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Dams commonly restrict fish movements in large rivers but can also help curtail the spread of invasive species, such as invasive bigheaded carps (Hypophthalmichthys spp). To determine how dams in the upper Mississippi River (UMR) affect large-scale invasive and native fish migrations, we tracked American paddlefish (Polyodon spathula) and bigheaded carp across > 600 river km (rkm) and 16 navigation locks and dams (LD) of the UMR during 2 years with contrasting water levels. In 2022, a low-water year, both native paddlefish and invasive bigheaded carp had low passage rates (4% and 0.6% respectively) through LD15, a movement bottleneck being studied for invasive carp control. In contrast, flooding in 2023 led to open-river conditions across multiple dams simultaneously, allowing 53% of paddlefish and 46% of bigheaded carp detected in Pool 16 to move upstream through LD15. Bigheaded carp passed upstream through LD15 rapidly (μ = 32 rkm per day) a maximum of 381 rkm, whereas paddlefish moved an average of 9 upstream rkm per day (maximum of 337 rkm). Our results can inform managers examining trade-offs between actions that enhance native fish passage or deter movements of invasive species. This understanding is critical because current climate change models project increases in flooding events like that observed during 2023. [ABSTRACT FROM AUTHOR]

In this paper, ground deformation measurements from synthetic aperture radar interferometry (InSAR) and ground-based prism monitoring are compared to finite-element (FE) simulation results for a recent tailings dam collapse. The InSAR monitoring demonstrated the complex spatial and temporal variability of the tailings dam deformation that is not captured in traditional, point-based monitoring approaches. Potentially anomalous deformation behaviour could have been detected from InSAR 1 year preceding the dam failure. A two-dimensional coupled-consolidation analysis was used to predict the dam behaviour during construction stages. The FE modelling results were in broad agreement with the deformation measurement sources, both in terms of magnitude and trends preceding failure. The results, however, deviate significantly immediately before failure, following the construction of the buttresses. Moreover, the FE modelling is sensitive to parameter uncertainties, such as spatial variability of foundation soil properties. The FE results revealed that deformation in both the upstream and downstream parts of the dam are sensitive to changing foundation properties. However, this impact is potentially much more significant on the downstream compared to the upstream parts of the dam, which are dominated by the behaviour of the tailings. This study highlights the efficacy and complementarity of geotechnical and remote sensing techniques for the monitoring of tailings dams. [ABSTRACT FROM AUTHOR]

Dam failure may lead to significant casualties among downstream residents. Therefore, it is crucial to study a reliable method to quantitatively assess the loss of life (LOL) caused by dam failure for emergency response to dam failure incidents. Based on a statistical analysis of typical dam failure accidents in China and the research on the formation mechanism of LOL, the study quantified the factors influencing LOL using fuzzy theory and constructed a quantitative database for the LOL. Then, it proposed an innovative algorithm integrating the grey wolf optimization (GWO) algorithm and the random forest (RF) model. Finally, a data-driven assessment model for the LOL caused by dam failure was developed by combining the gray correlation analysis of the factors. The performance of the GWO-RF model was validated using a dataset of the LOL caused. The proposed model was used to assess the LOL in typical dam failure events. The results indicate that the model has higher accuracy, with an average absolute error of approximately 945 persons, significantly lower than 2529 persons in the Graham method. Thus, it can effectively estimate the LOL caused by dam failure. This study developed a novel method for quantitatively assessing the LOL caused by dam failure, which could also serve as a reference for modeling disaster consequences in other fields. [ABSTRACT FROM AUTHOR]

The seismic assessment of concrete gravity dams is a problem of prediction of cracking and the corresponding consequences. With the widespread use of general-purpose finite element programs, the work in the field has shifted towards quantifying the behaviour in a framework for assessment. The nonlinear analysis and coupling with foundation–reservoir interaction, conversely, is still a challenging task. The modelling approach has significant effects on the analysis results and the assessment framework. The field remains an active area for research with many outstanding issues regarding damage quantification and assessment compared to any other major infrastructure component. A comprehensive overview of the seismic assessment of gravity dams is presented in this work with the goal to outline the issues in the field. Different models and modelling choices are compared in the context of damaged state assessment of gravity dams. The links between practical difficulties and theoretical issues are critically discussed. The aleatoric and epistemic uncertainties in the field, and their sources, are presented. Areas of future work are identified for improvement in seismic assessment as well as reducing and quantifying the uncertainties in the prediction of damaged states for concrete gravity dams. [ABSTRACT FROM AUTHOR]

The issue of rangeland governance and tenure in pastoral China has sparked significant controversy and discussion. Several models have been suggested, encompassing private, state and common property systems. However, what does the practical implementation of rangeland governance entail? A review of the history of rangeland governance and policy in Amdo, Tibet tells how land governance is constructed by pastoralists adapting existing norms, formulating rules in various contexts, and negotiating with various groups such as the monastery, religious organisations, and governmental authorities. The governance of rangeland in Amdo, Tibet is characterised by constant negotiations and contestations, including resistance from below, and is shaped by various processes in the real‐world context. Through the notion of assemblage, which involves bringing together an array of agents and objectives to intervene in social processes to produce desired outcomes and avert undesired ones, this paper adds to the existing body of research on land governance by examining how institutions are formed in the case of a hydroelectric dam on the land of the pastoralists. Consequently, the question arises: What does this mean for policy and practice for the rangelands of China? If hybrid rangeland governance is to be considered the prevailing practice, then what implications would this have for the framing of policies and their implementation? [ABSTRACT FROM AUTHOR]

Aquatic invasive species are a significant threat to global freshwater biodiversity. This study focuses on the banded mystery snail, Callinina georgiana, an invasive species in the Adirondack region of northern New York—an important section of the New York Great Lakes Basin. This project aims to explore the genetic connectivity of C. georgiana within its invasive range using a combination of mitochondrial and nuclear markers.Sampling was conducted in the Raquette River and adjacent waterways, with a total of 229 snails collected from 16 distinct populations distributed across eight different waterbodies. Also included were two populations from the species' native range in the southern U.S.A. DNA was extracted, and a 710‐bp fragment of the mitochondrial DNA marker cytochrome c oxidase 1 and a 351‐bp fragment of nuclear marker histone‐3 were amplified. Population genetic analyses including haplotype patterning, AMOVA and genetic diversity estimates, neutrality tests and tests for isolation by distance were performed to assess connectivity patterns.Results showed moderate to high levels of genetic admixture within the snail's invasive range as indicated by the lack of geographic patterning of haplotypes and low to moderate levels of genetic differentiation across multiple sites. Demographic analyses combined with high numbers of private haplotypes indicate historic population expansion. Interestingly, a case of mitonuclear discordance was detected for native and invasive populations as evident by incongruent haplotype patterns for the cytochrome c oxidase 1 and histone‐3 markers.Callinina georgiana exhibits a high level of genetic connectivity in its invasive range. The presence of dams does not significantly affect apparent gene flow, indicating that anthropogenic activities, such as boat traffic might be key in dispersing the snails across this fragmented freshwater system.This study offers new insights into the dispersal and genetic structure of an invasive freshwater snail. It highlights the importance of considering anthropogenic factors when confronting complex patterns of genetic diversity. The findings are significant for biodiversity conservation and provide a basis for developing strategies to manage and contain the spread of aquatic invasive species such as C. georgiana, especially in regions with high human activity. [ABSTRACT FROM AUTHOR]

Recent studies in dam displacement monitoring primarily focus on single‐response monitoring or model updating using advanced techniques. Few studies involve the combination analysis of displacement with other synchronized responses utilizing their monitoring characteristics. In situ strain data provide a strength‐safety perspective for dam displacement monitoring. The challenge lies in that estimating displacement directly using limited discrete strain data may be misleading. This paper analyzes the relationship between displacement and global, and multipoint local strains from the perspective of the differences in load effects of gravity dams, and indicates that introducing appropriate state factors improves the estimation. A displacement estimation model driven by strain data and state factors is developed using stacked convolutional neural network, and the variable relationships within the model are interpretated via accumulated local effects. Incorporating specific strength criteria, a novel displacement monitoring indicator based on the tensile safety of the dam heel is proposed. A case study of a gravity dam showcases the effectiveness of the proposed approach in comparison with the solely strain‐based model and the traditional hydrostatic‐seasonal‐time factors‐based model. [ABSTRACT FROM AUTHOR]

Community drivers shift over time in response to changes in landscape and environmental conditions. Although dams alter the landscape (e.g., by flooding areas) and environment (e.g., by increasing transparency), their impact on the influence of community drivers remains unclear. We investigated how the construction of a large Amazonian River dam altered the influence of environment and space on planktonic communities. From 2005 to 2015, we monitored environmental parameters and collected phytoplankton and zooplankton from 15 locations along the Madeira River and its tributaries. We conducted twenty-nine samplings upstream of the Jirau dam before, during filling, and after its construction, evaluating the influence of environment and space on communities and assessing any changes with damming. We documented the frequency of significant variables to determine if their importance (frequency) changed post-damming. Following damming, environmental heterogeneity decreased and communities comprised species adapted to lentic habitats, with the environment exerting the main influence. Damming did not significantly alter environmental influence but shifted specific drivers, with some factors decreasing (e.g., nutrients) and others increasing (e.g., oxygen) in importance, indicating changes in the environmental mechanisms underlying community assemblage. Monitoring programs in dam-affected regions should be regularly evaluated due to the temporal variability of aquatic community drivers. [ABSTRACT FROM AUTHOR]

The overtopping process, resulting from landslide-induced waves, has the potential to cause significant damage to downstream infrastructures. To minimize the associated losses, it is essential to study the overtopping phenomenon. Limited research has been conducted on physical modeling and volumetric calculation of wave overtopping in reservoirs with arch dams. The study designed a physical model experiment at a geometric scale of 1∶70 to investigate the occurrence of wave overtopping caused by landslides in arch dam reservoir areas at the maximum water depth scenario. Equations developed for straight dams, such as gravity dams, overestimate the volume of overtopping caused by landslides in arch dam reservoirs due to structural dissimilarities. Two volumetric overtopping equations specifically applicable to arch dams were derived through regression analysis. Additionally, the analysis of model experimental data unveiled the distribution pattern of the initial wave amplitude along the dam face, the overtopping duration characteristics, as well as the factors influencing the volume of overtopping. The underlying causes of these phenomena are explained in this paper. This study offers valuable insights into comprehending the intricate process of wave overtopping generated by landslides. These insights encompass the estimation of overtopping volume, as well as the safety assessment of downstream. [ABSTRACT FROM AUTHOR]

Studies on concrete dam breach are limited compared to earthen and other types of dams. With an increase in the construction of concrete dams, particularly in the developing world, it is imperative to have a better understanding of the dam breach phenomena and the identification of the most influential breach parameters. This study aims to contribute to this gap by taking the case of the concrete arch dam proposed for the 1200 MW Budhigandaki Hydropower Project located in central Nepal. This study carries special significance for Nepal, primarily because of the increasing number of under construction and proposed large dams for water resources development in the country. We carry out dam breach analysis of the Budhigandaki dam using HEC-RAS 2D model to calculate the flood discharge peaks, time to peak, water surface elevation and the extent of inundation for two scenarios (with and without probable maximum flood) to estimate the damage on four downstream settlements. We carry out sensitivity analysis of the breach parameters on the flood magnitudes and severity. Results show that all the study locations lie in the high flood hazard zone. Flood peaks can reach as high as 286,000 m3s− 1 to 511,000 m3s− 1 in the considered settlements. The time to peak ranges from 11.3 to 17 h after the breach at these locations. We estimate that if a breach should happen, it would most likely inundate around 150,000 buildings, impact nearly 672,000 lives and flood 3,500 km of road downstream. Furthermore, dam breach elevation is found to be the most sensitive parameter to downstream floods. Hence, rather than structural measures, it is recommended that non-structural measures are implemented for minimizing the impacts of flood disasters at the study locations. The findings could be a useful reference for future dam projects in Nepal and other areas with similar hydrological and topographical conditions. [ABSTRACT FROM AUTHOR]

Transboundary rivers raise critical concerns for state security amidst contemporary ecological strain and regional geopolitics in South Asia. The challenge of 'water security' is underscored by the substantial reliance on transboundary rivers, compounded by the multifaceted impacts of climate change and the simmering geopolitical tensions among riparian nations, especially in the complex dynamics between India–China and India–Pakistan. This study endeavours to illuminate distinctive characteristics of the South Asian transboundary governance framework, wherein rivers are subjected to intensive damming aimed at (a) harnessing hydroelectric potential and (b) leveraging water resources as geopolitical bargaining chips, thereby exerting pressure; however, order is not specified, particularly. In this intricate milieu, international conventions often fail to reconcile internal contradictions inherent within the transboundary governance paradigm. Consequently, transboundary water resources have metamorphosed into an extension of geopolitical realities, embodying intricate interplay between hydrology, geopolitics and state security within the region, especially between China, India and Pakistan. [ABSTRACT FROM AUTHOR]

Sedimentary landforms on Earth and other planetary bodies are built through scour, transport, and deposition of sediment. Sediment connectivity refers to the hypothesis that pathways of sediment transport do not occur in isolation, but rather are mechanistically linked. In dryland river systems, one such example of sediment connectivity is the transport of fluvially deposited sediment by wind. However, predictive tools that can forecast fluvial‐aeolian sediment connectivity at meaningful scales are rare. Here we develop a suite of models for quantifying the availability of river‐sourced sediment for aeolian transport as a function of river flow, wind regime, and land cover across 168 km of the Colorado River in Grand Canyon, USA. We compare and validate these models using topographic changes observed over 10 years in a coupled river sandbar‐aeolian dunefield setting. The models provide a path forward for directly linking fluvial hydrology with the management and understanding of aeolian landscapes. Plain Language Summary: Landscapes on Earth are built from sediment, which is deposited by a variety of processes, especially water and wind. In rivers located in dry regions, sediment is deposited by flowing water during river floods. Once this sediment dries, it is often then moved by wind across the landscape. Although we frequently observe this sediment connectivity between water and wind, we are not currently able to predict when and where windblown transport of river‐deposited sediment may occur. We used maps of sand in Grand Canyon along 168 km of the Colorado River, along with records of river flow, wind speed, and vegetation cover, to develop four models that predict how much sediment is available for wind to move. We compared the results of these models to actual windblown sediment transport at a study site in Grand Canyon, finding that when models predicted more sand was available at the site, we also observed more landscape changes there which were due to wind. Our research makes it possible to understand how changes in river flows affect the amount of sediment moved by wind. Key Points: We developed four methods for modeling the extent of exposed, bare sand available for windblown transport in river valleysOur models employ data on river flow, land cover, wind velocity, and vegetation to predict exposed, bare sand extent at corridor scalesWhere models predict increased areal extent of bare sand, we also observe a greater volume of topographic changes driven by wind [ABSTRACT FROM AUTHOR]

Background: Abiotic stress seriously affects the growth and yield of crops. It is necessary to search and utilize novel abiotic stress resistant genes for 2.0 breeding programme in quinoa. In this study, the impact of drought stress on glucose metabolism were investigated through transcriptomic and metabolomic analyses in quinoa seeds. Candidate drought tolerance genes on glucose metabolism pathway were verified by qRT-PCR combined with yeast expression system. Results: From 70 quinoa germplasms, drought tolerant material M059 and drought sensitive material M024 were selected by comprehensive evaluation of drought resistance. 7042 differentially expressed genes (DEGs) were indentified through transcriptomic analyses. Gene Ontology (GO) analysis revealed that these DEGs were closely related to carbohydrate metabolic process, phosphorus-containing groups, and intracellular membrane-bounded organelles. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis detected that DEGs were related to pathways involving carbohydrate metabolisms, glycolysis and gluconeogenesis. Twelve key differentially accumulated metabolites (DAMs), (D-galactose, UDP-glucose, succinate, inositol, D-galactose, D-fructose-6-phosphate, D-glucose-6-phosphate, D-glucose-1-phosphate, dihydroxyacetone phosphate, ribulose-5-phosphate, citric acid and L-malate), and ten key candidate DEGs (CqAGAL2, CqINV, CqFrK7, CqCELB, Cqbg1x, CqFBP, CqALDO, CqPGM, CqIDH3, and CqSDH) involved in drought response were identified. CqSDH, CqAGAL2, and Cqβ-GAL13 were candidate genes that have been validated in both transcriptomics and yeast expression screen system. Conclusion: These findings provide a foundation for elucidating the molecular regulatory mechanisms governing glucose metabolism in quinoa seeds under drought stress, providing insights for future research exploring responses to drought stress in quinoa. [ABSTRACT FROM AUTHOR]

Building flood reduction dams for territory protection is very often necessary as it allows the reduction of peak flows during flood events by creating a storage in upstream areas. An online structure with such characteristics is outlined, presenting one or more openings in order to allow normal and moderate flows to pass downstream. A stilling basin is provided downstream of the openings and, on one side of the flooded area, a spillway weir is set. For low river flows, the openings will act as free-surface weirs. The openings are equipped with a sill in such a way to let the discharge independent of the downstream flow conditions. For moderate flood flows, the water level upstream of the dam will rise, and the openings will become submerged, effectively behaving as an orifice arrangement. For large flood flows, the crest of the flood spillway weir is reached and they will be discharged via both the orifice structure and the flood spillway structure. The silled openings and the stilling basin are one only hydraulic complex. Since no examples exist of their behavior as a whole, the aim of this paper is to give the designers the opportunity to size them given the basic requirement of the flood reduction dam, i.e. the max discharge allowed downstream. For this reason, the paper will focus on the opening discharge coefficients, the stilling basin energy dissipation and water level. Both the orifices and the stilling basins were studied starting from the hydraulic models of three dams that were built in Calabria (Italy). The structures of the stilling basins are original. The results appear in dimensionless form and offer useful guidance for similar hydraulic cases, with the exception of specific terrain related issues. Finally, an example of a preliminary design of orifices and stilling basin is presented. [ABSTRACT FROM AUTHOR]

Simple Summary: The construction of dams in Mabiehe River has significantly impacted fish diversity, resulting in reduced species richness and diversity within dammed sections compared to undammed segments of the river. The environmental DNA (eDNA) technique is effective in assessing fish diversity in the challenging environment of canyon rivers. The successful detection of a variety of species, including both protected and exotic ones, highlights the robustness of eDNA as a comprehensive monitoring tool. Investigating fish diversity in canyon rivers through conventional fish surveys is challenging due to precipitous conditions, including steep slopes, rapid water flow, and complex habitats. Additionally, intensive construction of dams has further complicated the understanding of contemporary fish diversity in these rivers. In this study, we used the environmental DNA (eDNA) technique to assess fish diversity and examine the effects of dams on fish diversity in the Mabiehe River, a canyon river in the upper reaches of the Pearl River drainage. Water samples from 15 sampling sites were collected, yielding 9,356,148 valid sequences. Utilizing the NCBI public database, a total of 60 freshwater fish species were identified, with Carassius auratus, Cyprinus carpio, and Pelteobagrus fulvidraco being the most dominant species in the Mabiehe River. We also detected one nationally protected fish species, three provincially protected fish species, and six exotic species in this river. Furthermore, eDNA analyses demonstrated that the lotic river sections harbor more species and greater diversity than dammed sections, suggesting that dams might exert significant impacts on local fish diversity. Overall, this study supports the effectiveness of the eDNA technique as a complementary tool to traditional field surveys for monitoring fish biodiversity in canyon rivers. [ABSTRACT FROM AUTHOR]

The Steelhead ecotype (Oncorhynchus mykiss) and chinook salmon (Oncorhynchus tshawytscha) have promoted a recreational fishery in the Santa Cruz river, the last large free flowing river of Patagonia. However, two dams are being built upstream in the middle course, potentially affecting the life cycle of these anadromous salmonids. The study describes the dynamics of the recreational fishing of the Santa Cruz river around Piedrabuena city and anglers perceptions, discussing its trends according to possible river connectivity scenarios. The fishery was assessed through a monthly year-round field sampling from April 2018 to April 2019, developing instantaneous angler counts, discriminating fishing methods, effort, and catch per unit effort; also, in situ interviews were used to collect information on anglers’ motivations and perceptions. In addition, information on fishing tournaments was used. Three fishing zones (FZ) were identified near Piedrabuena city: FZ-1, located downstream where anglers used baited hook and line to catch the native marine Patagonian blenny (Eleginops maclovinus); FZ-2, located in the town where baited hook and line, spinning, and fly-cast are used to catch Patagonian blenny and salmonids; FZ-3 located upstream the town, where fishing effort was mainly directed to salmonids employing spinning and fly-cast. Fishing effort showed a seasonal pattern with high values from March to May and September to October, agreeing with Steelhead and Chinook salmon runs, respectively. The most relevant motivations for anglers were nonoriented catch variables. Anglers preferred the capture of salmonids over native species, considering dams to be a major threat to fishery. Although a postdamming scenario could allow the adult salmonids to migrate upstream, the current reproduction grounds of Steelhead will be flooded, and juveniles and adults of both species will be hindered in their downstream migration to sea. These aspects seem to seriously compromise the future of these unique fisheries. [ABSTRACT FROM AUTHOR]

• Inflammation can be socially transmitted in mice. • Exposure to immune challenged pups elicits a systemic immune response in their dams. • Social transmission of inflammation between pups and dams does not require physical contact. • In adult females, exposure to sick cagemates potentiates the immune response. The ability to detect and respond to sickness in others promotes survival. Here we show that mouse dams respond to immune challenged pups by mirroring their inflammatory response. Dams with pups subjected to immune challenge displayed a marked induction of inflammatory mediators in both the brain and the periphery, accompanied by an increase in maternal behaviors and corticosterone levels. This social transmission of inflammation did not require physical contact, and it contributed to the stress hormone response in the dams. In adult dyads, interaction with an immune challenged cagemate did not elicit robust inflammatory signaling but induced an increased responsiveness to a subsequent immune challenge. The identification of social transmission of inflammation, or inflammatory responsiveness, may open new avenues for research on social behavior, just like the description of similar phenomena such as observational fear and transmitted pain has done. [ABSTRACT FROM AUTHOR]

Dams are one of the greatest threats to freshwater biodiversity and efforts to remove dams to restore riverine systems are increasing. However, dam‐removal studies have primarily focused on taxonomic responses to large dam removals with little work on the functional trait responses of fish to small‐dam removals; such a focus limits the application of results in regions with different taxonomic compositions.We explored taxonomic and functional trait responses of fish assemblages to two small‐dam removals over 10 years using a Multiple Before After Control Impact design at a dammed and an undammed river. Eight life‐history traits were used to calculate functional diversity (RaoQ) and determine the position of each fish species within a multivariate life‐history space relative to three life‐history strategy endpoints: opportunistic, periodic, and equilibrium. The distance of each species relative to these endpoints was used to calculate community weighted means (CWM), allowing us to examine the shift in life‐history strategy of a given assemblage after dam removal. Based on life‐history theory, we predicted a decrease in the CWM of equilibrium strategists and an increase in the CWM opportunistic strategists after dam removal.For the dammed river, we observed changes in assemblage structure at both the control and impact sites driven primarily by shifts from a lentic to lotic assemblage, with the most apparent change occurring in the formerly impounded sites. These changes tended to occur within 1 year, suggesting rapid colonization by lotic species after habitat change. By contrast, no change in assemblage structure was found for the undammed river, suggesting that dam removal was the primary driver of the shifts in assemblage structure observed in the dammed river. We found no change in the CWM of periodic strategists or RaoQ of all life‐history traits at any site after dam removal.Based on CWM, life‐history strategies shifted in response to dam removal at impounded sites where equilibrium strategists decreased and opportunistic strategists tended to increase after the impounded sites changed from a stable lentic environment to an unstable lotic environment, supporting predictions made by life‐history theory.Our results suggest that small‐dam removal may provide ecological benefits by restoring fish assemblages to a more natural riverine state and reversing the negative effects of dam construction on the ecosystem. We demonstrate that combining both trait‐based and taxonomic approaches can improve our ecological understanding of the impacts of dam removal on fish assemblages and provide relevant data for local management. [ABSTRACT FROM AUTHOR]

Purpose: In the present study, the application of a recent damage plasticity model is presented for nonlinear dynamic analysis of the Koyna gravity dam. This is a single surface isotropic damage plasticity concrete model, which is based on the decomposition of stresses and was proposed in a previous study. The theoretical aspects of the model are initially reviewed, and a few preliminary verification examples are illustrated. Thereafter, the HHT-α (i.e. Hilber–Hughes–Taylor) algorithm is presented for nonlinear dynamic analysis of concrete gravity dams. Design/methodology/approach: Based on the prepared tools, nonlinear behavior of the Koyna Dam is studied by applying the invoked damage plasticity model. For this purpose, three cases are considered for the present study. Case A, which is based on the linear model, is mainly used for comparative purposes. The other two cases (B and C) correspond to the nonlinear (i.e. damage plasticity) model. The basic data for these two cases are similar. However, the employed damping algorithms are different and correspond to constant and variable damping algorithms, respectively. This means that the damping matrix is either kept constant or updated for all iterations of different time increments through the course of analysis. Findings: The time histories of horizontal displacement at the dam crest were initially compared for the three cases: the linear Case A, and two nonlinear Cases B and C. It was observed that nonlinear cases' responses begin to deviate from the corresponding linear case after the time of about 4.3 s. However, the amount of change for Case C (i.e. variable damping) was much greater than for Case B (i.e. constant damping). This was manifested initially in the peaks of response. It was also noticed that the period of response changed slightly for Case B in comparison with the linear Case A, while this change was significant for Case C. The obtained tensile and compressive damages were subsequently compared for the two nonlinear cases. For constant damping Case B, it was noticed that tensile damage occurred in the D/S face kink and on the U/S face slightly at a lower elevation. Moreover, it had a scattered nature. However, in variable damping Case C, it was noticed that tensile damage was much more localized and acted similar to a discrete crack. Of course, both cases also show tensile damages at the dam's heel. In regard to compressive damages, it is observed that low values are occurring for both nonlinear cases as expected. Originality/value: The application of a recent single surface isotropic damage plasticity concrete model is presented for nonlinear dynamic analysis of the Koyna gravity dam. The nonlinear response of the dam is investigated for two different damping algorithms. Moreover, the influence of variable characteristic length is also investigated in the latter part of this study. [ABSTRACT FROM AUTHOR]

This 5-year study (2015 - 2019) investigates the dynamics of phytoplankton and their correlation with environmental factors including water volume, physicochemical and nutrient availability in Mae Kuang Dam, Northern Thailand. The study identified 177 taxa across 6 groups, with Charophyta being predominant (53.3 %) in both wet and dry seasons, specifically in the genus Staurastrum. Taxonomic richness was higher in the wet season, with green algae being the most abundant. In addition, Cyanobacteria, Bacillariophyceae and Chrysophyceae showed increased densities. Annual variations peaked in 2015, decreased in 2017 and exhibited a slight increase thereafter. Cyanobacteria experienced blooms in the wet season, accompanied by significant fluctuations in Charophyta, Cyanophyta, Dinophyta and Euglenophyta. Notably, Cyanophyta exhibited a 20-fold increase from 2015 to 2019. Redundancy Analysis (RDA) highlighted the influence of soluble reactive phosphorus (SRP), conductivity, air temperature, pH, total dissolved solids (TDS) and biochemical oxygen demand (BOD) on phytoplankton during the dry season. Lower water volumes and concentrations of water bodies may intensify the impact of certain factors on phytoplankton communities during this period. In the wet season, pH, conductivity, TDS, ammonia, air temperature and BOD played significant roles, as increased rainfall and nutrient runoff occurred. These results indicate that the combined effects of these environmental variables and hydrological events, including water volume and water static, could influence the dynamics of phytoplankton and water quality. This finding helps us understand the shifts in the aquatic ecosystem under the environmental factors in Thailand. Therefore, further research is needed, emphasizing the necessity for well-planned dam management to maintain both water quality and ecological stability. [ABSTRACT FROM AUTHOR]

The use of temperature field to detect leakage in earth-rock dams has a low cost and high efficiency, which is crucial to the safety of dams. This paper briefly introduces the principle of temperature field leak detection, reviews the research results of temperature leak detection, and categorises the research on the detection of leakage through the temperature field of earth-rock dam into three levels: 1) technical research based on temperature field detection; 2) study on the theoretical model of temperature detection; 3) research on numerical calculations of multi-field coupling such as temperature field and seepage field. The main achievements and characteristics of various research levels are reviewed, revealing the development trends of the field of temperature field leakage detection in earth-rock dams. Consequently, UAVs mounted with infrared thermal imaging leak detection technology are integrated, and the technical scheme for patrol leak detection is noted. Finally, future research directions for the temperature field detection of earth-rock dam leakage are explored for the timely and accurate detection of the location of leakage channels and to establish an intuitive and effective judgement and identification method for dam leakage. [ABSTRACT FROM AUTHOR]

An increasing number of asphalt concrete core wall earthen dams (ACCDs) are being constructed under complex topographical conditions. The narrow or asymmetrical river valleys might lead to significant arching effects and excessive shear deformations in the core walls, which affect structural safety. This paper focuses on the effect of valley topography on the behavior of asphalt concrete core walls in earthen dams with numerical analysis. The nonlinear behavior of asphalt concrete and rockfill materials is described using the Duncan–Zhang E–B model. The contact behavior between the core wall and transition layer is described by the Goodman contact surface model. Six parametric three-dimensional (3D) finite-element models with different valley topographies are established based on the Jiangjiakou (Bazhong City, Sichuan Province, China) ACCD and the statistical analysis of the valley topography. The effects of valley width, slope steepness, and asymmetry on the behavior of the asphalt concrete core wall are discussed. Compared with wide valleys, the stresses and displacements in the core walls in narrow valleys are relatively smaller. However, significant arching effects are observed in the upper-middle portion of the core walls. The tensile and shear stresses on both sides of the core wall in a steep-sloped valley are significantly larger than the core wall in a gentle-sloped valley. Uneven deformations are evident in the core walls in the asymmetric valley, which leads to large axial tensile strains in the core wall. [ABSTRACT FROM AUTHOR]

To reduce uncertainties regarding seismic loading scenarios and numerical modeling limitations, the performance-based fragility curves of two California clayey-core earth fill dams (the Anderson and Lexington dams) were developed for the first time using the results of over 170 finite difference seismic analyses. Permanent deformations were considered as the damage index (DI), and fragility curves were generated based on three intensity measures, including the peak ground acceleration (PGA), specific energy density (SED), and Arias intensity (Ia). The results illustrated that the intensity measure significantly affected damage possibilities, and it was essential to simultaneously use all fragility curves based on various intensity measures for proper assessment of seismic vulnerability. Furthermore, evaluation of SED- and Ia-based fragility curves demonstrated that separation of near- and far-field records was critical to generate correct fragility curves when using energy-based parameters as intensity measures. Besides, SED-based fragility curves had the most conservative results, followed by PGA- and Ia-based ones. [ABSTRACT FROM AUTHOR]

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This study analyzes quantitative algae mitigation, using chlorophyll-a as an indicator, through waterbody management techniques such as pulses released from upstream dams, employing a three-dimensional numerical model. Numerical simulations focused on algae reduction through dam operations by investigating nine scenarios based on Chuncheon Dam, Soyang Dam, and Uiam Dam, located in the upper and lower reaches of Uiam Reservoir of Korea. These scenarios, aligned with actual dam operation manuals, aimed to differentiate the impact of each dam's operation by decreasing water residence time for Uiam Reservoir. The Uiam Reservoir, smaller than the upstream Chuncheon Dam and Soyang River Dam, is significantly influenced by their discharge rates. During summer, temperature differences exceeding 7 °C between discharges from Chuncheon Dam and Soyang Dam inflowed into the right side and the left side, respectively, of the reservoir, leading to poor mixing, which was further hindered by islands within the reservoir. Consequently, due to the influence of the different base water temperatures of the Bukhan River and Soyang River and the topographical characteristics, the impact range varied depending on the operation of each dam, and the amount of algae mitigation differed at each point. In emergency situations where algae blooms proliferate rapidly, appropriate dam operations in water bodies with large dams upstream and downstream, like Uiam Reservoir, can be effective in mitigating algae at specific regions of the reservoir. [ABSTRACT FROM AUTHOR]

As the Nasserist state built a large hydroelectric dam in the south of Egypt in the early 1960s, Egyptian botanists undertook salvage surveys of the area to be flooded behind the dam, known as historic Nubia. Scientists in these surveys searched for a type of palm tree (Medemia argun) well documented in ancient Egyptian tombs but unrecorded "in living condition" since the late eighteenth century. Gathering written and photographic accounts in memoirs, archives, and botanical tracts, this essay charts the documentary traces of the search for Medemia argun and the affective responses that surface along the margins of texts to show how debate over the potential absence or extinction of a "flagship" endogenous plant coincided with two important shifts in botanical knowledge production: transitions in botany as a discipline that employed new research methodologies and located Egypt "geobotanically" as the temporal and spatial origin for world flora; and transitions in botany as an arena of scientific expertise during postcolonial nationalism's reordering of the Egyptian academy. Building on extinction and destroyed landscape studies, this article explores ecological lexicons of absence and practices of "following" in botany. [ABSTRACT FROM AUTHOR]

Subsurface physical barriers are widely used to prevent seawater intrusion in the world. After the construction of physical barriers, the residual saltwater is trapped upstream the barriers. Traditional physical barriers, including cutoff walls and subsurface dams, are fixed in structure and fail in prohibiting active seawater intrusion. In this work, a novel subsurface adjustable dam, composed of dam bodies and sluice gates, was designed to prevent active seawater intrusion and store groundwater flexibly according to seasonal variations in precipitation. We set three-dimensional field-scale numerical simulations to compare the control effects of adjustable dams, cutoff walls, and subsurface dams. The results revealed that the traditional subsurface physical barriers could mitigate the velocity of active seawater intrusion but were inadequate in completely preventing the intrusion process. Furthermore, although the traditional physical barriers temporarily alleviate the residual saltwater during the wet periods, the saltwater wedge would subsequently invade during next dry periods. Thus, the salt mass in the aquifer of traditional physical barriers scenarios exhibited a gradual annual increase. In contrast, the novel subsurface adjustable dam demonstrated the ability to prevent active seawater intrusion and remove the residual saltwater. During the dry periods, characterized by low precipitation recharge, the sluice gates were closed to obstruct the path of active seawater intrusion. Conversely, during the wet periods with abundant precipitation, the sluice gates were opened, facilitating the gradual removal of the residual saltwater. The flexible adjustment mechanism of subsurface adjustable dams resulted in a annual decrease in both the seawater intrusion length and the salt mass in the entire aquifer. These findings underscore the efficacy of the subsurface adjustable dam as a measure for preventing active seawater intrusion and simultaneously eliminating the residual saltwater. [ABSTRACT FROM AUTHOR]

Beaver‐based restoration techniques seek to assist with the recovery of stream systems that have been damaged, degraded, or destroyed. In addition to reintroducing beaver, restoration practitioners have sought to mimic the influence of beaver dams on stream processes by building beaver dam analogs (BDAs). Stream restoration has been criticized for a lack of extended monitoring and a dearth of empirical evidence for the efficacy of BDAs. Here, we extend early and previously reported 1‐ to 2‐year monitoring of five BDAs on a low‐gradient stream lacking woody riparian vegetation to 3–6 years, depending on the parameter examined. BDAs raised groundwater near the stream and did not affect water temperatures during the duration of monitoring. Consistent with elevated groundwater levels, riparian willow cuttings grew 2.8–9.6 times more when planted near BDAs than far from BDAs, which was more than the 1.3‐ to 1.4‐fold difference after the first growing season. In contrast, a short‐term association between BDAs and willow survival disappeared in the long term. Likewise, sediment aggradation above the upstream BDA 1 year after construction reversed completely 4 years later, probably due to structural damage during high flows that could not be repaired until flows abated. Annual peak flow levels explained over 80% of the variation in the number of structures requiring annual repair. Our results suggest that BDA‐based restoration should account for both the costs of structure maintenance during project planning and the importance of long‐term monitoring during project assessment. [ABSTRACT FROM AUTHOR]

Ensuring a balance between supply and demand is critical within electricity grids, requiring a supply composition that guarantees consistent service provision in the short and medium term. Between 2008 and 2017, Ecuador's electricity generation capacity expanded significantly, with an investment of approximately USD 8150 million into harnessing the potential energy of water. This led to the construction of five high-capacity hydroelectric projects by 2017, contributing 33.4% of the sector's energy output by 2023. However, it is important to note that if installed hydroelectric projects operate as run-of-river plants, with limited reservoir capacity, they can only regulate water use for electricity generation on an hourly basis. As of 2023, these run-of-river plants represent 68.8% of Ecuador's total hydroelectric capacity within the National Interconnected System (SNI). Consequently, during periods of low inflows, supplementary energy from other power generation plants is necessary to prevent energy crises. This paper addresses the impact on energy storing for electricity generation resulting from the evolution of hydroelectric power plant entry from 2006 to 2023. This aspect has not been thoroughly examined in hydrothermal systems, which primarily focus on potential energy obtained from dams. Our approach involves a statistical analysis of hydroelectric dam reservoir operational levels. We further explore the influence on demand service within Ecuador's electricity system, particularly during observed energy crises towards the end of 2023. [ABSTRACT FROM AUTHOR]

Rodent pups use a variety of ultrasonic vocalizations (USVs) to facilitate maternal care. Importantly, infant USV repertoires are dependent on both the age and early life experiences of the pups. We have shown that an adverse rearing environment modeled with the maternal separation (MS) paradigm alters caregiving behavior but little is known about how pup USVs differentially elicit maternal attention. In the present study, maternal approach towards a vocalizing pup over a non‐vocalizing pup was tested in a Y‐maze apparatus at two developmental time points over the course of MS. At postnatal day (P)10, MS dams engaged in longer interaction times with vocalizing pups compared to non‐vocalizing pup, and this effect was strongest in male pups. As expected at P20, dams did not show a preference for either the vocalizing or non‐vocalizing pups regardless of rearing environment; however, MS dams spent a greater amount of time in the center of the apparatus as compared to control dams, which can be interpreted as a measure of uncertainty or indecision. These effects of MS on dam USV sensitivity are important considering the sex specific effects of MS exposure across all developmental stages. Our novel findings support the hypothesis that sex‐specific pup‐dam interactions may drive later life outcomes following adversity. [ABSTRACT FROM AUTHOR]

Check dams are a critical soil and water conservation engineering measure in gullies that significantly influence erosion, transportation, and sediment accumulation. Check dams help reduce erosion in the upstream area, ignoring the off‐site erosion reduction capacity due to erosion dynamics, and it also alters the morphology of gullies. The morphology of the gully cross‐section from the head to the inlet of the gully is mainly "V" shaped, "V, U," transitional shaped, "U" shaped and trapezoidal shaped. The construction of check dams can force the geomorphologic evolution of the sub‐watershed to accelerate the transition to "old age" and reduce the allocation of sediment initiation during field sub‐flooding, thus promoting sediment deposition processes. The percentage of downstream scour hours in watersheds where check dams were constructed was 0.65% and 0.80%, respectively, compared to 19.78% and 19.06% in watersheds where there are no check dams. The results reveal the role check dam constructions play in gully morphology evolution from a hydrodynamic perspective and fill the gaps in off‐site erosion reduction, providing theoretical support for assessing the role of check dams in soil and water conservation work. [ABSTRACT FROM AUTHOR]

The Nam Theun 2 dam is an influential case of applying safeguards to mitigate social and environmental impacts from hydropower, being used as a model for large dams globally. However, these safeguards have produced mixed results. We examine the role of safeguards in hydropower, and how stakeholders have discussed its use. Based on a literature review and stakeholder interviews, we conduct a discourse analysis of narratives used to frame hydropower. We find four discourses being used for different purposes: Green Neoliberalism to legitimize, Ecological Modernization to operationalize, Green Radicalism to criticize, and Radical Incrementalism to repurpose hydropower. Whereas green radicalism in high-income countries challenges over-consumption, we find that green radicalism in low-income countries highlights environmental justice and shortcomings of conventional development models. We argue for a broader understanding of discourses to include Radical Incrementalism as one strategy for change of careful and considered actions over time. [ABSTRACT FROM AUTHOR]

Recently, the influence of subsurface dams on solute transport in coastal aquifers has become a hot research topic. Although many studies have been conducted, the combined effects of subsurface dam and tides on variable-density solute transport remain unclear, and this study aimed to fill this research gap. In the current study, a numerical model representing a 2-D cross-shore coastal aquifer was established. The model simulated cases with and without a subsurface dam, and sensitivity analysis cases with different height and location of the subsurface dam and solute concentration. The results show that a subsurface dam blocks a portion of the solute plume, which can only be discharged by dilution at the edges, thereby altering its discharge pattern and reducing their discharge rate. The addition of a subsurface dam may either prolong or shorten the residence time of solute, depending on the location rather than the height of the subsurface dam. In particular, a more landward subsurface dam would significantly increase the residence time; sensitivity analysis demonstrates that both the landward shift and the height increase of the subsurface dam contribute to a heightened ratio of dynamic mass distribution for the solute plume within the freshwater and saltwater zones of the aquifer, with maximum changes in mass distribution ratios of 87.22% and 300%, respectively. Also, these factors cause the solute to migrate both seaward and landward, respectively, across the primary outflow regions of the aquifer-ocean interface. Results from this study may provide theoretical guidance for the optimal design and environmental impact assessment of subsurface dams. [ABSTRACT FROM AUTHOR]

Background: Seepage control measures are essential in earth dams to enhance their safety against seepage and slope failures. A diaphragm is a thin impervious wall that is used in the core area of the dam to prevent the seepage of water. Any crack in the diaphragm can reduce its efficiency and threaten the safety and stability of the dam. Extensive evaluation of the influence of diaphragm fracturing on dam safety is required to establish a safe design and offer the appropriate measures. This study investigates the effect of diaphragm cracking on the safety of the dam for seepage and slope stability. A permeability tank is first used to validate the numerical model; then, different scenarios for cracked diaphragm walls are studied numerically. The crack's height, width, direction, and number are all investigated. The effect of having a downstream horizontal blanket drain with cracked internal diaphragms is also evaluated. Results: The results showed that the internal diaphragm enhances the safety of earth dams as it reduced the seepage discharge by 98% and increased the downstream slope safety by 34%. Considering the development of a crack in the internal diaphragm, the most critical location was at the base of the dam, wider cracks were more destructive, and the most critical direction was the horizontal crack. The fracturing of the diaphragm at multiple locations proved to be detrimental to the safety of the dam. Having three cracks caused the seepage discharge to reach 74% of its value for no diaphragm, the pore water pressure to raise drastically, and the downstream critical factor of safety to be higher than the case of no diaphragm by 8% only. Conclusions: According to the findings, it is advised to continuously monitor the components of diaphragm-type earth dams and perform the necessary maintenance works whenever any sign of damage or water seepage appears. Furthermore, using a well-graded horizontal drain of sufficient length and high permeability with the internal diaphragm is highly recommended as a mitigation measure if diaphragm fracturing occurs. This helps to quickly release the seeping water and keep the phreatic line away from the downstream slope. [ABSTRACT FROM AUTHOR]

Dams have negatively affected freshwater biodiversity throughout the world. These negative effects tend to be exacerbated for aquatic taxa with migratory life histories, and for taxa whose habitat is fundamentally altered by the formation of large reservoirs. Sauger (Sander candadensis; Percidae), large‐bodied migratory fishes native to North America, have seen population declines over much of the species' range, and dams are often implicated for their role in blocking access to spawning habitat and otherwise negatively affecting river habitat. Furthermore, hybridization appears to be more frequent between sauger and walleye in the reservoirs formed by large dams. In this study, we examine the role of dams in altering sauger population connectivity and facilitating hybridization with introduced walleye in Wyoming's Wind River and Bighorn River systems. We collected genomic data from individuals sampled over a large spatial scale and replicated sampling throughout the spawning season, with the intent to capture potential variation in hybridization prevalence or genomic divergence between sauger with different life histories. The timing of sampling was not related to hybridization prevalence or population divergence, suggesting limited genetic differences between sauger spawning in different time and places. Overall, there was limited hybridization detected, however, hybridization was most prevalent in Boysen Reservoir (a large impounded section of the Wind River). Dams in the lower Wind River and upper Bighorn River were associated with population divergence between sauger upstream and downstream of the dams, and demographic models suggest that this divergence has occurred in concordance with the construction of the dam. Sauger upstream of the dams exhibited substantially lower estimates of genetic diversity, which implies that disrupted connectivity between Wind River and Bighorn River sauger populations may already be causing negative demographic effects. This research points towards the importance of considering the evolutionary consequences of dams on fish populations in addition to the threats they pose to population persistence. [ABSTRACT FROM AUTHOR]

A new freshwater benthic diatom species, Gomphonema incrassatasp. n. (Mohan and Prabha), is described from the Walayar Dam, Palakkad district, Kerala, India. The description is based on data derived from light and scanning electron microscopic studies. The main features of Gomphonema incrassata are: valves are weakly heteropolar; linear-lanceolate; head pole is bluntly round; basal or foot pole is sharply rounded; and the frustule is club-shaped and flexed (bent) in the girdle view. In addition, the analysed physicochemical characteristics revealed that Walayar Dam is moderately polluted, due to various human activities. The newly identified freshwater diatom species adds to the knowledge of diatom diversity in the Indian subcontinent. [ABSTRACT FROM AUTHOR]

Dam removal in the United States has grown exponentially, yet we do not know whether the pattern of such removals comports with principles of environmental justice. This exploratory study investigates the spatial pattern of dam removals across the United States to ascertain whether there were any geographic areas where the probability of removal was correlated with the racial or ethnic composition of the environs. We analyze dam removals since 2010 using national data on existing dams, removed dams, and demographics. We estimate multivariate probability models of dam removal stratified by census region and dam ownership to pinpoint contexts where significant spatial-racial patterns occur that cannot be attributed to dam characteristics. Our exploration reveals only a few such contexts. After controlling for dam purpose, construction type, age, and height, the probability of a dam being removed since 2010 is positively associated with the proportion of nearby White residents for dams owned by local or state governments in the South. The probability of removal is negatively associated with the proportion of nearby White residents for dams owned privately or by state or local governments in the West. Future case studies should probe these contexts of clear spatial–racial patterns from an environmental justice perspective. [ABSTRACT FROM AUTHOR]

In the task of classifying images of cracks in underwater dams, symmetry serves as a crucial geometric feature that aids in distinguishing cracks from other structural elements. Nevertheless, the asymmetry in the distribution of positive and negative samples within the underwater dam crack image dataset results in a long-tail problem. This asymmetry, coupled with the subtle nature of crack features, leads to inadequate feature extraction by existing convolutional neural networks, thereby reducing classification accuracy. To address these issues, this paper improves VanillaNet. First, the Seesaw Loss loss function is introduced to tackle the long-tail problem in classifying underwater dam crack images, enhancing the model's ability to recognize tail categories. Second, the Adaptive Frequency Filtering Token Mixer (AFF Token Mixer) is implemented to improve the model's capability to capture crack image features and enhance classification accuracy. Finally, label smoothing is applied to prevent overfitting to the training data and improve the model's generalization performance. The experimental results demonstrate that the proposed improvements significantly enhance the model's classification accuracy for underwater dam crack images. The optimized algorithm achieves superior average accuracy in classifying underwater dam crack images, showing improvements of 1.29% and 0.64% over the relatively more accurate models ConvNeXtV2 and RepVGG, respectively. Compared to VanillaNet, the proposed algorithm increases average accuracy by 2.66%. The improved model also achieves higher accuracy compared to the pre-improved model and other mainstream networks. [ABSTRACT FROM AUTHOR]

The waters of the Nile River offer salvation amid the deserts of Northeast Africa, as well as competition and division between the rival states that share its basin. Ethiopia is nearing completion on the building and filling ofthe massive Grand Ethiopian Renaissance Dam at the source of the Blue Nile in the Ethiopian highlands. The downstream states of Egypt and Sudan believe that the building of this dam jeopardizes their Nile water allocations and violates colonial-era treaties. Interpretation of three of these colonial-era water-sharing treaties lies at the center of the debates. Egypt and Sudan must recognize that treaties not signed by Ethiopia cannot be extrapolated as binding upon it, while Ethiopia must recognize that the one of the three treaties it did sign is still binding. The Grand Ethiopian Renaissance Dam offers revolutionary energy and economic production, not only for Ethiopia, but also for the entire region. However, the three states must respect the historical rights of their neighbors' peoples to the Nile's waters. They must learn from other successful interstate water and energy sharing deals to actually seize the production in a cooperative way that betters the lives of all three states' citizens. [ABSTRACT FROM AUTHOR]

Dams modify river physical and chemical attributes. This disruption hampers fish migration, leading to the introduction of non‐native species and losses of specialised native species. Small hydropower plants (SHPs) have been suggested for replacing large dams to minimise reservoir size and preserve natural flow regimes. We evaluated the influences of two SHPs on the ichthyofauna in a tropical river, comparing fish taxonomic and functional beta‐diversity in three periods. Period‐1 preceded SHP construction (Pre‐2008), when the river was free‐flowing. Period‐2 was 1 year after completion of SHP construction (Post‐2012). Period‐3 was after 10 years of SHP operation (Current‐2021). We calculated 10 functional ichthyofaunal attributes based on 12 quantitative morphometric measurements related to habitat use, feeding, and locomotion. The ichthyofaunal composition varied among the periods (p =.001) and seasons (p =.009), with the highest species richness in the Post period compared to the other two periods (p =.002). Abundance significantly decreased over time (p =.004). Taxonomic beta‐diversity increased in the Post period remaining stable in the Current period. Functional beta‐diversity did not change between the Pre and Post periods but significantly increased in the Current period. The turnover component had the greater influence on both taxonomic and functional beta‐diversity, with no temporal changes observed in nestedness. The ichthyofauna appears to have undergone heterogenisation and restructuring. Changes include the emergence of more tolerant species (e.g., Hoplosternum littorale and Pimelodus maculatus), displacement of native and sensitive species (e.g., Pogonopoma parahybae and Steindachneridion parahybae), and colonisation by a non‐native predator (Plagioscion squamosissimus). This indicates that small‐scale projects such as SHPs harm fish populations by altering habitats and restructuring the ichthyofauna. [ABSTRACT FROM AUTHOR]

Dams fragment streams, alter hydrology and habitat, and facilitate establishment of nonnative species worldwide to the detriment of native biota. Understanding and mitigating these effects to conserve and restore stream fish assemblages has relied on short‐ and long‐term datasets to assess acute and chronic change through time, craft management strategies, and measure remediation success. We used sampling records collected over a 29‐year period (1993–2021) to examine likely causes of fish assemblage change in the Cache la Poudre River, Colorado, USA. Numerous low‐head dams have reduced connectivity and altered flow, temperature, and habitat in the transition zone, a reach that historically supported rare and sensitive taxa valuable to regional biodiversity. We found diversity, distribution, and abundance of native species declined since the early 1990s, with formerly rare taxa extirpated and some common species becoming rare. Native taxa remained numerically dominant in warmer downstream reaches most affected by streamflow diversion but were incrementally reduced in richness and abundance upstream of low‐head dams without fishways. Concurrently, nonnative Brown Trout Salmo trutta increased in distribution and abundance, dominating upstream reaches that receive cooler and more stable flows, and expanding into downstream reaches where they were formerly absent, with likely negative consequences for native fishes. In the absence of mitigation, these collective effects, plus recent wildfire disturbance and future water development, will continue to degrade stream fish assemblages in our study area, and worldwide, where resource managers face the often‐competing interests of conserving native species, providing recreational fisheries, and meeting increasing water demands. [ABSTRACT FROM AUTHOR]

The construction of dams and other in‐stream structures for human use has altered river ecosystems worldwide. Dams degrade rivers, and environmental flow releases aim to mitigate flow alterations and restore rivers downstream of dams by returning elements of the pre‐regulation flow regime, resulting in an ecosystem that resembles a more natural state. We examined the responses of benthic invertebrate communities in riffles and pool‐edge habitats to an environmental flow regime (EFR) in the highly regulated Snowy River over 17 years (2000–2016). Benthic invertebrate communities significantly changed in response to prolonged increases in the magnitude of all components of the flow regime. The composition of the benthos in the regulated river became more dissimilar to pre‐EFR communities and more closely resembled those of nearby unregulated rivers. These changes were apparent in both riffle and pool‐edge habitats and were most pronounced when flow magnitudes were highest. Scrapers increased as flows increased, and in contrast, the relative abundances of gatherers declined with prolonged high flows and could be attributed to increased daily flows and high flow events mobilizing fine sediment and scouring benthic substrates. These results indicated that the EFR altered abiotic conditions or resources that previously limited invertebrate abundances, facilitating changes to the benthic community. Community changes we observed were in response to a flow regime that remained drastically lower than natural, demonstrating that restoration targets can be achieved with small flow increases that mimic natural flow patterns. [ABSTRACT FROM AUTHOR]

In this paper, we propose double-arrowed auxetic metamaterials (DAMs) featuring bidirectional wall thickness gradients. Their crushing behavior under low-velocity impact is systematically investigated using a validated finite element (FE) model. The results show that the bidirectional gradient design effectively improves the transverse necking effect observed in uniform DAMs. The bidirectional gradient configuration contributes to improved energy absorption and impact strength. Specifically, there is a 60.7% increase in specific energy absorption (SEA) and a 40.5% improvement in plateau stress, compared to uniform DAMs. Furthermore, the bidirectional gradient configuration reduces the initial peak stresses generated during the dynamic crushing process and exhibits higher crash load efficiency (CLE). [ABSTRACT FROM AUTHOR]

Earth-fill dams should be monitored during the first filling of the reservoir to avoid several potential risks. Following the completion of dam construction, the primary safety check is monitoring the dam behavior during the first interaction of the earth material with water. The presented work fills the gap in the literature on the determination of intermediary hold durations of multistage filling schedule and provides insights into the first-filling process. The study investigated the behavior of a 20 m high earth-fill dam model subjected to staged reservoir filling. The durations of the intermediary holds were determined based on coupled stress and pore water pressure analyses using the finite-element method, with a particular emphasis on the transient behavior of the filling process. Hydraulic fracturing and internal erosion possibilities were evaluated based on minimum principal stress and seepage quantities at critical sections. It was observed that the minimum principal stress reaches a local minimum and tends to increase, leading to significant convergence for longer hold alternatives. In addition, seepage quantities exhibited similar behavior of decreasing with longer hold durations. A specific hold duration was recommended for the low-pool level, which resulted in a hold-to-height ratio of 2.35. At the high-pool level, it was found that further waiting has a positive effect in mitigating the risk of hydraulic fracturing and internal erosion initiation. The presented practical methodology is proposed to be used for the design of filling schedules of new dams. Practical Applications: This study provides practical insights for design engineers to determine the first-filling schedule of earth-fill dams. The stress–pore pressure coupled finite-element model information obtained from this study can be helpful for onsite engineers who have access to instrumentation data during the first filling. These data can be used to predict the convergence of key parameters. For intermediary holds at low-pool levels, monitoring minimum principal stress and effective stress behavior over time is crucial to prevent cracking which can lead to hydraulic fracturing if filling continues. Specifically, the initially decreasing principal stress at the upstream face of the core should be closely monitored until an increasing trend is observed, to ensure that sufficient time is allowed before the dam is subjected to higher loads. [ABSTRACT FROM AUTHOR]

Current engineering practice in dam maintenance and safety evaluation generally neglects the contribution of three-dimensional (3D) roughness along a gravity dam's base to its sliding stability. This important question is addressed in this article through the development and stability analysis of nonlinear finite element (FE) models of dam-rock foundation systems. These models implement realistic large-scale 3D dam-rock joints based on topographic data extracted from existing dam sites. Detailed analyses of the stability response of the studied dam-rock interfaces are presented in terms of limit friction angles, sliding safety factors, aperture and interface roughness coefficients (IRC). The effects of 3D roughness on the distribution of apertures and shearing stresses are discussed. It is shown that the location of asperities within a dam-rock interface may greatly affect the sliding stability. It is also found that 3D roughness may significantly increase the shear strength of dam-rock joints and that bidimensional (2D) sliding stability analyses may over-estimate the shear strength of natural shear keys. However, the asperities along 3D dam-rock interfaces are found to increase the global shear strength in comparison to 2D stability analyses. Limitations of currently available roughness parameters and shear strength criteria are also discussed. [ABSTRACT FROM AUTHOR]

Settlement of Medical Disputes through litigation and non-litigation, a special institution which functions as a legal institution whose function is to resolve disputes, the Ethics Committee of the Indonesian Medical Discipline Honorary Council (MKDKI) was formed, the Medical Ethics Honorary Council (MKEK) Dispute Settlement through the Consumer Dispute Resolution Agency (BPSK) ). The Health Law Settlement contains various new provisions in the health sector, including procedures for resolving disputes in the medical and health sectors, prioritizing restorative justice as stated in Article 310 of Law no. 17 of 2023 Obstacles in restorative care that can arise are a lack of commitment from the parties involved in resolving a dispute peacefully, the patient insisting on defending his report/lawsuit, the process outside the court is deemed unable to realize the sense of justice that the victim desires. There is no special institution that acts as a legal institution whose function is to resolve medical disputes. to carry out settlements outside the court process. [ABSTRACT FROM AUTHOR]

Copyright of Pasado y Memoria. Revista de Historia Contemporánea is the property of Pasado y Memoria 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 Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) 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.)

Balancing between sediment removal discharge and dam reservoir storage loss considering river environmental impact is of major and practical concern. The paper presents indices for evaluating the sediment removal performance of a Vertical Multi-hole Hydrosuction System (VMHS) in view of environmental impacts. A new hole arrangement on the vertical pipe of VMHS was experimentally examined. The compiled data of the temporal variations of the sediment concentration and the cumulative volume of removed sediment demonstrated that the arrangement of the holes on the vertical pipe of VMHS has profound impact on the speed of sediment removal and on the reservoir water loss. The high concentration of the outflow from the reservoir, however, might affect the downstream water course environment. The proposed indices could be applied to determine the proper duration for terminating the hydrosuction process in order to obtain a balance between the storage capacity and the downstream water course environment. [ABSTRACT FROM AUTHOR]