Natural River Research Articles

Social buffering of oxidative stress and cortisol in an endemic cyprinid fish

Fish exhibit complex social behaviours that can influence their stress levels and well-being. However, little is known about the link between social interactions and stress in wild fish, especially in running water environments. While many studies have explored the stress axis in fish, most have focused on specific social contexts, leaving gaps in understanding stress responses to social changes. Our study investigated collective behaviour and stress in wild Italian riffle dace (Telestes muticellus) in a controlled experimental setup simulating a natural river system. Results reveal that group-living fish have lower cortisol and oxidative stress levels in muscle tissue compared to solitary counterparts, suggesting a calming effect of conspecific presence. Additionally, we observed upregulated expression of antioxidant enzymes in group-living fish, indicating potential benefits to antioxidant defence systems. These insights shed light on the dynamic relationship between group behaviour and stress in wild fish within running water habitats and emphasise the use of multidisciplinary approaches.

Ecosystem health evaluation of urban rivers based on multitrophic aquatic organisms

The ecosystem health evaluation method of urban rivers is significantly different from natural rivers, because of intensive human interferences and ecological restoration measures. Biotic integrity index (IBI) provides a method to quantify the response of aquatic organisms to environmental stress. Multi-trophic aquatic organisms may exhibit different responses and sensitivities to stress factors, which affects the reliability of the IBIs. This study proposed a hypothesis that the biota with the higher trophic level (whose habitat was not completely destroyed) or that of the biota with the shorter life cycle would be more sensitive in urban rivers. To prove the above hypothesis, the ecosystem health status of urban rivers was evaluated by the IBIs across multitrophic groups, including benthic invertebrates, zooplankton, phytoplankton, periphyton algae and microorganisms. The reliability of the IBIs was assessed by estimating their relationship with water quality index (WQI). The spatial distribution differences of the IBIs were distinguished by spatial autocorrelation analysis. The results showed that the IBI based on benthic invertebrates cannot mask the effects of dredging. Compared with the IBIs from other trophic groups, the correlation coefficients between the IBIs based on zooplankton and microorganisms and WQI were higher. Moreover, the evaluation results of Z (Zooplankton)-IBI and M (Microorganism)-IBI were able to discriminate the least, medium and highly impaired site groups divided by WQI. For the spatial response mode, Z-IBI and M-IBI could identify the high-value river sections under ecosystem restoration projects, and Z-IBI could also identify the low-value river sections under intensive human interferences. Therefore, Z-IBI and M-IBI could be recommended as the priority application in urban rivers. The constructed ecosystem health evaluation framework for urban rivers would play a guiding role in reducing impairments and restoring water ecosystem quality.

Evaluating the effectiveness of the MicroPlastic Sediment Separator (MPSS)

Effective laboratory methods are a requirement to obtain accurate data on the contamination of the environment with microplastics. However, current methods often lack specification and validation of performance. The aim of this work was to provide the first evaluation of the effectiveness of the commercially available MicroPlastic Sediment Separator (MPSS) operated with sodium chloride. We performed density separation experiments with pristine plastic particles spiked into both commercial sand (experiment I) and natural river sediments (experiment II) and with environmental microplastics contained in natural river sediments (experiment III). The natural sediments were taken from the Lahn River in Germany, a medium-scale central European tributary. The pristine test particles were ground polypropylene fragments, sieved in three different size classes: larger than 1 mm, 0.5–1 mm, and 0.3–0.5 mm. In experiment I, the mean recovery rate was 97 % for particles of the largest size class (standard deviation s=6~%; n=30 per size class), but dropped to 75.33 % (s=21.29~%) in the medium and to 54 % (s=25~%) in the smallest size class. After density separation, 87 % of all unsuccessfully separated test particles were found at the inner walls of the MPSS. In experiment II, the recovery rate was not correlated with the particle size distribution of the natural river sediments. In experiment III, a subsequent second density separation step contributed on average 38 % (s=18~%; n=5) to the total number of extracted environmental microplastics. This study illuminates central aspects of a density separation and aims to contribute to quality improvements of recovery rate experiments and field studies for the generation of reliable data on microplastics in the environment.

Hydrodynamic characteristics and particle tracking of 90° lateral intakes at an inclined river slope

Lateral intakes are common in rivers. The pump efficiency and sediment deposition are determined by the local hydrodynamic characteristics and mainstream division width. The hydraulic characteristics of lateral withdrawal from inclined river slopes at different intake elevations should be investigated. Meanwhile, the division width exhibits significant vertical non-uniformity at an inclined river slope, which should be clarified. Hence, a three-dimensional (3-D) hydrodynamic and particle-tracking model was developed with the Open Source Field Operation and Manipulation (OpenFOAM), and the model was validated with physical model tests for 90° lateral withdrawal from an inclined side bank. The flow fields, withdrawal sources, and division widths were investigated with different intake bottom elevations, withdrawal discharges, and main channel velocities. This study showed that under inclined side bank conditions, water entered the intake at an oblique angle, causing significant 3-D spiral flows in the intake rather than two-dimensional closed recirculation. A lower withdrawal discharge, a lower bottom elevation of the intake, or a higher main channel velocity could further strengthen this phenomenon. The average division width and turbulent kinetic energy were smaller under inclined side bank conditions than under vertical bank conditions. With a low intake bottom elevation, a low withdrawal discharge, or a high main channel velocity, the sources of lateral withdrawal were in similar ranges near the local inclined bank in the vertical direction. Under inclined slope conditions, sediment deposition near the intake entrance could be reduced, compared to that under vertical slope conditions. The results provide hydrodynamic and sediment references for engineering designs for natural rivers with inclined terrains.

Interpreting floodplain heterogeneity: Using field data to understand unsupervised floodplain classifications

The dynamic environment of natural river floodplains creates spatial heterogeneity that influences floodplain functions. Diverse human activities have homogenized natural floodplains and reduced their functions across many river networks in the temperate latitudes. Consequently, quantification of floodplain heterogeneity is needed to understand patterns of spatial heterogeneity on diverse floodplains and to inform floodplain restoration. We use a novel approach of spatially connecting field and remotely sensed data in order to interpret the output of, and build upon, a previous unsupervised classification workflow. We apply the method to three rivers in the US Pacific Northwest and the Altamaha River in the southeastern US and compare our results to a previous study. We find that field classifications, relative topography, and NDVI are useful for interpreting results from the unsupervised classification workflow. The interpretations are visually interesting, but we propose that it is the heterogeneity within the groups that is vital to floodplain functioning. Natural floodplains in the Pacific Northwest and coastal Southeast have moderate to high evenness, moderate to high intermixing, and moderate aggregation; and aggregation and evenness similar to rivers in Colorado and Oklahoma, USA, but lower intermixing. We attribute lower intermixing at the Altamaha River to slower rates of lateral channel migration, and lower intermixing at the Hoh River to the different hydrologic and sediment regimes and less stable braided planform. The results show that the larger rivers in this study (Altamaha, Hoh, and Sol Duc Rivers) have spatial heterogeneity similar to beaver-modified and shortgrass prairie rivers in Colorado, whereas the more inland and smaller river (Lookout Creek) has spatial heterogeneity similar to the tallgrass prairie site (Sand Creek). From the results of an ad hoc sensitivity analysis, we suggest using the highest spatial resolution topographic data available, using aerial imagery/mosaics from the same sensor, and removing largest patch index from the suite of comparable indices. The metrics reveal similarities and differences between rivers in the United States, and indicate that discernable trends may arise from a meta study comparing heterogeneity from more rivers across the country.

Leaf thermal safety margins decline at hotter temperatures in a natural warming 'experiment' in the Amazon.

The threat of rising global temperatures may be especially pronounced for low-latitude, lowland plant species that have evolved under stable climatic conditions. However, little is known about how these species may acclimate to elevated temperatures. Here, we leveraged a strong, steep thermal gradient along a natural geothermal river to assess the ability of woody plants in the Amazon to acclimate to elevated air temperatures. We measured leaf traits in six common tropical woody species along the thermal gradient to investigate whether individuals of these species: acclimate their thermoregulatory traits to maintain stable leaf temperatures despite higher ambient temperatures; acclimate their photosynthetic thermal tolerances to withstand hotter leaf temperatures; and whether acclimation is sufficient to maintain stable leaf thermal safety margins (TSMs) across different growth temperatures. Individuals of three species acclimated their thermoregulatory traits, and three species increased their thermal tolerances with growth temperature. However, acclimation was generally insufficient to maintain constant TSMs. Notwithstanding, leaf health was generally consistent across growth temperatures. Acclimation in woody Amazonian plants is generally too weak to maintain TSMs at high growth temperatures, supporting previous findings that Amazonian plants will be increasingly vulnerable to thermal stress as temperatures rise.

Microbial dynamics in Manaus river, Brazil

Rivers, which are vital ecosystems that support a variety of life forms and provide many ecosystem services, have been degraded by human activities, such as urbanization, pollution, and overexploitation. Habitat restoration projects have been implemented in different parts of the world to restore the ecological health and functioning of degraded rivers. The microbial community that forms biofilms on various substrates is one of the key components of river ecosystems. Organic matter is decomposed and carbon dioxide is produced by these biofilms, which affects the oxygen levels and nutrient cycles in the water. However, the effects of habitat restoration on the biofilm microbial community are not well understood. High-throughput DNA sequencing was used in this study to compare the bacterial composition of biofilms in three types of rivers: degraded urban rivers, urban rivers with restored habitats, and forested rivers that serve as reference conditions. The following questions were aimed to be answered: (i) How is the biofilm bacterial community composition affected by habitat restoration? (ii) How does bacterial diversity change in restored rivers compared to degraded and reference rivers? (iii) What are the environmental factors that influence the biofilm bacterial community composition? It was found that water quality was improved by habitat restoration by increasing the dissolved oxygen and reducing the organic pollutants in urban rivers. A decrease in bacterial diversity and a shift in the biofilm bacterial community structure towards that of the reference forested rivers were accompanied by this. This suggests that the biofilm microbial community can be altered by habitat restoration and its role in processing organic pollutants can be enhanced. However, it was also found that there was still a significant difference in the biofilm bacterial community between the restored and reference rivers, indicating that more time and effort are needed to achieve a similar ecological quality as the natural forested rivers.

Influence of moisture states of recycled sand from construction sites on mechanical strengths of cement-based mortar

This study focuses on investigating the influence of moisture states of recycled sand (RS) from construction sites on properties of cement-based mortars. The major goal of this study was to utilize the amount of RS as a waste at the construction sites, as well as to reduce the burden on natural sand extraction and to save the construction cost. The use of RS as a partial replacement for natural river sand (NS) at various percentages (0% and 50% by mass of fine aggregate) was employed. Various investigations of properties including consistency of fresh mortar, compressive and flexural strengths of hardened mortar specimens, were conducted. The two moisture states for both sands were saturated surface dry (SSD) and dry state (DS). When increasing the percentages of RS replacement, regardless of the moisture states of sand, the results indicated that consistency of fresh mortar, compressive and flexural strengths at 28 days tended to decrease by 11.1–20.0%, 7.8–8.9%, and 7.4–13.8%, respectively. When compared with mortar using sand at DS state, the improvement of consistency, compressive and flexural strengths at 28 days of mortar using sand at SSD state was 20.0–33.3%, 72.2–74.3%, and 23.3–32.4%, respectively, depending on the type of sand (NS or RS). Furthermore, the correlation between compressive and flexural strengths of the mortar was linear. In conclusion, the replacement of NS by RS at 50% reduced the consistency and mechanical strengths of the cement-based mortar, while the use of RS in SSD state can be considered as an effective solution for enhancing the strengths of cement-based mortar compared to that in DS state.

The impact of primary colonizers on the community composition of river biofilm.

As a strategy for minimizing microbial infections in fish hatcheries, we have investigated how putatively probiotic bacterial populations influence biofilm formation. All surfaces that are exposed to the aquatic milieu develop a microbial community through the selective assembly of microbial populations into a surface-adhering biofilm. In the investigations reported herein, we describe laboratory experiments designed to determine how initial colonization of a surface by nonpathogenic isolates from sturgeon eggs influence the subsequent assembly of populations from a pelagic river community, into the existing biofilm. All eight of the tested strains altered the assembly of river biofilm in a strain-specific manner. Previously formed isolate biofilm was challenged with natural river populations and after 24 hours, two strains and two-isolate combinations proved highly resistant to invasion, comprising at least 80% of the biofilm community, four isolates were intermediate in resistance, accounting for at least 45% of the biofilm community and two isolates were reduced to 4% of the biofilm community. Founding biofilms of Serratia sp, and combinations of Brevundimonas sp.-Hydrogenophaga sp. and Brevundimonas sp.-Acidovorax sp. specifically blocked populations of Aeromonas and Flavobacterium, potential fish pathogens, from colonizing the biofilm. In addition, all isolate biofilms were effective at blocking invading populations of Arcobacter. Several strains, notably Deinococcus sp., recruited specific low-abundance river populations into the top 25 most abundant populations within biofilm. The experiments suggest that relatively simple measures can be used to control the assembly of biofilm on the eggs surface and perhaps offer protection from pathogens. In addition, the methodology provides a relatively rapid way to detect potentially strong ecological interactions between bacterial populations in the formation of biofilms.

Numerical Simulation of 3D Flow Structure and Turbulence Characteristics near Permeable Spur Dike in Channels with Varying Sinuosities

Owing to the different degrees of bending in rivers in nature, it is difficult to conduct experiments in situ. In this study, the renormalization group (RNG) k-ε turbulence model in ANSYS Fluent was used to analyze the three-dimensional flow structure and turbulence characteristics near a spur dike and to evaluate the variation trend of flow in rivers with different degrees of bending. The results show that in channels with different curvatures, the vortex appears between the spur dikes and is disturbed by the permeable hole, and the backflow area moves downstream. The strength of secondary flow (SSF) fluctuates greatly in the vicinity of the spur dike and the downstream region, and the peak value appears 3.22 m (21.5 times L) away from the inlet of the bend. The SSF increases as the bend curvature increases. The SSF displays similar variation trends in the three kinds of bends. The peak value of normalized turbulent kinetic energy (NTKE) appears 3.14 m away from the entrance of the bend, the NTKE is the largest in the 45° bend and the smallest in the 180° bend, and it decreases only at distances of 3.25–4.19 m away from the entrance of the bend as the bend curvature increases.

Luminescence for sedimentary provenance quantification in river basins: A methodological advancement

Multiple luminescence signals such as optically stimulated luminescence, infrared stimulated luminescence and thermoluminescence etc. are characteristic of the crystal/material. Recent studies have shown the potential of luminescence signals for sedimentary provenance studies, sediment fingerprinting and tracking. It is based on the premise that different provenances have different compositions of trace impurities in minerals which are responsible for the luminescence properties of the minerals. However, use of luminescence for provenance studies is still in its developmental stage and needs validation in modern sediments. The current work utilizes the differences in the luminescence signals from different geological provenances to quantitatively estimate the sediment influx to the mainstream from its tributaries based on a 2-component mixing model. Samples from natural river confluences and control samples prepared by mixing two samples in a known proportion by weight were used to estimate the sediment flux based on the luminescence characteristics. This study successfully demonstrates the use of luminescence parameters for sediment fingerprinting and budgeting using natural and controlled samples.

Gas Chromatography-Mass Spectrometric Study of Low-Molecular-Weight Exogenous Metabolites of Algae-Bacterial Communities in the Laboratory Accumulative Culture

The study of exogenous metabolites of algae-bacterial communities in the laboratory accumulative culture obtained from natural river water was conducted using gas chromatography-mass spectrometry. Exometabolites of the algae-bacterial community (including microalgae and cyanobacteria) in the culture medium were represented by saturated, unsaturated, and aromatic hydrocarbons, carboxylic acids, phenolic, and terpene compounds and their derivatives. Possible biological activities of the discovered exometabolites are considered. The study has demonstrated that an increase in the number of main groups of microorganisms, along with changes in the composition of algae and cyanobacteria, are responsible for the increase in the composition and concentration of metabolites in the microecosystem’s culture medium after one month of cultivation. The presence of octacosane in high concentration (0.0603 mg/L; 23.78% of the total content of low molecular weight organic compounds) by the end of exposure accumulative culture is associated with the strong development of the cyanobacterium Gloeocapsa sp. in the presence of diatom algae of the genus Navicula and green algae of the genera Chlorella and Scenedesmus. Due to the need to comprehend the ecological and biochemical mechanisms of the formation and functioning of algae-bacterial communities, as well as to predict potential paths of transformation and evolution of aquatic ecosystems, the specificity of exometabolite complexes of algae and microorganisms, as well as their allelopathic and other biochemical interactions in freshwater ecosystems, requires further serious study.

Simulating tectonically controlled fractal landscape evolution in the Three Rivers Region (SE Tibetan Plateau margin)

The long-term development of fluvial landscapes is sensitive to tectonic movement. This is the case for the Three Rivers Region, located on the southeastern margin of the Tibetan Plateau, where it is critical for understanding the continuous collision and compression between the Indian and Eurasian plates. However, quantitative perspectives on this landscape evolution are lacking. Based on present global positioning system (GPS) data, a quantitative expression of two phases of regional deformation, a northeast-southwest shortening and dextral shear deformation, was proposed to represent the continuous Indian-Eurasian collision. By incorporating this tectonic pattern into a landscape evolution model and integrating the regional differential uplift, the numerical results quantitatively present a dynamic shaping of the Nu, Lancang, and Jinsha rivers in the SE Tibetan plateau margin. Analyses of the fractal dimensions of these river networks indicate that two tectonic deformation phases significantly controlled regional landscape development and its unique drainage features. The numerical simulations depict the river networks to comprise very long and relatively straight stream trunks, and relatively small and short tributaries. The tectonic shortening and its accompanying rapid uplift prevented the development and lengthening of the tributaries, which might have promoted the formation of low-relief surfaces. With comparison to the digital elevation model (DEM), the fractal features of the river networks extracted from the numerical results are consistent with those extracted from the natural river networks, despite the simplicity of the numerical model. More broadly, based on the more realistic kinematic scenarios and reasonable constraints, this study contributes to the development of an effective and applicable model that can reveal important implications for the landscape evolution of the region.

Mechanical properties and drying shrinkage of graphite tailing-basalt fiber cement mortar

By replacing part of standard sand with graphite tailings (GT) and adding green basalt fibers (BF) together to prepare cement mortar, it could effectively alleviate the environmental problems caused by the massive discharge of tailings and the shortage of resources caused by the massive use of natural river sand. In this study, graphite tailings and basalt fibers were added to cement mortar, and the impact of mixing GT and BF fibers on the mechanical characteristics and drying shrinkage properties of cement mortar were analysed through experimental studies. The hydration of cement mortar was investigated by using techniques such as energy spectroscopy (EDS), differential thermogravimetric analysis (DTG-TG), electron microscopy (BSEM, SEM), and x-ray diffraction (XRD). And the microstructures of the matrix, fiber, and fiber–matrix interface underwent evaluation. The findings demonstrated that the cement mortar with a 20 % GT substitution rate and 0.1 % BF by volume admixture was the most optimized combination, and the compressive strength and flexural strength at an estimated 28 days of curing time were improved the most, by 13.89 % and 14.08 %, respectively. And the early drying shrinkage performance could be improved more substantially; the drying shrinkage at the age of 7 days was 54 % that of cementitious sand. According to the microscopic test results, it was known that GT would adversely affect cement hydration due to higher sulphide levels, but it had a pozzolanic effect. The appropriate amount of GT could give full play to the pozzolanic effect, reduce the porosity of cement mortar and lower the Ca/Si value within the matrix–matrix fiber interface transitional region, improve the adverse effect of its sulphide on cement mortar, and help improve the mechanical and crack-resisting properties of cement mortar.

Quick extraction of recycled sand morphology parameters based on deep learning and their effect on mortar property

Due to the limited application of the natural river sand in China, recycled sand (RS) has been considered as an important replacement of natural sand in sustainable construction. The morphology of recycled sand is critical to its effective application in mortar and concrete. An environmentally friendly approach is introduced in this work to improve the morphology of recycled sand during its crushing process. This paper presents a newly developed image acquisition device, which obtained 25,328 RS images to use as a dataset for the construction of a segmentation model based on deep learning technology with an automatic segmentation of RS characteristics. Evaluation indices including accuracy (ACC), Recall, intersection over union (IoU), and F1-score index are reaching up to 99.8%, 88.1%, 84.9% and 84.3%, respectively. RS morphological characteristics including the flat and elongation ratio (FER), angularity index (AI), roundness (R) are automatically extracted by the proposed model, and the predicted results agreed well with the experimental ones. Finally, the effect of FER of RS on mortar’s mechanical properties is investigated by a series of experiments. Results reveal that the flowability, flexural strength and compressive strength of mortar decreased invariably with the lower FER of sand.

Application of Green Technology in Clean Water Treatment Installation: A Case Study of Batuah Village

Access to clean water is a fundamental human right, critical to life and health, especially in many rural regions such as Batuah Village. However, several obstacles, including the geographic layout, absence of natural rivers or surface water, and lack of a comprehensive public water supply network, have made the provision of clean water to these communities exceedingly challenging. This study, titled "The Application of Green Technology in Clean Water Treatment Installation: A Case Study of Batuah Village," is concentrated on employing environmentally-friendly technology in water purification. The objective is to ascertain its impact on the efficiency and effectiveness of water treatment processes. Through the deployment of sustainable water treatment systems, the research aspires to evaluate the performance of such technologies in enhancing water quality, accessibility, and sustainability. This research delves into the strengths and weaknesses of the existing system, proposes potential improvements, and assesses the implications of adopting these green technologies on the socio-economic fabric of the village. The insights derived could be beneficial for other similar contexts striving to ensure clean water availability in challenging environments. This research applied a collaborative strategic planning method, involving Batuah Village Government, Samarinda State Polytechnic, and the community in planning the Pamsimas program. The Pamsimas Water Treatment Installation (IPA Pamsimas) Karya Makmur, a community-managed system guided by government, educational institutions, and BSSR, demonstrated this synergistic approach. The study aimed to implement, sustain, and assess the clean water program's effectiveness using observations, interviews, and tests in the Batuah village area.

The Effect of Sediment Supply on Pool‐Riffle Morphology

AbstractDownstream width variations can generate pool‐riffle morphology under experimental conditions, in numerical simulations and natural river channels. The present understanding of how pool‐riffle morphology varies with sediment supply and caliber, however, is insufficient due to the limited range of sediment supply rates explored in previous experiments and the little attention paid to sand supply and sediment size distribution in the laboratory and in the field. We present a model of river morphodynamics that can account for the spatial variability of channel width, and we validate the model with experimental data. Model validation shows how this one‐dimensional model can capture pool‐riffle formation, growth, and equilibration with errors that are comparable with those of other 1D models of river morphodynamics. We then apply the validated model to study the effects of sediment supply rate and caliber on pool‐riffle morphology. Model results show that pool‐riffle morphology is resilient to the range of tested sediment supply (i.e., five‐fold the sediment amount, 41‐fold the sand amount and coarsening the gravel supply). Bed and water surface slopes are sensitive to all types of change of sediment supply, whereas the sensitivity of bed surface sediment grain size varies with the type of change. These findings support prior research emphasizing the role of downstream width variations for the development/maintenance of pool‐riffle morphology and can help in the restoration and recovery of pool‐riffle gravel‐bed rivers.

River Park Assessment: 2D Hydraulic Watercourse Modeling for Nature-based Solutions in Urban Area

Over time, fragmentation of semi-natural habitats in urban areas has become a pressing concern, disrupting ecological processes within cities. The focus on preserving open ecosystems has grown, highlighting the need to enhance resilience in urban riverside areas for effective ecosystem restoration. Comprehensive studies on river valleys, considering both hydrology and ecology, play a crucial role in urban river ecosystem development. Our article explores the potential of protective zones with urban vegetation and watercourses as Nature-based Solution within Krakow's ongoing riverine park system development. The study's cross-sections in the River Park area revealed dominant velocities ranging from 0.67 to 2.0 m s-1for SWQ (mean annual maximum flow) and below 0.67 m s-1for Q1% (1% annual exceedance probability flow). The hydrological analysis accurately captured the natural river bed channels' curvature, providing the basis for a two-dimensional mathematical model to visualize the hydraulic structure of protected sites. Integrating water and greenery management systems in urban areas offers significant potential for adapting to climate change, mitigating extreme weather events. Our research's novelty lies in applying 2D hydraulic modeling, demonstrating how River Parks can serve as climate change mitigation solutions in urban environments.

Computing River Discharge Using Water Surface Elevation Based on Deep Learning Networks

Accurately computing river discharge is crucial, but traditional computing methods are complex and need the assistance of many other hydraulic parameters. Therefore, it is of practical value to develop a convenient and effective auto-computation technique for river discharge. Water surface elevation is relatively easy to obtain and there is a strong relationship between river discharge and water surface elevation, which can be used to compute river discharge. Unlike previous usage of deep learning to predict short-term river discharge that need multiple parameters besides water level, this paper proved that deep learning has the potential to accurately compute long-term river discharge purely based on water level. It showed that the majority of relative errors on the test dataset were within ±5%, particularly it could operate continuously for almost one year with high precision without retraining. Then, we used BiGRU to compute river flow with different hyperparameters, and its best RMSE, NSE, MAE, and MAPE values were 256 m3/s, 0.9973, 207 m3/s, and 0.0336, respectively. With this data-driven based technology, it will be more convenient to obtain river discharge time series directly from local water surface elevation time series accurately in natural rivers, which is of practical value to water resources management and flood protection.

Cascade dams altered taxonomic and functional composition of bacterioplankton community at the regional scale.

Dams are increasingly disrupting natural river systems, yet studies investigating their impact on microbial communities at regional scale are limited. Given the indispensable role of bacterioplankton in aquatic ecosystems, 16S rRNA gene sequencing was performed to explore how these communities respond to dam-influenced environmental changes at the regional scale in the Shaying River Basin. Our findings revealed that cascade dams create distinct environments, shaping bacterioplankton communities near the dams differently from those in natural rivers. In the upstream of the cascade dams, water quality was superior, while bacterioplankton community structure was simple with weak community interactions. In the midstream, nutrient and heavy metal content were increased, making bacterioplankton structures more susceptible to environmental changes. In the downstream of the cascade dams, water quality had a significant impact on the community and the bacterioplankton structures were highly complex. Additionally, environmental variables significantly influenced bacterioplankton functional groups. However, the response to these factors, as well as the interplay between functional and taxonomic diversity, varied markedly depending on the specific region of the cascade dams. We here delved into the effects of cascade dams on the taxonomic diversity and functional groups of bacterioplankton to provide a theoretical basis for segmentally regulating these dams.