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The River Chief System (RCS), an innovative top-down and bottom-up water resource management system in China, is implemented to manage increasingly complex water environment issues. However, there has been a time lag in policy implementation. To accurately and scientifically assess the effect of RCS, a dynamic multiple-attribute decision-making method considering the time factor (DMADM) has been proposed. We have constructed the model consisting of 17 indicators from four aspects and determined the index weights and time weights by using the gray relation analysis method, the maximum entropy principle, and the subjective empowerment method. Finally, we applied the model to evaluate the water environment governance effect in the Taihu Basin from 2008 to 2020. The results have been ranked by possibility degree matrix, showing that: (1) The water environment in Taihu Basin maintains a steady improvement trend until 2014, except in Jiangsu Province;(2) The ranking result of the final comprehensive evaluation value is Shanghai ([0.334, 0.376]) ≻ Zhejiang ([0.316, 0.353]) ≻ Jiangsu ([0.305, 0.336]). Shanghai is far ahead with systematic pollution control measures, while Jiangsu lags due to the large fluctuation of pollutants (COD, NH3-N) in the wastewater. The study finds that the water environment management in Taihu Basin did improve over the past years, but failed to achieve the RCS governance goals at each stage. Enhancing coordination and cooperation and improving supervision mechanism for precise governance can better consolidate the results of RCS governance. [ABSTRACT FROM AUTHOR]

Environmental context: Environmental estrogens can disrupt the normal functioning of endocrine systems, and their occurrence in drinking water sources could cause potential health risk. We investigated concentrations of four estrogens in the lakes from the Taihu Basin, and found that BPA and EE2 were elevated in some sites. However, concentrations of all four environmental estrogens were below the national standards, and caused no health threat to local population. Rationale: The Taihu Basin is a critical freshwater ecosystem susceptible to contamination from various anthropogenic activities. Environmental estrogens (also known as endocrine disrupting chemicals, EDCs) are exogenous substances that can disrupt the normal functioning of endocrine systems. The contamination of water by EDCs is primarily caused by effluents from sewage treatment plants and livestock poultry farms. In this study, we assessed the spatial distribution and potential risks of environmental estrogens in surface water in the Taihu basin. Various statistical evaluations were employed to establish connections between measured concentration of heavy elements, estrogens and physicochemical parameters, to identify potential sources of these contaminants. Methodology: Water samples from 44 sampling points in five lakes in Suzhou were taken for evaluation of environmental estrogens. Gas chromatography-mass spectrometry was used for identification of concentrations of estrone (E1), estradiol (E2), ethinyl estradiol (EE2) and bisphenol A (BPA). Inductively coupled plasma-mass spectrometry was employed to identify heavy element concentrations in water samples. Results: Environmental estrogen concentrations were detected ranging from 0.001 to 209 ng L-1, with the highest attributed to BPA, whereas E1, E2 and EE2 were comparatively lower. Correlation evaluation between environmental estrogens, physicochemical parameters and heavy element contents revealed a positive correlation (P < 0.05) between the total chromium and environmental estrogen contents. Consequently, the risk entropy value of Shanghu Lake exceeded 0.5, indicating a potentially high risk of estrogenic activity. Discussion: The widespread distribution and high concentrations of BPA in freshwater raise urgent concerns, highlighting the need for frequent monitoring of environmental estrogens in surface waters throughout the year to mitigate potential risks in the future. Our results suggest that a potential estrogen risk exists in the Shanghu Lake in the Taihu basin. Potential treatment methods for endocrine disruptors have been proposed, which could provide actionable plans for stakeholders. [ABSTRACT FROM AUTHOR]

Copyright of Pearl River is the property of Pearl River Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Sediments are an important archive of rich information about the natural environmental changes and human activities in the basin. Exploring the historical trends and environmental significance of nutrients in the sediments will provide a reference for the restoration of the water environment. Materials and methods: In this study, two sediment cores were collected in the northern Taihu Basin, China. Total nitrogen (TN) and total phosphorus (TP) values in the sediments were measured by the potassium persulfate digestion method and molybdenum-antimony spectrometry, respectively. Total organic carbon (TOC) level was analyzed by a TOC-L analyzer. The historical source of organic matter (OM) was identified by combining the C/N ratio and nitrogen isotope (δ15N). Comprehensive pollution index and organic pollution index (OI) were performed to evaluate the TN/TP pollution levels and organic pollution status of sediments, respectively. Results and discussion: The results showed that TN, TP, and TOC concentrations were 0.16–3.19 mg g−1, 0.03–0.15 mg g−1, and 1.08–37.44 mg g−1, respectively. A rising trend of TN, TP, and TOC levels was observed after the 1960s. The correlation results revealed that nutrient concentrations (TN and TP) were positively correlated with the concentration of TOC and silty sand (p ≤ 0.01), respectively. The combined C/N ratio (1.55–25.39) and δ15N value (2.96–9.96‰) reflected the increasing input of exogenous OM. The result of the pollution risk assessment showed that the standard index of TN (STN) and TP (STP) ranged from 0.30–5.79 and 0.05–0.25, respectively, and the OI fluctuated widely from 0.22 × 10–2 to 1.13, indicating that TN and TOC were the dominant control factor of sedimentary environmental quality in the study area, and N and organic pollution of sediments cannot be ignored. Conclusions: TOC and silty sand showed a great positive effect on the distribution of TN and TP. The primary source of sediment OM turned from algae and plankton to terrestrial plants since the 1940s, and soil N loss and agricultural effluent were the dominant reasons for N accumulation in the sediments. The values of STN and OI reflect the mild-severe contamination and potential risk to the aquatic environment. [ABSTRACT FROM AUTHOR]

The driving effects of landscape metrics on water quality have been acknowledged widely, however, the guiding significance of human activity intensity and landscape metrics based on reference conditions for water environment management remains to be explored. Thus, we used the self-organized map, long- and short-term memory (LSTM) algorithm, and geographic detectors to simulate the response of human activity intensity and landscape metrics to water quality in Taihu Lake Basin, China. Fitting results of LSTM displayed that the accuracy was acceptable, and scenario 2 (regional heterogeneity) was more efficient than scenario 1 (regional consistent) in the improvement of water quality. In the driving analysis for the reference conditions, clusters I and II (urban agglomeration areas) were mainly affected by the amount of production wastewater per unit of developed land and the amount of livelihood wastewater per unit of developed land, respectively. Their optimal values were 0.09 × 103 t/km2 (reduction of 35.71%) and 0.2 × 103 t/km2 (reduction of 4.76%). Cluster III (agricultural production areas) was mainly affected by interference intensity, and the optimal value was 2.17 (increased 38.22%), and cluster IV (ecological forest areas) was mainly affected by the fragmentation of cropland, and the optimal value was 1.14 (reduction of 1.72%). The research provides a reference for the prediction of water quality response and presents an ecological and economic sustainability way for watershed governance. [ABSTRACT FROM AUTHOR]

As a systematic research at basin scale, this study investigated the spatial distribution, source apportionment and ecological risks of eighteen polycyclic aromatic hydrocarbons (PAHs) in surface sediments at different functional regions (rivers, lakes and reservoirs) from Taihu basin. Results showed that the mean values of 18 PAHs (defined as ∑18PAHs) in river sediments (1277 ng/g) was much higher than those observed in lake sediments (243 ng/g) and reservoir sediments (134 ng/g). The accumulation of PAHs in river sediments was largely impacted by the local social-economic development and energy consumption. The positive matrix factorization (PMF) and isomer ratios analysis of PAHs suggest that relative contributions to PAHs in sediments were 15% for gasoline and heavy oil combustion, 9% for oil spills, 30% for coal combustion, 23% for traffic source, and 23% for diagenetic source. Ecological risk assessment based upon risk quotient (RQ) method indicated that sediments at Taihu basin have suffered moderate risk of PAHs. [ABSTRACT FROM AUTHOR]

Water sources carry chemicals that can have a significant impact on the water environment of a river network, and understanding the contribution of different water sources to the river network can help to manage the pollution of the river network at its source. The hydrological connectivity of a river network affects the self‐purification capacity and flood prevention capacity of the river. Therefore, an isotope tracer approach was applied to determine the contribution rate of different water bodies to a river network and hydrological connectivity was quantified by introducing the retention rate. Changzhou city was selected as the study area because it is an urbanized city with the characteristics of a plain river network and it is faced with poor hydrological connectivity due to artificial constructions (dams and pumps) and human activity (urbanization). River water, well water (shallow groundwater), lake water and rainfall were collected during the flood season and nonflood season, and hydrogen and oxygen isotopes were determined. The temporal and spatial variations in hydrogen and oxygen isotopes in different water bodies and the state of the water cycle in different water bodies were analysed. IsoSource and MixSIAR models were established to analyse the contribution rate of river network water sources in the study area, and their effectiveness was compared. The results of the MixSIAR model were selected to evaluate the hydrological connectivity of the river network in the study area, providing a method to quantify the hydrological connectivity of specific rivers of the river network in Changzhou city. This method could also be applied to other urban plain river network areas to study river connectivity. [ABSTRACT FROM AUTHOR]

The construction of polders in plain water network areas has changed the pattern of flood control and drainage,and the transfer of urban flood risks caused by it is still unclear.By comprehensively applying urban flood coupling simulation and risk assessment method,this paper quantitatively revealed the urban flood risk transfer caused by polders for flood control in Changzhou City and put forward the flood risk coordination scheme through typical flood simulation analysis.The results show that:① The use of polders for flood control reduces the inundated area by 56%~64% and the severely inundated area (>1.0 m) by 70.2% and aggravates the flood disaster in the southern and eastern parts of the enclosure;② the implementation of polders for flood control accelerates the transfer of flood risks from urban areas to suburbs,which can reduce the flood risk of 4~5 subcatchment areas within the enclosure by more than 50%,while the flood risk increases significantly in the three subcatchment areas in the southern and eastern parts of the enclosure;③ according to the principle of risk sharing,the water level of polders for flood control is increased by 0~0.10 m,which can be used as an alternative scheme for Changzhou flood control dispatching in the future.The research results can provide a reference for urban flood control and disaster reduction and flood optimal dispatching in plain water network areas.

Owing to the publicity and externality of watershed governance, collaborative governance among cities has become an inevitable choice to improve watershed governance performance and promote sustainable development of watersheds. Existing studies have provided many enlightenment on promoting watershed collaborative governance (WCG), while most of them investigated WCG from single or several dimensions with scanty quantitative empirical studies. Against this background, this study aims to establish a comprehensive WCG research framework involving multiple phases and diverse actors to empirically measure the synergy degree of WCG. Specifically, this study constructs a WCG index system composed of resource investment, open cooperation, and performance supervision subsystems that involves actors of government, enterprise, and the public. Using the complex system synergy model, an empirical analysis is performed to evaluate the synergy degree of Taihu Basin collaborative governance among and within cities in Jiangsu province, China during 2014–2020. The results reveal that the Tai Basin collaborative governance among cities was still in the run-in adaptation stage, which was primarily constrained by the discrete open cooperation subsystems among cities. The synergy degree of Taihu Basin collaborative governance within cities presented significant differences. Several targeted implications are proposed according to the results. This study provides a comprehensive index system for synergy degree measurement of WCG and could offer effective guidance for policymakers to design effective strategies for improving WCG performance. [ABSTRACT FROM AUTHOR]

Eco-compensation is effective in promoting the sustainable development of a watershed. The exploration of the public’s willingness to pay for such compensation, along with the corresponding influencing factors, are important for improving the efficacy of eco-compensation programs. However, motivating the public to participate in eco-compensation remains a challenge. In this study, the influencing factors behind public willingness to participate in eco-compensation in China’s Taihu Basin are measured using a contingent valuation method and a random forest model. The main results are as follows: 1) In the Taihu Basin, the mean people are willing to pay for eco-compensation is 287.344 CNY/person/year. 2) The significant factors influencing willingness to pay are recognition of the importance of watershed protection; the impact of the watershed environment on people’s lives; annual incomes; and perceived improvements to the watershed environment over the past five years. 3) Awareness of the need for environmental protection can encourage people to pay eco-compensation. This study provides references that governments can use to formulate and implement eco-compensation policies and hence promote public participation in those policies.

Flood events are typically triggered by extreme precipitation in rain-dominant basins. In this study, to better understand the genetic mechanisms and characteristics of floods, copula functions are used to analyze the response of flood events to extreme precipitation. The coincidence probabilities of the typical extreme flood and precipitation events are calculated; different return periods of their arbitrary combinations are calculated, whereas the dangerous domains for flood control under different return periods are identified; furthermore, flood risk analysis under different extreme precipitation scenarios is performed via their conditional exceedance probabilities. The Xitiaoxi catchment (XC) and Dongtiaoxi catchment (DC) in the Zhexi Region of the Taihu Basin are selected as the study area. The results show that in four scenarios with precipitation frequencies of 80%, 90%, 93.33%, and 95%, the probabilities of the dangerous flood are 9.72%, 10.57%, 10.86%, and 11.01% in the XC, respectively, and 5.91%, 6.31%, 6.44%, and 6.51% in the DC, respectively. This study provides a practical basis and guidance for the computation of rainstorm designs, management of flood control safety, and water resource scheduling in the Taihu Basin. HIGHLIGHTS This study focused on the flood risk in the main water source of Taihu Lake, i.e., the Zhexi Region, which had a direct and significant impact on the floods in the Taihu Basin.; Extreme hydrological and meteorological events were considered as the objects of this study. Their joint probability distribution and combined effects were directly related to the degree of flood risk.;

In order to fully understand the current situation of water resources utilization in the cities in the Taihu Basin under the background of the most stringent water resources management system, this paper summarizes the existing problems, and explores the future development direction of sustainable water resources. Based on the perspective of water footprint, it studies the utilization of water resources in the Taihu Basin and eight cities including Shanghai in the basin from 2015 to 2019, combined with the LMDI (Lograrithmic Mean Divisia Index Method) model to analyze the driving effect of population, wealth, and technical level on the changing in water footprint, and build an evaluation index system for the sustainable use of water resources.The results show that the total water footprint of the Taihu Basin has been declining in the past five years, the industrial and agricultural water footprints have been declining, and the domestic water footprint has been rising. Among the cities, Shanghai has the largest total water footprint and Jiaxing has the smallest. Technical level factors have the greatest impact on water footprint change, and population factors have the least impact. The degree of affluence and population are positively driven, and the technical level is negatively driven. The water footprint structure of the Taihu Basin is relatively stable, Shanghai and Suzhou are highly dependent on external water resources. The overall water footprint benefit continues to increase, with significant differences among cities in each indicator the ecological security situation of the water footprint is not optimistic, but it has shown a continuous improvement in the past three years. The research results indicate that in the future, cities in the Taihu Basin should increase investment in water-saving technologies, techniques and equipment when formulating and adjusting water resources management policies, promote the efficient development and utilization of agricultural and industrial water, strengthen the management of domestic water quotas, and pay attention to the pressure of population growth on water resources, continuously improve the utilization rate of water resources, and realize the sustainable use of regional water resources. [ABSTRACT FROM AUTHOR]

Climate change and human activities have changed a number of characteristics of river flow in the Taihu Basin. Based on long-term time series of hydrological data from 1986 to 2015, we analyzed variability in precipitation, water stage, water diversion from the Yangtze River, and net inflow into Taihu Lake with the Mann-Kendall test. The non-stationary relationship between precipitation and water stage was first analyzed for the Taihu Basin and the Wuchengxiyu (WCXY) sub-region. The optimized regional and urban regulation schemes were explored to tackle high water stage problems through the hydrodynamic model. The results showed the following: (1) The highest, lowest, and average Taihu Lake water stages of all months had increasing trends. The total net inflow into Taihu Lake from the Huxi (HX) sub-region and the Wangting Sluice increased significantly. (2) The Taihu Lake water stage decreased much more slowly after 2002; it was steadier and higher after 2002. After the construction of Wuxi urban flood control projects, the average water stage of the inner city was 0.16–0.40 m lower than that of suburbs in the flood season, leading to the transfer of flooding in inner cities to suburbs and increasing inflow from HX into Taihu Lake. (3) The regional optimized schemes were more satisfactory in not increasing the inner city flood control burden, thereby decreasing the average water stage by 0.04–0.13 m, and the highest water stage by 0.04–0.09 m for Taihu Lake and the sub-region in the flood season. Future flood control research should set the basin as the basic unit. Decreasing diversion and drainage lines along the Yangtze River can take an active role in flood control.

Purpose: Polycyclic aromatic hydrocarbons (PAHs) in the environment are strongly influenced by anthropogenic activities and negatively impact human health. Identifying the sources and potential risks of PAHs in soils will help to prevent soil pollution and utilize land more effectively. Materials and methods: In this study, soils under different land-use types in the northern Taihu Basin were investigated. The PAHs in soils were measured by gas chromatography-mass spectrometry. The toxicity of PAHs from different sources was quantitatively evaluated based on the positive matrix factorization-toxic equivalent quantity (PMF-TEQ) model. The incremental lifetime cancer risk (ILCR) method was used to assess the health risk of PAHs. Results and discussion: The results showed that the Σ16PAHs concentrations varied between 142.26 and 9278.51 ng g-1, with a mean value of 1640.43 ng g-1. High molecular weight PAHs were found to account for the largest fractions (87%) of the Σ16PAHs. Significant variation of the PAHs concentrations in soils was observed under different land-use types. The mean concentration of Σ16PAHs in different areas was in the order of industrial area > traffic area > commercial area > residential area > park > farmland. Vehicle emissions and coal/coke combustion were the predominant sources, accounting for 54% and 37% of the Σ16PAHs loading, respectively. The total predicted TEQ of PAHs ranged from 15.71 to 867.35 ng g-1 (mean 189.29 ng g-1), and benzo(a)pyrene was the major species. The total ILCR value for soil PAHs exposure was in a range of (0.13 ~ 9.13) × 10-6. Conclusions: Source identification showed that the dominant source of soil PAHs was vehicle emissions in commercial (89%) and traffic (85%) area, while coal/coke combustion was the main source of soil PAHs in industrial area (43%). The total TEQ indicated a potential carcinogenic risk in the study area, with vehicle emissions and coal/coke combustion making the primary contribution to the total TEQ (95%). The total ILCR value was in a range of 10-7 ~ 10-5, which indicated a low health risk. Children experienced a higher cancer risk than adults due to their sensitivity to the carcinogenic effects of PAHs. [ABSTRACT FROM AUTHOR]

Copyright of New Architecture is the property of New Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding the complexity of catchment-scale human activities, natural factors, and stream water quality is particularly important for basin water resources management. Thorough investigations on how multiple environmental factors quantitatively and simultaneously affect water quality are limited. This study employed Spearman's correlation and ridge regression analysis (RRA) to disentangle the hydraulic geometry and land use contributions to water quality variables (WQVs). Nine and six indicators were used to describe the hydraulic geometry and land use characteristics, respectively, in the Taihu Basin. The results revealed significant correlations between the land use, hydraulic geometry, and stream water quality. Built-up land and cropland negatively impacted the stream water quality, while woodland had the opposite trend. The structure and morphological connectivity of the river network were associated with most WQVs. The hydrologic connectivity characteristics strongly influenced ammonia–nitrogen (NH3-N), permanganate index (CODMn), and dissolved oxygen (DO). Six equations that estimated the stream water quality were established through RRA. Human factors impose a greater impact on the stream water quality than natural factors in the Taihu Basin. Our findings provide quantitative insights to mitigate water pollution via reasonable management and control of the river structure and connectivity and land-use patterns. [ABSTRACT FROM AUTHOR]

In this paper, a new method for pollution load control was proposed to solve the transboundary pollution problem in plain river network. The spatial distribution of load capacity, considering both multiple management requirements and local hydrodynamic features, has been studied in three steps: (1) the multiple objectives calculation system featured by multiple constraints has been proposed considering water quality requirements for different kinds of objectives. (2) the corresponding 1-d and 0-d models for load capacity calculation, considering the complex hydrodynamic characteristic, have been established separately. (3) based on the multi-objective calculation system, the load capacity satisfying the multiple objectives in different administrative units could be calculated. The results indicated that pollution load capacity of the whole transboundary area in Taihu basin is 151806 t/y for chemical oxygen demand, 15,099 t/y for ammonia nitrogen and 3394 t/y for total phosphorus, respectively. Then the rationality of the result has been analyzed and the load capacity calculated has been proved reasonable. [ABSTRACT FROM AUTHOR]

Understanding the relationship between land use and water quality at different scales is essential in the restoration and protection of water quality. On March 2014, we collected 97 samples in highly urbanized Taihu Basin and analyzed their water quality characteristics. Spatial differences in water quality were evident in sub-basins. The Hu Xi zone with the largest forest area had the best water quality among all the sub-basins. The correlation analysis indicated that the proportions of forest and construction land were significantly associated with multiple water quality variables from buffer to sub-basin scale. Farmland was significantly related to NO3–N at the sub-basin scale. The impact of landscape metrics at the sub-basin was insignificant. Forest and construction land in the 1–2 km buffer zone appeared to have a greater influence on the water quality than the buffers with smaller distance. These results are beneficial toward the understanding of water quality status in highly urbanized watersheds and provide a reference for water quality conservation and land use management in the future. [ABSTRACT FROM AUTHOR]

Under the background of the change of management objectives of Taihu Basin, it is particularly important to establish a set of scientific and concise evaluation methods for functional areas of aquatic eco-environment that are convenient for operational application. Based on the collected data at home and abroad, and the theory of biological integrity, combined with the actual biological monitoring ability, a comprehensive quality evaluation method for aquatic eco-environment function area was established, with total taxa number, biological density, and the dominance of former three dominant species chosen for the constitution of planktonic algae integrity index; molluscan taxa number, the dominance of dominant species and biological monitoring working party (BMWP) chosen for the constitution of benthic invertebrates integrity index; chlorophyll a, transparency, permanganate index, total phosphorus and total nitrogen used for lake and reservoir water quality evaluation; dissolved oxygen, ammonia nitrogen, permanganate index, total phosphorus and total nitrogen used for river water quality evaluation. The evaluation method is strongly to support the target demand of continuous improvement of water ecological environment quality in the process of watershed management target transformation. [ABSTRACT FROM AUTHOR]

The variation of hydrological processes has been extensively discussed worldwide, yet little is known about the relative impact of human activities, and the precipitation–water level relationship in urbanized, watery areas. Thus, the change in water level and the influential variables are analysed for 1960–2014 in the urbanized and watery Taihu Basin, China. The results indicate that the water level displays a significant increasing trend. Furthermore, low-oscillation and high-oscillation periods were found to have occurred in the 1960s–1970s and 2000s, respectively, by the quantile perturbation method. A strong relationship was shown between water level and precipitation in the 1960s–1980s, especially in the flood season. Since then, human activities, such as land-use change, river system degradation and hydrological structures, have played distinct roles and caused more than 82% of the annual and flood-seasonal water level variation. The results may provide a more comprehensive understanding of the hydrological processes and provide a good reference for flood control. [ABSTRACT FROM AUTHOR]

The distribution and composition of organic pollutants in sediment are affected by the source and regional environment. To understand the characteristics and risk of polybrominated diphenyl ethers (PBDEs) in the area around Taihu Lake, composite sediment samples (n = 41) were collected in rivers around Taihu Lake to explore the level, spatial distribution, and source of PBDEs. The results showed that the most abundant BDE congener in river sediment was BDE209, followed by BDE99 and BDE47, with median values of 48.7, 2.17, and 1.52 ng g−1, respectively. Concentrations of PBDEs in sediments from northern rivers were significantly higher than those from other areas, but the overall risk was at a moderate-lower level compared with research results in other references. Results of principle component analysis (PCA) and source characteristics analysis revealed that most of PBDEs in river sediments around Taihu Lake were mixture of multiple sources, which mainly originated from atmospheric deposition, industrial wastewater, and municipal sewage. TOC showed good correlations with most PBDEs, which implied that PBDE components were influenced by sediment organic matter. Meanwhile, the risk of PBDEs in river sediments in this study area is a moderate-lower level. [ABSTRACT FROM AUTHOR]

Soil erosion induced by rainfall has become one of the major environmental disasters. It can lead to degradation of land productivity and water pollution, which limit human survival and development. Therefore, understanding the effects of rainfall intensities on soil nutrient and sediment transportation from farmland via surface runoff is important. This study simulated three types of rainfall intensities (low intensity 0.83 mm min−1; medium intensity 1.17 mm min−1 and 1.67 mm min−1; and high intensity 2.50 mm min−1). Field plots were established to evaluate the effects of rainfall intensities on sediment yield and phosphorus enrichment ratio (ERP) in runoff sediment. Each plot was 2 m long and 1 m wide. The rainfall lasted for 30 min after effective runoff generation. Runoff and sediment, as well as the phosphorus (P) concentration of sediment, were measured. Results showed that the low rainfall intensity had a longer time to begin runoff than high rainfall intensity. The runoff volume increased with the rainfall intensity; however, no obvious differences were observed in the runoff rate under three rainfall intensities, except for 2.50 mm min−1. The curve value of sediment concentration increased after 5–10 min of effective runoff decreased slightly, and then relatively became stable after 20 min of effective runoff. Although no obvious differences were observed in the dynamic changes of sediment concentration and rainfall intensity, a power function existed between rainfall intensity and sediment loss. The similar curves of ERP value showed that it was higher in the initial stage, decreased gradually, and reached a stable level after 25 min of effective runoff, which varied around 1. During the rainfall–runoff event, no significant correlation was noted between ERP and sediment yield. Whether any relationship existed between them needs to be further studied by setting up different field plots under large-scale conditions. The findings of this study provide valuable aid to farmers on how to manage farmland effectively to prevent soil nutrient loss and reduce water eutrophication. [ABSTRACT FROM AUTHOR]

The Taihu Basin constitutes a complex river network and variable hydrodynamic forces, which contributing to alterations in regional water quality within the Yangtze River Delta. In this study, to explore the underlying mechanism of these dual factors on water quality in the upper Taihu Basin, a combination of graphical analysis, the water quality index (WQI) method, and the partial least square-structural equation model (PLS-SEM) were employed to quantitatively investigate the river structure indices (water surface ratio, W P ; river system fractal, Δα; river network connectivity, γ) and hydrodynamic force indices (the flow index, FI), and their influence on water quality. Negative correlations were found between both W P and Δα with FI and a positive correlation between γ and FI. The southern water network had a higher water body area and greater difference in river network density, while the northern river network had enhanced connectivity and stronger water flow, thus exhibiting superior water quality. Regarding the influence of these factors on water quality, the impact of river structure on WQI was statistically insignificant (P > 0.05), while hydrodynamic force was significantly positively correlated with the WQI (P < 0.05). Moreover, in comparison to the path coefficient of 0.657 for the river structure's influence on the WQI, the hydrodynamic force exerted an even more significant impact on water quality with a path coefficient of 0.715. This study suggested that water quality improvements depend on optimizing the structural integrity of river systems and promoting favorable hydrodynamic conditions, with the latter having greater influence. This research provided theoretical underpinning for optimizing river structure and advancing river and lake water environments within the Taihu Basin. • The distribution variations of river structure, hydrodynamics, and water quality in the upper Taihu Basin were delineated. • The impact of hydrodynamic force on regional water quality was more pronounced when compared to the river structure. • Enhanced river network connectivity and increased hydrodynamics contributed to improve water quality in the flatland region. [ABSTRACT FROM AUTHOR]

The objective of this study is to examine the relationship between benthic macroinvertebrates and various environmental factors (i.e., physicochemical properties of sediment and hydromorphological condition) in the typical inflow river sediments of the Taihu Basin in China. Pearson correlation and redundancy analysis (RDA) were used to investigate associations between environmental factors and benthic macroinvertebrate community structure. The RDA results indicated that the environmental factors account for 58.6% of the spatial differentiation of benthic macroinvertebrate community. High density of Oligochaeta species, which were potential indicators of heavy metal pollution within sediments, was observed as the pollution-tolerant species in the study area, indicating that the benthic community was seriously polluted by heavy metals and nutrients. Moreover, the variation in benthic macroinvertebrate community structure and trait composition were mainly explained by physicochemical properties of sediment (e.g., Pb, temperature, and phosphate), whereas hydrological condition (e.g., turbidity) alterations played a less important role. Thus, the environmental factors are significantly correlated with the abundance and biomass of benthic macroinvertebrate by taking interacts of multi-environmental factors into account. These results provide scientific basis for water environment health management and pollution control in Taihu Basin river network area. [ABSTRACT FROM AUTHOR]

With the rapid economic development and urbanization in Taihu Basin (eastern China), the river system has decayed and the connectivity of rivers and lakes has weakened, resulting in frequent floods. The impact of changes in river system structure on hydrological processes in the plain river network area was analysed against a background of urbanization. An indicator system was built to describe the quantitative, morphological and spatial structure of the river system. Analysis of the change in annual average and extreme water levels revealed the influencing mechanism of the changes in river system structure on the hydrological processes. The results indicate a decreasing tendency in the density of the river system in the study area, with a reduction in water surface ratio by about 20% in the past 50 years. Since the 1960s, the maximum and annual average water levels have increased. The degree of change in the mean monthly, annual lowest and annual highest water levels was great, with that in the non-flood season being higher than in the flood season. The decrease in the number of rivers directly reduced the storage and adjustable capacity of the basin. [ABSTRACT FROM AUTHOR]

Global warming and land-use change affects runoff in the regional basin. Affected by different factors, such as abundant rainfall and increased impervious surface, the Taihu basin becomes more vulnerable to floods. As a result, a future flood risk analysis is of great significance. This paper simulated the land-use expansion and analyzed the surface change from 2020 to 2050 using the neural network Cellular Automata Markov (CA-Markov) model. Moreover, the NASA Earth Exchange Global Daily Downscaled Climate Projections (NEX-GDDP) dataset was corrected for deviation and used to analyze the climate trend. Second, the verified SWAT model was applied to simulate future runoff and to analyze the future flood risk. The results show that (1) land use is dominated by cultivated land and forests. In the future, the area of cultivated land will decrease and construction land will expand to 1.5 times its present size. (2) The average annual precipitation and temperature will increase by 1.2% and 1.5 degrees from 2020 to 2050, respectively. During the verified period, the NSE and r-square values of the SWAT model are greater than 0.7. (3) Compared with the historical extreme runoff, the extreme runoff in the return period will increase 10%~25% under the eight climate models in 2050. In general, the flood risk will increase further under the climate scenarios.

Owing to the crucial environmental and hydrological functions of river systems and intensive human disturbance, further investigations of their change patterns and flood control functions are urgently needed. The Rapidly Urbanized Taihu Basin (RUTB) was selected as the study region to investigate changes in the river networks, the relationship between changes in river systems and urbanization, and the changes in the static drainage storage capacity (SC) and regulation capacity (RC) from the 1980s to the 2010s. The results indicated that the total drainage density in RUTB decreased by 10.17%. For the first‐, second‐, and third‐order rivers, the changes are +7.61%, −14.35%, and −17.84%, respectively. Spatially, the change pattern of the third‐order river drainage density displayed significant spatial clustering. The ratio of main to tributary river length (Rmt) was increased from 0.31 in the 1980s to 0.39 in the 2010s. Spatially, the drastic increases were found in the south‐east of Wu–Cheng–Xi–Yu, the east of Yang–Cheng–Dian–Mao, and the central southern part of Hang–Jia–Hu. Results moreover show that urbanization has the greatest influence on the third‐order drainage density, especially around the secondary and rapidly developing cities. The demand for flood control has led to a slight increase in the density of main rivers. The values of SC and RC decreased by 0.69% and 40.61% in RUTB, respectively. These changes were mainly concentrated around the major cities and urban corridors. The decrease in SC was caused by the decay of the river system, and the reduction in RC was caused by a combination of river system degradation and increase in ordinary water levels. [ABSTRACT FROM AUTHOR]

Cyanobacterial bloom has posed a serious threat to the sustainable development of Taihu Basin. All basin stakeholders could not make an agreement on pollution solution. During decision-making, they insist on “gross domestic product (GDP) only” rather than a sustainable development preference. This paper establishes a new cost-risk decision-making system from the sustainable perspective. Contrary to the work carried out by others, water rather than money is taken as management cost here. With grey water footprint concept, pollution in water can be measured by converting into water. Due to emission reduction space limitation, some basin areas suffer the vicious circle of “management after pollution”. Management responsibility allocation alone cannot combat the pollution management due to the mismatch between responsibilities and reduction space, which should be optimized. Therefore, it is suggested that each agent, with the purpose of cost (water) saving, selects responsibility allocation schemes and cost allocation institutions through mutual negotiation. It is found that a grand coalition in any scheme or institution can achieve the minimum management cost, with approximately 24.05 billion m 3 water being saved. In the grand coalition, Changzhou has the largest discharge reduction space with small management responsibility, so the other five cities may transfer their responsibilities to it by inside compensation. However, to achieve fairness and stability inside the grand coalition, Nash-Harsanyi institution in the Emission Sharing is the most optimized scheme, which can ensure a sustainable full-cooperative pollution management in Taihu Basin. In short, this paper provides a new decision-making plan to pollution management in Taihu Basin. [ABSTRACT FROM AUTHOR]

Transboundary water pollution has resulted in increasing conflicts between upstream and downstream administrative districts. Ecological compensation is an efficient means of restricting pollutant discharge and achieving sustainable utilization of water resources. The tri-provincial region of Taihu Basin is a typical river networks area. Pollutant flux across provincial boundaries in the Taihu Basin is hard to determine due to complex hydrologic and hydrodynamic conditions. In this study, ecological compensation estimation for the tri-provincial area based on a mathematical model is investigated for better environmental management. River discharge and water quality are predicted with the one-dimensional mathematical model and validated with field measurements. Different ecological compensation criteria are identified considering the notable regional discrepancy in sewage treatment costs. Finally, the total compensation payment is estimated. Our study indicates that Shanghai should be the receiver of payment from both Jiangsu and Zhenjiang in 2013, with 305 million and 300 million CNY, respectively. Zhejiang also contributes more pollutants to Jiangsu, and the compensation to Jiangsu is estimated as 9.3 million CNY. The proposed ecological compensation method provides an efficient way for solving the transboundary conflicts in a complex river networks area and is instructive for future policy-making. [ABSTRACT FROM AUTHOR]

The development of microbial community-based biological indicators for assessing aquatic ecological status is urgently needed in heavily impaired regions, due to the local extinction of traditional indicator macroorganisms. The aim of this study was to develop and validate a microbial community-based index of biotic integrity (MC-IBI) for the assessment of rivers in the Taihu Basin, China. MC-IBI was developed based on sediment samples collected from 55 sites of 42 rivers, with least disturbed sites as reference sites. High-throughput sequencing and real-time PCR methods were employed to measure the microbial diversity and abundance of the samples. A total of 341 candidate metrics related to microbial diversity, composition, pollution tolerance and function categories were established based on microbial data. Five core metrics, including% FCA (percentage of Firmicutes, Chloroflexi and Acidobacteria), log 16S rRNA /ARG (log the ratio of 16S rRNA gene to antibiotic resistance gene), log AOB/AOA (log the ratio of ammonium oxidizing bacteria to ammonium oxidizing archaea), nirK / nirS (ratio of nirK gene to nirS gene) and BFG/A (ratio of Bacteroidetes, Firmicutes and Gammaproteobacteria to Alphaproteobacteria), were identified to develop a MC-IBI. The developed MC-IBI was demonstrated to be robust using a validation dataset. Further, the MC-IBI showed a significantly negative association with the index of water quality. The river ecological conditions of the 55 sampled sites in the Taihu Basin were defined as excellent (9.1%), good (14.5%), moderate (25.5%), poor (23.6%) and bad (27.3%) separately based on the MC-IBI scores. Overall, the MC-IBI provides a novel assessment tool for the ecological health status of freshwater rivers. [ABSTRACT FROM AUTHOR]

China has suffered from increasingly severe flood events in recent years, most of which are caused by heavy rains. The substantial casualties and damage caused by flooding necessitates a better understanding of precipitation extremes, especially in heavily populated urban areas. Based on L-moments from a regional perspective, this paper analyzes precipitation extremes in the Taihu Basin, utilizing annual maximum daily precipitation and partial duration series at 96 rain gages. The comparison of regional and at-site analysis results shows that the former provides more robust estimates, especially in the upper tail of a distribution (higher quantiles). Also, the use of partial duration series, which captures more information about extreme events, was found to be preferable to describe the extreme precipitation events in the Taihu Basin. Given the recently observed more frequent occurrence and greater magnitude of precipitation extremes, it is suggested that the food design standard used in the basin should be updated, especially for the urbanizing zones. [ABSTRACT FROM AUTHOR]

In the recent decades, most rivers and lakes in the Taihu Basin have experienced degradation from an excess of nutrients. The presence of the nitrogen in water contributes to the increase of eutrophication. The riparian zones are associated with these watercourses and can effectively reduce any excess nitrogen. Soil denitrification is the most significant process in the transfer of nitrogen, which migrates from the terrestrial to the aquatic ecosystem. The relationship between soil denitrification and soil characteristics is well documented. However, the degree of soil denitrification and the main impact factors during different processes within the riparian zones due to gradual changes in the surroundings are not well understood. The present study selected four types of riparian soils that are contained in three different watersheds. The soil denitrification potential was determined within these soils using the acetylene block technique. The results indicate that, among the local factors studied, the soil denitrification potential increased with the intensity of anthropogenic activities, which varied significantly within the basin. This variation indicated a trend in the soil denitrification potential: cropland > woodland > grassland > bareland. Results suggest that soil moisture, nitrate-nitrogen concentration, and microbial biomass carbon concentration are the dominant factors that influence the riparian soil denitrification potential in the Tiaoxi watershed, while soil organic matter is the major factor for soil denitrification potential in the Hexi watershed and nitrate-nitrogen concentration is the dominant factor in the Tianmuhu watershed. [ABSTRACT FROM AUTHOR]