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Water level fluctuation and modification in human activities induced by dam construction have significantly affected the production and input of nutrients in the tributary watersheds. In this study, numerical simulation and time series analysis methods are used to explore the input of phosphorus (P) in different types of tributary watersheds around the reservoirs in river reservoir systems and the impact of dam construction on reservoir water quality. Watersheds within a reservoir were divided into larger and smaller tributary watersheds according to whether their area was greater than or less than 1000 km2. The results showed that smaller tributary watersheds, which account for 29% of the area of the Three Gorges Reservoir Region (TGRR), transported approximately 36%∼45% of P and 43.7%∼47.8% of sediment deposited into the mainstream from 2003 to 2017. P from the smaller tributary watersheds of the reservoir had a stronger influence on the aquatic environment of the river-reservoir system than that from the larger tributary watersheds. In addition, the annual mean contributions of the P inputs from the “three rivers” (the Yangtze River, the Jialingjiang River and the Wujiang River) and tributary watersheds within the reservoir were 68.76% and 31.18% from 2003 to 2017, respectively. The dam altered the composition of the form of P in the river-reservoir system, and the waterbody close to the dam was identified as the main area containing dissolved P (DP) enrichment. Accordingly, the risk of eutrophication remains high in head area of the dam due to the relatively high and stable P concentration. This study provides critical information for the management of nutrients in a river-reservoir system and the prevention of eutrophication of water bodies.
Shibo Chen; Lei Chen; Yang Gao; Jinsong Guo; Leifang Li; Zhenyao Shen. Larger phosphorus flux triggered by smaller tributary watersheds in a river reservoir system after dam construction. Journal of Hydrology 2021, 601, 126819 .
AMA StyleShibo Chen, Lei Chen, Yang Gao, Jinsong Guo, Leifang Li, Zhenyao Shen. Larger phosphorus flux triggered by smaller tributary watersheds in a river reservoir system after dam construction. Journal of Hydrology. 2021; 601 ():126819.
Chicago/Turabian StyleShibo Chen; Lei Chen; Yang Gao; Jinsong Guo; Leifang Li; Zhenyao Shen. 2021. "Larger phosphorus flux triggered by smaller tributary watersheds in a river reservoir system after dam construction." Journal of Hydrology 601, no. : 126819.
Nitrogen in urban stormwater has been widely studied, and effective management of nitrogen pollution is critical for improving urban stormwater and receiving water quality. This requires an in-depth understanding of the transport process and source contribution to both dissolved and particulate nitrogen in stormwater from urban catchments. In this study, 123 stormwater runoff samples were collected from an urban catchment during different rainfall events. Dissolved and particulate nitrogen concentrations in roof runoff, road runoff, and sewer flow were analyzed. The concentration of dissolved nitrogen was higher in roof runoff than in road runoff and sewer flow. However, the concentration of particulate nitrogen was lower in roof runoff than in road runoff and sewer flow. Isotopic analysis and Bayesian mixing models showed that road runoff was the largest source contributor of both nitrate and particulate organic nitrogen (PON) in sewer flow discharged from the study catchment. In addition, road runoff contributed the majority of PON associated with coarse particles (>105 μm), whereas PON associated with fine particles (<105 μm) was primarily washed-off of sewer sediments. The results provided several suggestions for the management of nitrogen pollution in urban catchments. This study could help to fully understand the transport and sources of nitrogen pollution in urban stormwater and provide recommendations to the government for implementing appropriate stormwater management strategies to minimize stormwater pollution.
Yukun Ma; Shihui Wang; Xiaoyue Zhang; Zhenyao Shen. Transport process and source contribution of nitrogen in stormwater runoff from urban catchments. Environmental Pollution 2021, 289, 117824 .
AMA StyleYukun Ma, Shihui Wang, Xiaoyue Zhang, Zhenyao Shen. Transport process and source contribution of nitrogen in stormwater runoff from urban catchments. Environmental Pollution. 2021; 289 ():117824.
Chicago/Turabian StyleYukun Ma; Shihui Wang; Xiaoyue Zhang; Zhenyao Shen. 2021. "Transport process and source contribution of nitrogen in stormwater runoff from urban catchments." Environmental Pollution 289, no. : 117824.
Based on the missing situation and actual needs of maritime search and rescue data, multiple imputation methods were used to construct complete data sets under different missing patterns. Probability density curves and overimputation diagnostics were used to explore the effects of multiple imputation. The results showed that the Data Augmentation (DA) algorithm had the characteristics of high operation efficiency and good imputation effect, but the algorithm was not suitable for data imputation when there was a high data missing rate. The EMB algorithm effectively restored the distribution of datasets with different data missing rates, and was less affected by the missing position; the EMB algorithm could obtain a good imputation effect even when there was a high data missing rate. Overimputation diagnostics could not only reflect the data imputation effect, but also show the correlation between different datasets, which was of great importance for deep data mining and imputation effect improvement. The Expectation-Maximization with Bootstrap (EMB) algorithm had a poor estimation effect on extreme data and failed to reflect the dataset’s variability characteristics.
Guobo Wang; Minglu Ma; Lili Jiang; Fengyun Chen; Liansheng Xu. Multiple imputation of maritime search and rescue data at multiple missing patterns. PLOS ONE 2021, 16, e0252129 .
AMA StyleGuobo Wang, Minglu Ma, Lili Jiang, Fengyun Chen, Liansheng Xu. Multiple imputation of maritime search and rescue data at multiple missing patterns. PLOS ONE. 2021; 16 (6):e0252129.
Chicago/Turabian StyleGuobo Wang; Minglu Ma; Lili Jiang; Fengyun Chen; Liansheng Xu. 2021. "Multiple imputation of maritime search and rescue data at multiple missing patterns." PLOS ONE 16, no. 6: e0252129.
This study explored the sources, transformations of suspended particulate organic matter (POM), and the influence of landscape patterns on POM within the Beiyun River Watershed by applying the stable carbon and nitrogen isotope technique combined with multiple statistical analyses. The POM variables showed great spatial fluctuations under different urban development gradients. Analysis of multiple isotopes revealed that assimilation of phytoplankton might exist in the rainy season, while nitrification occurs in the dry season. SIAR modeling results indicated that the sewage debris and phytoplankton were the main sources of POM in both seasons, accounting for 52.58% and 38.39% in the rainy season, 33.17% and 31.95% in the dry season, respectively. Spatiotemporal variations of POM sources existed in the study watershed, probably due to urbanization and human disturbance. The multiple linear stepwise regression and redundant analysis results indicated that landscape metrics reflecting contagion and fragmentation at the class level correlated well with the POM variables over seasons. Interspersion and juxtaposition indices of grassland and water were negatively related to POM variables in the rainy season, whereas the landscape division index of buildup land showed negative correlations with POM parameters in the dry season. Increasing the adjacency of grassland and water to other land uses, while reducing the aggregation of buildup lands would be an efficient way for urban river water quality improvement.
Jin Liu; Tiezhu Yan; Zhenyao Shen. Sources, transformations of suspended particulate organic matter and their linkage with landscape patterns in the urbanized Beiyun river Watershed of Beijing, China. Science of The Total Environment 2021, 791, 148309 .
AMA StyleJin Liu, Tiezhu Yan, Zhenyao Shen. Sources, transformations of suspended particulate organic matter and their linkage with landscape patterns in the urbanized Beiyun river Watershed of Beijing, China. Science of The Total Environment. 2021; 791 ():148309.
Chicago/Turabian StyleJin Liu; Tiezhu Yan; Zhenyao Shen. 2021. "Sources, transformations of suspended particulate organic matter and their linkage with landscape patterns in the urbanized Beiyun river Watershed of Beijing, China." Science of The Total Environment 791, no. : 148309.
The Miyun Reservoir is an important source of surface drinking water in Beijing. Due to climate change and human activities, the inflow of Miyun Reservoir watershed (MRW) has been continuously reduced in the past 30 years, which has seriously affected the safety of Beijing’s water supply. Therefore, this study aimed to assess the mitigation measures based on the quantification of the integrated impacts of climate and land use change in MRW. The non-point source (NPS) model (soil and water assessment tool, SWAT) was used for the development of future climate scenarios which were derived from two regional climate models (RCMs) under two representative concentration pathways (RCPs). Three land use scenarios were generated by the land use model (conversion of land-use and its effects (CLUE-S)): (1) historical trend scenario, (2) ecological protection without consideration of spatial configuration scenario and (3) ecological protection scenario. Moreover, the reduction of sediment and nutrients under three future land use patterns in future climate scenarios was evaluated. The results showed that an appropriate land use change project led to the desired reduction effect on sediment and nutrients output under future climate scenarios. The average reduction rates of sediment, total nitrogen and total phosphorus were 11.4%, 6.3% and 7.4%, respectively. The ecological protection scenario considering spatial configuration showed the best reduction effect on sediment, total nitrogen and total phosphorus. Therefore, the addition of region-specific preference variables as part of land use change provides better pollutant control effects. Overall, this research provides technical support to protect the safety of Beijing’s drinking water and future management of non-point source pollution in MRW.
Mao Feng; Zhenyao Shen. Assessment of the Impacts of Land Use Change on Non-Point Source Loading under Future Climate Scenarios Using the SWAT Model. Water 2021, 13, 874 .
AMA StyleMao Feng, Zhenyao Shen. Assessment of the Impacts of Land Use Change on Non-Point Source Loading under Future Climate Scenarios Using the SWAT Model. Water. 2021; 13 (6):874.
Chicago/Turabian StyleMao Feng; Zhenyao Shen. 2021. "Assessment of the Impacts of Land Use Change on Non-Point Source Loading under Future Climate Scenarios Using the SWAT Model." Water 13, no. 6: 874.
Microbial pollution is an environmental problem of growing concern for threatening human health. However, the impacts of rapid urbanization on characteristics, sources and variation of fecal coliform (FC) at watershed scale have not been fully explored. In this study, FC characteristics were monitored monthly for 2 years at 21 river sections in an urbanizing watershed, while the sources and continuously annual variation were quantified by integrating two commonly-used models. The results showed that FC varied from 103 to 106 MPN/L, indicating a great spatiotemporal variation at watershed scale. Peak FC occurred in summer and autumn among upstream and downstream areas, respectively. Besides, 65% impermeable surface was identified as the threshold of urban level, beyond which the key FC source would shift from agriculture to urban. It was also found that the changes of urban landscape patterns had poor correlation with annual variation of FC. In comparison, urbanization speed was identified as the major driver with the threshold of 30% for deteriorating FC pollution. The Low Impact Development could result in a 5.13%–97.59% reduction of FC at watershed scale.
Xiaoyue Zhang; Lei Chen; Zhenyao Shen. Impacts of rapid urbanization on characteristics, sources and variation of fecal coliform at watershed scale. Journal of Environmental Management 2021, 286, 112195 .
AMA StyleXiaoyue Zhang, Lei Chen, Zhenyao Shen. Impacts of rapid urbanization on characteristics, sources and variation of fecal coliform at watershed scale. Journal of Environmental Management. 2021; 286 ():112195.
Chicago/Turabian StyleXiaoyue Zhang; Lei Chen; Zhenyao Shen. 2021. "Impacts of rapid urbanization on characteristics, sources and variation of fecal coliform at watershed scale." Journal of Environmental Management 286, no. : 112195.
Spatial planning is crucial for Sponge City (SC) construction; however, prioritizing SC sites at the watershed scale has not been fully explored. In this study, a multi-criteria decision model, considering demand and suitability of SC construction, was established by monitoring, model simulation and index calculation. This new model was then tested in a rapidly urbanizing watershed, Beijing, China and the priority of SC construction at both grid scale (1km 1km) and subwatershed scale was ranked. The results showed that the highest priority was found in emerging regions where urbanization is ongoing, and followed by urban core areas. In addition, six indexes were identified by clustering heatmaps as key factors affecting the priority of SC planning, including topographic index, water pollution index, pollution rate based on the state standard of surface water environment quality, urbanization planning, urban levels, and vegetation index, which could guide SC planning in data-lacking regions. The approach and findings in this study can not only provide helpful references for watershed managers and urban planners but also can be easily used in other regions.
Xiaoyue Zhang; Lei Chen; Meng Zhang; Zhenyao Shen. Prioritizing Sponge City Sites in Rapidly Urbanizing Watersheds Using Multi-Criteria Decision Model. 2021, 1 .
AMA StyleXiaoyue Zhang, Lei Chen, Meng Zhang, Zhenyao Shen. Prioritizing Sponge City Sites in Rapidly Urbanizing Watersheds Using Multi-Criteria Decision Model. . 2021; ():1.
Chicago/Turabian StyleXiaoyue Zhang; Lei Chen; Meng Zhang; Zhenyao Shen. 2021. "Prioritizing Sponge City Sites in Rapidly Urbanizing Watersheds Using Multi-Criteria Decision Model." , no. : 1.
Calibration is an essential part of watershed models, and a universal calibration platform based on advanced genetic algorithms is needed. In this study, a universal platform was constructed for different watershed models by transferring the configuration files of models and incorporating the Non-dominated Sorted Genetic Algorithm-Ⅱ (NSGA-Ⅱ). It was tested in two real cases studies by using two commonly used models, including the Hydrological Simulation Program-FORTRAN (HSPF) and the Storm Water Manage- ment Model (SWMM). For HSPF, the results showed that the goodness-of-fit indicators, in terms of NSE and R2, were 0.82, 0.83 and 0.66, 0.67 during the calibration and validation period, respectively. For SWMM, NSE ranged from 0.854 to 0.920 and R2 ranged from 0.737 to 0.912. The results indicated that this universal platform provided good model calibrations for both two models and it could be extended to other watershed models and other catchments as an effective and robust method for model calibration.
L. Chen; W. Z. Wang; G. Y. Wei; K. Wang; H. B. Liu; L. M. Zhai; Z. Y. Shen. Development of A Universal Calibration Platform for Watershed Models Using Global Optimization. Journal of Environmental Informatics 2021, 1 .
AMA StyleL. Chen, W. Z. Wang, G. Y. Wei, K. Wang, H. B. Liu, L. M. Zhai, Z. Y. Shen. Development of A Universal Calibration Platform for Watershed Models Using Global Optimization. Journal of Environmental Informatics. 2021; ():1.
Chicago/Turabian StyleL. Chen; W. Z. Wang; G. Y. Wei; K. Wang; H. B. Liu; L. M. Zhai; Z. Y. Shen. 2021. "Development of A Universal Calibration Platform for Watershed Models Using Global Optimization." Journal of Environmental Informatics , no. : 1.
The classic export coefficient model has been questioned due to its fixed coefficient, especially for those large-scale watersheds where great temporal-spatial heterogeneity exists. In this paper, a dynamic export coefficient model (DECM) was proposed for simulating non-point source (NPS) pollution by incorporating the impacts of factors on export coefficients. The relationships between rainfall, slope, soil, land use, other factors and export coefficients were constructed at relatively smaller catchment based on the information of mechanistic-based model, while these dynamic export coefficients were then extended to the large ungauged basins. This new model was tested in the Three Gorges Reservoir Region (TGRR), China. The results indicated the new method improved the accuracy of large-scale NPS prediction as well as reducing the computation burden. The rainfall temporal variability was identified as the major factor influencing the variability of flow and NPS pollution with the coefficient of variation being 0.1678 and 0.2046, respectively. Using the new method, the Long watershed, the Jialing watershed, the Quxi watershed, the Xiangxi watershed and the main stream in the TGRR were identified as those sensitive regions under the changing environment. The DECM could be extended to other large scale to quantify the NPS pollution, especially data-poor watersheds.
Wenzhuo Wang; Lei Chen; Zhenyao Shen. Dynamic export coefficient model for evaluating the effects of environmental changes on non-point source pollution. Science of The Total Environment 2020, 747, 141164 .
AMA StyleWenzhuo Wang, Lei Chen, Zhenyao Shen. Dynamic export coefficient model for evaluating the effects of environmental changes on non-point source pollution. Science of The Total Environment. 2020; 747 ():141164.
Chicago/Turabian StyleWenzhuo Wang; Lei Chen; Zhenyao Shen. 2020. "Dynamic export coefficient model for evaluating the effects of environmental changes on non-point source pollution." Science of The Total Environment 747, no. : 141164.
Best management practices (BMPs) have been widely applied to mitigate non-point source (NPS) pollution in agricultural watersheds. However, a prediction of the multivariate reduction effect of NPS pollutants by BMPs considering its stochastic nature has not been conducted. A new modeling approach combining a hydrological model and copulas was proposed to predict the multivariate effect of BMPs fully considering the stochastic characteristics of BMPs effects and the dependence structure between them. Two levels of reduction effect, i.e., the multi-indicator effect of a single BMP and the combined effect of multiple BMPs, were simulated. The approach was demonstrated in Zhangjiachong watershed, a typical small watershed in the Three Gorges Reservoir area, China. Results show that copulas can effectively simulate the dependence between the univariate effects of BMPs. The approach can accurately predict the probability to achieve the reduction objective for multiple pollutants and multiple BMPs in a watershed. It provides a stochastic way to predict the multivariate effect of BMPs and has great potential to be widely applied in BMPs related decision making.
Pu Zhang; Yucong Yang; Lei Chen; Hui Xie; Zhenyao Shen. Applying copulas to predict the multivariate reduction effect of best management practices. Journal of Environmental Management 2020, 267, 110641 .
AMA StylePu Zhang, Yucong Yang, Lei Chen, Hui Xie, Zhenyao Shen. Applying copulas to predict the multivariate reduction effect of best management practices. Journal of Environmental Management. 2020; 267 ():110641.
Chicago/Turabian StylePu Zhang; Yucong Yang; Lei Chen; Hui Xie; Zhenyao Shen. 2020. "Applying copulas to predict the multivariate reduction effect of best management practices." Journal of Environmental Management 267, no. : 110641.
Optimizing long-term best management practices (BMPs) is of vital importance for water quality management, especially for nonpoint source (NPS) pollution. However, changes in the efficiency of BMPs over time have not been incorporated and a proper method for determining long-term BMP configuration strategies is still lacking. In this study, the long-term BMP optimization method (LBMP-OM) was developed for recommending the BMP maintenance-replacement strategies and optimizing the BMP configuration. This new method was then tested in the Daning Watershed, Three Gorges Reservoir Region, China. Based on the results, a 1-year maintenance period and a 3-year replacement period was recommended for a filter strip by considering a changing BMP effectiveness rather than a constant effectiveness and by discussing the rationality of experts' suggestions for maintenance and replacement strategies regarding the regulation of NPS pollution. At the watershed scale, the total cost dropped by 57.36% by introducing the LBMP-OM method compare to the original method. This new method extended the long-term management and configuration of BMPs.
Guowangchen Liu; Lei Chen; Wenzhuo Wang; Cheng Sun; Zhenyao Shen. A water quality management methodology for optimizing best management practices considering changes in long-term efficiency. Science of The Total Environment 2020, 725, 138091 .
AMA StyleGuowangchen Liu, Lei Chen, Wenzhuo Wang, Cheng Sun, Zhenyao Shen. A water quality management methodology for optimizing best management practices considering changes in long-term efficiency. Science of The Total Environment. 2020; 725 ():138091.
Chicago/Turabian StyleGuowangchen Liu; Lei Chen; Wenzhuo Wang; Cheng Sun; Zhenyao Shen. 2020. "A water quality management methodology for optimizing best management practices considering changes in long-term efficiency." Science of The Total Environment 725, no. : 138091.
Low impact development (LID) has been widely applied to mitigate urban rainwater problems since the 1990s. However, the effect of LID practices has seldom been evaluated in detail. In this study, the effect of individual and combined LID practices on the reduction of roof runoff are specifically quantified considering the hydrological relationship between LID at the building scale and the campus scale at Beijing Normal University (BNU). The results show that individual and combined LID practices effectively reduce roof runoff for all types of rainfall and for rainfall with return periods from 0.5 to 50 years at the building scale. Combination scenarios maintain good performance with fewer areas of composed LID. Most values for the effect of combination scenarios are between the effects of composed LID. To achieve the highest cost efficiency, low elevation greenbelts should be the first choice, and green roofs should only be selected when low elevation greenbelts and rain barrels cannot be implemented. At the campus scale, individual and combined LID practices effectively reduce the outflow from and the overflow in the campus and combination scenarios have the best reduction performance. This study provides an important reference for urban water management and LID related decision making.
Pu Zhang; Lei Chen; Xiaoshu Hou; Guoyuan Wei; Xiaoyue Zhang; Zhenyao Shen. Detailed Quantification of the Reduction Effect of Roof Runoff by Low Impact Development Practices. Water 2020, 12, 795 .
AMA StylePu Zhang, Lei Chen, Xiaoshu Hou, Guoyuan Wei, Xiaoyue Zhang, Zhenyao Shen. Detailed Quantification of the Reduction Effect of Roof Runoff by Low Impact Development Practices. Water. 2020; 12 (3):795.
Chicago/Turabian StylePu Zhang; Lei Chen; Xiaoshu Hou; Guoyuan Wei; Xiaoyue Zhang; Zhenyao Shen. 2020. "Detailed Quantification of the Reduction Effect of Roof Runoff by Low Impact Development Practices." Water 12, no. 3: 795.
Faecal microorganisms represent a key threat to human health. Potential origins of faecal microbial contamination in a typical urban-representative micro-scale were evaluated. The quantitative polymerase chain reaction (qPCR) method was used in this study. The Bacteroidetes is selected as the indicative microorganism in runoff samples that are collected during four representative stormwater events in north China. The principal component analysis (PCA) method indicated the distribution feature of the environmental factors. The largest contributor is dog, followed by bird and human to the faecal pollution in stormwater runoff. The output of human and dog faecal pollutants in response to the first flush effect of nonpoint source pollution while the transmit time of bird faecal pollutant is relatively longer. In addition, the number of antecedent drying days represents the key factor for dog faecal pollution, while human faecal pollution is impacted by more factors. The results of this study will provide sound evidence for the tracking and management of nonpoint source faecal pollution in urban catchment areas.
Lei Chen; Xiaoyue Zhang; Xiaosha Zhi; Ying Dai; Pu Zhang; Yuechen Xiao; Zhenyao Shen. Tracking faecal microorganisms using the qPCR method in a typical urban catchment in China. Environmental Monitoring and Assessment 2020, 192, 158 .
AMA StyleLei Chen, Xiaoyue Zhang, Xiaosha Zhi, Ying Dai, Pu Zhang, Yuechen Xiao, Zhenyao Shen. Tracking faecal microorganisms using the qPCR method in a typical urban catchment in China. Environmental Monitoring and Assessment. 2020; 192 (3):158.
Chicago/Turabian StyleLei Chen; Xiaoyue Zhang; Xiaosha Zhi; Ying Dai; Pu Zhang; Yuechen Xiao; Zhenyao Shen. 2020. "Tracking faecal microorganisms using the qPCR method in a typical urban catchment in China." Environmental Monitoring and Assessment 192, no. 3: 158.
Climate change is one of the major challenges in watershed management systems. Rising air temperatures, increasing precipitation in winter, and decreasing precipitation in summer as well as increases in extreme weather events have increased flooding and droughts and further affected water quality in the Miyun Reservoir Watershed (MRW). This study used the Soil and Water Assessment Tool (SWAT) model with five downscaled general circulation models (GCMs) to quantify the impact of climate change on hydrology, soil erosion, nutrient cycling, and the performance of Best Management Practices (BMPs) at watershed scale, driven by RCPs 2.6, 4.5, and 8.5. Compared with the baseline scenario, the results indicated that climate variability, especially precipitation and temperature, had great effects on surface runoff, sediment yields, and nutrient losses and further significantly affected BMP efficiency, although the magnitudes of change differed among the RCPs. Monthly sediment and nutrient loads increased substantially in all climate change scenarios, especially in flood season, due to the increase in precipitation intensity. Although BMPs were identified to be not appreciably effective in controlling water balance, they were effective in reducing sediment and nutrient losses. Based on this case, a simulation-optimization framework was applied to develop future watershed management strategies with BMP configurations because of their climate adaptation benefits, water improvement targets, and economical cost. The results indicated that the discrepancy among different climate scenarios was reflected by the number and types of BMPs and their spatial distributions, especially structural BMPs. This study suggests that the increasing frequency of rainfall events may decrease the efficiency of BMPs in the MRW, and watershed management should be adjusted according to changing climate in the future.
Jiali Qiu; Zhenyao Shen; Xiaoshu Hou; Hui Xie; Guoyong Leng. Evaluating the performance of conservation practices under climate change scenarios in the Miyun Reservoir Watershed, China. Ecological Engineering 2019, 143, 105700 .
AMA StyleJiali Qiu, Zhenyao Shen, Xiaoshu Hou, Hui Xie, Guoyong Leng. Evaluating the performance of conservation practices under climate change scenarios in the Miyun Reservoir Watershed, China. Ecological Engineering. 2019; 143 ():105700.
Chicago/Turabian StyleJiali Qiu; Zhenyao Shen; Xiaoshu Hou; Hui Xie; Guoyong Leng. 2019. "Evaluating the performance of conservation practices under climate change scenarios in the Miyun Reservoir Watershed, China." Ecological Engineering 143, no. : 105700.
Semi-distributed models, such as SWMM, have become effective tools for quantifying the urban nonpoint source (NPS) pollution. However, these models could not provide detailed overland routing simulations and often face the difficulty in collecting data of municipal drainage network due to confidentiality requirements. In this study, the cellular automate (CA) based overland routing algorithm was coupled to the SWMM for providing reliable NPS pollution simulations. The CA-SWMM was validated in a typical small urban catchment with scarce municipal drainage data. The results indicated a significant improvement of performances could be obtained by the CA-SWMM in both rainfall-runoff and NPS pollution simulations compared to the SWMM. As a distributed model, the scale effect exists for the CA-SWMM, where the appropriate cell resolution should guarantee most of the cells to be homogeneous in land-cover configuration and the heterogeneous cells to be configured just by roofs and ground land covers. The input data could be used as references for choosing cell resolution because the CA would seldom work in tracking the inner routing between land uses when the cell size is larger than most of the sewer-inlet intervals. The results of this study provide reliable tool for advanced overland routing simulations of NPS pollution as well as the optimal design of low development practices, especially for those data-scarce regions.
Ying Dai; Lei Chen; Zhenyao Shen. A cellular automata (CA)-based method to improve the SWMM performance with scarce drainage data and its spatial scale effect. Journal of Hydrology 2019, 581, 124402 .
AMA StyleYing Dai, Lei Chen, Zhenyao Shen. A cellular automata (CA)-based method to improve the SWMM performance with scarce drainage data and its spatial scale effect. Journal of Hydrology. 2019; 581 ():124402.
Chicago/Turabian StyleYing Dai; Lei Chen; Zhenyao Shen. 2019. "A cellular automata (CA)-based method to improve the SWMM performance with scarce drainage data and its spatial scale effect." Journal of Hydrology 581, no. : 124402.
To explore the spatial variation of source-specific ecological risks and identify critical sources of heavy metals in road dust, 36 road dust samples collected in Beijing in March 2017 were analyzed for heavy metals. A new method that takes into consideration the heavy-metal toxic response and is flexible to changes in the number of calculated heavy metals, called the Nemerow integrated risk index (NIRI), was developed for ecological risk assessment. The NIRI indicated that heavy metals posed considerable to high risks at the majority of sites, and 22 % of the sites suffered extreme risk in spring (NIRI > 320). Four main sources were identified based on positive matrix factorization (PMF): traffic exhaust, fuel combustion, construction, and use of pesticides and fertilizers. Owing to the lower toxic response factors of representative heavy metals of fuel combustion than those of other sources, although fuel combustion had the highest contribution (34.21 %) to heavy metals in spring, it only contributed 5.57 % to ecological risks. Critical sources and critical source areas were determined by considering the contributions to both heavy metals and ecological risks. The use of pesticide and fertilizer and traffic-related exhaust were identified as critical sources of heavy metals in spring. Source-specific ecological risks and critical sources of heavy metals changed with the changing seasons, which suggests that different strategies should be adopted in different seasons.
Cong Men; Ruimin Liu; Libing Xu; Qingrui Wang; Lijia Guo; Yuexi Miao; Zhenyao Shen. Source-specific ecological risk analysis and critical source identification of heavy metals in road dust in Beijing, China. Journal of Hazardous Materials 2019, 388, 121763 .
AMA StyleCong Men, Ruimin Liu, Libing Xu, Qingrui Wang, Lijia Guo, Yuexi Miao, Zhenyao Shen. Source-specific ecological risk analysis and critical source identification of heavy metals in road dust in Beijing, China. Journal of Hazardous Materials. 2019; 388 ():121763.
Chicago/Turabian StyleCong Men; Ruimin Liu; Libing Xu; Qingrui Wang; Lijia Guo; Yuexi Miao; Zhenyao Shen. 2019. "Source-specific ecological risk analysis and critical source identification of heavy metals in road dust in Beijing, China." Journal of Hazardous Materials 388, no. : 121763.
Bioretention facilities have been widely used in the construction of Sponge City in China, but there have also been doubts about whether road runoff pollutants have adverse effects on plant growth. In response to this problem, this paper explored the effects of bioretention on the removal of pollutants and explored the effects of runoff on plant growth and physiology. The results showed that (1) the average concentration reduction rate and load removal rate of TN and NO3--N were above 70%, the average NH4+-N concentration reduction rate and load removal rate were greater than 90%, and the removal of elemental N was affected by the influent concentration. The removal effect of the four heavy metals was not very great. The average concentration reduction rate and load removal rate of heavy metals were 65.4–95.7% and 85.4–99.4%, respectively. The cumulative load removal rate of various pollutants was above 87.0%. (2) The runoff of high–concentration pollutants had a negative or no significant effects on the net photosynthesis rates (Pn), chlorophyll contents (CC), and electrolyte leakage (EL) of most plants (e.g., Iris tectorum Maxim, Rosa xanthina Lindl, and Ligustrum vicaryi). It had a significantly negative effect on the plant height of shrub plants (e.g., Rosa xanthina Lindl and Ligustrum vicaryi), but had a positive effect on Pn and CC of Iris lactea var. chinensis. (3) The runoff of low–concentration pollutants had a positive or no significant effects on the physiological indexes of herbaceous plants (e.g., Iris tectorum Maxim and Iris lactea var. chinensis), but there were no explicit conclusions regarding the physiological indicators of shrub plants (e.g., Rosa xanthina Lindl and Ligustrum vicaryi). It had no obvious effects on the plant height of these four species of plants.
Yongwei Gong; Yan Hao; Junqi Li; Haiyan Li; Zhenyao Shen; Wenhai Wang; Sisi Wang. The Effects of Rainfall Runoff Pollutants on Plant Physiology in a Bioretention System Based on Pilot Experiments. Sustainability 2019, 11, 6402 .
AMA StyleYongwei Gong, Yan Hao, Junqi Li, Haiyan Li, Zhenyao Shen, Wenhai Wang, Sisi Wang. The Effects of Rainfall Runoff Pollutants on Plant Physiology in a Bioretention System Based on Pilot Experiments. Sustainability. 2019; 11 (22):6402.
Chicago/Turabian StyleYongwei Gong; Yan Hao; Junqi Li; Haiyan Li; Zhenyao Shen; Wenhai Wang; Sisi Wang. 2019. "The Effects of Rainfall Runoff Pollutants on Plant Physiology in a Bioretention System Based on Pilot Experiments." Sustainability 11, no. 22: 6402.
As one typical land use change, the mechanism of returning farmland to forests (RFF) on nonpoint source pollution (NPS) is not clear, especially at multiple spatial scales. In this study, by using the Soil and Water Assessment Tool (SWAT), the changes in several flow-related and NPS-related indicators across several nested catchments were quantified and compared in the Three Gorges Reservoir Region, China. The results indicated that RFF could reduce the total flow and total phosphorus (TP), which are higher in the dry season (41% and 79%, respectively) than in the wet season (21% and 47%, respectively) at the watershed with a total area of 2423.74 km2. In comparison, RFF has a larger impact on the baseflow index during the wet season (367.02%) than during the dry season (166.54%). The results also indicated that a spatial scaling effect did exist, while the reduction in TP increased from 24.57% to 48.46% as the drainage area increased from 65.92 km2 to 2104.35 km2. Specific thresholds of RFF efficiency were also observed (approximately 2000 km2 for the study area). It is suggested that other source control measures could supplement RFF by stabilizing the efficiency of RFF across different spatial scales. The results of this study could provide valuable suggestions for land use development and water quality protection, especially for large, complex watersheds.
Wenzhuo Wang; Lei Chen; Yingxin Zhu; Kai Wang; Shibo Chen; Zhenyao Shen. Is returning farmland to forest an effective measure to reduce phosphorus delivery across distinct spatial scales? Journal of Environmental Management 2019, 252, 109663 .
AMA StyleWenzhuo Wang, Lei Chen, Yingxin Zhu, Kai Wang, Shibo Chen, Zhenyao Shen. Is returning farmland to forest an effective measure to reduce phosphorus delivery across distinct spatial scales? Journal of Environmental Management. 2019; 252 ():109663.
Chicago/Turabian StyleWenzhuo Wang; Lei Chen; Yingxin Zhu; Kai Wang; Shibo Chen; Zhenyao Shen. 2019. "Is returning farmland to forest an effective measure to reduce phosphorus delivery across distinct spatial scales?" Journal of Environmental Management 252, no. : 109663.
Effective water-quality management requires full understanding of the nonpoint source (NPS) pollutant pathways. However, the spatial scaling effect has become one key barrier for the estimation of baseflow NPS pollutants. In this study, the scaling effect of baseflow NPS pollutants was investigated. The Soil and Water Assessment Tool was used for flow and NPS pollutants simulation at nested river sections, while the baseflow NPS pollutants was then estimated based on 17 levels of nested watersheds in a watershed of China. The results indicated that as the spatial scale increased, the baseflow became an important pathway of NPS pollutants, as its average contribution increased from 0.27 in the small headwater catchment to 0.45 in the nested large watershed. The scaling effects of the baseflow index (BFI) and the contribution of the baseflow NPS pollutants were closely related to the land use distribution among those upstream catchments, whereas for the mainstream, the tributary inflow would become another important reason for the scaling effect. Furthermore, the spatial scaling effect of the BFI was less obvious during the dry period, whereas the spatial scaling of the baseflow NPS pollutants did not show much difference among different hydrological periods.
Yingxin Zhu; Lei Chen; Kai Wang; Wenzhuo Wang; Chengcheng Wang; Zhenyao Shen. Evaluating the spatial scaling effect of baseflow and baseflow nonpoint source pollution in a nested watershed. Journal of Hydrology 2019, 579, 124221 .
AMA StyleYingxin Zhu, Lei Chen, Kai Wang, Wenzhuo Wang, Chengcheng Wang, Zhenyao Shen. Evaluating the spatial scaling effect of baseflow and baseflow nonpoint source pollution in a nested watershed. Journal of Hydrology. 2019; 579 ():124221.
Chicago/Turabian StyleYingxin Zhu; Lei Chen; Kai Wang; Wenzhuo Wang; Chengcheng Wang; Zhenyao Shen. 2019. "Evaluating the spatial scaling effect of baseflow and baseflow nonpoint source pollution in a nested watershed." Journal of Hydrology 579, no. : 124221.
The optimal design of best management practices (BMPs) is of vital importance for the control of nonpoint source (NPS) pollutants, but proper methods for multiple-scale BMP design are still lacking, especially for large-scale watersheds. In this study, a new framework (MS-BMPs) was proposed for multiscale BMP design by combining multiscale design ideas, hydrological models, cost estimators and shuffled frog leaping algorithms. In addition, the computation efficiency of BMP design was improved by modifying the memetic evolution process. This new framework was then tested in the Daning River Watershed, Three Gorges Reservoir Region, China. Based on the results, the new framework could provide more powerful convergence and optimization ability, while the rationality of BMP configuration was increased by four times. From the Pareto front of the MS-BMPs, the maximum removal of TN and TP improved by 19.42% and 14.36%, indicating a more cost-effective BMP design. This study also highlighted the priority of fertilization management in the regulation of NPS pollution. This new framework can be easily extended to any watershed to assist managers with the optimal design of BMPs.
Guowangchen Liu; Lei Chen; Guoyuan Wei; Zhenyao Shen. New framework for optimizing best management practices at multiple scales. Journal of Hydrology 2019, 578, 124133 .
AMA StyleGuowangchen Liu, Lei Chen, Guoyuan Wei, Zhenyao Shen. New framework for optimizing best management practices at multiple scales. Journal of Hydrology. 2019; 578 ():124133.
Chicago/Turabian StyleGuowangchen Liu; Lei Chen; Guoyuan Wei; Zhenyao Shen. 2019. "New framework for optimizing best management practices at multiple scales." Journal of Hydrology 578, no. : 124133.