partial derivatives were served as the sensitivity coefficients in the hydrological sensitivity method. We used them to differentiate and quantify the impact of climate change and human activities on ΔVWC and finally calculate its corresponding relative contribution. We demonstrate this framework in Shijiazhuang Plain, an agricultural district in northern China where the VWC of major crops has decreased in recent decades. We found that the relative contribution of human activities to the changes of VWC was greater than 97%, versus less than 3% for climate change. This finding suggests that human activities play a dominant and essential role in shaping the evolution of VWC as the region's water scarcity increases.

Carbon taxation has long been proposed to mitigate carbon emissions. Carbon tax rate determination and tax revenue recycling are two key steps to achieve a double dividend under carbon taxation. However, few research has sought to optimize the allocation proportion of tax revenue to various categories of taxpayers (households, enterprises, sectors, etc.), or to optimize the two steps synchronously based on nonlinear optimization methods. In this study, a computable general equilibrium model was established to explore the influence of carbon tax rate and tax revenue recycling shares on the economy and on carbon emissions. Meanwhile, a nonlinear optimization model was proposed, for optimizing both steps of carbon taxation synchronously, as well as for promoting GDP and CO2 emission reduction. The Bohai Bay area, a typical area with enormous carbon emissions in China, was adopted as the study case for this research. The results showed that the optimized taxation scheme could lead to lower carbon emissions and greater economic growth, i.e., a strong double dividend was obtained. The optimized taxation scheme could lead to both cleaner air and cleaner energy and industrial structures while still promoting economic growth.

Reservoir operation relies on two sets of flow data to conduct error analysis: inflow data and release data. Previous studies applied only the inflow data to reduce errors and improve the reservoir’s operational effectiveness. Little attention has been paid to the accuracy of the release data. However, release data provides more accurate information than inflow data for the protection of downstream river ecosystems. In this paper, we aim to illustrate the necessity of fully using the release data to improve a reservoir’s operational performance in a real-time reservoir operation system. Firstly, we designed a hypothetical reservoir system, performed five numerical experiments with different ranges of model parameters, and found that the error variances of reservoir releases were always larger than those of inflows. This indicates that the post-processing of reservoir releases is required to improve the accuracy of release data and support real-time reservoir operation. Then, we used a Bayesian joint probability (BJP) model for post-processing release data to reduce errors and quantify the uncertainty. We also applied the ecodeficit and ecosurplus based on flow duration curves to evaluate downstream hydrological alterations and further demonstrate the necessity of post-processing of release data. Results showed that the BJP model led to considerable improvement in the root-mean-square error and the continuous ranked-probability score. This demonstrates that the BJP model was effective in reducing errors. Our results highlight the importance of applying release data and improving their accuracy to support reservoir operation. If the release data is neglected, operational performance will degrade.

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.

Intensive coastal reclamation activities can lead to ecological degeneration in coastal areas. Therefore, the engineering design concept of an ecosystem-based coastal reclamation has aroused great interest. However, the inconsistency of standards and the unclear understanding of ecological processes are the difficulties in this field. In this paper, we selected eco-seawall as object to determine and optimize the 4 engineering parameters (including L1, L2, a, and h1). We set up 20 groups of working conditions under analyzing, and applying a computational framework to optimize eco-seawall designing processes. The computational efficiency would be enhanced by this developed method from the following aspects: (a) establishing surrogate model for eco-seawall to replace the high cost of simulation process; (b) searching engineering control parameters to optimize eco-seawall design; (c) obtaining the Petro curve set of optimal parameters for coastal reclamation management and ecological restoration. The design domain of the related parameters was determined by analyzing simulated and experimental data. As the results, the design domain were obviously reduced through optimization process: L1∈[0.1, 0.3]; L2∈[0.2, 0.8]; a∈(30,60]; h1∈[0.2,0.4]. Additionally, according to pilot-scale experiment, it can be concluded that the overtopping frequency for the low slope angle dam is 66.7%; the overtopping frequency for the high slope angle dam is 44.4%. The optimal design range for the practical engineering design can be provided by the optimal solution set of eco-seawall obtained from the optimization results. The calculation approach used in this research will provide reference for other engineering optimization work.

Here, we propose an approach to environmental flow assessment that pays attention to species dispersal among fragmented potential habitat patches affected by river inflow and tidal currents in estuaries. The approach consists of three steps. In step one, potential suitable habitats were mapped and the Habitat Aggregation Index (HAI) was determined to understand the fragmentation of potential suitable habitats by integrating the requirements for critical environmental factors that have temporal and spatial variability. In the second step, an individual-based model was developed to simulate the dispersal of target species among potential habitat patches. The model provided the species distributions for altered hydrological processes. In the third step, environmental flows were defined by comparing the occupancy of suitable habitat patches by individual organisms and habitat aggregation for varying freshwater inflows. This approach was tested using a case study in the Yangtze River Estuary. We stressed the ecological importance of flood pulse, rather than average discharge, and recommend a Gaussian-type flood pulse, as provides a win–win point for both the numbers of individuals that could occupy suitable habitat and the HAI. We also demonstrated the importance of the peak flow and flood pulse duration in terms of affecting species distribution. Based on the results presented here, the proposed approach offers a flexible assessment of environmental flow for aquatic ecosystems.

An integrated indicator system was developed for determining synthetic environmental responses under multiple types of coastal reclamation engineering in the Yellow River estuary, China. Four types of coastal engineering works were analyzed, namely port construction, petroleum exploitation, fishery and aquaculture, and seawall defense. In addition, two areas with limited human disturbances were considered for comparison. From the weights of the response value for each indicator, port construction was determined to be the primary impact contributor among the four engineering works studies. Specifically, hydrodynamic conditions, ecological status, economic costs, and engineering intensity were on average 72.78%, 65.03%, 75.03%, and 66.35% higher than those of other engineering types. Furthermore, fishery and aquaculture impact on water quality was 42.51% higher than that of other engineering types, whereas seawall defense impact on landscape variation was 51.75% higher than that of other engineering types. The proposed indicator system may provide effective coastal management in future.

An integrated approach of system dynamics (SD), orthogonal experimental design (OED) and inexact optimization modeling was proposed for water resources management under uncertainty. The developed method adopted a combination of SD and OED to identify key scenarios within multiple factors, through which interval solutions for water demands could be obtained as input data for consequential optimization modeling. Also, optimal schemes could be obtained in the combination of inexact two-stage stochastic programming and credibility constrained programming. The developed method was applied to a real-world case study for supporting allocation of multiple-source water resources to multiple users in Dalian city within a multi-year context. The results indicated that a lower credibility-satisfaction level would generate higher allocation efficiency, a higher system benefit and a lower system violation risk. The developed model could successfully reflect and address the variety of uncertainties through provision of credibility levels, which corresponds to the decision makers’ preference regarding the tradeoffs between system benefits and violation risks.

Reservoir construction changes a river's natural flows and temperature, thereby threatening fish migration. Researchers have tried to restore fish migration passages by ensuring environmental flows in downstream river channels. However, reservoir impoundment changes upstream environments from lotic to lentic and thereby hinders fish migration by eliminating migration cues, which has been rarely considered. This study characterized the invisible barriers that large reservoirs create for migratory fish. Water currents are the primary orientation cues for migration due to fish's natural rheotactic tendency. Fish also require suitable temperatures during migration. We built a quasi-3-D model to simulate hydrodynamic and temperature conditions in large reservoirs and tested whether these conditions met the velocity and temperature requirements of fish. Due to the strong effects of operation on reservoir conditions, we proposed an eco-friendly technical operating solution to restore migration passages. We added an ecological constraint (i.e., creating a suitable velocity field for fish migration) to reservoir operation model and applied multiobjective optimization to simultaneously protect reservoir benefits. As a case, we applied our approach to China's Danjiangkou Reservoir. We found that velocities in more than half of the zones along the potential fish migration route through the reservoir were lower than the fish requirement and could not offer orientation cues for migration. The eco-friendly operating scheme effectively restored a fish migration passage by managing reservoir releases during key migration periods, slightly reducing the reservoir's socioeconomic benefits by 1.67–5.03%. This study provides a new perspective on biodiversity and fisheries protection in global regulated rivers.

Biodiversity conservation is significant for restoring service and function in riverine ecosystems. Migratory fishes are important components of river biodiversity, requiring acceptable flow discharge for migration. The discharge should be no lower than the minimum acceptable value to trigger fish migration and provide guiding flow, while it should be no higher than the maximum acceptable value to ensure that the swimming ability of migratory fish is sufficient for them to pass through high flows. The species–discharge relationship (SDR) in a river is commonly described by a continuous curve, but this study proposes that SDR in a river should be a piecewise model, with two jump discontinuities. Species diversity has a sudden increase when discharge reaches the minimum acceptable value for migratory fishes, and has a sudden decrease when the discharge exceeds the maximum. Locations of jump discontinuities were determined according to the flow requirements for migratory fishes in the river. Then we evaluated the performances of eight common functions applied to the pieces of the model, and chose the best one based on goodness of fit ( R 2 ). Last, we used the Rio Grande river in North America as a case study and proposed a piecewise power model for the SDR. The results demonstrated that the piecewise power model ( R 2 = 0.77) performed better than the traditional power model ( R 2 = 0.67) and species diversity had an obvious decrease when flow discharge exceeded the maximum acceptable value for migratory fishes. These results offer fresh implications for future restoration of river ecosystems.

Assessment of flow regime alteration is significant for the scientific protection and restoration of rivers. The range of variability approach (RVA) and its revised versions, based on a suite of Indicators of Hydrological Alteration (IHA), have been widely used for flow regime alteration assessment. In these methods, the IHA of each specific year are treated separately, and their individual alterations are used to reflect the alteration of flow regime. However, it is known that one hydrological year is an important hydrological period, and the alteration of inner characteristics of one hydrological year (ICOHY), collectively characterized by the 32 IHA values of the year, can also lead to serious ecological degradation of rivers. In other words, treating the 32 IHA individually and separately in RVA and its revisions can not reflect the alteration of ICOHY. To overcome this limitation, a revised RVA is proposed. In the revised method, the 32 IHA values for each specific year are considered as a set, and the alteration of the set (SA) is measured by the set pair analyses method. The assessment of individual alteration (IA) of each IHA is carried out according to RVA. SA and IA are incorporated into a single index to reflect the overall flow regime alteration (OA). The proposed method is applied to a case study of the Xi Dayang Reservoir in China to test its effectiveness. The results suggest that the RVA underestimates the alteration degree and that the new method could give a more comprehensive assessment.

Environmental flow plays an important role in sustaining or improving wetland ecosystems. There are many methods for environmental flow assessments, most of which only focus on simplistic environmental flow standards or theoretical cause–effect relations between flow regimes and target species. However, traditional assessments may not be suitable for ecosystems with severe water quality deterioration. Ignoring relationships among flow, water quality, and multi-level ecological responses in real and complex ecosystems may misguide management practices and lead to further ecosystem degradation. To investigate impacts of flow alteration on ecosystems with different pollution rates, and examine the underlying mechanisms, a two-dimensional hydraulic and ecological model was developed in this study. This model simulates flow circulation; pollutant transport; and the interactions between flow, nutrients, and holistic ecosystem characteristics. The integrated model was applied to 21 scenarios to understand ecosystem characteristics in response to various environmental flow rates and water quality standards. Finally, holistic indicators including total primary production/total respiration, total biomass/total production, eco-exergy, and structural eco-exergy are used to quantify the effects of different scenarios on ecosystem health, and provide scientific environmental flow recommendations. The proposed method was applied to Baiyangdian, the largest wetland in the North China Plain. The results indicate that the annual environmental flow should be higher than 2 m3/s in order to prevent the Baiyangdian ecosystem from further degradation. To maintain an optimal ecosystem status, the minimum environmental flow should be kept as 5–9.5 m3/s, and the maximum environmental flow should be kept as 9–13.5 m3/s in different hydrological years. In addition, the water quality should be always kept at or above the Chinese class IV standard. This result can guide basic research in hydroecology and assist further implementation of comprehensive environmental flow management.

Ecofriendly reservoir operation is an important tool for sustainable water resource management in regulated rivers. Optimization of reservoir operation is potentially affected by the stochastic characteristics of inflows. However, inflow stochastics are not widely incorporated in ecofriendly reservoir operation optimization. The reasons might be that computational cost and unsatisfactory performance are two key issues for reservoir operation under uncertainty inflows, since traditional simulation methods are usually needed to evaluate over many realizations and the results vary between different realizations. To solve this problem, a noisy genetic algorithm (NGA) is adopted in this study. The NGA uses an improved type of fitness function called sampling fitness function to reduce the noise of fitness assessment. Meanwhile, the Monte Carlo method, which is a commonly used approach to handle the stochastic problem, is also adopted here to compare the effectiveness of the NGA. Degree of hydrologic alteration and water supply reliability, are used to indicate satisfaction of environmental flow requirements and human needs. Using the Tanghe Reservoir in China as an example, the results of this study showed that the NGA can be a useful tool for ecofriendly reservoir operation under stochastic inflow conditions. Compared with the Monte Carlo method, the NGA reduces ~90% of the computational time and obtains higher water supply reliability in the optimization.

Energy and water are closely related resources, so environmental tax policies for energy resources will also influence the use of water resources. Different environmental tax policies have different emphases. However, few research has compared their effects on the energy–water nexus. In the present study, we considered two commonly used environmental tax policies to regulate energy use (energy and carbon taxes), and established a dynamic computable general equilibrium model to compare the comprehensive impacts of different tax types and intensities on the energy–water nexus. In addition to the direct-use nexus (direct water and energy consumption), we also considered the embodied-use nexus (energy-related water consumption and water-related energy consumption) and the hybrid-use nexus (hybrid water and energy consumption). Besides, both the effects of tax rates and time spans are simulated simultaneously. China was adopted as a case study. For the direct-use nexus, both taxes would increase the proportion of direct water consumption versus direct energy consumption. The average differences in the proportion change rates between the two taxes were 3.8, 7.8, and 9.7% for the low, medium, and high tax intensities, respectively. For the embodied-use nexus, the carbon tax could increase the proportion of energy-related water consumption versus water-related energy consumption. The average differences in the proportion change rates between the two taxes were 4.4, 8.4, and 10.2% for the low, medium, and high tax intensities, respectively. For the hybrid-use nexus, the effects of the taxes were similar to those for the direct-use nexus.

Reducing carbon emissions is part of an international agreement to alleviate the negative effects of climate change, and a carbon tax is a widely used measure to decrease carbon intensity. A carbon tax’s impacts on economic development and carbon emissions reduction vary among sectors, and differentiated carbon tax rates across sectors may offer better potential for balancing the two objectives. However, seldom has any research proposed differentiated carbon tax rates. In this study, a carbon tax rate optimization method based on the computable general equilibrium (CGE) model is proposed, to more effectively control carbon emissions and reduce carbon intensity. Two alternative models are proposed: maximizing GDP and minimizing carbon emissions. China is adopted as a study case to demonstrate the method. The results show that an optimized taxation scheme is more effective in reducing the carbon intensity, and additional CO2 can be reduced without additional GDP decline. Besides, the optimized taxation scheme could lead to greener energy structure.

Wetland eutrophication is a global environmental problem. Besides reducing pollutant emissions, improving nutrient assimilative capacity in wetlands is also significant for preventing eutrophication. Hydrological management can improve nutrient assimilative capacity in wetlands through physical effects on the dilution capacity of water body and ecological effects on wetland nutrient cycles. The ecological effects are significant while were rarely considered in previous research. This study focused on the ecological effects of hydrological management on two crucial nutrient removal processes, plant uptake and biological denitrification, in plant-dominated wetlands. A dual-objective optimization model for hydrological management was developed to improve wetland nitrogen and phosphorus assimilative capacities, using upstream reservoir release as water regulating measure. The model considered the interactions between ecological processes and hydrological cycles in wetlands, and their joint effects on nutrient assimilative capacity. Baiyangdian Wetland, the largest freshwater wetland in northern China, was chosen as a case study. The results found that the annual total assimilative capacity of nitrogen (phosphorus) was 4754 (493) t under the optimal scheme for upstream reservoir operation. The capacity of nutrient removal during the summer season accounted for over 80% of the annual total removal capacity. It was interesting to find that the relationship between water inflow and nutrient assimilative capacity in a plant-dominated wetland satisfied a dose-response relationship commonly describing the response of an organism to an external stressor in the medical field. It illustrates that a plant-dominated wetland shows similar characteristics to an organism. This study offers a useful tool and some fresh implications for future management of wetland eutrophication prevention.

Assessing nutrient assimilative capacity of water body is an essential component of the Total Maximum Daily Load program. Nutrient assimilative capacity of lakes is affected by hydrological changes through physical effects on the dilution capacity of water body and ecological effects on nutrient removal processes. Previous research has focused on the effects of hydrological changes on dilution capacity, but rarely considered the ecological effects on nutrient assimilative capacity. In this study, a process-based model considering both ecological effects and dilution effects of hydrological changes is proposed for assessing nitrogen and phosphorus assimilative capacities of plant-dominated lakes. Plant uptake and biological denitrification are two crucial nutrient removal processes. Water depths in a lake affect plant growing area. Lake submerged condition affects nutrient accumulation capacity of plants and the intensity of biological denitrification. The model considered dynamic variations of lake water depths and submerged condition, and the associated effects on nutrient removal by plant nutrient uptake and biological denitrification in lake systems. It is a discrete 0D model depending on a small amount of data and has satisfactory simulation accuracy. We chose the largest freshwater lake in northern China (Baiyangdian Lake) as a case. The annual total assimilative capacity in the lake was 1536 t for nitrogen and 157 t for phosphorus. Assimilative capacity during plant-growing season accounted for over 90% of the annual total capacity. The results determined by the new model were less than half of that from previous model, demonstrating the significance of considering ecological effects of hydrological changes. The new assessment model offers a useful tool for directing pollutant emission control and eutrophication prevention in global plant-dominated lakes.

Along with globalization, countries consume a large amount of goods and services from both domestic and international markets. As one of the world's largest agricultural countries, China is faced with serious water scarcity and has to reduce the water consumption from both domestic and global aspects, of which the crop planting structure optimization (CPSO) between regions based on the virtual water perspective could be a solution for efficient agricultural water consumption. In this article, three scenarios of Chinese agriculture, including agricultural water consumption restrictions relaxed scenario, agricultural water consumption limited scenario, and net utilization ratio of water resources limited scenario, were designed to minimize the national agricultural water consumption under various water, land, and crop planting constraints in individual provinces and analyze the impacts of the CPSO. The results showed that compared with the historical situation of crop planting in 2007, 53.3%, 51.4%, and 47.3% of the agricultural water consumption and more than 10% of the sown area of China was saved under the three scenarios, respectively. Because of the reduction of agricultural water consumption and land use, it brought about the expansion of crops production in China. CPSO is found to have notable effects on water saving and food security considering the dependence of the crops by international trade.

Agriculture plays a central role in maintaining food security and achieving sustainable development for human society. It is a challenge for the agricultural sector to mitigate greenhouse gas (GHG) emissions and maintain agricultural production. However, dual-level uncertainties exist in the processes of agricultural GHG accounting and emission reduction management. In this research, an integrated approach for identifying adaptation strategies in agricultural GHG emission reduction management was developed through incorporating life cycle analysis (LCA) of agricultural production into a general mathematical programming model. This approach strengthened the applicability of LCA and the comprehensiveness of programming models in generating agricultural adaptive actions under different GHG emission restriction targets. Also, dual-level uncertainties of LCA and adaptation management can be effectively addressed. A case study was proposed to illustrate application of the approach in Dalian City, China. The results indicated that farming patterns in eight districts would change significantly. The total area of maize fields would account for the primary proportion (i.e., 40–45 %) in its agricultural sector. Rice, peanut and cabbage fields would be the minor contributors in terms of GHG emissions. In addition to effective rainfall (i.e., [156, 259] mm/ha), a certain amount of water would be supplied for agricultural irrigation to maximize the city’s agricultural yields. Compared with other agricultural crops, rice fields would need the largest amount of irrigation water (i.e., [153.72, 277.98] Mt) to meet the requirements of local government plans.

Regional disparity is due to economic development, physical geography, and lifestyle. Jing-Jin-Ji urban agglomeration is advocating integrated development, but its development is not so smooth. The goals of this research are to identify the energy utilization characteristics of the three regions and their ecological roles, and to promote the integrated development of this agglomeration system. To do so, we used the concept of “urban metabolism”, and abstracted sectors and energy flows as nodes and paths in a network model. Based on multi-regional input–output tables in China in 2002 and 2007, the monetary values in the tables can be converted into physical units. Furthermore, combining these tables with ecological network analysis can assess the indirect energy consumption of each sector, then its embodied energy consumption will be accounted for. Also, this method can reflect the roles (producer or consumer) of the three regions and of the five sectors in each region in regional energy exchanges. The results showed that Hebei had the largest embodied energy consumption in both years, with Beijing coming second. The ecological roles of the three regions did not change greatly between 2002 and 2007: Hebei acted as a producer, and Beijing and Tianjin served as consumers. Exploitation relationships were dominant in both years. This analysis provided insights that will support planning to adjust the industrial structure and future integrated development of the agglomeration.