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The article describes the specific features and difficulties of monitoring the condition of an embankment dam with a clay-cement-concrete diaphragm. Moreover, it provides an overview and an evaluation of the applied monitoring methods. Additions to the existing set of measures for monitoring embankment dams with a clay-cement-concrete diaphragm are proposed. [ABSTRACT FROM AUTHOR]

Environmental and ecological effects of the dam of the high-pressure Bratsk Hydroelectric Power Station (HPS) on the fish population and the probability of fish downstream migration from the Bratsk Reservoir have been studied. It has been revealed that thermal stratification of the water column is a significant factor in the ecological differentiation of the fish population in the upper reaches of high-pressure hydroelectric plants. According to hydroacoustics data, most of the ichthyomass, consisting of "warm-water" representatives of the Percidae (65%) and Cyprinidae (22%) families, is concentrated in the relatively warm layer of the epilimnion. Juvenile fish from 30 to 50 mm in size (up to 70% of the total fish number in this layer) are also concentrated here. In the cold-water hypolimnion, the fish population is represented by large single individuals of whitefish (Coregoninae). The data on distribution of fish in the lower and upper reaches of the dam, fish nutrition patterns, growth rate, and the presence of injuries that occur when fish pass downstream through hydroelectric plant dams are presented. Revealed differences in the growth rate of perches from the upper and lower reaches are associated with their constant inhabiting of water masses with contrasting temperatures. Net catches in the lower reaches over the four seasons of research lack injured individuals. These facts prove the absence of mass downstream passage of fish through the Bratsk HPS dam. Juveniles of cyprinids and perches accumulate in the upper warm layer of 0–10 m, i.e. outside the zone of the intake flow formation, which makes their entrance to intake openings at a depth of more than 20 m hardly possible. [ABSTRACT FROM AUTHOR]

The purpose of this study is to propose an impact analysis model to explore the effect of the post-earthquake landslide surge on local damage to ultra-high arch dams. Based on the existing pressure model of landslide-generated waves impacting the dam, nonlinear dynamic analysis is conducted on a high arch dam subjected to the landslide surge of different surge heights after the earthquake, through numerical simulation. According to the theory of nonlinear least squares, the relationship between the surge height and the damage value of all dam elements is fitted with a Sigmoid function, and the results show good fitting performance. This result proves that the proposed impact analysis model can well reflect the influence of the surge height on the local damage to arch dams. In addition, three parameters are defined based on this model. The influence of the post-earthquake landslide surge on the local damage of arch dams at different positions is analyzed based on these three parameters, and the vulnerable positions of the dam body under the impact of the post-earthquake landslide surge are determined. The model has important significance for the safety evaluation of dams affected by landslide-generated waves after an earthquake. [ABSTRACT FROM AUTHOR]

The stress-strain state and strength of the cutoff wall in the base layer of a tailings dam is assessed through numerical simulation [ABSTRACT FROM AUTHOR]

Dam health monitoring is an important method for quantitative evaluation of dam safety. After long-term operation, there have missing data in dam monitoring data series inevitably due to the sensor damage or monitoring system failure problem which seriously affects the correctness of dam safety evaluation. The imputation accuracy of missing value is affected by data decomposition, reconstruction, and prediction methods. Therefore, in view of the high-precision imputation model of missing data in dam health monitoring, this paper proposes a data-driven fusion imputation model based on novel mode decomposition and deep learning method. First, the fusion imputation model is constructed based on extreme-point symmetric mode decomposition (ESMD), permutation entropy (PE), and bidirectional gate recurrent unit neural network (BiGRU). The ESMD-PE data preprocessing module can decompose the original data into a series of stable subsequences which can be input into the advanced deep learning BiGRU model to improve the interpolation accuracy. Then, the types of dam missing data and interpolation steps are studied. The engineering example illustrates that the root mean square error of the proposed model is decreased by 55.32% on average compared with four classical imputation models. The ESMD-PE–BiGRU fusion model can effectively simulate the inherent law of dam monitoring data and predict the missing data, which provides complete monitoring data for dam safety analysis. [ABSTRACT FROM AUTHOR]

Periphyton is the dominant primary producer in mountain streams and sustains the higher trophic levels. While certain periphyton groups, particularly diatoms, have received extensive study, the comprehensive characterization of the entire community has been largely neglected. This study aims to investigate the temporal pattern of biofilm in mountain streams characterized by different water thermal regimes. A one-year quantitative campaign, involving monthly samplings, was conducted in five subalpine streams in Northern Italy's Orobic Alps to collect epilithic biofilm from a wide surface area. The total biomass was quantified and the periphyton was analyzed both for composition (diatoms, green algae, cyanobacteria, and red algae) and for pigments. Disturbance, water temperature, physico-chemical conditions, nutrients, substrate diversity, and light availability were assessed concurrently with biofilm samplings. Results show sharp biofilm variations over months. In all sites, the disturbance was the primary factor reducing biomass and pigment content. Annually, all sites experienced similar turnover in periphyton composition mainly associated with light and water temperature. Overall, the study indicates that frequent quantitative investigations of biofilm help understand intra-annual variations and identify key drivers. Such information is useful to understand the ecosystem processes and the food web dynamics. [ABSTRACT FROM AUTHOR]

In this study, the changes in groundwater temperature at the base of the future dam of the Rogun hydropower plant are studied, with the aim of assessing the filtration characteristics of the base rock and determining the filtration coefficient and concentrated filtration path. In addition, the equation for the filtration coefficient is derived, which is used to calculate the filtration coefficient and rate of the filtered turbulent water movement. [ABSTRACT FROM AUTHOR]

Context: Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are two families of persistent organic pollutants that are dangerous as they remain in the atmosphere for long periods and are toxic for humans and animals. They are found all over the world, including the penguins of Antarctica. One of the mechanisms that explains the toxicity of these compounds is related to oxidative stress. The main idea of this theoretical research is to use conceptual density functional theory as a theory of chemical reactivity to analyze the oxidative stress that PCBs and PBDEs can produce. The electron transfer properties as well as the interaction with DNA nitrogenous bases of nine PCBs and ten PBDEs found in Antarctic penguins are investigated. From this study, it can be concluded that compounds with more chlorine or bromine atoms are more oxidizing and produce more oxidative stress. These molecules also interact directly with the nitrogenous bases of DNA, forming hydrogen bonds, and this may be an explanation for the toxicity. Since quinone-type metabolites of PCBs and PBDEs can cause neurotoxicity, examples of quinones are also investigated. Condensed Fukui functions are included to analyze local reactivity. These results are important as the reactivity of these compounds helps to explain the toxicity of PCBs and PBDEs. Methods: All DFT computations were performed using Gaussian16 at M06-2x/6–311 + g(2d,p) level of theory without symmetry constraints. Electro-donating (ω-) and electro-accepting (ω +) powers were used as global response functions and condensed Fukui functions as local parameters of reactivity. [ABSTRACT FROM AUTHOR]

In November 2015, the Fundão Dam break released millions of tons of metal-rich tailings into the Doce River Basin (DRB), causing catastrophic damage and potential ecological effects that reached the Atlantic Ocean. This study aimed to evaluate the geochemistry and toxicity of water and sediments collected in the DRB from 2015 to 2019 and to determine the spatial and temporal trends. Water and sediment samples were analyzed for metals and As by inductively coupled plasma optical emission spectrometry (ICP-OES), and acute toxicity for Daphnia similis or D. magna. Results were explored using geochemical indices and correlation analyzes. Overall, higher concentrations of metals and As in water and sediments were observed immediately after dam breakage, but the levels exhibited a decreasing trend over time, although the levels of some elements such as As and Mn remained high in the upper DRB. The geochemical indices indicated mostly low to moderate contamination, and the enrichment factor (EF) demonstrated a higher enrichment of Mn in the upper DRB. Acute toxicity to water fleas (D. similis and D. magna) was occasionally observed in waters and sediments, but the reference samples were toxic, and the short-term effects were not correlated with metals and As. Overall, the results showed limited bioavailability of metals and As and a decreasing trend in their concentrations, indicating an ongoing recovery process in DRB. These results are important to decision-making regarding the disaster and actions for environmental restoration. [ABSTRACT FROM AUTHOR]

During the construction of the tailings dump of Udokan Mining and Metallurgical Works, filtration appeared at the base of the western dam. To increase the filtration density of the dam, a diaphragm wall made of bored-secant piles was constructed in the ground. Developing a composition of clay-cement concrete for the wall in the ground requires a significant amount of manufacturing and testing of samples. [ABSTRACT FROM AUTHOR]

Landslide dams, forming when a landslide blocks a watercourse, are significant components of slope-river systems. Dams can fail suddenly and catastrophically, threatening downstream populations and structures. So it is important to understand where they could form, how long they persist in the landscape, and the extent of downstream inundation once they fail. To investigate dam formation, longevity, and stability effectively in Aotearoa New Zealand, we present version 1.0 of the New Zealand Landslide Dam Database (NZLDD). The database includes compilation, mapping, and/or remapping of 1036 dams, including those generated by the 2016 Kaikōura Earthquake. A representative subset of 265 dams was selected to analyse dam stability and breaching in detail (ongoing work). The database architecture, description of datasets included, attribute definitions, and some summary statistics are presented here. Many dams in the database have formed in greywacke bedrock terrain, by earthquake-triggered rock avalanches, falls, and slides. Most are small (Dam Type I—small dam that does not reach opposite valley side), and have since failed and no longer impede or impound water. The NZLDD represents a significant increase in catalogued landslide dams—almost doubling the existing number of known and studied dams worldwide. [ABSTRACT FROM AUTHOR]

Water pollution imperils the Neosho madtom (Noturus placidus), which is threatened federally and in Kansas. Within Kansas, madtom densities were historically lower in the Spring River compared to the Cottonwood and Neosho Rivers, especially within the Spring River below tributary inputs that delivered cadmium, copper, lead, and zinc pollution from the Tri-State Mining District of Missouri, Kansas, and Oklahoma. Neosho madtom are less numerous in waters containing elevated metal concentrations because of direct toxicity and lower benthic macroinvertebrate (i.e., food) availability. Long-term reductions in metal concentrations in the Spring River have occurred, but no study has examined whether madtom and macroinvertebrate densities have responded to improved water quality. We addressed this question by comparing madtom and macroinvertebrate abundances between the Neosho-Cottonwood system and the Spring River above and below metal pollution inputs. However, madtoms are influenced by environmental factors and anthropogenic stressors beyond mining-derived metal pollution, so we also examined if food availability, local habitat variables, and watershed characteristics were related to madtom densities. We found that madtom and macroinvertebrate population densities in the Spring River below metal pollution were similar to those in the Spring River above metal pollution and the Neosho-Cottonwood River system. Furthermore, macroinvertebrate availability and watershed characteristics were not associated with madtom abundance. However, two local habitat variables (turbidity and depth) were associated with madtom densities, such that an increase in turbidity or decrease in depth resulted in higher madtom densities. Our results highlight the benefits that water quality improvements can have on imperiled stream organisms. [ABSTRACT FROM AUTHOR]

Seepage flow through pervious media or formations is one of the causative factors for dam failure. In order to reduce and control this problem, seepage modeling and analysis are very important. The main aim of this article is to present the comprehensive review on various modeling approaches and methods available for seepage evaluation through or beneath dam. Furthermore, an attempt is also made to assess the application and effectiveness of these techniques in dam seepage modeling and analysis. Moreover, case studies of dam seepage analysis in Ethiopia were also reviewed. For a century, various techniques have been developed that can be used to study the seepage cases of hydraulic structures including dams. Broadly, these techniques can be categorized in to continuum and discontinuum seepage modeling approaches. Continuum approach includes pore-network model, whereas discontinuum approach includes equivalent continuum, discrete fracture network, dual-porosity, and triple-porosity models. Each of these approaches may consider different causative factors and utilizes various methods for seepage analysis. The experimental, analytical, and numerical methods are commonly used in the modeling approaches based on Darcian and non-Darcian laws. The selection of appropriate modeling approaches depends on various factors and considerations including the spatial and temporal scale of flow regime, material type and properties, dam width and height, water level, availability of data, and modeler's skill. In comparison, each of these models has its own advantages and disadvantages over the other. [ABSTRACT FROM AUTHOR]

Numerous dams in North America are constructed on foundations and/or abutments consisting of unstable weak materials or low-friction pre-sheared surfaces such as the Oldman River Dam (ORD), in southern Alberta, Canada. The objective of this paper is to examine the performance of Interferometric Synthetic Aperture Radar (InSAR) on the slow-moving ORD site by comparing the mapped velocities obtained through InSAR analysis in 2015–2022 with velocities from previous investigations. Additionally, the study aims to determine the precision of estimated velocities by analyzing InSAR temporal decorrelation and incorporating the error of simplifying the assumption necessary to decompose line-of-sight velocities. The results indicate the spillway, covering an area of ~ 26 × 103 m2, has been moving at an average total velocity of 1.26 mm/year. On the slope of the embankment, measuring ~ 160 × 103 m2, an active area next to the left abutment is also experiencing a higher average velocity of 8.29 mm/year (both rates in millimeters per year). An analysis of the precision of the estimations showed an accuracy of 0.72 and 2.78 mm/year for the spillway and embankment, respectively. Overall, the spillway velocities have not deviated much from 1 mm/year in the study period but the embankment’s active area decelerated from > 20 to 5 mm/year toward the end of 2022. Eventually, a lagged spillway displacement in response to seasonal variation of the reservoir level was also observed. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the effect of geological and geomorphological factors on the water quality of Gotvand Dam in Iran. Given the role of geomorphological parameters in water quality, the water quality indices were analyzed in the Excel and Chemistry applications. Water quality was evaluated by analyzing water samples obtained from the Statistical Data Center of Water and Power Organization of Khuzestan, and the total dissolved solids (TDS), electrical conductivity (EC), and pH of water were measured using the Mann-Kendall test. Then the effect of geomorphological factors on the physicochemical properties of the Karun River was assessed. The qualitative variables were pH, EC, and TDS in the statistical period of 2006–2021. The results of the Mann-Kendall test showed an insignificant decreasing trend in the TDS series in the Gotvand station. Meanwhile, August had a significant increasing trend in TDS, and considering the calculated Sen's slope, this parameter increased by 35% in the last 15 years (2006–2021). Like TDS, EC had both increasing and decreasing trends of changes. On the monthly scale, pH had a significant decreasing trend, meaning that the water is acidified, which severely affects the downstream fields and reservoirs. In the Gotvand station, the trend of changes in TDS and EC increased in 11 and 12 months of the year, respectively. [ABSTRACT FROM AUTHOR]

The damming in a watershed alters all its fluvial dynamics, affecting the patterns of occurrence and distribution of the fish community. Despite being an important refuge for fish communities in tropical Brazil, the river–estuarine continuum is strongly affected by human activities that have considerably disturbed the natural dynamics. In this study, our objective was to evaluate the spatial and seasonal composition of the fish community in three distinct regions along the river–estuarine continuum of the São Francisco River, raising the hypothesis that the seasonal effect does not interfere in the structuring of the fish assemblage. Our results demonstrate that seasonality does not influence the composition and distribution of fish species in the lower São Francisco, this differentiation is due to the spatial effect of the regions studied. These findings add to the available knowledge about the absence of the seasonal effect in highly dammed environments. [ABSTRACT FROM AUTHOR]

The article provides information about the natural conditions of the Mullalaq HPP construction area, as well as the main layout solutions and parameters of this hydroelectric complex. [ABSTRACT FROM AUTHOR]

The stress-strain state of earth-fill dams with impervious asphalt concrete and clay-cement concrete diaphragms is discussed based on the results of field observations. [ABSTRACT FROM AUTHOR]

Understanding the main processes shaping the assemblage of fish species of basin headwaters is still challenging. We aimed to assess the effect of spatial factors at two different scales and the effect of environmental factors and dams on the stream fish assemblage in the Upper Paraná Basin. We performed a partial redundancy analysis (pRDA) to compute the effect of broad and fine-scale spatial and environmental factors on the fish assemblage. The model explained 25% of the total variation of fish assemblage in the region (environmental plus spatial effects), with 5% of the variation of fish composition explained purely by environment, 10% purely by broad-scale spatial variables, and 3% purely by fine-scale spatial variables. Dams did not explain the stream fish assemblage when taking into account the spatial range studied. Our results show the relevance of isolation in the spatial configuration of the entire drainage basin to understand the primary processes shaping stream fish assemblages. At the same time, local environmental filters seem not to be strong enough to generate species sorting at broad scales in the basin, although they become more relevant at finer scales. Therefore, different processes are coinciding in different intensities and at different scales, which explains the stream fish assemblage in the region. [ABSTRACT FROM AUTHOR]

Traditional methods for diagnosing dam health often rely on single point measurements, which require assumptions about the distributions of these measurements. These approaches fail to integrate multiple measured values for joint diagnosis and overlook the true distribution of the measured values, leading to potential misdiagnosis. This paper proposes a dam health diagnosis method based on kernel density estimation (KDE) and copula functions to address these limitations. The method incorporates a measurement analysis flow that extends from a single point to multiple points and establishes criteria for dam health diagnosis. In addition, this paper proposes to select the optimal copula function based on the Akaike information criterion (AIC). An engineering example is presented to demonstrate the proposed method's effectiveness in diagnosing a dam's health without assuming a specific measurement distribution function. This research contributes to the field of engineering safety management by enabling comprehensive dam health diagnosis from local dam states to the entire dam structure. [ABSTRACT FROM AUTHOR]

Compressibility of strong and structurally disturbed rocks is determined for predicting land subsidence and stability during operation of transport machines. The plate-bearing tests are carried out on a large bench tester at different normal pressures and different densities of strong overburden rocks. The method to estimate deformability of strong overburden rocks using a plate and a station rod is described. The results were used to assess passability of transport machines during damming, and for the damp stability calculation. [ABSTRACT FROM AUTHOR]

The earthquake hazard of the wide plateau comprising significant dams around the East Anatolian Fault Zone (EAFZ) in eastern Türkiye is studied by means of the seismicity assessment and probabilistic seismic hazard analysis (PSHA). The fault segments of the EAFZ in the east of Kahramanmaraş city, which were previously assigned as a seismic gap, are shown to produce an earthquake in the order of at least Mw = 7.4. b values of the frequency–magnitude distribution calculated from the declustered Mw ≥ 3.2 seismicity after 1995 indicate significant temporal (a gradual decrease from 1.6 to 0.8 between 2010 and 2019) and spatial variations (between 0.75 and 2.1), leading to a short recurrence time estimation of as low as 90 years for an earthquake size comparable to the 2020 Sivrice earthquake (Mw = 6.7). No matter which attenuation relationship is used, the PSHA assuming a 475-year recurrence period results in considerably higher PGA values (average 0.25–0.64 g) as compared to the previous local and regional scale studies, suggesting higher seismic hazard than known so far. The presence of the seismic gap, the decreasing b value as an indication of rising ambient crustal stresses, the estimated shortest recurrence time of 90 years and the computed PGA values imply a significant earthquake hazard for the study area. Considering that the study area contains large cities with historic heritages, important industrial capacities and the existence of big crucial dams, requiring to be on alert in terms of seismic safety and preparedness of the population. [ABSTRACT FROM AUTHOR]

When studying the ecological effects of the influence of a hydroelectric power station (HPS) dam on the zooplankton of the regulated section of the Angara River and the effect of the zooplankton downstream drift on the feeding conditions of fish of the Bratsk Reservoir during the vegetation period of 2022, it has been established that water column stratification is a significant factor in the ecological differentiation of plankton communities from the upper reaches of the Bratsk HPS. Relative to the heated epilimnion layer, a specific, poor in species, low-abundant and low-productive plankton, entering the dam water intakes, deve-lops in the cold-water hypolimnion. A rigorous analysis revealed no transformation in the composition of communities, a statistically significant decrease in abundance and productivity, and an increased mortality of invertebrates during the transition through the dam, as well as a deterioration in the ecological quality of water in the lower reaches of the HPS. Zooplankton (both alive and dead) drifting downstream from the re-servoir constitute a significant portion of the diet of fish, which get as close as possible to the HPS during feeding and form clusters that are denser than those in the water area of the Bratsk Reservoir. The data indicate the efficient adaptation of the lake–river planktocenosis to a specific natural and technogenic mode of operation of a large hydraulic structure. Locally, the Bratsk HPS has no ecologically significant negative effect on the plankton of the Bratsk Reservoir and Angara River and it has a positive effect on the fish population of the lower reaches through the enrichment of its forage base. [ABSTRACT FROM AUTHOR]

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature 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.)

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature 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.)

Copyright of Österreichische Wasser- und Abfallwirtschaft is the property of Springer Nature 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.)

Several studies have shown an elevated amount of microplastics around dammed areas, indicating that the presence of in-stream barriers in riverine ecosystems could influence the fate and transport of microplastics. However, in-stream barriers have not been extensively investigated as potential causes of microplastic spatial heterogeneity. In this study, we measured microplastic concentration and assessed its ecological risk in rivers connected to the dam in the midstream Citarum region, West Java Province, Indonesia. Samples were processed using the digestion method using hydrogen peroxide, followed by visual counting and Fourier transform infrared spectroscopy (FTIR) validation. An average of 22.92 ± 19.94 MP particles per 100 g of dry sediment was found in midstream Citarum. We found a significant difference in microplastic concentration between the upstream and downstream of the first dam (P < 0.05). The river before the first dam (Saguling Dam) had the highest microplastic concentration, while after the first dam, microplastic concentration tended to decrease. The Potential Ecological Risk Index (PERI) in this study ranged from 11.2 (low risk) to 12.006 (very dangerous), while the Pollution Load Index (PLI) in the midstream Citarum River ranged from 3.82 (low risk) to 10.19 (high risk). This is the first baseline survey of microplastic pollution in midstream Citarum, which would improve our understanding of microplastic's ecological impacts in freshwater environments. [ABSTRACT FROM AUTHOR]

Dams interrupt the longitudinal connectivity of rivers and consequently disrupt the structure and function of downstream communities. The Serial Discontinuity Concept recognizes these disruptions and suggests that the impacts of dams on downstream communities should attenuate with increasing distance from the dam. The impacts of dams on communities immediately downstream are well studied, but less is known about how dams affect longitudinal patterns of community structure and functional attributes. To investigate the impacts of a large hydropower dam on downstream macroinvertebrate assemblage structure and function, we sampled riffle habitats along a 49-km reach on the Green River below Flaming Gorge Dam for 1 year. We collected monthly samples from seven sites, ranging from 0.8 to 49 km below the dam. Macroinvertebrate assemblage composition differed among sites below the dam and exhibited distinct longitudinal patterns. Taxonomic richness increased with increasing distance from the dam, but total macroinvertebrate abundance and annual secondary production decreased with increasing distance from the dam. Furthermore, functional feeding group composition differed among sites and also exhibited longitudinal patterns. Our results contribute to a body of evidence that demonstrates longitudinal effects of dams on downstream macroinvertebrate community structure and function. [ABSTRACT FROM AUTHOR]

Dams are undoubtedly a primary threat to global freshwater fishes. However, how fish functional traits respond to dams at the global scale remains poorly understood, which hinders a general understanding of related ecological processes, conservation, and management. By synthesizing fish data from 4040 relevant publications, this study investigates the species compositional and functional differences before and after dam construction, aiming to obtain general fish response patterns to dams and to propose pertinent conservation suggestions. The mean values of body size and trophic level of the occurrence-increased (OI) fishes and occurrence-decreased (OD) fishes were found to be larger than those of global freshwater fishes obtained from FishBase, respectively. In terms of mouth orientation, most OI fishes have terminal mouths, while a large proportion of the OD fishes have inferior mouths. The sensitive functional traits that respond to dams are habitat preferences and reproductive traits because the OI fishes are mainly lentic-adapted, warm-water, non-migratory, and produce demersal eggs, while the majority of the OD fishes are lotic-adapted, cold-water, migratory, and produce floating eggs. These results indicate that functional trait-based evaluations are essential for predicting the impacts of dam development on fish assemblages and guiding global biodiversity conservation, management, and sustainability. [ABSTRACT FROM AUTHOR]

The horizontal impact experiments were carried out by using the scale down model of uranium tailing pond dams to analyze the trend of radon precipitation rate after the destruction of uranium tailing pond dams and the persistence of radon precipitation rate in time series judged by R/S fractal fractal method. The results show that with the gradual increase of impact velocity and penetration depth of impactor, the average accumulated radon concentration in the post-impact uranium tailings pond dam model gradually increases compared with the background accumulated radon concentration in the pre-impact uranium tailings pond dam model. [ABSTRACT FROM AUTHOR]

The Djorf Torba dam belongs to the arid zones and is losing its performance due to a combination of natural and anthropogenic constraints. Indeed, the correlations between rainfall stations are contrasted (r − 0.2 to 0.97), reflecting a strong heterogeneity of rainfall in the same basin. The SPI shows that the basin is subject to recurrent and persistent drought years. Drought conditions predominate in terms of frequency, 58% of years (1972/73 to 2017/2018). In contrast, wet periods are limited to 42% of the total series. For the period from 2009/10 to 2017/18, which is very significant for the water stock of the dam, drought frequencies increase to 69%, and wet periods decrease to 31%. This dam is not spared from siltation, which impacts storage capacity; the 1986 bathymetric survey showed a loss of 09.4% of its original capacity. The loss in volume is 1,976,470 m3/year. The second survey in 2004 indicated a loss of 25.64% of its initial capacity. Siltation forecasts indicate that by 2020 the siltation rate will be 33.29%. The water supply volume in 1999/2000 was 8.78 Mm3/year, increasing to 10.38 Mm3/year in 2014/2015 and 18.06 Mm3/year in 2019/2020. This dam is subject to a persistent drought due to insufficient precipitation and runoff compared to expected or normal values. Its storage capacity is constantly decreasing and has been reduced by more than 1/3 of its initial capacity. At the same time, there is increasing use of the stored water. This state of affairs prompts us to reflect on the effectiveness of constructing large dams in arid zones. [ABSTRACT FROM AUTHOR]

The seepage of the dam is an important representation of the operation characteristics of the dam, and there are many factors affecting the seepage with a certain lag. It is still difficult to predict its change and sensitivity because of complex operating conditions. At present, the lag-sensitivity of influence factors of the dam seepage has not been studied. The time series influence factors of seepage are determined by HTRT (hydrostatic-thermal-rainfall-time) model in this paper. To avoid the pseudo fitting of conventional methods, HTRT model nested random forest algorithm is used to establish the predicting model of the dam seepage. And MIC algorithm is used to achieve the dual purposes of time lag and sensitivity analysis. Firstly, the time lag of relationship between seepage and its influencing factors is characterized, and the most appropriate lag time of the HTRT model factors is determined. Secondly, independent correlation analysis on all influencing factors is carried out and the sensitivity of each factor is analyzed by MIC. Meanwhile, the sensitivity of the factors to seepage is quantitatively analyzed by the two parameters of %IncMSE and IncNodePurity of RF algorithm. The sensitivity of influencing factors is analyzed by comparing MIC results with RF results. Combined with the case, taking the error of fitting prediction as the evaluation index of seepage prediction, the prediction accuracy of MIC-RF model, RF model and MIC-BPNN (Back Propagation neural network) model is calculated and compared. Case study showed that MIC- RF monitoring model has high prediction accuracy, strong adaptability and high robustness in dam seepage, and the sensitivity and time lag of influencing factors can be quantitatively analyzed. The water pressure and rainfall of the lag time are 14 days and 16 days respectively. The sensitivity study of the time series influencing factors of seepage showed that the water pressure component is the main controlling factor of seepage, and rainfall component is more sensitive to later stage. The MIC-RF model can be used as a new dam seepage safety monitoring model. [ABSTRACT FROM AUTHOR]

This study is presenting a multidisciplinary approach for mitigations of water resources in the irrigation, water supply, energy, and flood protection using hydrological model coupled with multi-criteria decision analysis (MCDA). The study area is originated in the northern Afghanistan with serious water issues. Soil and Water Assessment Tool (SWAT) was adopted for the hydrological modelling. The model was calibrated and validated using monthly streamflow from 2010 to 2018. The current irrigation state of the watershed was revised based on the crop water requirements and land area to address water shortages. The investigations lead to an engineering-based solution (dam construction) to regulate and control the streamflow, especially during winter and flood season. Analytical hierarchy process (AHP) based on expert's opinions were used to determine suitable dam site locations. Then, the dam was added to the SWAT model for dam's impact assessment. The dam reservoir capacity (197,900,938 m3), dam storage area (748 ha), dam height (69 m), electricity generation (Ave = 25.4 MW, Min =16.23 MW, , Max = 66.5 MW), and flood protection ability were estimated. Finally, cost–benefit analysis (CBA) was conducted to ensure the project feasibility. The CBA proves the feasibility and applicability of proposal. The surplus water can address the water shortages with an extra capacity of irrigating 17,180.5 ha or provision of water supply for the Mazar-i-Sharif city (the fourth biggest city in the Afghanistan). These findings can be used as guidance for the decision-makers in the BRB for the future development of water resource management strategies. [ABSTRACT FROM AUTHOR]

Dams are studied not only for potential advantages but also for possible environmental repercussions. The objective of this case study is to see the effects caused by Gomal Zam Dam on temperature, humidity and precipitation in their surroundings, both spatially and temporally. The meteorology parameters' characteristics have been detected using two different approaches, Mann–Kendall statistical test and Sen's slope estimator. Data stations chosen were those that have been close to the dam and sufficiently far away from the dam. As a consequence, although temporal changes in mean heat were established, periodic and regional disparities in humidity readings were found. [ABSTRACT FROM AUTHOR]

The current situation of the water resources of Istanbul, which is one of the important metropolises of Europe, should be known and constantly monitored by the reasons of the rapid increase in the city population, the acceleration of production-related industrial activities, the expansion of the city with construction activities, and the decrease in precipitation. The purpose of this study was to reveal the situations of surface sediments collected from Istanbul water reservoirs in terms of PCDD/Fs and DL-PCBs, to identify possible sources, and to conduct their ecological risk assessment. Total PCDD/Fs and DL-PCBs concentrations varied between 28.13 and 457.4 pg/g (average 136.8 pg/g) and 12.19–340.1 pg/g (average 72.09 pg/g). The corresponding TEQ values of PCDD/Fs and DL-PCBs were between 0.53 and 5.37 pg TEQ/g (average 2.23 pg TEQ/g) and 0.02–0.44 pg TEQ/g (average 0.12 pg TEQ/g), respectively. Octachlorodibenzo-p-dioxin (OCDD) is the dominant congener by constituting about 75% of the total PCDD/Fs on average, while congener distributions of DL-PCBs showed the dominance of PCB-118 and PCB-105. The sediments taken from Kazandere dam have the lowest pollution levels for both PCDD/Fs and DL-PCBs. The highest PCDD/F and DL-PCB amounts were measured in sediments of Alibey and Elmalı dams (closest to highly populated settlements of Istanbul), which are most affected by the air pollution caused by the traffic, commercial/industrial combustion (like waste incineration facility) and combustion for residential heating. Almost all the sediments have total dioxin-like toxicity levels higher than the safe threshold level (with two exceptions) of 0.85 pg TEQ/g dw, proposed for ecological risk. Health risk assessment shows that levels of dioxin-like compounds would result in a total intake of 0.33 pg TEQ/kg bw/day even in the worst-case scenario, not exceeding the tolerable daily intake value of 1 pg TEQ/kg bw/day. Among exposure pathways, consumption of fish constitutes almost all the total intake, while contributions of other pathways are minimal. [ABSTRACT FROM AUTHOR]

The June 2013 disaster in Kedarnath hit the Mandakini–Alaknanda river valley, resulting in devastating floods. This study deals with the pre- and post-flood event changes in the channel morphology and aims to investigate the geomorphological processes under river management in the Alaknanda valley, NW Himalaya and how the hydroelectric reservoir may have impeded the natural impact of the disaster and created geomorphic discontinuity. This work analyses the spatio-temporal variations in channel morphology over the last decade 2010–2020, discussing the impact of 2013 extreme event; the role of gradient in morphological patterns in river basin system. It highlights how the channel parameters like the thalweg shifts, active channel width, and area under sedimentation responded, from headwaters to lower gradient Lesser Himalayan zones to the 2013 event and suggests that any positive changes in these parameters diminish soon after the reservoir. The study implies that the capability of the reservoir to adjust the sediment load of the event in its upstream is an immediate short-term effect, but brings out the fact that it creates a geomorphic disconnect in the channel between upstream and downstream channel reaches of the reservoir. This disconnect may have a negative impact on sediment storage and sediment–water routing of the river and should be factored into the dam design ensuring natural continuum of geomorphic processes. Further, the study argues that the terrain north of the Main Central Thrust (Higher Himalaya) should be kept free from major human interventions to reduce flood hazards. [ABSTRACT FROM AUTHOR]

Eurasian beavers Castor fiber are important ecosystem engineers, able to modify freshwater environments and influence local biodiversity. Beaver activity affects not only aquatic ecosystems but also terrestrial habitats and organisms. In recent times, beaver populations have been detected in Central Italy. In this work, we determined the use of beaver lodges and dams by native animal species in Central Italy through intensive camera trapping between March 2021 and May 2022. Saproxylic beetles were searched by sight in spring and summer on lodges, dams, and gnawed trunks on river shorelines. We collected 132 records belonging to at least 17 species on beaver dams and lodges, several of them of conservation concern (e.g. the European bittern Botaurus stellaris and the endemic water vole Arvicola italicus). The most detected species within beaver structure was the yellow-necked field mouse Apodemus flavicollis, with 67 independent videos. Despite being confirmed as a nocturnal species, in our study area, A. flavicollis showed an activity peak on bright moonlight nights. The lodge may thus be used as a protection site from predation risk for small rodents, which may benefit from the beaver presence. By building dams and lodges, Eurasian beavers can increase habitat heterogeneity, thus promoting biodiversity increase and improvement. The potential expansion of beaver populations into these ecosystems may serve as a biotic restoration strategy. [ABSTRACT FROM AUTHOR]

Current research was done to evaluate the level of pesticide residues and heavy metals in fish and water bodies. Surface water samples and samples of Oreochromis niloticus and Tor putitora were collected from different sites from Rawal and Simly Dams. Following the physicochemical analysis of water samples, heavy metals were analyzed by Atomic Absorption Spectrophotometer (AAS) while pesticide residues were detected by GC–MS. Acid digestion of fish muscles was done for heavy metal analysis. Soxhlet extraction was used to extract pesticide residues from fish samples, which were concentrated in a rotary evaporator followed by GC–MS analysis. The physicochemical analysis of water samples revealed pH within the WHO guidelines. Pb, Cr, Cd, and Ni found in Rawal and Simly Dam water were higher than the prescribed WHO guidelines. The average heavy metal concentration in all fish samples was also high. Toxic pesticides detected in Rawal Dam water and fish samples included HCB, Heptachlor, 2, 4′-DDT, 4, 4′-DDT, and 4, 4′-DDE, whereas HCB, PP-DDT, OP-DDE, and Chlordane were detected in Simly Dam water and fish samples. The study emanates the menace of possible bioaccumulation of heavy metals and toxic pesticides in food chain. [ABSTRACT FROM AUTHOR]

Microorganisms play a critical role in the process of nitrogen removal in aquatic environment, which is regulated by multiple environmental factors. As a high-altitude region, the Qinghai-Tibet Plateau has unique composition of bacterial communities due to its unique geographical conditions, which may affect the nitrogen conversion of Plateau rivers. However, the regulation of nitrogen removal by environmental factors and bacterial community in high-altitude rivers has been rarely reported. This study investigated denitrification, anammox, and dissimilatory nitrate reduction to ammonium rates as well as the community of bacteria and denitrifiers in the Yarlung Zangbo River. The results showed that denitrification was the dominant nitrate removal process. Redundancy analysis revealed that environmental factors including suspended particulate matter, chemical oxygen demand, dissolved oxygen, nitrogen and phosphorus content, electrical conductivity, and pH explained a large amount of the variance in bacterial community. Denitrifiers carrying nitrite reductase-related gene were an important driver of denitrification in the Yarlung Zangbo River. The low water temperature brought by high altitude significantly reduced the denitrification rate. The cascade dams on the river affected the particle size distribution of sediment, changed the community composition of bacteria and denitrifying bacteria, and increased the denitrification rate in the downstream. Our findings highlight that nitrogen removal processes in high-altitude rivers are jointly regulated by environmental and anthropogenic factors through shaping denitrifier abundance. [ABSTRACT FROM AUTHOR]

A large number of long hydraulic and civil structures have been built around the world. Over time, most ground and concrete structures naturally have several problems associated with material aging and changes in operating and natural conditions. The occurrence of these problems necessitates the monitoring of their evolution and assessment of the corresponding risks to the integrity of structures. However, the monitoring of such structures is complicated owing to their considerable length. The optimal solution to this problem is the use of distributed fiber-optic sensors, which have many undoubted advantages over their point-based counterparts. This article discusses the experience of using this technology in other countries, identifies the fields of its use, and presents recommendations on the use of distributed sensors on long structures in the Russian Federation. [ABSTRACT FROM AUTHOR]

There are approximately 2.5 million small rivers in the Russian Federation, whose energy potential is estimated at 382 billion kWh. In the middle of the 20th century, the creation of large hydropower plants (HPPs) became a priority in the Russian energy sector. As a result, the maintenance and operation of a significant part of small HPPs (SHPPs) were suspended. Currently, about 10% of previously built SHPPs remain in operation. This article discusses the development history, existing problems, and future prospects for SHPPs. [ABSTRACT FROM AUTHOR]

Information about species diversity, integration of local data, and the dynamics of regional diversity is essential for understanding the mechanisms that maintain diversity in biological communities, especially in aquatic environments, which have extensive connectivity. Here, we used phytoplankton community data from two subtropical reservoirs and evaluated the site contributions to phytoplankton beta diversity. We partitioned beta diversity into two mechanisms, replacement and differences in species richness and abundance, and we related to environmental heterogeneity. We tested whether there is a predominance of replacement or differences in richness and abundance in beta diversity, and whether environmental heterogeneity predicts beta diversity and its components. Our results indicated the temporal and spatial variation of the environmental conditions of the reservoirs. The species replacement was prevalent in lentic sites, while differences in richness and abundance contributed to lotic sites. Dissolved oxygen, total phosphorus, euphotic zone light availability, orthophosphate, water flow, and total dissolved solids were predictors of beta diversity and its components. Thus, studies that consider the local and regional variability of species in the function of environmental heterogeneity are essential in understanding ecological determinants and should be considered for the conservation of aquatic biodiversity and the maintenance of ecosystem services in reservoirs. [ABSTRACT FROM AUTHOR]

Understanding the behavior of reservoirs with flow regularization formed by hydroelectric power plants is essential for assessing water availability. The operationalization of reservoirs can be influenced both by climatic characteristics and by the consequences resulting from human actions in the basin. The objective of this study was to evaluate the existing relationships between the inflows and outflows of a reservoir, as well as with the conventional streamflow gauge stations downstream of the dam. Also evaluated were trends in the behavior of minimum, average and maximum flows, in the post-operation period, considering the characteristics of rainfall and irrigation in the region. The results indicated that reservoir operationalization is strongly related to the behavior of inflows. Moreover, a reduction was also verified in all the variables analyzed related to inflows and outflows, as well as in the stations downstream of the dam, except for the maximum flow in the station farthest from the reservoir, which showed a stationary behavior. The reductions in the flows may be related to the almost three-fold increase in the area irrigated by the center pivot in the basin; however, the same cannot be said in relation to the annual rainfall regime of the region, since it showed a stationary behavior for most of the stations evaluated. The work demonstrates the importance of trend analysis of flows over the years in order to identify possible factors responsible for their variability and assist in decision making regarding measures for the recovery and preservation of water resources. [ABSTRACT FROM AUTHOR]

Numerical modelling, a physically based method, is adopted to obtain an in-depth understanding of the mechanism of sediment-related hazards such as landslides and debris flows. With its ability to address large deformation problems, the particle flow analysis method (the particle flow code or PFC model) can simulate propagation and runout from landslides to debris flows under complex landslide material compositions with a proper rheological model. Hence, this study aims to analyse the kinematic characteristics of a landslide-generated debris flow event in Shaziba, Enshi City, that occurred on June 8, 2020, with the PFC3D numerical model and linear parallel bonding method. To determine the differences among various processes, field surveys, unmanned aerial vehicle (UAV) photography campaigns, and laboratory direct shear tests were conducted to invert the relevant parameters, such as the digital elevation model (DEM) and shear strength, corresponding to the rheological properties of landslide debris flow materials. In dynamic analysis, the velocity, displacement, and characteristics of landslide deposition were considered. The results indicate that the initial landslide stage started with overall acceleration, and the movement of gravel–silty clay materials lasted approximately 733 s with double-peak velocity curves and nonsynchronous displacement. The maximum velocity of the landslide body was 17.5 m/s, and the maximum displacement exceeded 1000 m. The volume of the landslide body was 9.31 × 105 m3. The simulation results agree with the actual landslide volume (1.5 × 106 m3) and morphology of the landslide dam observed in Qingjiang. The study provides detailed information on the recent Shaziba landslide, thereby providing a useful reference for better understanding the dynamics of gravel–silty clay landslides and preventing the potential hazard for remobilisation of the Shaziba landslide. [ABSTRACT FROM AUTHOR]

Shortjaw tapertail anchovy, Coilia brachygnathus, has invaded and expanded in the Three Gorges Reservoir (TGR) over the last few years. The population size and biological characteristics related to this invasion are poorly understood. To investigate its invasion mechanisms, we studied spatial and temporal changes in C. brachygnathus biomass and abundance and its reproductive traits and diet. Evidence of progressive directional invasion suggested that C. brachygnathus invaded the TGR from downstream in 2016. The TGR provided an initial blockage and later facilitated C. brachygnathus dispersal. In 2020 and 2021, C. brachygnathus accounted for 11.66% and 16.06% of biomass and abundance, respectively, of the TGR fish community and both biomass and abundance decreased with distance to the dam. The fecundity in the TGR was higher than that in downstream native areas. Although their contributions to diet exhibited spatial differences, C. brachygnathus mainly consumed shrimps (Exopalaemon modestus and Macrobrachium nipponensis) and zooplankton in the TGR. Within a short period, C. brachygnathus has successfully colonized and expanded into the whole reservoir. Its fast maturity and high fecundity, coupled with the lentic habitats and abundant food availability, are probable key factors that explain its invasion. We propose that prevention measures to block the expansion of this species are urgently needed after the impoundment of cascaded reservoirs with navigation passages located upstream of the TGR. [ABSTRACT FROM AUTHOR]

China's many dams are increasingly facing safety problems resulting from the natural aging of the dam hydraulic structure and geological disasters such as earthquakes under the operating condition of holding a vast amount of water. Problems such as dam leakage and concrete cracking and erosion seriously affect the normal operation and effectiveness of a reservior. It is impossible to empty a large reservoir with a high dam for many reasons, such as serious environmental consequences, and it is thus difficult to detect the working conditions of the underwater part of the facility. There is an increasingly urgent demand for detection and repair technologies that can be used in the deepwater environment. Indeed, there are cutting-edge deepwater detection and processing technologies for hidden dangers in dam engineering. The core technologies include underwater detection equipment, diving technologies, and underwater operation technologies. This paper analyzes safety-oriented detection equipment recently used in unmanned detection, manned detection, and deepwater diver detection from the viewpoint of practical application. The paper further reviews 100-m-depth-class technologies and applications of safety inspection, repair, and reinforcement equiment in the deepwater environment of reservoir dams. An outlook is provided on technology trends of deepwater detection, repair, and reinforcement and critical problems. [ABSTRACT FROM AUTHOR]

Understanding and improving passage by diadromous species at tidal barriers is less well advanced than that for non-tidal anthropogenic river barriers. This study assessed factors affecting upstream passage of anadromous river lamprey (Lampetra fluviatilis) at a tidal weir with pool-and-weir (PAW) and bypass (BP) fishways. A Continuous Time Markov Model (CTMM) was used to analyse migration behaviours of 120 acoustic- and PIT-tagged lamprey across 2 years. The weir was a major barrier to upstream migration with a mean time of 31.0 days taken to pass the weir compared to 2.5 days for the unobstructed reach immediately downstream. River stage was the most important variable associated with weir passage, with a 5.68 (CI = 3.95, 8.17) increase in passage probability for every 1 m river stage increase. Passage was predominately over the weir directly rather than by the fishways. Monitoring the fishways using additional PIT-tagged lamprey (n = 2814) suggested poor entrance efficiency (BP2018, 28.6%; BP2019, 53.1%; PAW2018, 37.0%). Successful fishway passage was estimated as 5.4% (BP2019)–9.0% (PAW2018) of lamprey that entered. Effective fishway entrance for lamprey is probably facilitated by high fishway discharge, yet high-velocity areas may have made it difficult for river lamprey to successfully ascend the fishways. [ABSTRACT FROM AUTHOR]

Free overfall structures might affect the structural safety of weirs. Thus, it is essential to minimize local scour in the downstream pool to ensure structural safety. In the present study, triangular, trapezoidal, and labyrinth weirs were analyzed numerically for free overfall with the Computational Fluid Dynamics method to estimate local scour depths. The finite-volume approach was employed to solve the RANS equations by using Flow-3D software. For turbulence closure, the standard k–ɛ turbulence model was preferred, which is widely used in the literature with certain confidence especially in open channel problems. The numerical results were tested with some experimental observations, and a reasonable agreement was achieved between numerical and physical model results. The findings also indicated that the local scour at the labyrinth weir downstream is lower than that of the classical weirs, while the horizontal distance of maximum scour depth in the labyrinth weir is lower than that in the classical ones. [ABSTRACT FROM AUTHOR]

Grout curtains are commonly constructed under dams to reduce the seepage through the rock foundation. In the design of grout curtains, empirical methods have mainly been used since the introduction of dam foundation grouting. Although empirical methods have been used with success in several projects, they have their limitations, such as poor control of the grout spread, only an indirect consideration of the threat of internal erosion of fracture infillings in the grouted zones, and the risk of hydraulic jacking. This paper presents a theory-based design methodology for grout curtains under dams founded on rock. In the design methodology, the grout curtain is designed as a structural component of the dam. The risk of erosion of fracture infilling material is explicitly accounted for along with the reduction of the hydraulic conductivity of the rock mass, and an optimization of the total uplift force. By applying the proposed design methodology, engineers can create a design better adapted to the prevailing geological and hydrogeological conditions in the rock mass, resulting in more durable grout curtains. The proposed methodology also enables cost and time estimates to be calculated for the grout curtain's construction. Applying the principles of the observational method during the grouting execution also allows the design to be modified via predefined measures if the initial design is found to be unsuitable. [ABSTRACT FROM AUTHOR]