Search

Freshwater aquatic ecosystems are threatened globally. Biological monitoring is required to deliver rapid and replicable assessment of changes in habitat quality. The Ephemeroptera, Plectoptera, Trichoptera (EPT) index is a globally recognised rapid bioassessment that measures taxa richness of three insect orders whose larvae are considered sensitive to freshwater habitat degradation. South-western Australia contains threatened freshwater ecosystems but has depauperate EPT fauna and high endemism, potentially reducing the capacity of the EPT index to track degradation. This study investigated if EPT species richness, composition or individual species tracked physical or chemical river degradation in three catchments in south-western Australia. We sampled EPT fauna and measured water chemistry, erosion, sedimentation, riparian vegetation cover and instream habitat at 98 sites in the winters of 2007 and 2023. We found 35 EPT taxa across the study area with a median number of species per site of two. EPT species richness had weak positive associations with a composite water quality index and dissolved oxygen and weak negative associations with electrical conductivity and total nitrogen. No association was found between physical and fringing zone degradation measures and EPT species richness. EPT community structure generally did not distinguish between sites with high or low degradation levels. The presence of the mayfly Nyungara bunni tracked salinity, dissolved oxygen and nitrogen levels, but its usefulness as a bioindicator could be limited by its restricted range. This study suggests that the EPT index would need modification or combination with other indices to be a useful rapid bioassessment in south-western Australia. [ABSTRACT FROM AUTHOR]

Predictive models leverage the relationships between environmental factors and river health to predict the river health at unmonitored sites. Such models should be generalizable to unseen data. Among various machine learning models, heterogeneous ensembles are known to be generalizable owing to their structural diversity. The present study compares the generalizability of heterogeneous ensembles with those of homogeneous ensembles and single models. The models classified five grades (very good to very poor) of river health indices (RHIs) for three taxa (benthic macroinvertebrates, fish, and diatoms) given various environmental factors (water quality, hydrology, meteorological, land cover, and stream properties) as inputs. The data were monitored at 2915 sites in the four major river watersheds in South Korea during the 2016–2021 period. The results indicated better generalizability of the heterogeneous and homogeneous ensembles than single models. Moreover, heterogeneous ensembles tended to show higher generalizability than homogeneous ensembles, although the differences were marginal. Weighted soft voting was the most generalizable of the heterogeneous ensembles, with losses ranging from 0.49 to 0.59 across the three taxa. Weighted soft voting also delivered acceptable classification performance on the test set, with accuracies ranging from 0.42 to 0.52 across the taxa. The relative contributions of the environmental factors to RHI predictions and the directions of their effects agreed with established knowledge, confirming the reliability of the predictions. However, as heterogeneous ensembles have been rarely applied to RHI prediction, the extent to which heterogeneous ensembles improve the generalizability of prediction must be investigated in future studies.

Evaluation of the ecological health of rivers requires a focused examination of how biological indicators respond to chemical stressors to offer key insights for effective conservation strategies. We examined the influence of stressors on aquatic ecosystems by analyzing various ecological entities and biotic integrity metrics of fish communities. A nonmetric multidimensional scaling (NMDS) approach was applied to determine scores based on 19 fish ecological entities (FEs) and a fish-based multi-metric index of biotic integrity (mIBI-F). The composition of fish communities in reference clusters differed from the disturbed clusters due to instream chemical stressors. These chemical stressors, including high levels of nutrients, organic matter, and ionic/suspended solids, were linked to variation in the key indicator FEs, whose guild identities were closely associated with instream chemical degradation. The scores of FEs (abundance weighted) and mIBI-F metrics in the first NMDS axis (NMDS1) were significantly linked with chemical health indicators (p < 0.001), such as total phosphorus (R2 = 0.67 and 0.47), electrical conductivity (R2 = 0.59 and 0.49), and chlorophyll-a (R2 = 0.48 and 0.25). These NMDS1 scores showed better accuracy than the conventional mIBI-F score in capturing river ecological health linked with chemical health status as determined by a multi-metric index of water pollution. Our study suggests that based on the ordination approach, the biological integrity of these systems reflected the chemical health. [ABSTRACT FROM AUTHOR]

Surveys of sociocultural relations to rivers provide critical baseline information to appraise the effectiveness of restoration programmes. Findings from a mixed‐methods case study (document analysis, catchment‐wide questionnaire, semi‐structured interviews) show how local relations to the Waimatā River vary in upper, middle and lower catchment areas, in part influenced by historical (family) connections. Personal interactions with the river, and implications for mental and physical well‐being, decline with the perceived condition of the river. While respondents indicate the negative influence of governance arrangements upon river condition, they also highlight positive prospects that blue spaces can shape the co‐design and implementation of restoration activities. [ABSTRACT FROM AUTHOR]

The accumulation of pollutants in the sediment along surface water may negatively affect riparian zones and increase ecological risk. This article investigates the effects of metal sediments on riparian soil via field monitoring and ICP-OES analysis. To this end, pollution levels, seasonal changes, and potential sources of the pollutants were determined for the Melen River watershed, Turkey. The ecological statuses (contamination factor, enrichment factor, index of geo-accumulation, pollution index, modified pollution index, and potential and modified ecological risk indexes) of the watershed were also analyzed. Although no significant seasonal differences in the metal sediments were observed, their spatial distribution in the sediments and riparian soils varied markedly. Cr (11.4 to 136), Co (7.7 to 21.52), Cu (11.4 to 76.6), and Ni (14.06 to 128.2) recorded as mg/kg significantly increased from the upstream to the downstream. The metals possessing the highest risk in the sediment and riparian soil regarding the river health were Cu, Co, and Ni. The risk values were found to be heavily polluted (PI > 3 and MPI > 10), and the risk indexes were above the "desired environment without the risk". The risk index was found to be more than 50, and the modified risk indexes exceeded 200 at many points. The transportation of pollutants in surface water became evident in the sediment, resulting in adverse effects on the riparian zone and the ecological system. [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.)

Continued large-scale public investment in declining ecosystems depends on demonstrations of “success”. While the public conception of “success” often focuses on restoration to a pre-disturbance condition, the scientific community is more likely to measure success in terms of improved ecosystem health. Using a combination of literature review, workshops and expert solicitation we propose a generalized framework to improve ecosystem health in highly altered river basins by reducing ecosystem stressors, enhancing ecosystem processes and increasing ecosystem resilience. We illustrate the use of this framework in the Mississippi-Atchafalaya River Basin (MARB) of the central United States (U.S.), by (i) identifying key stressors related to human activities, and (ii) creating a conceptual ecosystem model relating those stressors to effects on ecosystem structure and processes. As a result of our analysis, we identify a set of landscape-level indicators of ecosystem health, emphasizing leading indicators of stressor removal (e.g., reduced anthropogenic nutrient inputs), increased ecosystem function (e.g., increased water storage in the landscape) and increased resilience (e.g., changes in the percentage of perennial vegetative cover). We suggest that by including these indicators, along with lagging indicators such as direct measurements of water quality, stakeholders will be better able to assess the effectiveness of management actions. For example, if both leading and lagging indicators show improvement over time, then management actions are on track to attain desired ecosystem condition. If, however, leading indicators are not improving or even declining, then fundamental challenges to ecosystem health remain to be addressed and failure to address these will ultimately lead to declines in lagging indicators such as water quality. Although our model and indicators are specific to the MARB, we believe that the generalized framework and the process of model and indicator development will be valuable in an array of altered river basins.

The present study tries to analyze the impact of human activities on the physical and chemical health of the Dwarkeswar River. The river flows through a densely populated area. As a result, nearly 4000 t of sand are being extracted per day from the four segments of the river. Moreover, huge materials are extracted from the river to supply the raw materials of 97 brick kilns developed along the banks of the river. An industrial plant extracts 2,200,000 L d−1 of water from the Dwarkeswar River, besides nearly 80 water lifting pumps. Similarly, a number of bridges are constructed across the river, and embankments are made along the banks. Per day 15.10 million liters of untreated sewage drain into the Dwarkeswar River from Bankura Town. The town also generates 63,111 kg/d of solid waste, some parts of which are disposed on the bank of the river. Intensive field surveys, analysis of multi-dated satellite images, and water quality parameters of the last ten years (2011–2020) were carried out in the present study to assess the impact of these interventions on river morphology, hydrology, and water quality. The comprehensive pollution index (CPI) was used to assess water quality. Results reveal that the Dwarkeswar River is highly affected, including the planform change, reduction of mean discharge and increase in the concentration of pollutants in the river water. The CPI value increased from 0.72 (2011) to 2.81 (2020), which indicates a severe increase in the level of pollution.

In 2015, the sudden decline in the only known population of Myuchelys georgesi (the Bellinger River snapping turtle) triggered a strong community response, and a link between turtle mortality and poor water quality in the Bellinger River was suggested. A multi-agency investigation later attributed the mortalities of M. georgesi to a novel virus (the Bellinger River virus) and not a direct effect of poor water quality. However, a lack of consistent water quality or river health data in the catchment limited the research of factors that may have heightened susceptibility to the virus or exacerbated its symptoms. Community consultation identified strong connections with the riverine environment and highlighted the cultural, social, economic, and environmental values of the Bellinger River catchment. In 2017 OzGREEN, a not-for-profit environmental education charity based in Bellingen, built upon their existing citizen science water quality monitoring program in collaboration with the Saving our Species (SoS) team in the New South Wales (NSW) Department of Planning and Environment (DPE), who provided funding and equipment and solicited the involvement of NSW Waterwatch, Western Sydney University and Taronga Zoo. Now known as Bellingen Riverwatch (Riverwatch), the program has become a long-term citizen science program that aims to assist the recovery of M. georgesi, now a critically endangered species, through the delivery of monthly water quality data covering the Bellinger River and its tributaries. SoS also engaged the DPE Estuaries and Catchments Team to commence the Bellinger River Health Program (BRHP), focusing on water quality and aquatic macroinvertebrates to assess river health, with the aim of providing scientifically rigorous data to support the management and recovery of M. georgesi. This case study compares and evaluates the Riverwatch citizen science and the BRHP professional science, examining methods and results to compare the accuracy of the citizen science data and assess its reliability for informing ongoing river management. The results demonstrate that Bellingen Riverwatch is a well-managed citizen science program and generally provides valid, accurate, and representative results that can be confidently used to enhance the spatial and temporal coverage of the professional science monitoring program.

In this study, the fish biotic integrity index (IBI) was applied to evaluate the health status of Liao River mainstem in China. A total of 3565 fish individuals were collected from seven sampling sites in May (spring) and September (autumn) of 2020 and 2021. 24 candidate indicators selected for building the Fish Integrity Index (F-IBI) of the mainstream Liao River. The F-IBI values of each index were calculated using the 1, 3 and 5 assignment method, and the river health criteria were divided into four quartiles based on the 75% quantile of the F-IBI values below the sampling points to determine the evaluation criteria of the F-IBI system of the main stream of the Liao River, which were divided into five grades, namely healthy, subhealthy, fair, poor and very poor. The results show that the health of the main stream of the Liao River is mostly at average or below average level, and the evaluation results of station1, station5 and station7 were all at poor or below health level for two consecutive years; among them, station2 and station3 have higher overall scores in each season, and most of the points are above sub-healthy level, which is similar to the results of previous periods. The results indicate that F-IBI is feasible for evaluating the health of the Liao River and can be used as a basis for assessing the ecological health of the main stream of the Liao River. [ABSTRACT FROM AUTHOR]

River health assessments and threat analysis on the riparian corridors in Sub-Saharan Africa have received little or no attention, therefore this study assessed the healthiness of riparian corridors using the Rapid Appraisal of Riparian Condition (RARC) indices within a river catchment. The biogeography of the riparian corridor, factors responsible for the modification of riparian vegetation, and causes of riparian disturbance were examined. Twelve study sites were randomly selected from where reaches were identified. The riparian corridor extents were delimited from the bank of the river to the uppermost point within reaches. Species diversity indices were computed while bank height, width, and average depth were measured. Also, cross-sectional area and river discharge were derived along each riparian zone using standard measurement techniques. The ecological values and threat severity along each riparian zone were assessed following the RARC model. The ecological values and disturbance level revealed r as −0.7(p < 0.05). The variation in species composition along the river orders suggests that the first-order streams have the highest number of taxa. The level of ecological destruction is fairly low in the first-order streams and increases as order increases. This study concludes that higher-order rivers have low diversity, low ecological values, and consequently, relatively poor health, especially when under severe anthropogenic pressure. [ABSTRACT FROM AUTHOR]

The accumulation of pollutants in the sediment along surface water may negatively affect riparian zones and increase ecological risk. This article investigates the effects of metal sediments on riparian soil via field monitoring and ICP-OES analysis. To this end, pollution levels, seasonal changes, and potential sources of the pollutants were determined for the Melen River watershed, Turkey. The ecological statuses (contamination factor, enrichment factor, index of geo-accumulation, pollution index, modified pollution index, and potential and modified ecological risk indexes) of the watershed were also analyzed. Although no significant seasonal differences in the metal sediments were observed, their spatial distribution in the sediments and riparian soils varied markedly. Cr (11.4 to 136), Co (7.7 to 21.52), Cu (11.4 to 76.6), and Ni (14.06 to 128.2) recorded as mg/kg significantly increased from the upstream to the downstream. The metals possessing the highest risk in the sediment and riparian soil regarding the river health were Cu, Co, and Ni. The risk values were found to be heavily polluted (PI > 3 and MPI > 10), and the risk indexes were above the “desired environment without the risk”. The risk index was found to be more than 50, and the modified risk indexes exceeded 200 at many points. The transportation of pollutants in surface water became evident in the sediment, resulting in adverse effects on the riparian zone and the ecological system.

The assessment of river health holds paramount significance in diagnosing the conditions of river water environments, and its research serves as a crucial foundation for the functional management and restoration of rivers. We discuss the concept and assessment criteria of health in areas characterized by significant human activity. Utilizing the "over the riverbank" and "under the riverbank" quantification criteria as the framework, a comprehensive river health assessment index system is developed, encompassing seven aspects (riparian zone condition, pollution discharge condition, human–water interaction, physical structure, water environment, water ecology, and socio-economic service function) and 35 indicators. This study introduces the River Health Index (RHI), specifically tailored for regions with significant human activity, facilitating the quantitative assessment of river health status and precise calculation of the River Health Index in these areas. The research employs the RHI to assess the health condition of the Cangzhou section of the Qingliang River in China. The results indicate that the Qingliang River is in a suboptimal state of health, with the key limiting factors being the aspects of "water environment" and "water ecology". The research demonstrates that the proposed river health assessment system for areas with significant human activity effectively reflects the objective reality of the Qingliang River, exhibiting a high level of reliability and applicability. [ABSTRACT FROM AUTHOR]

Citizen science is increasingly recognised as an important, indeed necessary, contribution to environmental research and policy, as well as for fostering stronger relationships between scientists and the broader community. Well-established citizen science projects offer valuable insights by virtue of the long-term contribution of volunteers to sustained research and monitoring activities. Here we draw on two of Australia's longest running citizen science projects, Waterwatch and the Australian Shorebird Monitoring Program (formerly Shorebirds 2020), to argue that such projects reflect successful citizen science in terms of their program persistence, reputation and impact. This success has been enabled by (1) developing a clear vision; (2) effective knowledge management; (3) relationship building; (4) meaningful volunteer engagement; and (5) a capacity to adapt to change. We recommend that new and emerging projects embed these principles in their program development, particularly those aiming to generate longitudinal datasets while building motivated, informed and connected communities. Long-term citizen science programs offer important insights for new and emerging projects by virtue of their persistence, reputation and impact. Developing a clear vision, effective knowledge management, relationship building, meaningful volunteer engagement, and adapting to change will help programs measure environmental change while building motivated, informed and connected communities. [ABSTRACT FROM AUTHOR]

Copyright of Water Conservancy Science & Techonlogy & Economy is the property of Water Conservancy Science & Technology & Economy 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.)

Risk assessment of microplastics (MPs) contamination in the assemblage of 15 important fish species with different feeding habits and microhabitats was studied in the River Ravi, Pakistan. Fishes with different feeding habits (omnivore, herbivore, and carnivore) and microhabitat preferences (surface, column, and bottom dweller) were sampled at Balloki and Sidhnai barrages during the post-monsoon seasons of 2019–2020. The gastrointestinal tract (GIT) of fish samples were found to be contaminated with MPs, with an average of 28.1 ± 20.7 MPs/individual and 26.8 ± 15.9 MPs/individual at Balloki and Sidhnai barrages, respectively. The surface dweller fish exhibited the highest MPs abundance, followed by the bottom dweller and column dweller. In addition, the highest MPs recovered from the omnivore generalist feeding group as compared to herbivores and carnivores. The fibers were the most abundant shape and generally made up of polyethylene terephthalate (PET) and polyethylene (PE). These PET and PE (low-density MPs) exhibit low hazard level, whereas high-density MPs with high hazard level and rarely present in GIT of sampled fishes. Based on MP polymer toxicity assessment, nine fish species were categorized in minor risk, two species in medium risk, and four species in highrisk group. Bottom dwelling fishes were at the highest plastic polymer risk level III due to the presence of a high density of MPs with high toxicity hazards. The high-risk prone fishes are under direct threat from MPs pollution, which may disrupt the ecological integrity of the river ecosystem and human health. The findings of the current study highlight the urgent need to address plastic pollution issues in River Ravi, and will be helpful for managers, researchers, and fisheries experts to mitigate this emerging challenge.speciesspecies [ABSTRACT FROM AUTHOR]

The water quality and phytoplankton diversity of the Okamini Stream, Port Harcourt, Nigeria was studied between April and June 2018 at three stations. The data was used to assess the health of the system for supporting local communities. Compared to national and international standards, the stream was found to be acidic, but pH levels (5.87 ± 0.40) were similar to other systems in the New Calabar River catchment. Analysis of variance showed that there was no significant variation (p < 0.05) in water quality between the stations, with the exception of PO4 (0.82 ± 0.40 mg l-1), which was significantly higher than other local systems. A total of 26 species of plankton were recorded during the study. These species belonged to the Bacillariophyceae (n = 10), Chlorophyceae (n = 6), Cyanophyceae (n = 5), Euglenoidea (n = 3), and Chrysophyceae (n = 2), but phytoplankton density was low. The most frequently occurring phytoplankton species were indicators of organic pollution, such as Cyclotella comta, while Melosira varians was recorded at all sampling occasions. Relatively high diversity indices indicated a stable environment. We conclude that the Okamini Stream is not yet degraded, but that the water quality should be monitored, and anthropogenic activities managed to avoid potential future deterioration. [ABSTRACT FROM AUTHOR]

Rivers are a vital part of the earth's environment and the basis for human survival. River health has been widely concerned by scholars and practitioners, and the number of studies in this area is increasing. In order to examine the evolution of river health research and identify the research frontiers, a total of 675 articles were retrieved from the Web of Science Core Collection database, and CiteSpace was used for bibliometrics. The results revealed that the research on river health is multidisciplinary. Freshwater Biology and Ecological Indicators were two of the most influential journals. Researchers and institutions from America, Australia, and China were the core research forces, and a certain gap was observed between developed and developing countries in river health. The most productive institution was Michigan State University, followed by Griffith University and Hohai University. There are three development trends in river health: (1) Research scale is expanding; (2) Research methods are diversified and interdisciplinary; and (3) Evaluation index is more comprehensive and systematic. The frontier of river health had been expanded from the connotation of river health to the evaluation methods, evaluation indexes, and comprehensive river ecological research. Overall, research on river health is a well-developed and promising research field. This study provides a framework in the river health field for new researchers and helps scholars to identify further potential perspectives on collaborators, research frontiers, hotspots, and research trends. [ABSTRACT FROM AUTHOR]

This study aimed to effectively evaluate the ecological restoration of the river reach where a small hydropower station was retired or renovated. An ecological health index system was constructed based on the environmental characteristics of the upstream and downstream of the small hydropower station after its retirement and renovation. Based on the combination weighting concept of game theory, the combination weights were obtained by the comprehensive analytic hierarchy process (subjective weight) and entropy method (objective weight). This ecological health assessment with fuzzy comprehensive evaluation was applied to assess the health status of Shimen (dam removal) and Changqiao (renovation in ecological flow) reaches of the Tufang River in Changting County, China. The results showed that the ecological health assessment index system proposed in this study was comprehensive and reasonable, and the revision degree of the hydropower station obviously influenced the process of ecological river restoration. The findings from this study would benefit for the rational utilization of water resources and the river ecological health maintenance in mountainous areas. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) becomes a promising technology for macroinvertebrate monitoring worldwide. In recent decades, with increasing humanization processes, such as water pollution and habitat fragmentation, the richness and abundance of macroinvertebrates show a dramatic decline, which is particularly evident in tropical or subtropical rivers. The high-throughput and rapid monitoring of species' survival and the ecological status of their habitats are relevant to river management. Here, we used the eDNA technology to detect macroinvertebrates in the Dongjiang River—a typical subtropical river in Southern China, to assess the ecological status, based on eDNA datasets. Our data showed a total of 640 OTUs detected by eDNA technology, belonging to three phyla, five classes, 13 orders, 33 families and 71 genera of macroinvertebrates, and these taxa had a 36.6% coverage rate with historical data at the genus level. The traditional water quality index (WQI) showed that the upstream of Dongjiang River were mainly levels I~II, the middle stream were levels II~III, and the downstream were levels IV~V. The eDNA-based biotic indices showed almost the same findings, that is, the overall ecological status of Dongjiang River was: upstream > middle reaches > downstream. Overall, this study provides important datasets and technical support for eDNA technology in macroinvertebrate monitoring and ecosystem management in the subtropical rivers. [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.)

This study analyses the heavy metal contamination in freshly deposited sediment of 210 km stretch of River Ganga between Kanpur and Prayagraj, Uttar Pradesh (U.P.), India. As per APHA (2012)30 digested samples were prepared after collecting from 10 sampling sites. Then the samples were analyzed for 8 heavy metals namely Cadmium (Cd), Chromium (Cr), Copper (Cu), Iron (Fe), Manganese (Mn), Nickel (Ni), Lead (Pb), and Zinc (Zn) by Atomic Absorption Spectroscopy (AAS) (Shimadzu AA-6300). Risk assessment was done by employing four pollution indices. The average values of contamination factor (CF) indicate that the level of contamination by Pb is moderate (1 < CF < 3) and significant by Cd (3 < CF < 6). Whereas, the average value of Geo-accumulation index (Igeo) indicates that the sediments are uncontaminated or in a moderate level of contamination by Pb (0 < Igeo < 1) and in a moderate level of contamination by Cd (1 < Igeo < 2), which may have harmful effects on Ganga River ecology. The values of Pollution load index (PLI) indicate that the Ganga River sediment has a low level of contamination. Based on various pollution indicators, it has been observed that concentrations of Cd and Pb in the river sediment is a matter of concern and may lead to further deterioration of sediment quality in near future due to increasing anthropogenic activities in the river basin, hence proper management strategies should be taken to control the direct dumping of both domestic and industrial wastewater in the river. [ABSTRACT FROM AUTHOR]

Predictive models leverage the relationships between environmental factors and river health to predict the river health at unmonitored sites. Such models should be generalizable to unseen data. Among various machine learning models, heterogeneous ensembles are known to be generalizable owing to their structural diversity. The present study compares the generalizability of heterogeneous ensembles with those of homogeneous ensembles and single models. The models classified five grades (very good to very poor) of river health indices (RHIs) for three taxa (benthic macroinvertebrates, fish, and diatoms) given various environmental factors (water quality, hydrology, meteorological, land cover, and stream properties) as inputs. The data were monitored at 2915 sites in the four major river watersheds in South Korea during the 2016–2021 period. The results indicated better generalizability of the heterogeneous and homogeneous ensembles than single models. Moreover, heterogeneous ensembles tended to show higher generalizability than homogeneous ensembles, although the differences were marginal. Weighted soft voting was the most generalizable of the heterogeneous ensembles, with losses ranging from 0.49 to 0.59 across the three taxa. Weighted soft voting also delivered acceptable classification performance on the test set, with accuracies ranging from 0.42 to 0.52 across the taxa. The relative contributions of the environmental factors to RHI predictions and the directions of their effects agreed with established knowledge, confirming the reliability of the predictions. However, as heterogeneous ensembles have been rarely applied to RHI prediction, the extent to which heterogeneous ensembles improve the generalizability of prediction must be investigated in future studies. [Display omitted] • Grades of river health indices were predicted using machine learning models. • Generalizability was evaluated based on variance–bias decomposition. • Ensemble models showed better generalizability than single models. • Weighted soft voting was the most generalizable of the ensembles. • Important environmental factors were identified using a post-hoc method. [ABSTRACT FROM AUTHOR]

Abstract Undertaking environmental assessments on non‐wadeable rivers is challenging due to their size, depth, and water velocity. The cotton strip assay (CSA) is a functional indicator used in assessing the ecological health of non‐wadeable rivers by measuring cellulose decomposition potential. Enhancing knowledge on the microbial communities responsible for decomposition would assist in developing a microbial‐based biotic index that could complement the CSA. The aims of this study were to explore the temporal and spatial variability of bacterial communities on cotton strips, identify environmental drivers of differences, and detect potential indicator taxa. Cotton strips were deployed at 12 sites, spanning a range of water quality and catchment land uses in three separate months. Each site was placed into an ecological health category (EHC) from A (healthy) to D (poor). Metabarcoding (16S rRNA) was used to characterize bacterial communities. There was a significant interaction between month and site and between month and EHC. Higher temperatures and pH were identified as key drivers of differences in bacterial communities in February (summer) and higher levels of ammoniacal nitrogen, nitrate/nitrite nitrogen, and turbidity in August (winter). After removal of amplicon sequence variants (ASVs) in low abundance, 27 taxa indicative of EHCs were identified. ASVs associated with EHC‐A were generally negatively correlated with modified land use and nitrate/nitrite nitrogen. In contrast, ASVs associated with EHC‐D were positively correlated to modified land use and temperature. With further validation, a molecular microbial index could be developed to aid in assessing the health of non‐wadeable rivers.

Comprehensive assessment of river health is challenging due to the diversity of rivers, the complexity of their ecosystem and functional service. This paper updates the river health assessment indicator system, weight, and assignment criteria in China by reviewing and examining the peer-reviewed literature. We propose an indicator system, weight, and criteria, validated by nine case studies and able to assess the country-scale river health. Our analysis shows that the rule layer of indicator system includes hydrology, water quality, aquatic organism, physical habitats, and functional service; its corresponding weights are set to 0.15, 0.21, 0.18, 0.22, and 0.24, respectively. The ten most representative indicators are selected that incorporates the indicator layer with their corresponding weights. The evaluation based on case studies shows that in eight out of nine cases, our results are consistent with those obtained in previous studies. Therefore, the suggested index system, weight, and three-assessment criteria are well suited for the complex cases in China. This paper can serve as a reference for a river health assessment and present a comprehensive listing of assessment criteria. HIGHLIGHTS We popose an indicator system which can provide an objective and universally applicable way to evaluate river health.; We classify the rivers into three types, and the corresponding assignment criteria are proposed, respectively. With this method, the health status of rivers of different types can be determined more accurately and compared horizontally.;

Recognizing the interrelatedness of water use and conceptual value of IWRM, progressive water resource management systems are moving beyond hierarchical arrangements toward more integrated networks. Increasing calls for participation recognize the value of broadened perspectives that provide both technical expertise as well as social, cultural, and administrative knowledge. Moreover, the call for evidence-based policy of '00s has been tempered by recognition of the political nature of data and science. As such, water decision-makers striving to coproduce and employ shared knowledge must grapple with integrating inputs from diverse participant groups to characterize policy problems and identify effective and feasible solutions. Participatory mandates, coordination bodies, and collaborative networks have emerged to facilitate such integration, and their effective cooperation and alignment relies upon some degree of shared purpose, rather than command and control. But guidance is limited with respect to how to accomplish such integrative aims, including how to support discussions across sectors and silos of practice in order to foster better understanding regarding the problems a policy network collectively aims to address. Motivated by observations within the discourse on water quality in the Brantas River basin in Indonesia, this research explores alternative concepts and problem structures regarding river health via Q methodology. Q methodology, an approach that uses factor analysis to explore human subjectivity, is applied to explore conceptualizations of water quality and the structures of the “water quality problem” in the Brantas. The results show that different groups of perspectives emerge regarding the concept itself, as well as characterization of the current condition of the Brantas. Surprisingly, these variant perspectives do not follow oft-cited government-business-civil society divisions. Moreover, the emergent perspectives demonstrate which aspects of the policy problem are consistent and which are contested, suggesting several starting points for early collaboration and several areas that require further research and facilitated deliberation. The results also offer participants in the collaborative network greater appreciation of the various perspectives and definitions in use, within and across organizations, when discussing water quality.

The assessment of river health holds paramount significance in diagnosing the conditions of river water environments, and its research serves as a crucial foundation for the functional management and restoration of rivers. We discuss the concept and assessment criteria of health in areas characterized by significant human activity. Utilizing the “over the riverbank” and “under the riverbank” quantification criteria as the framework, a comprehensive river health assessment index system is developed, encompassing seven aspects (riparian zone condition, pollution discharge condition, human–water interaction, physical structure, water environment, water ecology, and socio-economic service function) and 35 indicators. This study introduces the River Health Index (RHI), specifically tailored for regions with significant human activity, facilitating the quantitative assessment of river health status and precise calculation of the River Health Index in these areas. The research employs the RHI to assess the health condition of the Cangzhou section of the Qingliang River in China. The results indicate that the Qingliang River is in a suboptimal state of health, with the key limiting factors being the aspects of “water environment” and “water ecology”. The research demonstrates that the proposed river health assessment system for areas with significant human activity effectively reflects the objective reality of the Qingliang River, exhibiting a high level of reliability and applicability.

Rapid bioassessment protocols have been developed as inexpensive monitoring tools to assess the health of streams, rivers and lakes. The present study was conducted to adapt macroinvertebrate-based field protocol for assessing the ecological health of streams and rivers in the central and south-eastern highlands of Ethiopia. Abiotic and biotic data were collected from 154 sites distributed in the upper section of four major basins, namely Awash and Rift-Valleyin the centeral highlands, and Wabi-Shebele and Genale. The field-based assessment protocol was adapted based on the rapid field protocol developed for assessing highland streams in the Hindu-Kush-Himalayan regions in 2010. The decision support table of the protocol includes both abiotic and biota components that can be identified in the field, with a special focus on benthic macro-invertebrates as bioindicator. The sensitivity of a specific benthic invertebrate (BMI) taxon to different level of degradation was based on biotic score (ETHbios) developed for assessing Ethiopian highland streams and rivers in 2015. To ensure simplicity of the protocol, only 15 BMI taxa with clear ecological quality preference are included. The sensitivity ranges from less tolerant taxa such as Perlidae, Scirtidae and Lepidostomatidae to tolerant taxa such as Psychodidae, Chironomidae and Syrphidae. The protocol is manually calculated in the field and used to categorize streams and rivers into five ecological water quality classes namely high (I), good (II), moderate (III), poor (IV) and bad (V). This categorization serves as an 'early warning' method to identify areas that require urgent attention for intervention measures or detailed investigation in the future studies. The method can be considered as rapid, inexpensive but scientifically sound monitoring method to evaluate the ecological conditions of running waters in the highlands of Ethiopia. [ABSTRACT FROM AUTHOR]

Many rivers in semiarid areas have ecological degradation and flood control problems that need to be addressed urgently. In order to maintain river health and to promote the sustainable development of cities near these rivers, a comprehensive river regulation project must be carried out. In this study, first, the factors influencing river health are discussed, and the principles and main restrictions involved in comprehensive regulations are studied. The scientific regulation mode is proposed, and new financing channels for water conservancy construction are also suggested. Second, a river reach adjacent to a city in the middle part of the Luanhe River in North China is used as a case study. The health status of the river is analyzed, and a comprehensive river regulation plan combined with urban development is put forward on this basis. The plan includes embankment construction, river regulations, multilevel rubber dam storage, ecological restoration, and artificial lake and riverside landscape construction. The influence of the engineering treatment on the river flood discharge capacity is examined, and the treatment effect is verified by a hydraulic scale model. After implementation of the comprehensive river regulations, the flood control safety of the city and river ecological environment are found to be significantly improved, with the hidden danger of dust storms eliminated. The treatment project incurs environmental, social, and economic benefits and preliminarily achieves the coordination and mutual promotion of river regulation and urban development. [ABSTRACT FROM AUTHOR]

Aotearoa New Zealand has shifted towards more collaborative decision‐making for freshwater in recent years, as national and local authorities seek new ways of working with communities. While the potential benefits of collaboration are well established, the messiness of collaborative processes can challenge institutional imperatives to develop formally justified, implementable plans. This paper explores a collaboration‐first attempt, 'Healthy Rivers/Wai Ora: Proposed Waikato Regional Plan Change 1', demonstrating that while more inclusive forms of plan‐making may better reflect diverse values, interests and knowledges, relinquishing control over planning processes can present significant challenges in the face of existing institutional structures and legislative requirements. [ABSTRACT FROM AUTHOR]

Environmental hydraulics, a neighboring research field to ecohydrology, is an intermediate area between hydrodynamics and ecology/biology. The main research topic of this emerging scientific discipline is the interdependency and interconnectedness between water flow and the behavior of various aquatic organisms. This truly interdisciplinary approach reveals numerous unanswered questions, mostly related to the relationship between water flow, sediment, vegetation, nutrients, and harmful substances in the hydro-environment, and leads to better insight into river status, often called "river health". In this paper, we review some of the basic research questions and challenges in the field of environmental hydraulics. The discussion is inspired by the outcomes of the recent 6th IAHR Europe Congress 2020 where the community of hydro-engineers met experts engaged in the UNESCO Intergovernmental Hydrological Programme (IHP-VIII). [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.)