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Although eco-flows (ecosurplus (ES) and ecodeficit (ED)) based on the flow duration curve (FDC) have been used to assess hydrologic alterations in recent years, they are defective, and their limitations have never been clarified. In this study, the causes of these limitations were analyzed, and the ES and ED on different time scales were redefined using the discharge hydrograph (DH). The monthly ES was redefined as the surplus monthly runoff exceeding the 75th percentile DH divided by its maximum ecological water requirement, and the monthly ED was redefined as the deficient monthly runoff below the 25th percentile DH divided by its minimum ecological water requirement. The seasonal eco-flows were the sum of three corresponding monthly eco-flows, and the annual eco-flows were the sum of twelve consecutive monthly eco-flows. The daily discharge time series from 1956 to 2015 at Xiaolangdi Station was used to test the new method. The results showed that the inconsistencies of eco-flows on different time scales based on FDCs were closely related to the loss of time-dependent information in FDCs. The correlation coefficients and Frechet distance between Shannon Index (SI) and annual eco-flows showed that DHs performed better than FDCs in assessing eco-flows. Annual EDs calculated from DHs changed synchronously with SI in most years. This novel method for calculating eco-flows are useful for assessing river health in the future.

The health of medium and small river ecosystems is threatened by increasing hydropower development and human activities. How to properly diagnose rivers has become a global concern. As a well-accepted theory, the aquatic organism density can be an indicator of river health. A new river health assessment method based on macroinvertebrates habitat suitability curves (M-HSC) was proposed. In this study, the health of Qiaobian River (QBR), a tributary of Yangtze River, China was evaluated by investigating the distribution of macroinvertebrates, chemical and physical parameters during winter 2018 (low flow season) and summer 2019 (high flow season). Based on habitat suitability of dominant macroinvertebrates, the key habitat factors were screened by canonical correspondence analysis (CCA) and Pearson correlation analysis. Suitability curves were determined by Generalized Additive Model (GAM). Ecosystem health comprehensive index method was used to evaluate the health status. The results show most suitable conditions for Corbicula fluminea containing chemical oxygen demand (CODMn) of 1.48 mg L−1, total nitrogen (TN) of 0.27 mg L−1, dissolved oxygen (DO) of 11.17 mg L−1, pH of 8.42, turbidity of 1.76 NTU, and water depth (Dep) of 0.35 m. The health status of QBR is spatially heterogeneous with the apparently better upstream than the downstream. In general, 25, 12.5, 12.5% of the samples were classified as nature, health and sub-health status, respectively and the rest 50% were lower than sub-health. The results are consistent with the environmental quality standards for surface water in China (GB3838-2002), suggesting the applicability of macroinvertebrates habitat suitability for evaluating river health. By minimizing the temporal and spatial limitations of comprehensive evaluation method and indicator species method, this study, for the first time, used macroinvertebrates habitat suitability curves to assess the health of medium and small rivers. The study will provide new insights for future river health assessments.

Rivers provide many eco-services functions for human being, but with the intensive impacted by human activities, river health had been leading to the poor condition. In this study, an assessment index system including eleven elements consisting of physical habitat, chemical condition and biotic structure were established to assess river health in the Wei River Basin. The improved gray incidence model and comprehensive rough set weight model were combined as the assessment. The results indicate that the river health of Wei River, Jing River and Beiluo River were at the sick level, and the whole Wei River Basin was at the sick level too, land use changed, water pollution are the most important influence factors affected the river health. Compared with other models, the uncertainties can be mostly eliminated and the assessment index’s weight can be determined more objective, the proposed method is effective and feasible for river health assessment. The research results are aimed to provide a scientific basis for improving river health and water allocation to the policy makers.

In order to facilitate watershed management, we developed an expansive river health assessment method based on ecological flow hydrology method in this study that estimates the ecological flow of a river by using a probability density curve combined with six levels of river flow in different states of a river ecosystem. We apply the above method to a river health assessment in the middle reaches of the Yangtze River. The results show that the ecological flow calculated by this method is more accurate than that of the traditional hydrology method and the fish spawning water demand method and can better describe the actual demand of river ecosystems to flow; thus, this method is reasonable for evaluating river health. Moreover, the river health assessment method described in this study covers the different health states of river ecosystems, including all intervals of river flow, and takes into account the influences of extreme flow events and the uneven distribution of flow during the year. It is a reasonable river health assessment method that can evaluate river health status systematically, comprehensively and accurately. Moreover, we demonstrate the feasibility of this method in watershed management. The results show that this method can provide a scientific decision-making basis for river health management in actual watershed management.

The accumulation and redistribution of heavy metals in soil in a water-level fluctuation zone (WLFZ) can create ecological risks to reservoirs and reduce river health. Little is known about how heavy metals are accumulated and redistributed in the WLFZ of reservoirs with a high background value of the heavy metal in soil. The site chosen for this case study is the Nuozhadu mega reservoir in the upper Mekong River Basin, which is held back by a dam with a height exceeding 250 m. Five sampling transects were established around the reservoir. Each transect contained three vertical sampling lines representing three land-use types: forest, farmland, and rubber plantations. Soil samples were collected both in the WLFZ and in the infralittoral reference zone (IRZ), and the concentrations of the heavy metals Zn, Cr, Ni, Cu, Mn, and Fe (%) were measured in these samples. We found that the average concentrations of each of these heavy metals were higher in the WLFZ than in the IRZ. The land-use types, especially the rubber plantations and farmlands, determine the redistribution of the heavy metals in the soil of the WLFZ. The heavy metals Cu, Mn, and Ni increased with increasing elevation within the WLFZ, but the metals Cr and Zn decreased with elevation. The results of analysis of variance indicate that the soil properties had certain differences under different land-use types and inundation durations at various elevations, which partly determined the accumulation and redistribution of heavy metals in the WLFZ. We suggest that long-term monitoring of the concentration of heavy metals is needed for soil and water management in the WLFZ of the Nuozhadu reservoir.

The ecological heterogeneity created by river bends benefits the diversity of microorganisms, which is vital for the pollutant degradation and overall river health. However, quantitative tools capable of determining the interactions among different trophic levels and species are lacking, and research regarding ecological heterogeneity has been limited to a few species. By integrating the multi-species-based index of biotic integrity (Mt-IBI) and the structure equation model (SEM), an interactions-based prediction modeling framework was established. Based on DNA metabarcoding, a multi-species (i.e., bacteria, protozoans, and metazoans) based index of biotic integrity including 309 candidate metrics was developed. After a three-step screening process, eight core metrics were obtained to assess the ecological heterogeneity, quantitatively. The Mt-IBI value, which ranged from 2.08 to 7.17, was calculated as the sum of each single core metric value. The Mt-IBI revealed that the ecological heterogeneity of concave banks was higher than other sites. According to the result of the SEM, D90 was the controlling factor (r = −0.779) of the ecological heterogeneity under the influence of the river bends. The bend-induced redistribution of sediment particle further influenced the concentrations of carbon, nitrogen, and sulphur. The nitrogen group (r = 0.668) also played an essential role in determining the ecological heterogeneity, follow by carbon group (r = 0.455). Furthermore, the alteration of niches would make a difference on the ecological heterogeneity. This multi-species interactions-based prediction modeling framework proposed a novel method to quantify ecological heterogeneity and provided insight into the enhancement of ecological heterogeneity in river bends.

Concern about the impacts of water regulation upon the aquatic environment has led to increasingly stringent regulatory constraints on the quantity and timing of freshwater withdrawals. For the time being these regulatory constraints tend to be articulated in terms of limits upon withdrawals, partly because of limited knowledge of the condition and resilience of the aquatic ecosystems. A more sophisticated approach to regulation would be more directly related to indicators of ecological condition. Moreover, it would consider ecosystem response to climatic events not present in the historical record. In this paper we use a combination of empirical evidence of ecosystem condition with simulation to propose and test reductions to regulatory limits on river water withdrawals and downstream minimum flow requirements. The study uses multi-level linear regression to relate the Lotic-invertebrate Index for Flow Evaluation (LIFE) to antecedent flow statistics observed in the Lee catchment, England. The selected flow statistics included extreme low (Q90) and high (Q10) flows in the summer season (April-Sept), and the median flows observed in the winter season (Oct-Mar). The derived model is used to forecast the response of the macroinvertebrate index to future flow scenarios and demand forecasts, incorporating the uncertainties in ecosystem response. Simulation is used to evaluate the sensitivity of the indices to different regulatory limits. Results indicate that macroinvertebrate health will worsen under 21st Century climate conditions, and that the existing regulation policy must be modified to maintain historically observed LIFE scores into the future. The framework demonstrates how regulations could move from precautionary limits on withdrawals to an approach based on observations, forecasting and simulation, allowing planners to refine the trade-offs between river health and reliable water supply in the face of uncertainty.

Urban river sediments usually serve as a sink for potentially toxic elements (PTEs) during the process of urbanization. A systematic evaluation of human influence, contamination, and risk assessment of PTEs in urban river sediments is essential for sustaining river health. In this study, 24 sediment samples were collected from 5 rivers in Qingdao, a coastal urbanized city in East China. Zinc had the highest concentration (141 ± 134 mg/kg), followed by Cr, Cu, Pb, Ni, Co, As, and Cd. Generally, the PTE concentrations were higher in eastern rivers than those in western rivers affected by intensive industrialization and urbanization. The principal component analysis identified three principal components: natural origins (As, Co, Cr, and Ni), urban activities (Cd, Cu, Pb, and Zn), and atmospheric deposition (Pb), respectively. The excessive concentrations of Cd and Pb were frequently appeared in the sampling sites, with the anthropogenic contribution rates of 8.4%-77% and 6.6%-87%, respectively. Additionally, the river sediments experienced moderate contamination of As, Cd, Cu, Pb, and Zn. Among the PTEs, Cd had moderate ecological risk and others had low risk. The results of Monte Carlo simulation were generally in accordance with the detected contamination and risk levels, except for several elements (Cu and Zn) with huge spatial heterogeneity. According to the Monte Carlo simulation, the river sediments could undergo extremely high contamination and high ecological risk of the PTEs in the worst situation. Thus, it becomes essential that PTEs in the urban rivers should not be overlooked before their discharge into the sea.

Environmental flow assessments (e-flows) are relatively new practices, especially in developing countries such as Nepal. This study presents a comprehensive analysis of the influence of hydrologically based e-flow methods in the natural flow regime. The study used different hydrological-based methods, namely, the Global Environmental Flow Calculator, the Tennant method, the flow duration curve method, the dynamic method, the mean annual flow method, and the annual distribution method to allocate e-flows in the Kaligandaki River. The most common practice for setting e-flows consists of allocating a specific percentage of mean annual flow or portion of flow derived from specific percentiles of the flow duration curve. However, e-flow releases should mimic the river’s intra-annual variability to meet the specific ecological function at different river trophic levels and in different periods over a year covering biotas life stages. The suitability of the methods was analyzed using the Indicators of Hydrological Alterations and e-flows components. The annual distribution method and the 30%Q-D (30% of daily discharge) methods showed a low alteration at the five global indexes for each group of Indicators of Hydrological Alterations and e-flows components, which allowed us to conclude that these methods are superior to the other methods. Hence, the study results concluded that 30%Q-D and annual distribution methods are more suitable for the e-flows implementation to meet the riverine ecosystem’s annual dynamic demand to maintain the river’s health. This case study can be used as a guideline to allocate e-flows in the Kaligandaki River, particularly for small hydropower plants.

Latar belakang : Sungai menjadi salah satu pemasok air terbesar untuk kebutuhan mahluk hidup yang memiliki fungsi penting bagi kehidupan manusia. Sungai Musi merupakan sumberdaya alam yang menjadi salah satu jalur utama perdagangan dan pemasok air terbesar bagi penduduk Sumatera Selatan. Akan tetapi kondisi Sungai Musi telah mengalami perubahan disebabkan saratnya pemukiman dan industri. Aktivitas ini akan berdampak terhadap kondisi fisik sungai serta habitat hewan air yang menghuni perairan. Penelitian ini bertujuan untuk mengidentifikasi habitat fisik sungai serta keberagaman biotilik sebagai indicator pencemaran perairan Sungai Musi Kota Palembang. Metode : Penilaian pencemaran perairan ditentukan dengan melihat indicator habitat fisik sungai dan keberagaman biotilik sungai melalui biota makro invertebrata, serta menggunakan metode wawancara. Hasil : Hasil penelitian menunjukkan bahwa kualitas air perairan Sungai Musi di Wilayah Sebrang Ulu I dan II berada dalam kondisi buruk, terlihat dari hasil observasi yang menunjukkan bahwa mayoritas (lebih dari 70%) parameter berada pada indicator buruk (C). Serta hanya ditemukan satu biota air yaitu ikan. Hasil laboratorium menunjukkan nilai TSS di kedua titik melebihi nilai standar normal, sedangkan nilai COD dan BOD masih di bawah nilai standar normal. Simpulan : Perairan Sungai Musi di Wilayah Sebrang Ulu I dan II, termasuk ke dalam kategori Buruk (C). Hal ini didasarkan hasil pemeriksaan habitat fisik sungai, pemeriksaan hewan biotilik Serta pemeriksaan kadar TSS, BOD dan COD. ABSTRACT Title :Identification of thePhysicalHabitatandDiversityRiverBiotilikas Indicatorsof Water PollutionMusi RiverPalembang Background : Rivers became one of the largest water supplier for the needs of living things that have important functions for human life. Musi River is a natural resource that is becoming one of the main lines of trade and the largest supplier of water for the residents of South Sumatra. But conditions have changed Musi River caused there are more residential and industrial. This activity will have an impact on the physical condition of the river as well as the habitat of aquatic animals that inhabit the waters. This study aims to identify the physical habitat of the river as well as the diversity biotilik as an indicator of pollution of the waters of the Musi River Palembang. Method: The assessment of water pollution is determined by observing the indicator of the river's physical habitat by looking at the baseline substrate characteristic indicator consisting of 6 (six) parameters and indicators of river health disturbance factor consisting of 12 (twelve) parameters and biotenic diversity of the river through invertebrate macro biota, using interview methods to the local community. Result : The results showed that the water quality of the waters of the Musi River in Sebrang Ulu I and II were in poor condition, visible from the observation showed that the majority (over 70%) the parameters that were in bad indicator (C). As well as just founded the water biota was fish. The laboratory result showes the value of TSS in the second point of exceeding the normal standard, while the COD and BOD values were still below the normal standard. Conclusion: T he waters of the Musi River in Sebrang Ulu I and II are included in the Bad category (C). This is based on the results of examination of the river's physical habitat, examination of biotic animals and examination of TSS, BOD and COD levels

Rivers provide many services to humans, however, globally, they have been historically impacted from over-exploitation for human needs. Such impacts are likely to increase into the future leading to poorer river health and the service functions provided by rivers are being lost. This study focused on the river health evaluation for river protection and sustainable water management. Eight indices were selected to structure an evaluation index system, consisting of physical, chemical, and biological elements, for river health evaluation. Among them, a new index, Ratio of Environmental flow to Streamflow (RES), was proposed to evaluate the satisfaction degree of environmental flow and to establish a common standard for the comparison of habitat quality among different rivers. A combined model consisted of fuzzy matter-element and projection pursuit models was established for the evaluation of river health, which was adopted to convert several indices in the evaluation index system to a comprehensive indicator. The Huai River Basin was selected as the case study area. The results showed that the river health of the whole Huai River was at the medium level. Four river reaches such as Reach I, II, IV and V were in the middle level, while only Reach III was at the sub-healthy level. This study is expected to provide scientific knowledge for the improvement of river health and water allocation.

River health is one of the important issues today because of various threats by multiple anthropogenic stressors that have long-term impacts on the physical habitats, biodiversity, ecological functions, and their services. The main objectives of this study is to diagnose the chemical and biological river health in the watershed of Geum River with regard to the chemical regimes (N, P) and fish community using multi-metric chemical pollution index (CPI), and the index of biotic integrity model (IBI), respectively. The empirical models of sestonic chlorophyll, nutrients (N, P), and nutrient ratios of N:P indicated that the watershed, including all sampling sites, was a phosphorus-limited system. Analysis of fish trophic and tolerance guilds showed that the omnivore fish species and tolerant fish species were dominant in the watershed, while the sensitive fish species decreased downstream because of nutrient enrichments (such as TN, TP) and organic matter pollutions (such as BOD, COD). The chemical model of CPI showed that 11 sampling sites were in the fair&mdash, good condition, and 8 sites were in poor&mdash, very poor condition. Species composition analysis indicated that Zacco platypus was most widely distributed in the watersheds and dominated the fish community. The biological health of the watershed, based on the multimetric IBI model, was in poor condition and was getting worse downstream. The degradation of the river health was matched with the chemical health and showed a decreased abundance of insectivores and sensitive fish species. The outcomes of the river health were supported by principal component analysis (PCA) and cluster analysis (CA) of fish model metrics and the physicochemical parameters. Overall, our study suggests that river health was directly influenced by the chemical pollutions of nutrients and organic matter inputs.

Climate change represents a major threat to lotic freshwater ecosystems and their ability to support the provision of ecosystem services. England&rsquo, s chalk streams are in a poor state of health, with significant concerns regarding their resilience, the ability to adapt, under a changing climate. This paper aims to quantify the effect of climate change on hydroecological response for the River Nar, south-east England. To this end, we apply a coupled hydrological and hydroecological modelling framework, with the UK probabilistic climate projections 2009 (UKCP09) weather generator serving as input (CMIP3 A1B high emissions scenario, 2021 to the end-of-century). The results indicate a minimal change in the long-term mean hydroecological response over this period. In terms of interannual variability, the median hydroecological response is subject to increased uncertainty, whilst lower probability extremes are virtually certain to become more homogeneous (assuming a high emissions scenario). A functional matrix, relating species-level macroinvertebrate functional flow preferences to functional food groups reveals that, on the baseline, under extreme conditions, key groups are underrepresented. To date, despite this limited range, the River Nar has been able to adapt to extreme events due to interannual variation. In the future, this variation is greatly reduced, raising real concerns over the resilience of the river ecosystem, and chalk ecosystems more generally, under climate change.

The impact of agricultural and anthropogenic activities can play a significant role in heavy metal precipitation and transport in water. Human activities along two rivers: the Palmiet and Sezela Rivers in KwaZulu-Natal, South Africa, have been classified and metal contamination (Cr, Cu, Pb and Zn) and mobility assessed using a range of factors including contamination and enrichment factors, pollution load indices and water quality parameters. The overall assessment of the Palmiet River, which is characterised by industrial zone (predominantly metal works), followed by residential areas and informal settlements shows significantly elevated metal concentrations with high mobility and bioavailability. In contrast, the Sezela River, characterised by agricultural activities and informal settlements, shows total metal concentrations that pose a limited-to-no threat to human health and very limited metal mobility. The overall environmental assessment indicates that both rivers show deterioration; the Palmiet River has been severely impacted by the type of industrial activity, whereas the Sezela River has been more impacted by agricultural activity. This study highlights the role of different anthropogenic activities on river health and the potential health implications with the associated metal mobility.

Bioassessment has become a hot topic and could provide important information for river management and restoration. In this study, we developed multiple biological indices using three groups of aquatic organisms – benthic algae, macroinvertebrates and fish – for river health assessment. The main steps for development of multiple biological indices were selection of sensitive indices, optimization of core indices, setting target and critical values for core indices, and calculation of final scores of health condition. In order to evaluate the 19 candidate indices, disturbance gradients were constructed for water contamination, sediment contamination and land use change using principal components analysis. Thirteen indices showed significant and relatively high coefficients of determination with the disturbance gradients using multiple regression analysis (P

The Yamuna's stretch within Delhi is considered as the dirtiest river reach in India and despite numerous restoration plans, pollution levels have risen unabated. However, the enforcement of a nationwide lockdown due to the ongoing COVID-19 pandemic can possibly provide a ray of hope. We analyze the lockdown's impact on the water quality status of this stretch using a combination of measured parameters and satellite image derived indices. Class C Water Quality Index estimates of nine stations indicate an improvement of 37% during the lockdown period. The Biological Oxygen Demand and Chemical Oxygen Demand values reduced by 42.83% and 39.25%, respectively, compared to the pre-lockdown phase, while Faecal Coliform declined by over 40%. Similar analysis of 20 major drains that meet the Yamuna revealed declining effluent loads and discernable improvements in drain contaminant status were ascertained via a hierarchical cluster analysis. Reach-wise suspended particulate matter content, turbidity and algal signatures were derived from multi-temporal Landsat-8 images of prior and ongoing lockdown periods for 117 channel segment zones. These parameters also declined notably within most stretches, although their extents were spatially varied. While the partial/non-operational status of most industries during the lockdown enabled significant reduction in effluent loads and a consequent betterment in the river water quality, its spatial variations and even deterioration in some locations resulted from the largely undiminished inflow of domestic sewage through multiple drains. This study provides an estimate of possible river recovery extents and degree of improvement if deleterious polluting activities and contaminants are regulated properly., Graphical abstract Unlabelled Image, Highlights • Examines the lockdown's effects on the Yamuna's water quality parameters at Delhi. • Uses multi-temporal water sample measurements and satellite image derived indices. • Reductions in turbidity and suspended particulate matter observed in some reaches. • Extent of improvement dependent on flow conditions and point-pollution sources. • Domestic sewage increases pollution load markedly despite no industrial effluents.

The river system connectivity has become an important indicator of current river health assessment. The proper connectivity of river systems has the functions of allocating resources, improving water and soil environment, and preventing floods and droughts. However, it will be affected by many factors. In this paper, take Zhangjiagang, Jiangsu Province as an example, the influence degree of the structural connectivity index (expressed as static indicators) and hydroconnectivity index (expressed as static and dynamic indicators) on the connectivity of river flow system is analyzed based on the TOPSIS model. The study finds that the order of influence of each index on the connectivity of water system in the study area is: The structure connectivity index (α、 γ) is greater than hydrological connectivity index (R b 、 W p 、 R d 、 E p 、 C EN ), and the Closeness T j =(0.546, 0.546, 0.471, 0.479, 0.506, 0.519, 0.463). when analyzing the regional scale, we should consider the local conditions and consider comprehensively from the perspectives of structural connectivity and hydrological connectivity. The results of the study hope to provide theoretical basis for water system planning and management.

Dissolved oxygen (DO) plays a major role in sustaining aquatic communities; its concentration and regulatory determinants are considered a key node predicting eutrophy, ecosystem health, and biogeochemical feedbacks. Here we report the status of dissolved oxygen deficit (DOD; hypoxia), and its mechanistic links with sediment oxygen demand (SOD) in the Ganga River. We conducted two independent but interlinked studies during summer low flows of three consecutive years (2016–2018) considering: 1) a 518 km middle segment of the Ganga River between Kanpur upstream and Varanasi downstream; and 2) trajectory analyses downstream two point sources, one flushing industrial effluents (Wazidpur drain) and the other with urban sewage (Assi drain). The concentration of DO at sediment-water interface (DOsw) did appear

Chapter 2 identified components of river health that are in poor or critical condition and have been adversely affected by the development of hydropower. In this chapter, we review the existing mitigation, management, and monitoring activities that are employed on the Lancang River and make recommendations for improvements that, if implemented, will further mitigate the adverse effects of hydropower development.

Rivers are valuable to human beings because of their various functions. Unfortunately, ecological integrity of rivers has been seriously threatened by human activities, resulting in poor river functions. It is thus necessary to evaluate and maintain river health. Meanwhile, it is challenging to comprehensively assess river health with a single method alone. It is therefore relevant to combine the advantages of multiple methods in river health assessment. By classifying and characterizing river functions, we first established an indicator system for river health assessment in plain river network regions. We then assessed the health status of the Taihu Plain in terms of an improved entropy-based fuzzy matter-element model. We found that the overall health status of the Taihu Plain is below “good”. In particular, the health status of Yang-Cheng-Dian-Mao and Hang-Jia-Hu Region is “moderate”; the Wu-Cheng-Xi-Yu Region displays the poorest natural and social river functions. We also found that flood control is the most important influential factor in river health. Our findings suggest that rivers in the Taihu Plain must be restored to maintain their health, with the Wu-Cheng-Xi-Yu Region that must be restored preferentially, and that the river function of flood control must be improved at the scale of whole watershed. Comparing with other four commonly used comprehensive assessment methods, our improved entropy-based fuzzy matter-element model outperforms in reflecting objective fact and can be applied to river health assessment. Our results are generally consistent with existing studies, confirming that the proposed method for river health assessment is effective and feasible. Therefore, it provides a useful reference for river health assessment in other plain river network regions.

Predicting the ecological responses to moderate nutrient additions in systems that are already impacted to some degree by nutrient inputs is an important management task. In this study, we have investigated the responses of phytoplankton and periphyton and macroinvertebrate assemblages to experimental nutrient additions using both laboratory and field bioassays. We looked at six lower river reach/upper estuary sites in two flow seasons (high flow and low flow) in the Glenelg Hopkins Region of Victoria, Australia. Despite the considerable differences in the physical and chemical environments between sites in this study, the results suggest that within the lower river reaches of the Glenelg Hopkins region all systems are likely to have the potential for nutrient limitation. Also, addition of moderate and realistic loads of nutrients are likely to cause ecological changes, including a reduction in diversity H′, increases or decreases in algal growth and increases in densities of consumers. Incorporating this information into land use suitability options for the area will provide mangers an insight into potential outcomes relating to river health in the region.

The benthic animal community was examinesd in Danshui River of Dongjiang in November 2013. The river health evaluation system was established, a more comprehensive evaluation of Dongjiang water quality, for the reference in chemical pollutants control and administration.

With the rapid socio-economic development, a series of functional decline of river system has emerged, such as water pollution, environmental degradation and river shrinkage. The health of ecological river and its comprehensive management has become a hot topic in many countries and regions. Based on the combined influence of various factors, the multiple index system of river health assessment in the upstream of Hun River is established by Driving Forces-Pressure-State-Impact-Responses Model, the evaluation of river health is calculated by the Variable Fuzzy Assessment. The result shows that the river health assessment value is 2.944, which belongs to the weak state of sub health. And given this existence of the research section is located in the upstream of Hun River, carrying a remarkable ecological service potential. Therefore, it is of significant importance to protect, improve and repair the river ecological environment.

We review the use of diatoms in monitoring and assessment of river health in the world. First, we summarize the use of diatoms as indicators of nutritional status, acidification, and organic and metal pollution. We then examine some problems that have been associated with diatoms and indices that were used in different regions around the world: 1) incomplete taxonomy; 2) effects of natural geographic differences on diatom distributions (e.g., climate, lithology); 3) effects of natural site differences on diatom distribution and abundance (e.g., substrate, depth, chemistry); 4) differences in sampling, sample processing, and analytical methods; and 5) difficulties in finding minimally disturbed reference sites. Based on these problems, we present the different selections and the research progress of diatoms and indices used in monitoring and assessing river health around the world including the Americas, Europe, Africa, Asia, and Australia. We recommend that future studies and uses of diatoms focus on the following aspects: 1) improve the classification and identification of diatoms; 2) increase the use of diatom predictive indices to monitor and assess water quality; 3) develop global standard methods for sampling diatoms in streams, rivers, and lakes; and 4) apply hind-casting predictive models.

Summary The release of water from deep below the surface of large dams causes significant disturbance to water temperature regimes in downstream river channels with consequent impacts upon aquatic biota and river health. The Murray–Darling Basin (MDB) has a large number of dams, which are known to cause cold water pollution (CWP) in the downstream reaches of the impounded rivers. This study reviews the situation with regard to CWP in the MDB including the location, magnitude and extent of temperature suppression, the impacts upon fish, constraints and progress towards ameliorating the problem.

The assessment of the eco-environmental benefits of rivers has important guiding significance for improving water resource management, establishing water resource protection mechanisms, and maintaining river health. In view of the current imprecise quantitative methods of determining the eco-environmental benefits of rivers and based on the viewpoint of ecology, the significance and composition of river eco-environmental benefits were discussed. An emergy theory was introduced to quantify both the solar transformity of subtypes of water bodies and the sediment transportation benefit, which improved the indicator system of eco-environmental benefits. Applying the indicator system to the management practice of the Yellow River Basin, the eco-environmental benefits in 2015 were calculated by dividing the Yellow River into 66 sections. A Geographic Information System (GIS) atlas was then used to describe their spatial distribution. Eight typical cities were selected for the key analysis. Among these eight cities, the eco-environmental benefit inside the river in Xi’an section is the largest with a total emergy benefit of 1.08 × 1021 solar equivalent joules (sej) and a corresponding monetary benefit of 28.03 Chinese Yuan (¥)/m3. The eco-environmental benefit outside the river in Jinan section is the largest with a total emergy benefit of 1.37 × 1020 sej and a corresponding monetary benefit of 12.39 ¥/m3. This study proposed that rivers have great eco-environmental benefits, and the harmonious development of economy, society, and environment should be pursued in water resources management.

The reference condition of a river ecosystem is often used as a benchmark against which restoration activities are framed. However, the reference condition approach is not suitable for all river health assessments given undisturbed reference sites similar to a test site may not exist. We tested the ability of applying individual Species Distribution Models (SDMs) to predict the “natural” fish assemblages in a regulated coastal Australian river. Environmental data and fish collections from training sites were used to generate predictive models for 21 species. Model accuracy was high with the area under the receiver operating curve greater than 0.80 for the majority of species. The SDMs were then used to determine the natural fish assemblages and the condition of the sites in the test river was then assessed as the observed to expected species ratio (O/E). We expected that the O/E ratio would decline upstream through a series of weirs that created barriers to fish passage. Results confirmed that an inverse relationship existed between the number of weirs present on the test river and the O/E ratio, largely due to the decline in diadromous species. Our study clearly demonstrates the usefulness of the SDM approach to riverine health assessment in situations where undisturbed reference sites do not exist.

Our past approach to water management is unlikely to meet growing human water needs in the face of accelerated change to our freshwater ecosystems, let alone address the consequences of continuing environmental decline. The aim of this “grand challenge” article is to highlight what can be done to address these problems, from global scale governance initiatives to local-scale on-ground actions, aimed at tackling problems at their source. I also wish to explore what more we can do to improve engagement among the scientific and technical disciplines with interests in freshwater management, and more effectively communicate the cause and consequence of these problems, and possible solutions to them, to decision makers and the broader community.

Gallart Gallego, Francesc et al., Temporary streams are those water courses that undergo the recurrent cessation of flow or the complete drying of their channel. The structure and composition of biological communities in temporary stream reaches are strongly dependent on the temporal changes of the aquatic habitats determined by the hydrological conditions. Therefore, the structural and functional characteristics of aquatic fauna to assess the ecological quality of a temporary stream reach cannot be used without taking into account the controls imposed by the hydrological regime. This paper develops methods for analysing temporary streams' aquatic regimes, based on the definition of six aquatic states that summarize the transient sets of mesohabitats occurring on a given reach at a particular moment, depending on the hydrological conditions: Hyperrheic, Eurheic, Oligorheic, Arheic, Hyporheic and Edaphic. When the hydrological conditions lead to a change in the aquatic state, the structure and composition of the aquatic community changes according to the new set of available habitats. We used the water discharge records from gauging stations or simulations with rainfall-runoff models to infer the temporal patterns of occurrence of these states in the Aquatic States Frequency Graph we developed. The visual analysis of this graph is complemented by the development of two metrics which describe the permanence of flow and the seasonal predictability of zero flow periods. Finally, a classification of temporary streams in four aquatic regimes in terms of their influence over the development of aquatic life is updated from the existing classifications, with stream aquatic regimes defined as Permanent, Temporary-pools, Temporary-dry and Episodic. While aquatic regimes describe the long-term overall variability of the hydrological conditions of the river section and have been used for many years by hydrologists and ecologists, aquatic states describe the availability of mesohabitats in given periods that determine the presence of different biotic assemblages. This novel concept links hydrological and ecological conditions in a unique way. All these methods were implemented with data from eight temporary streams around the Mediterranean within the MIRAGE project. Their application was a precondition to assessing the ecological quality of these streams., The research leading to these results received funding from the European Community’s Seventh Framework Programme (FP7/2007-2011) under grant agreement 211732 (MIRAGE project), as well from the Spanish Government under the RespHimed project (CGL2010-18374) and a research contract (Ram´on y Cajal programme) granted to J. Latron.

Instream ecological flow is essential determinant of river health. In this paper, the monthly minimum flow calculation method, the (new) monthly frequency calculation method were applied to calculate and evaluate the minimum instream ecological flow and the optimal instream ecological flow for the Irtysh River, and the different criteria of instream ecological flow was calculated by the improved Tennant method. It is expected to provide a scientific basis for the reasonable allocation of water resource in Irtysh River basin by calculating the instream ecological flow.

The paper analyses the affecting factors of river health points that river channel health is the key and foundation of river health. It proposes the index system for the Lower Yellow River's channel health and sets the appropriate evaluation criteria and indicator weight. It evaluates the Lower Yellow River's channel health using fuzzy comprehensive evaluation method and gets the conclusion that the Lower Yellow River's channel health has deteriorated in 50 years and has not improved until the beginning of this century. Finally, the paper points that river health is closely related to flow-sediment processes and the coordination of flow-sediment relationship is the key to maintaining the health of the Lower Yellow River.

Based on the current situation of the Lower Yellow River channel, this paper analyses the factors affecting river health, points out that river channel health is the foundation and key to river health. It evaluates the Yellow River's downstream channel health using fuzzy comprehensive evaluation method and gets the conclusion that the Yellow River's downstream channel health has deteriorated in 50 years and has improved in the beginning of this century. This paper analyses and points out that the reservoir to regulate natural flow-sediment process is the primary means that the human impact on river health. The regulation of reservoir has duality that "excessive" regulation will seriously damage river health and "moderate" regulation can better maintain and restore river health. Coordination of flow-sediment relationship is the key to maintaining the health of the Lower Yellow River.

The large and accumulating body of evidence for both the controlling effect of the flow regime on river ecology and for the dependence of river health on the natural flow regime has led to the increasing use of hydrologic indices in instream flow studies. The myriad of collinear hydrologic indices present a daunting challenge to water managers trying to select a manageable number of indices for use in a hydrology-based environmental flow framework. In this study, a large number of hydrologic indices were calculated from gauging sites in the prairie provinces of Canada. Principal component analysis (PCA) and two rank-based non-parametric techniques are compared in their ability to select a small number of statistically informative indices. Despite the data being skewed and far from normal, PCA and the non-parametric technique called BioEnv + stepwise (BEST) both led to similar interpretations and could identify a small number of indices that capture a majority of the statistical variability. BEST selected indices more evenly from among conceptual categories of flow than PCA. Copyright © 2011 John Wiley & Sons, Ltd.

A real-time water quality monitoring (RTWQM) network was established in the province of Newfoundland and Labrador in late 2001. The network has changed the way river health is assessed in the province and a great deal has been learned in recent years about using this innovation in resource management. This paper summarizes three new developments carried out in recent years using RTWQM data. First, regression models are developed using real-time data as a surrogate for the concentration of important indicators of water quality that have traditionally been determined through manual grab sample collection. Second, regression models are developed for the prediction of water temperature and dissolved oxygen at the real-time water quality stations. A graphical approach is presented that links air temperature to these two important indicators of water quality. Third, control charts are investigated as a means of analyzing the data collected by the network. These charts have traditionally been used in the manufac...

The capacity of river self-purification is an important indicator for the river health. The organic and inorganic pollutants in most of the rivers in China are beyond the self-purification capacity of the river, which has caused the serious pollution to the water body. The capacity of the self-purification of the river may act as one of the indicators in regulating the discharge standards. Three reaches in Juma River were selected including serious polluted, light polluted and clear reach. The samples of water and aquatic plants were taken for the pollutant test. The results indicate that the Juma River has a great ability to purify the organic pollutants such as TN and TP, but little ability to the heavy metal ions. By analyzing the pollutant absorption ability of the three aquatic plants, Myriophyllum spicatum has greatest ability to absorb the organic pollutants.

The maximum exploitation scale and rate of hydropower is the important scientific issue to which the researchers and policy-makers always pay close attention. In this paper, on basis of various assurance levels for instream flow and in accordance with the internal relation between installed capacity of the hydropower and discharge (flow), the calculation method for the maximum exploitation scale and rate of hydropower is discussed and the empirical test was conducted by southwest China case, the results show that: (1) The calculation of exploitation scale and rate of hydropower according to instream flow as well as the equilibrium point between installed capacity of the hydropower and discharge is a effective attempt and new approach. (2) In southwest China, at the same assurance level for instream flow, the hydropower exploitation scale and rate significantly vary in major rivers. Generally, the exploitation scale is large for the river with large theoretical potentials while small for the river with small theoretical potentials; as for the exploitation rate, basically the rule is opposite. (3) The river with the maximum hydropower exploitation rate is high generally lies in the industrialized, urbanized, and densely populated regions where the sensitivity of river ecosystem is relatively low; the river with low hydropower exploitation rate generally lies in eco-sensitive areas which has a high requirement on assurance level for instream flow. (4) The maximum, moderate and excellent exploitation rates of hydropower are 16%, 12% and 8% (based on theoretical potentials); 22%, 17% and 11% (based on technologically exploitable hydropower potentials); and 34%, 25% and 17% (based on economically exploitable hydropower potentials) respectively in southwest China.

In Malaysia, urban riparian refers to river reserve that reflects green space. As surviving greenery space amidst concrete jungle, urban riparian is essential for safe-keeping the river health, the surrounding environment, and the well-being of urbanites. The existing developments found by the Malaysian riversides are already in place prior to river reserves establishment, thus constricting expansion and synchronisation due to its guidelines applied in isolation within several related agencies. Prior studies have highlighted the potential of riparian vegetation as a viable method that lowers the temperature within urban space. Hence, this paper probes into the potential of river reserve as a passive cooling strategy by determining the vegetation technical requirements from the light of urban river physical planning and design guidelines in Malaysia. Thus, this study outlines the possibility of integration by comparing vegetation requirements for river buffer with vegetation function and ability in altering radiation, as well as heat transfer, through physical attributes. By focusing on vegetation physical structure, the riparian area can attain multiple functions and benefits. Thus, this finding serves as a basis for integration of passive cooling strategies with vegetation requirements for urban river reserve, and for further studies that investigate other essential physical attributes.

The US Environmental Protection Agency's (EPA) baseline Hudson River health risk assessment (HRA) is evaluated and found to be biased toward keeping polychlorinated biphenyls (PCBs) in sediments. T...

The use of fish communities to assess environmental quality is common for streams, but a standard methodology for large rivers is as yet largely undeveloped. We developed an index to assess the condition of fish assemblages along 1,580 km of the Ohio River. Representative samples of fish assemblages were collected from 709 Ohio River reaches, including 318 “least-impacted” sites, from 1991 to 2001 by means of standardized nighttime boat-electrofishing techniques. We evaluated 55 candidate metrics based on attributes of fish assemblage structure and function to derive a multimetric index of river health. We examined the spatial (by river kilometer) and temporal variability of these metrics and assessed their responsiveness to anthropogenic disturbances, namely, effluents, turbidity, and highly embedded substrates. The resulting Ohio River Fish Index (ORFIn) comprises 13 metrics selected because they responded predictably to measures of human disturbance or reflected desirable features of the Ohio ...

The Macroinvertebrate Community Index (MCI) and its quantitative version (QMCI) were developed to provide measures of organic pollution in streams on the Taranaki Ring Plain, New Zealand. Subsequently, they have been used widely to evaluate “river health” in many running water environments throughout New Zealand, although their suitability as general‐purpose monitoring tools needs evaluation. In the present study, the MCI and QMCI were calculated from fixed‐count macroinvertebrate data for 230 stream and river sites in Canterbury, New Zealand. Values ranged from 60 to 135 (MCI) and 2.0 to 8.8 (QMCI). The two indices ranked sites similarly (rs = 0.86), but the distribution of sites among published degradation bands (Stark 1998) differed. The MCI placed most sites in the “doubtful quality, or possible mild pollution” and “probable moderate pollution” categories, whereas the QMCI assigned most sites to the “clean water” and “probable severe pollution” groups. This implies either that category assess...