Z.F. Yang

Beijing Normal University, Peping, Beijing, China

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Publications (100)179.74 Total impact

  • X. A. Yin, Z. F. Yang, G. E. Petts
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    ABSTRACT: Assessing alterations of a river's flow regime provides the basis for river protection and restoration planning. The range of variation approach (RVA) is a commonly used method to evaluate alterations in a river's flow regime. However, RVA underestimates the degree of flow regime alteration potentially, because it only considers the difference in frequency between the pre-impact and post-impact hydrologic indicator values within certain target ranges and does not consider alteration of the order of hydrologic year types (HYTs; i.e. wet, average and dry years). The HYT order is an important holistic feature of the flow regime. The human-induced change of HYTs, such as from a dry year to a wet year or from an average year to a dry year, can be a major cause of ecosystem alteration. For some species, the order of the HYTs was more important than single-year events (such as the flood magnitude during a given year). To address this problem with the RVA, we proposed a modification of this method that accounts for alteration of the order of HYTs. We developed a metric for assessing the alteration of the HYT order based on Euclidean distance and then combined this metric with the RVA. We applied the revised method to a case study of the Sha River in northern China to test its effectiveness. The results demonstrated that the new method solved RVA's problem of potentially underestimating the degree of flow regime alteration and enabled a more comprehensive analysis of the alteration of the flow regime. Copyright © 2014 John Wiley & Sons, Ltd.
    River Research and Applications 08/2014; · 2.43 Impact Factor
  • X. A. Yin, Z. F. Yang, C. L. Liu
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    ABSTRACT: In deregulated electricity markets, hydropower portfolio design has become an essential task for producers. The previous research on hydropower portfolio optimisation focused mainly on the maximisation of profits but did not take into account riverine ecosystem protection. Although profit maximisation is the major objective for producers in deregulated markets, protection of riverine ecosystems must be incorporated into the process of hydropower portfolio optimisation, especially against a background of increasing attention to environmental protection and stronger opposition to hydropower generation. This research seeks mainly to remind hydropower producers of the requirement of river protection when they design portfolios and help shift portfolio optimisation from economically oriented to ecologically friendly. We establish a framework to determine the optimal portfolio for a hydropower reservoir, accounting for both economic benefits and ecological needs. In this framework, the degree of natural flow regime alteration is adopted as a constraint on hydropower generation to protect riverine ecosystems, and the maximisation of mean annual revenue is set as the optimisation objective. The electricity volumes assigned in different electricity submarkets are optimised by the noisy genetic algorithm. The proposed framework is applied to China's Wangkuai Reservoir to test its effectiveness. The results show that the new framework could help to design eco-friendly portfolios that can ensure a planned profit and reduce alteration of the natural flow regime.
    Hydrology and Earth System Sciences Discussions 03/2014; 18(4). · 3.59 Impact Factor
  • Z. F. Yang, T. Sun, R. Zhao
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    ABSTRACT: We developed an approach to assess environmental flows in estuaries related to preference of phytoplankton considering the complex relationship between hydrological modification and biomass in ecosystems. As a first step, a relationship was established between biomass requirements for organisms of primary and higher nutritional levels based on the principle of nutritional energy flow of ecosystem. Then, diagnostic pigments were employed to represent phytoplankton community biomass, which indicated competition between two groups of phytoplankton in the biochemistry process. Considering empirical relationships between diagnostic pigments and critical environmental factors, responses of biomass to river discharges were established based on a convection-diffusion model by simulating distributions of critical environmental factors under action of river discharges and tide currents. Consequently, environmental flows could be recommended for different requirements of fish biomass. In the case study in the Yellow River estuary, May and October were identified as critical months for fish reproduction and growth during dry years. Artificial hydrological regulation strategies should carefully consider the temporal variations of natural flow regime, especially for a high-amplitude flood pulse, which may cause negative effects on phytoplankton groups and higher organism biomass.
    Hydrology and Earth System Sciences 12/2013; 11(1). · 3.59 Impact Factor
  • L. J. Zhang, X. A. Yin, Y. Zhi, Z. F. Yang
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    ABSTRACT: China is a water-stressed country, and agriculture consumes the bulk of its water resources. Assessing the virtual water content (VWC) of crops is one important way to develop efficient water management measures to alleviate water resources conflicts among different sectors. In this research, the VWC of rice, as a major crop in China, was assessed and the spatial characteristics were analyzed. In addition to the calculation of green, blue and grey water - the direct water in VWC - the indirect water use of rice was also calculated, using the Input-Output model. The percentages of direct green, blue, grey and indirect water in the total VWC of rice in China were 43.8, 28.2, 27.6, and 0.4%. The total VWC of rice generally showed a three-tiered distribution, and decreased from southeast to northwest. The higher values of direct green water of rice were mainly concentrated in Southeast and Southwest China, while these values were relatively low in Northwest China and Inner Mongolia. The higher direct blue water values were mainly concentrated in the eastern and southern coastal regions and Northwest China, and low values were mainly concentrated in Southwest China. Grey water values were relatively high in Shanxi and Guangxi provinces and low in Northeast and Northwest China. The regions with high values for indirect water were randomly distributed but the regions with low values were mainly concentrated in Northwest and Southwest China. For the regions with relatively high total VWC the high values of blue water made the largest contribution, although for the country as a whole the direct green water is the most important contributor.
    12/2013; 11(1).
  • Z. H. Xu, X. A. Yin, Z. F. Yang
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    ABSTRACT: Lake eutrophication is a serious global environmental issue. Phytoremediation is a promising, cost-effective, and environmentally friendly technology for water quality restoration. However, besides nutrient removal, macrophytes also deeply affect the hydrologic cycle of lake system through evapotranspiration. Changes in hydrologic cycle caused by macrophytes have a great influence on lake water quality restoration. As a result of the two opposite effects of macrophytes on water quality restoration (i.e. an increase in macrophytes can increase nutrient removal and improve water quality while also increasing evapotranspiration, reducing water volume and consequently decreasing water quality), rational macrophyte control through planting and harvest is very important. In this study, a new approach is proposed to optimise the initial planting area and monthly harvest scheme of macrophytes for water quality restoration. The month-by-month effects of macrophyte management on lake water quality are considered. Baiyangdian Lake serves as a case study, using the common reed. It was found that water quality was closest to Grade III on the Chinese water quality scale when the reed planting area was 123 km2 (40% of the lake surface area) and most reeds would be harvested at the end of June. The optimisation approach proposed in this study will be a useful reference for lake restoration.
    Hydrology and Earth System Sciences 12/2013; 11(1). · 3.59 Impact Factor
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    Y. Zhi, Z. F. Yang, X. A. Yin
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    ABSTRACT: Decomposition analysis of water footprint (WF) changes, or assessing the changes in WF and identifying the contributions of factors leading to the changes, is important to water resource management. However, conventional studies focus on WF from the perspective of administrative region rather than river basin. Decomposition analysis of WF changes from the perspective of the river basin is more scientific. To address this perspective, we built a framework in which the input-output (IO) model and the Structural Decomposition Analysis (SDA) model for WF could be implemented in a river basin by computing IO data for the river basin with the Generating Regional IO Tables (GRIT) method. This framework is illustrated in the Haihe River Basin (HRB), which is a typical water-limited river basin. It shows that the total WF in the HRB increased from 4.3 × 1010 m3 in 2002 to 5.6 × 1010 m3 in 2007, and the agriculture sector makes the dominant contribution to the increase. Both the WF of domestic products (internal) and the WF of imported products (external) increased, and the proportion of external WF rose from 29.1% to 34.4%. The technological effect was the dominant contributor to offsetting the increase of WF; however, the growth of WF caused by the economic structural effect and the scale effect was greater, so the total WF increased. This study provides insights about water challenges in the HRB and proposes possible strategies for the future, and serves as a reference for WF management and policy making in other water-limited river basins.
    Hydrology and Earth System Sciences Discussions 12/2013; 10(12):14591-14615. · 3.59 Impact Factor
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    L. Chen, Z.F. Yang, B. Chen
    Energies 05/2013; 6:2319-2337. · 1.84 Impact Factor
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    M.R. Su, W.W. Lu, C. Chen, B. Chen, Z.F. Yang
    Entropy 04/2013; 10:1171-1185. · 1.35 Impact Factor
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    ABSTRACT: A number of inexact fuzzy programming methods have been developed for the planning of water-resources-management systems under uncertainty. However, most of them do not allow the parameters in the objective and constraints of a programming problem to be functional intervals (i.e., the lower and upper bounds of the intervals are functions of impact factors). In this study, an interval fuzzy bi-infinite De Novo programming (IFBDP) method is developed in response to the above concern. A case study is also conducted; the solutions are then compared with those obtained from inexact De Novo programming (IDNP) and interval-fuzzy De Novo programming (IFDNP) that takes no account of bi-infinite programming. It is indicated that the IFBDP method can generate more reliable solutions with a lower risk of system failure due to the possible constraints violation and provide a more flexible management planning since the budgets availability can be adjusted with the variations in water price. These solutions are more flexible than those identified through IFDNP since the tolerance intervals are introduced to measure the level of constraints satisfaction. Moreover, it can be used for analyzing various scenarios that are associated with different levels of economic consequences under uncertainty.
    Engineering Applications of Artificial Intelligence 03/2013; 26(3):1061–1071. · 1.96 Impact Factor
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    T. Sun, J. Xu, Z. F. Yang
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    ABSTRACT: An integrated multi-objective method for environmental flow assessments was developed that considered variability of potential habitats as a critical factor in determining how ecosystems respond to hydrological alterations. Responses of habitat area, and the magnitude of those responses as influenced by salinity and water depth, were established and assessed according to fluctuations in river discharge and tidal currents. The requirements of typical migratory species during pivotal life-stage seasons (e.g., reproduction and juvenile growth) and natural flow variations were integrated into the flow-needs assessment. Critical environmental flows for a typical species were defined based on two primary objectives: (1) high level of habitat area and (2) low variability of habitat area. After integrating the water requirements for various species with the maximum acceptable discharge boundary, appropriate temporal limits of environmental flows for ecosystems were recommended. The method was applied in the Yellow River estuary in eastern Shandong province, China. Our results show that, while recommended environmental flows established with variability of potential habitats in mind may not necessarily benefit short-term survival of a typical resident organism on a limited temporal or spatial scale, they may encourage long-term, stable biodiversity and ecosystem health. Thus, short-term ecosystem losses may be compensated by significant long-term gains.
    Hydrology and Earth System Sciences 02/2013; 17(2):751-760. · 3.59 Impact Factor
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    Entropy 01/2013; 15(1):1-9. · 1.35 Impact Factor
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    Energies 01/2013; 6:5486-5506. · 1.84 Impact Factor
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    ABSTRACT: Threatened by the huge pressure caused by climate change, low-carbon cities have become an inevitable part of urban evolution. It is essential to evaluate urban low-carbon development levels to smoothly promote the construction of low-carbon cities. This paper proposes an evaluation index system for urban low-carbon development from the points of view of economic development and social progress, energy structure and usage efficiency, living consumption, and development surroundings. A weighted sum model was also established. Selecting 12 typical Chinese cities as cases studies, an integrated evaluation was conducted based on the index system and the assessment model. The development speed and limiting factors of different cities were also analyzed. The 12 cities were ultimately classified into three groups in terms of their low-carbon development patterns by integrating all of the analysis results. Furthermore, suitable regulation and management for different patterns were suggested. This study both aids in assessing the executive effect of low-carbon city construction and helps to determine existing problems and suggest effective solutions.
    Energies 12/2012; 46(3):1796-1803. · 1.84 Impact Factor
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    T. Sun, J. Xu, Z. F. Yang
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    ABSTRACT: An integrated multi-objective method for environmental flow assessments was developed that considered adaptation as a pivotal factor affecting how ecosystems respond to hydrological alterations. Responses of habitat area, and the magnitude of those responses as a result of fluctuations in river discharge, were established. The requirements of typical migrated species during pivotal life-stage seasons (e.g. reproduction and juvenile growth) were integrated into the flow-needs assessment. Critical environmental flows for a typical species were defined based on two primary objectives: (1) high level of habitat area and (2) low variability. After integrating the water requirements for various species with the maximum acceptable discharge boundary, appropriate temporal limits of environmental flows for ecosystems were recommended. The method was applied in the Yellow River Estuary in Eastern Shandong province, China. Our data show that, while recommended environmental flows established with ecological adaptation in mind may not necessarily benefit short-term survival of a typical resident organism on a limited temporal or spatial scale, they may encourage long-term, stable biodiversity and ecosystem health. Thus, short-term ecosystem losses are compensated by significant long-term gains.
    Hydrology and Earth System Sciences Discussions 05/2012; 9(5):6753-6780. · 3.59 Impact Factor
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    ABSTRACT: The eleven symposia organized for the 2009 conference of the International Society for Ecological Modelling (ISEM 2009) held in Quebec City, Canada, October 6–9, 2009, included facilitated discussion sessions following formal presentations. Each symposium focused on a specific subject, and all the subjects could be classified into three broad categories: theoretical development, population dynamics and ecosystem processes. Following discussions with the symposia organizers, which indicated that they all shared similar issues and concerns, the facilitated discussions were task-oriented around four basic questions: (1) key challenges in the research area, (2) generating and sharing new ideas, (3) improving collaboration and networking, and (4) increasing visibility to decision-makers, partners and clients. Common challenges that emerged from the symposia included the need for improved communication and collaboration among different academic disciplines, further progress in both theoretical and practical modelling approaches, and accentuation of technology transfer. Regarding the generation and sharing of new ideas, the main issue that emerged was the type of positive interactions that should be encouraged among potential collaborators. The usefulness of the Internet, particularly for the sharing of open-source software and conducting discussion forums, was highlighted for improving collaboration and networking. Several communication tools are available today, and it is important for modellers to use them more intensively. Visibility can be increased by publishing professional newsletters, maintaining informal contacts with the public, organizing educational sessions in primary and secondary schools, and developing simplified analytical frameworks and pilot studies. Specific issues raised in each symposium are also discussed.
    Ecological Modelling 07/2011; 222(14):2456–2468. · 2.07 Impact Factor
  • Y. Li, Z. F. Yang
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    ABSTRACT: In ecological network theory, network efficiency and resilience are two essential but complementary attributes of the network structure, and a balance between these factors is critical for an ecosystem's long-term sustainability. Our paper introduces this method and related concepts into water use systems to provide a new angle for sustainability quantification. In this paper, we investigate the meanings of network efficiency and resilience in the context of sustainable development of water use systems, and define sustainable systems based on the optimal balance between network efficiency and resilience. With the consideration of complex artificial characteristics of water use, we propose an optimal water use network and quantify its flows. By ascendency calculation, the balanced network structure can be determined. We then use the four sub-basins of China's Haihe River as a case study to illustrate how the optimal network can be constructed and how the optimal balance for each scenario can be calculated. The results show that the optimal balance for the sub-basins has ascendency values ranging from 0.5970 to 0.7161. By analyzing the contribution of each water use activity to network's balance structure, the location of the optimal balance in water use systems can be better understood. This research represents the first attempt to explore the balance between a network structure's efficiency and resilience as a way to quantify the sustainability of water use systems, and builds a foundation for future studies on the assessment, regulation, and management of water resources.
    Ecological Modelling 05/2011; 222(10):1771-1780. · 2.07 Impact Factor
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    F. Xu, Z. F. Yang, B. Chen, Y. W. Zhao
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    ABSTRACT: Thermodynamic indicators, including eco-exergy and structural eco-exergy, have been widely applied to lake ecosystem health assessment in recent decades. In this paper, the index system, including phytoplankton biomass, microzooplankton biomass, trophic state index (TSI), eco-exergy, structural eco-exergy and ecological buffer capacity to total phosphorus for phytoplankton, were applied to assess the health states of fourteen typical water areas in the plant-dominated Baiyangdian Lake. Different types of organisms, including zooplankton, benthonic animals and macrophytes with various denotative meanings, were differentiated to some extent and the latest weighting factors, were used in the eco-exergy and structural eco-exergy calculations for a better characterization of health state. The results showed that only the water area in site 4, with relatively high eco-exergy, structural eco-exergy, ecological buffer capacity and low phytoplankton biomass, microzooplankton biomass and TSI, is in healthy state. Health states of the other water areas were all deteriorated at various degrees due to the human disturbances. The health states of the northeast and southeast water areas were better than those of the northern, central and southern water areas with aquaculture and villages and western water areas close to the Fu River. For the plant-dominated Baiyangdian Lake, combining eco-exergy with structural eco-exergy could better characterize the health state of ecosystem with macrophytes hypermorphosis and meanwhile based on the distinguishing of various organism components, specifically benthonic animals, to some extent for eco-exergy and structural eco-exergy calculations, spatial variations of health state obtained better description, which indicated eco-exergy and structural eco-exergy were the robust indicators for ecosystem health assessment of the plant-dominated lake.
    Ecological Modelling 01/2011; 222(1):201-209. · 2.07 Impact Factor
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    G. Y. Liu, Z. F. Yang, M. R. Su, B. Chen
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    ABSTRACT: Analyzing the structure and functioning of the urban system revealed ways to optimize its structure by adjusting the relationships among compartments, thereby demonstrating how ecological network analysis can be used in urban system research. Based on the account of the extended exergy utilization in the sector of urban socio-economic system, which is considered as the composition of extraction (Ex), conversion (Co), agriculture (Ag), industry (In), transportation (Tr), tertiary (Te) and households (Do) sectors, an urban ecological network model is constructed to gain insights into the sustainable urban development process. Taking Beijing city as a model case, the network accounting and related ecological evaluation of a practical urban economy are carried out in this study in the light of flux, utility and structure analysis. The results showed Beijing had made some progress in moving manufacturing economy into service economy during the 10years. The increased output of the domestic sector (labor services) relieves the energy demand being placed on agricultural, industrial, transportation and tertiary sectors. The transportation sector was becoming a controlling factor to fluctuate the other sectors and the cross-regional trade is beginning to overshadow the crucial role of local manufacturing, which is due partly to the restructuring of the Beijing's commodity markets since the 1990s. The major implication of our work is that the exergy-based network analysis can be refined to become an integrative tool for evaluation, policy-making and regulation for ecosystem management concerning structure and efficiency at urban levels.
    Ecological Informatics 01/2011; · 1.96 Impact Factor
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    X.F. Mao, Z.F. Yang, B. Chen
    Journal of Environmental Informatics 01/2011; 18(2):46-54. · 3.62 Impact Factor
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    M.R. Su, Z.F. Yang, B. Chen
    International Journal of Exergy 01/2011; · 0.92 Impact Factor

Publication Stats

869 Citations
179.74 Total Impact Points

Institutions

  • 2008–2014
    • Beijing Normal University
      • School of Environment
      Peping, Beijing, China
  • 2009
    • University of Waterloo
      • Department of Civil and Environmental Engineering
      Waterloo, Ontario, Canada
  • 1993
    • Peking University
      Peping, Beijing, China