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Integrated assessment of the water environment has become widespread in many rivers, lakes, and reservoirs; however, aquatic organisms in freshwater are often overlooked in this process. Zooplankton, as primary consumers, are sensitive and responsive to changes in the water environment. Water and zooplankton samples were collected on-site at Shanxi Reservoir quarterly to determine 12 water environmental indicators and to quantify the abundance of zooplankton of Cladocera, Copepoda and Rotifera by using the ZooScan zooplankton image-scanning analysis system, combined with OLYMPUS BX51 using machine learning recognition classification. The aim was to explore the relationship between water environmental factors and zooplankton through their spatial and temporal heterogeneity. Through principal component analysis, redundancy analysis and cluster analysis, variations in the factors driving zooplankton population growth in different seasons could be identified. At the same time, different taxa of zooplankton can form clusters with related water environmental factors during the abundant water period in summer and the dry water period in winter. Based on long-term monitoring, zooplankton can be used as a comprehensive indicator for water environment and water ecological health evaluation, as well as providing scientific support for regional water resources deployment and management.

Soil salinity and water scarcity adversely affect maize productivity. The use of biochar could enhance soil quality and increase the salt and/or drought threshold tolerance and yield of maize. Ther...

Water scarcity negatively affects maize yield, whereas biochar could enhance soil physical properties and improve the growth and water productivity (WP) of maize. Thus, field experiments were condu...

A hierarchical core–shell architecture of vertically arrayed ultrathin CuSe nanosheets decorating on hollow CuS microcages affords exceptional sodium storage performance with an admirable 303.1 mA h g−1 at 20.0 A g−1 after 1500 cycles.

Although plastic materials play an essential role in life, the intensive production of plastic products and mismanagement of plastic waste worldwide have resulted in microplastic pollution. The two major characteristics of environmental microplastics are having small size and resistance to degradation, which make microplastics a persistent organic pollutant. As microplastic pollution has been observed in diverse environmental matrices, it has attracted great attention of scholars globally. Over the last decade, scholars have mainly documented the particle properties of microplastics, such as size, shape or color and their adverse effects on organisms. However, no research has updated on environmental microplastics from the perspective of multi-media. Our review first summarized the literature in the occurrence, distribution, and characteristics of microplastics in three kinds of environmental matrices (water, soil, and air) to the public. We then identify the methodological challenges in researches and discuss the advantages and limitations of popular methods to analyze environmental microplastics. Eventually, our paper highlights the current challenges and proposes suggestions for the future research on microplastic pollution.

Phytoplankton is capable of responding to aquatic conditions and can therefore be used to monitor freshwater reservoir water quality. Numerous classification techniques, including morpho-functional approaches, have been developed. This study examined changes in phytoplankton assemblages and water quality, which were sampled quarterly from July 2018 to April 2019. The purpose was to contrast the applicability of three classification approaches (functional, morpho-functional and morphological-based functional groupings) for understanding the spatial and seasonal distribution of the biomass variance in phytoplankton functional groups and their driving environmental factors in the ecological zones of the Shanxi Reservoir through multivariate analysis. The results showed that the phytoplankton biomass was highest in the watercourse zone and lowest in the transition zone. Furthermore, the Shanxi Reservoir was characterized by several cyanobacteria (Microcystis spp.) and numerous bacillariophytes (Asterionella sp., Navicula spp. and Aulacoseira granulata). After evaluating the advantages and disadvantages of morpho-functional classifications, we determined that water temperature appeared to be an essential factor, and the morphology-based functional group approach provided the best results for demonstrating phytoplankton succession, despite having lower sensitivity than the others. Nevertheless, these approaches are all appropriate for identifying and monitoring phytoplankton community structure in aquatic systems of reservoirs with complex terrains.

Weirs are often constructed on mountainous rivers because of their low construction costs and their ability to provide irrigation and facilitate landscaping, yet there is little research on how fish habitat quality in mountainous rivers responds to weir distribution. This study categorized the distribution characteristics of weirs on typical reaches according to their sinuosity and calculated the corresponding habitat suitability index (HSI) and weighted usable area (WUA) under various discharge conditions using a coupled MIKE21 and habitat suitability model. Then, the relationship between the distribution characteristics of weirs and the quality of fish habitats under different discharge conditions was analyzed. The results show that weirs in mountainous rivers can affect the habitat suitability of the rivers, but this effect is closely related to discharge conditions and layout mainly because the key hydraulic factors that determine habitat quality for different sinuous reaches vary under different discharge conditions. This study found that in high-sinuosity rivers with high discharge conditions, water depth is the key factor determining the quality of fish habitats, so weirs can improve habitat quality by improving the suitability of downstream water depth. However, in other conditions, velocity is the key factor determining habitat quality, in which case weirs cannot improve habitat quality and can even degrade it. Therefore, other methods of improving velocity are needed to enhance habitat quality. The results of this study provide a reference for the protection of fish habitats in mountainous river channels and the determination of suitable locations for weir construction.

Topological nodal line (TNL) materials with one-dimensional band-crossing points (BCPs) exhibit interesting electronic characteristics and have special applications in electronic devices. Normally, based on the slopes of the crossing bands, the BCPs can be divided into two types, i.e., type I and type II nodal points. Based on the combination of the different types of nodal points, the nodal lines (NLs) can be divided into three categories: (i) type I NL, type II NL, and hybrid NL, these being formed by type I nodal points, type II nodal points, and type I and II nodal points, respectively. Compared with the large number of predicted type I NL materials, there are less type II and hybrid NL materials. In this study, it is predicted that P6

The presence of nodal points (NPs) and nodal lines (NLs) in the momentum space of topological materials is accompanied by many interesting properties. In this study, we predicted that an existing material ScPd with Pm3¯m-type structure would have closed NLs in the kx/y/z = 0 planes and one pair of triply degenerate NPs (TNPs) along the R-M-R′ paths, respectively, when the spin–orbit coupling (SOC) effect is not taken into consideration. Obvious nontrivial surface states were found around band-crossing points A, B, and C, which can be seen as good evidence for the topological signatures of ScPd metal. When the SOC effect was added, a TNP–Dirac NP (DNP) transition appeared along the R-M-R′ paths. Also, the band-crossing points belonging to the closed NL in the kx/y/z = 0 planes were gapped by the induction of SOC. However, the SOC-induced gaps were very small (

Topological materials with band-crossing points exhibit interesting electronic characteristics and have special applications in electronic devices. However, to further facilitate the experimental detection of the signatures of these band crossings, topological materials with a large linear energy range around the band-crossing points need to be found, which is challenging. Here, via first-principle approaches, we report that the previously prepared P6/mmm-type CrB2 material is a topological metal with one pair of 1D band-crossing points, that is, nodal lines, in the kz= 0 plane, and one pair of 0D band-crossing points, that is, triple points, along the A&ndash, &Gamma, &ndash, A&rsquo, paths. Remarkably, around these band-crossing points, a large linear energy range (larger than 1 eV) was found and the value was much larger than that found in previously studied materials with a similar linear crossing. The pair of nodal lines showed obvious surface states, which show promise for experimental detection. The effect of the spin&ndash, orbit coupling on the band-crossing points was examined and the gaps induced by spin&ndash, orbit coupling were found to be up to 69 meV. This material was shown to be phase stable in theory and was synthesized in experiments, and is therefore a potential material for use in investigating nodal lines and triple points.

Topological materials with band-crossing points exhibit interesting electronic characteristics and have special applications in electronic devices. However, to further facilitate the experimental detection of the signatures of these band crossings, topological materials with a large linear energy range around the band-crossing points need to be found, which is challenging. Here, via first-principle approaches, we report that the previously prepared P6/mmm-type CrB2 material is a topological metal with one pair of 1D band-crossing points, that is, nodal lines, in the kz = 0 plane, and one pair of 0D band-crossing points, that is, triple points, along the A–Γ–A’ paths. Remarkably, around these band-crossing points, a large linear energy range (larger than 1 eV) was found and the value was much larger than that found in previously studied materials with a similar linear crossing. The pair of nodal lines showed obvious surface states, which show promise for experimental detection. The effect of the spin–orbit coupling on the band-crossing points was examined and the gaps induced by spin–orbit coupling were found to be up to 69 meV. This material was shown to be phase stable in theory and was synthesized in experiments, and is therefore a potential material for use in investigating nodal lines and triple points.

The search for new topological materials that are realistic to synthesize has attracted increasing attention. In this study, we systematically investigated the electronic, mechanical, and topological semimetallic properties, as well as the interesting surface states, of the tetragonal monoxide of platinum, which is realistic to synthesize, via a first-principles approach. Our calculated results indicate that PtO is a novel topological semimetal with double nodal lines in the kz = 0 plane and a pair of triple topological nodal points along the A'-M-A directions. Obvious surface states, including Fermi arc and drum-head-like surfaces, could be found around nodal points and nodal lines. The dynamic and mechanical stabilities of P42/mmc-type PtO were examined in detail via calculation of the phonon dispersion and determination of elastic constants, respectively. Some other mechanical properties, including the bulk modulus, Young's modulus, shear modulus, Poisson's ratio, and Pugh's index, were considered in this study. P42/mmc-type PtO provides a good research platform for investigation of novel behaviors that combine mechanical properties and rich topological elements.

The aggregation kinetics of fragmental polyethylene glycol terephthalate (PET) nanoplastics under various chemistry conditions in aqueous environment were firstly investigated in this work. The aggregation of PET nanoplastics increased with increasing electrolyte concentrations and decreasing solution pH, which became stronger with the presence of divalent cations (e.g. Ca2+ and Mg2+) than that of monovalent cations (e.g. Na+ and K+). The effect of cations with the same valence on the aggregation of PET nanoplastics was similar. The measured critical coagulation concentrations (CCC) for PET nanoplastics at pH 6 were 55.0 mM KCl, 54.2 mM NaCl, 2.1 mM CaCl2 and 2.0 mM MgCl2, which increased to 110.4 mM NaCl and 5.6 mM CaCl2 at pH 10. In addition, the aggregation of PET nanoplastics was significantly inhibited with the presence of humic acid (HA), and the CCC values increased to 558.8 mM NaCl and 12.3 mM CaCl2 (1 mg L−1 HA). Results from this study showed that the fragmental PET nanoplastics had the quite higher CCC values and stability in aqueous environment. In addition, the aggregation behaviors of PET nanoplastics can be successfully predicted by the Derjguin Landau Verwey Overbeek (DLVO) theory.

As an important part of the riparian zone, bars are an important barrier for the interception of phosphorus (P) originated from leaching and runoff. The spatial variation in P as well as the influence of factors on the said spatial variation in mountainous river (Lingshan River) bars was investigated. A total of 100 soil samples were collected from 11 sampling sites. Soil total phosphorus (TP) and soil available P were determined to explore the spatial variation of soil P in mountainous river bars. One-way analysis of variance, Pearson's correlation analyses, stepwise multiple linear regressions and curve fitting were used to explore the dominant factors affecting the spatial variation of soil P in mountainous river bars. Affected by erosion effect of flowing water, the TP of the bar soils decreased in the longitudinal direction, the TP and available P of the bar soils increased in the cross-sectional direction and the variation in TP between the surface and deep soils firstly increased and then decreased as the height of the bar above the water surface increased. The stronger the erosion effect of flowing water, the more P releases to the water, which may cause the spatial variation of soil P in mountainous river bars, and the results of this study facilitated control of non-point source pollution in mountainous river and restoration of the ecosystems in mountainous river bars.

The environmental behaviors of graphitic carbon nitride (g-C

The environmental behaviors of microplastics (MPs) have garnered ever-increasing attention globally. To overcome the limitations of commonly used "black box", a real-time pore-scale visualization system including microscope, charge coupled device (CCD) microscope camera, and flow cell (connected with pump and sample collector) was used to unravel the transport and retention mechanisms of fragmental microplastics (FMPs) in saturated and unsaturated porous media. The breakthrough curves (BTCs) of effluent concentrations from the flow cells were used to quantitatively analyze FMPs transport. The videos gathered from different transport scenarios indicated that FMPs can move along with the bulk flow in porous media, but also move around the sand surfaces via sliding, rolling, and saltating patterns. The FMPs were retained in porous media mainly via deposition and straining in saturated porous media. Interestingly, little FMPs were captured by the air-water interface in unsaturated conditions. The mobility of FMPs varied with environmental factors, which became lower at higher solution ionic strength (IS), smaller grain size, and lower water content in porous media. Flow rate barely affected the transport of FMPs under 0.1 mM IS with the mass recovery rate ranging between 65.8 and 67.5%, but significantly enhanced FMPs mobility under 10 mM IS through reducing the moving rate. The IS and grain size showed a more significant effect on the transport of FMPs in unsaturated porous media. Our findings, for the first time, visually deciphered the transport and retention patterns of MPs with fragmental shapes on pore-scale, expanding our current knowledge of the fate and transport of more realistic MPs in the environment.

The aggregation behaviors of graphitic carbon nitride (g-C

In this study, zeta potentials of graphitic carbon nitride (g-C3N4) nanoparticles were detailedly investigated under various electrolytes, solution pH, and humic acid (HA) concentration conditions. The hydrodynamic radius of g-C3N4 nanoparticles was measured to be 388.9 ± 24 nm, and the specific surface area of the g-C3N4 nanoparticles was measured to be 46.2 m2 g−1. The absolute values of g-C3N4 zeta potentials significantly decreased with the increasing ionic strength (IS) due to the charge screening. Compared to the monovalent cation, the zeta potentials of g-C3N4 were less negative with the presence of divalent cations. In addition, K+ was more effective than Na+ in decreasing the absolute values of g-C3N4 zeta potentials, and Ca2+ was more effective than Mg2+ in decreasing the absolute values of g-C3N4 zeta potentials. When NaCl and CaCl2 were used as the electrolytes, the zeta potentials of g-C3N4 became less negative with the decreasing pH conditions. When FeCl3 and AlCl3 were used as the electrolytes, the zeta potentials of g-C3N4 became more positive with increasing solution pH due to the changing species of Fe3+ and Al3+. The zeta potentials of g-C3N4 were significantly more negative with the presence of HA. The results from this work indicated electrolytes, solution pH, and HA concentration conditions play a complex role in zeta potentials of g-C3N4 nanoparticles in aqueous environment.

Transport characteristics of fragmental polyethylene glycol terephthalate (PET) microplastics in porous media were elucidated via column experiments under a series combination of electrolytes, pH, and humic acid (HA) conditions. Fragmental PET microplastics showed low mobility in porous media with a small mass recovery rate (50.1%) even under unfavorable retention conditions. The electrolyte, pH, and HA showed combined impact on PET microplastic transport. PET microplastics mobility was enhanced with decreasing electrolyte concentration, increasing pH, and increasing HA concentration. Basic properties (e.g. destiny and shape) of PET microplastics showed stronger effect on their transport behaviors in porous media rather than the experimental chemical conditions. In general, both environmental factors and basic properties played important roles in controlling the retention and transport of PET microplastics in porous media. A numerical model considering the second order kinetic deposition sites was applied to depict the retention and transport of PET microplastics in porous media. Model simulations well matched the experimental breakthrough curves. Given the fragmental PET microplastics have more realistic and irregular shapes, results from this study can improve present knowledge of the environmental fate and risk of microplastics in underground soil and water systems.

Vegetation filter strips (VFS) have been shown to effectively intercept water flow and remove nitrogen. Studies of the vegetation effects on water flow and nitrogen transport are typically studied based on qualitative analyses with species, layouts, growth stage, seasonal changes, and other vegetation conditions and did not considered quantification based on plant traits. In this study, the transport path and retention efficiency of nitrate nitrogen (NO3-N) in VFSs are investigated from the view of the plant specific trait effects by simulating runoff experiments using three grassed VFSs (centipede grass, tall fescue, and vetiver grass), as well as a bare VFS under different slope gradients (2%, 7%, and 12% slope gradients). The primary grass traits (stem spacing, root depth, root length density, and nitrogen total uptake) were measured, and the responses of water flow and NO3-N loss above and below ground to those were quantitatively assessed using the grey correlation analysis method. Results indicated that grasses and slope gradient significantly influenced the water flow and NO3-N loss in general, except the NO3-N loss concentration of the surface flow, in which the tall fescue VFS showed the highest NO3-N total retention rates under each slope condition. Considering the impact of specific grass traits, stem density and root length density has the greatest effects on the surface flow and the subsurface flow respectively, while the effect of roots was lower than that of stems on NO3-N loss below ground. Additionally, the NO3-N loss mass in the surface and subsurface flow were mostly related to the water flow volume and the NO3-N loss concentration respectively. This indicated that grass traits that reduce water flow should be considered more to control the NO3-N loss mass above ground, whereas the grass traits reducing NO3-N loss concentration should be considered more to control the NO3-N loss mass below ground.

Topological nodal line (TNL) materials with one-dimensional band-crossing points (BCPs) exhibit interesting electronic characteristics and have special applications in electronic devices. Normally, based on the slopes of the crossing bands, the BCPs can be divided into two types, i.e., type I and type II nodal points. Based on the combination of the different types of nodal points, the nodal lines (NLs) can be divided into three categories: (i) type I NL, type II NL, and hybrid NL, these being formed by type I nodal points, type II nodal points, and type I and II nodal points, respectively. Compared with the large number of predicted type I NL materials, there are less type II and hybrid NL materials. In this study, it is predicted that P63/mmc type TiSe metal is a topological material which exhibits all types of NL states. Furthermore, the dynamic stability as well as the effect of spin–orbit coupling on the topological signatures are examined. Also, the nontrivial surface states are shown to provide evidence for the occurrence of the NL states. This novel material can be seen as a good platform to use for further investigations on the three types of NLs and diverse fermions.

The environmental behaviors of graphitic carbon nitride (g-C3N4) have drawn increasing attention in recent. Understanding the fate and transport of g-C3N4 in porous media is necessary for evaluating its environmental risks. Column experiments were used in this study to investigate the combined effect of ionic strength (IS) and other common physicochemical factors (i.e. sand grain size, solution pH, and humic acid concentration) on g-C3N4 transport. The one-site kinetic models were applied to simulate the retention and transport of g-C3N4 in porous media, which fitted the breakthrough curves very well. Experimental and model results showed that g-C3N4 had a weak mobility with the transport mass recovery (TMR) less than 39.6% at pH 6.0 in absence of humic acid (HA). The mobility of g-C3N4 was inhibited with decreasing sand grain size, and the inhibited efficiency was enhanced with IS. However, g-C3N4 transport was significantly enhanced with increasing pH and HA concentration, and the enhanced efficiency was more obviously at high IS. The maximum TMR (78.3%) of g-C3N4 was observed with the presence of 5 mg L−1 HA. These results indicated that physicochemical factors played an important and combined role in controlling g-C3N4 transport in porous media, which would lead to the more complex evaluation on the environmental behaviors of g-C3N4.

The presence of one-dimensional (1D) nodal lines, which are formed by band crossing points along a line in the momentum space of materials, is accompanied by several interesting features. However, in order to facilitate experimental detection of the band crossing point signatures, the materials must possess a large linear energy range around the band crossing points. In this work, we focused on a topological metal, YB2, with phase stability and a P6/mmm space group, and studied the phonon dispersion, electronic structure, and topological nodal line signatures via first principles. The computed results show that YB2 is a metallic material with one pair of closed nodal lines in the kz = 0 plane. Importantly, around the band crossing points, a large linear energy range in excess of 2 eV was observed, which was rarely reported in previous reports that focus on linear-crossing materials. Furthermore, YB2 has the following advantages: (1) An absence of a virtual frequency for phonon dispersion, (2) an obvious nontrivial surface state around the band crossing point, and (3) small spin&ndash, orbit coupling-induced gaps for the band crossing points.

The aggregation behaviors of graphitic carbon nitride (g-C3N4) nanosheets under various electrolytes and pH conditions were systematically investigated. The aggregation of g-C3N4 nanosheets was significantly enhanced with increasing electrolyte concentrations. The divalent electrolytes (CaCl2 and MgCl2) were more effective than monovalent electrolytes (NaCl and KCl) in promoting the aggregation of g-C3N4 nanosheets. At the same valence, cations with higher atomic weight were more effective in enhancing the aggregation of g-C3N4 nanosheets. The measured critical coagulation concentrations (CCC) of g-C3N4 nanosheets were 4.7 mM KCl, 9.2 mM NaCl, 1.0 mM CaCl2 and 1.9 mM MgCl2 at pH 6.0, which were lower than some of other two-dimensional nanoparticles. The CCC values of g-C3N4 nanosheets were decreased to 5.5 mM NaCl at pH 2.0, but increased to 29.0 mM NaCl and 2.1 mM CaCl2 at pH 10.0, indicating that the aggregation degree of g-C3N4 nanosheets was decreased with increasing pH. The Fe/Al hydrated complexes generated at the specific pH inhibited the aggregation of g-C3N4 nanosheets and enhanced the stability. Overall, findings from this study demonstrated that the electrolytes and pH conditions played important and combined roles on the aggregation of g-C3N4 nanosheets. In addition, the aggregation behaviors of g-C3N4 nanosheets could be well predicted with the DLVO theory.

Quantitative evaluation of the aquatic ecosystem health is crucial to formulate policies about environmental water management and ecological restoration. However, it is often difficult to quantitatively compare or estimate the health of aquatic ecosystems for different watersheds. In this study, we developed a Freshwater Ecosystem Health Index (FEHI) based on a modified Zooplankton-based Index of Biotic Integrity (ZIBI) to address this difficulty. The ZIBI was developed based on the top six principal components (cumulative % = 88.6%) of 32 zooplankton community indicators. Then the ZIBI was transformed into the FEHI by using the arc-tangent function (to make FEHI fall into (0,1)). FEHI rating scales that were defined as (0,0.2), [0.2,0.4), [0.4,0.6), [0.6,0.8), [0.8,1) fall within bad, poor, fair, good, and excellent freshwater ecosystem health condition, respectively. Moreover, we established six estimation models of FEHI, respectively, directing at six situations that the available indicators are limited. The FEHI calculation and estimation models were then applied to evaluate three lakes and four river basins in eastern China. The results showed that the aquatic ecosystem health was good in areas that included rivers in Tongxiang plain, Meiliang Bay of Taihu Lake, rural area of Qinhuai River basin, Shahu Lake during Summer/Autumn. However, the aquatic ecosystem health was bad or fair in Xuanwu Lake (an urban shallow lake), the urban area of Qinhuai River basin, Huaihe basin, Yinghe basin, and Shahu Lake in winter. The FEHI will be a new and effective approach for quantitative evaluation/estimation of freshwater aquatic ecosystem health in eastern China.

Embankments are common structures along rivers or lakes in riparian zones in plain areas. They should have natural slopes instead of slopes covered by concrete or other hard materials, in order to rebuild sustainable ecosystems for riparian zones. This study was conducted to evaluate the effects of vegetative slopes on water flow and pollutant transport through the embankments. Three embankments with different slope treatments (a bare slope, a slope covered in centipede grass, a slope covered in tall fescue) were examined, and three inflow applications of pollute water with different concentration of total nitrogen (TN) and total phosphorus (TP) used to simulate different agricultural non-point pollution levels. The results showed that the water flux rates of the three embankments were relatively stable under all inflow events, and almost all values were higher than 80%. The embankments with vegetative slopes had better nitrogen removal than the bare slope under all events, and the one with tall fescue slope was best, but the benefits of vegetative slopes decreased with increasing inflow concentration. Moreover, there were no significant differences between the embankments on phosphorus removal, for which the reductions were all high (above 90%) with most loads remaining in the front third of embankment bodies. Overall, the embankments with vegetative slopes had positive effects on water exchange and reducing non-point pollutant into lake or river water, which provides a quantitative scientific basis for the actual layout of lakeshores.

Ecological revetments make an important role in river restauration. However, evaluating the ecological efficiency of revetments as a major determinant of revetments selecting is lack of quantitative methods. Here, we developed an Index of Ecological Integrity (IEI) to assess the ecological efficiency of seven model restauration revetments quantitatively based on four times regular ecological investigation in a representative river plain. Thirteen metrics of the IEI were identified from the candidate pool made up of 46 indicators. These indicators corresponded to the metrics of 5 existing synthetic indexes respectively, Index of Biotic Integrity (IBI) of fish, IBI of benthic macro-invertebrate, IBI of zooplankton, Habitat Index, and Water Quality Index. Signal-noise ratio and one-way analysis of variance indicated that the IEI was more effective to distinguish the differences of ecological efficiency among revetments. Furthermore, IEI suggested that 7 types of restauration revetment could improve the ecological quality of plain rivers to different degree. Rock, eco-bag, and eco-concrete tetrad-ball as ecological revetments were more suitable for river plains like Hang-jia-hu Plain (Zhejiang Province, China) because of highly positive ecological efficiency in two years after restoration engineering completing.

The development of a decision support system (DSS) to inform policy making has been progressing rapidly. This paper presents a generic framework and the development steps of a decision tool prototype of geographic information systems (GIS)-based decision support system of river health diagnosis (RHD-DSS). This system integrates data, calculation models, and human knowledge of river health status assessment, causal factors diagnosis, and restoration decision making to assist decision makers during river restoration and management in Zhejiang Province, China. Our RHD-DSS is composed of four main elements: the graphical user interface (GUI), the database, the model base, and the knowledge base. It has five functional components: the input module, the database management, the diagnostic indicators management, the assessment and diagnosis, and the visual result module. The system design is illustrated with particular emphasis on the development of the database, model schemas, diagnosis and analytical processing techniques, and map management design. Finally, the application of the prototype RHD-DSS is presented and implemented for Xinjiangtang River of Haining County in Zhejiang Province, China. This case study is used to demonstrate the advantages gained by the application of this system. We conclude that there is great potential for using the RHD-DSS to systematically manage river basins in order to effectively mitigate environmental issues. The proposed approach will provide river managers and designers with improved insight into river degradation conditions, thereby strengthening the assessment process and the administration of human activities in river management.

Vegetation in riparian zones has a significant influence on resistance, velocity distribution and turbulence intensity. This study experimentally investigated the effect of emergent bending riparian zone vegetation on the flow. The results showed that the frond and stem parts of Acorus calami had different influences on hydraulic features and that the relative depth ratio of water depth h to stem height hs was a key determinant of those influences. Manning coefficient n varied greatly with the variation of vegetation densities, relative depth ratio of water depth h to stem height hs, Re and Fr. Manning coefficient n increased with increasing vegetation density, particularly in cases when h/hs > 1. The velocity distributions did not follow logarithmic profiles, but they instead exhibited double logarithmic profiles. In addition, vegetation characteristics were shown to influence the height of maximum velocity. The position of maximum velocity is further away from the bed in cases with denser vegetation distribution. Finally, turbulence intensity showed more significant variation in the stem part and peaked near the middle of the stem, at z/hs = 0.5, where z was the distance from the bottom.

A healthy river system means its structures can cooperatively and orderly work together and all functions can be well brought to exert when the external disturbance is under a limit extent. This paper had presented the concept framework, which had included status assessment (SA) and cause diagnosis (CD). On the base of the method of describing entropy, health index (HI) of a river system had been defined via order degrees of indicators, which had been calculated by distance far away from their criteria as well as the health grade had been classified and the main problems had been addressed. Using partial least square (PLS) regression, CD had been conducted to diagnose main factors inducing these problems and to establish the regression equation between external variables and internal variable. Meanwhile, the variable importance projection (VIP) had been quantified. In the case of Anxi River, results of status assessment indicated that this river system was healthy in general. However, abiotic indices were low in S2 and S3 reach. After CD had been conducted, it had been revealed that problems of this river system had been induced by the variable of upstream discharge. It had been suggested helpfully that upstream discharge should be controlled in management. Therefore, river system health diagnosis was very helpful and beneficial to river system management. Key words: River system health, status assessment, causal factors diagnosis, degree of order entropy, partial least square (PLS).