Hydropower Station Research Articles

Numerical prediction of erosion of Francis turbine in sediment laden flow

Abstract Francis turbine is adopted in many hydropower stations widely. Usually, the operating environment is sandy water flow, and the unit will suffer from sediment wear, affecting the operating life of the unit. This article focuses on the wear problem of hydraulic turbines and uses numerical simulation to conduct research on sediment wear. Lagrange model is adopted to predict the sediment concentration in the flowpassageof the unit, and Tabakoff model is used as the wear model. The results indicate that the guide vane blades, seat rings, end clearance, and runner blades and lower rings of hydraulic turbines are prone to sediment erosion. According to friction mechanics, these areas are mainly subjected to impact wear caused by particle impact at the inlet of the guide vane and the runner. The wear on the surface of the blade passage is mainly caused by frictional wear caused by particle sliding motion. The research results provide a certain help for the optimization of hydraulic turbine wear resistance in engineering.

Effect of uneven inflow on hydrodynamic performance of bulb turbine

Abstract Bulb turbine unit is characterized by its low head, large discharge, and short flow passage. The guiding wall separating the power house section from the flood discharge section may cause uneven inflow before its neighbor units when the power house section is located off the river’s mainstream. In this study, selecting a bulb turbine hydropower station in China as the subject, we establish a three-dimensional CFD model that contains the full flow passage of the turbine unit and partial upstream reservoir, to analyze the effects of uneven inflow on the hydrodynamic performance of the bulb turbine. The results show that under this power station layout, flow separation occurs on the left side of the guiding wall, resulting in a low pressure zone and causing the flow in a three-dimensional vortical pattern. The low pressure and flow energy loss lead to the reduction of the neighbor units’ head, causing the discharge decreasing, and the output cannot reach the expectations. This situation can be improved by shortening the guiding wall, indicating that the unit’s performance is strongly related to the hydraulic structure arrangement. The results can provide some references for the design and operation of the related project.

Research on incipient and critical cavitation of a Francis turbine

Abstract Cavitation is an important performance index to evaluate the comprehensive performance of hydraulic turbine. Determination of the plant cavitation coefficient is one of the most important tasks in the design phase of a hydro-power station. In order to improve the design rationality of the cavitation coefficient, numerical simulations of a Francis turbine were carried out to study the cavitation evolution characteristics. A detailed comparative analysis were made to clarify the different cavitation coefficients and impacts on the Francis turbine. Discussions on plant cavitation coefficient selection of hydro-power plant were made form the perspective of cavitation influence on the unit. Based on these investigations, it can be concluded that a certain safety margin of incipient and critical cavitation coefficient were needed considering the rapid efficiency drop near the critical cavitation and serious pressure pulsation near the incipient cavitation condition. The ratio between the plant cavitation coefficient and critical cavitation of the studied Francis turbine were larger than the current standard in China, which means the good cavitation performance of the unit after it put into operation. This study can provide a reference for determining the cavitation coefficient more accurately and ensuring the operation safety of the unit.

ЭНЕРГЕТИЧЕСКИЙ ПЕРЕХОД И ЭНЕРГОСБЕРЕЖЕНИЕ НА НОВОМ ЭТАПЕ РАЗВИТИЯ

The problem of increasing energy efficiency in the Russian Federation is considered. The USSR energy system was unique in size and efficiency; due to large interconnected energy facilities and the development of district heating, it made it possible to efficiently consume fuel, which resulted in annual savings of 40-60 million tons of standard fuel and 10-15 GW of capacity. After a period of decline in the 90s of the last century, over the past 15 years the country's energy consumption has increased by a third, and structural changes have occurred in the main energy-intensive sectors of the Russian economy. It is noted that industry accounts for about 45% of the Russian energy balance, which is many times more than thermal power engineering (21%). The country's reserves for energy saving and energy efficiency can be divided into two groups. System reserves, consisting of an increase in the capacity and load of “carbon-free” sources - hydroelectric power stations and nuclear power plants, active use of losses and heat from technological processes, optimization of heat supply schemes, account for more than two-thirds of the potential for increasing energy efficiency. The second group consists of the use of renewable energy sources, waste, and biofuels. The country’s energy strategy should not consist in the quick payback of energy-saving projects, but in working on the systemic, multiplier effects of industrial development and infrastructure projects, the growth of large and small cities, and the development of hard-to-reach areas.

Swing Trend Prediction of Main Guide Bearing in Hydropower Units Based on MFS-DCGNN.

Hydropower units are the core equipment of hydropower stations, and research on the fault prediction and health management of these units can help improve their safety, stability, and the level of reliable operation and can effectively reduce costs. Therefore, it is necessary to predict the swing trend of these units. Firstly, this study considers the influence of various factors, such as electrical, mechanical, and hydraulic swing factors, on the swing signal of the main guide bearing y-axis. Before swing trend prediction, the multi-index feature selection algorithm is used to obtain suitable state variables, and the low-dimensional effective feature subset is obtained using the Pearson correlation coefficient and distance correlation coefficient algorithms. Secondly, the dilated convolution graph neural network (DCGNN) algorithm, with a dilated convolution graph, is used to predict the swing trend of the main guide bearing. Existing GNN methods rely heavily on predefined graph structures for prediction. The DCGNN algorithm can solve the problem of spatial dependence between variables without defining the graph structure and provides the adjacency matrix of the graph learning layer simulation, avoiding the over-smoothing problem often seen in graph convolutional networks; furthermore, it effectively improves the prediction accuracy. The experimental results showed that, compared with the RNN-GRU, LSTNet, and TAP-LSTM algorithms, the MAEs of the DCGNN algorithm decreased by 6.05%, 6.32%, and 3.04%; the RMSEs decreased by 9.21%, 9.01%, and 2.83%; and the CORR values increased by 0.63%, 1.05%, and 0.37%, respectively. Thus, the prediction accuracy was effectively improved.

A prediction method for salt frost resistance of dam rock foundation based on improved BP neural network

Hydraulic resources can be utilized in a cascade manner, with the advantages of energy conservation, economy, and environmental protection. In order to study the anti salt freezing performance of rock foundation in hydroelectric power dams and accurately predict the degree of rock and soil freeze-thaw damage under salt freezing conditions, this paper proposes a prediction method for the anti salt freezing performance of dam rock foundation based on an improved BP neural network. Firstly, freeze-thaw cycle tests were conducted on the rock foundation materials of dams poured with different proportions of fiber reinforced concrete to study the changes in soil mass loss rate and dynamic elastic modulus; Then, based on BP neural network and particle swarm optimization algorithm, a prediction model for rock and soil freeze-thaw damage is established; Finally, using the historical data of the Baihetan hydropower station, optimization was carried out and model prediction errors were compared and analyzed. The method proposed in this article has been verified to have good accuracy and stability, providing guidance for the operation and construction design of hydropower projects.

Integration study of a reverse osmosis desalination plant in a hydroelectric pumping station

The archipelagos of Macaronesia (Canary Islands, Azores, Madeira and Cape Verde) have isolated energy systems (IES). This makes the island systems dependent on themselves for energy production. In the case of an island like Gran Canaria, energy production is mainly obtained from: a) Wind and solar energy, 19 % of the total energy produced, b) Energy obtained from the burning of fossil fuels in the energy production equipment of the existing power plants. Thermal power plants, 81 % of the total energy produced. It is necessary to find a solution to the current production system, which is already partially obsolete and must be renewed and/or dismantled, in order to avoid "Zero Energy", which implies a change in the production cycle. In addition, the incorporation of the "Chira-Soria" pumped-storage hydroelectric power plant into the Gran Canaria electricity system represents another, even more important, change in the dynamics followed up to now. Basically, this plant, hydraulically stabilized by means of a seawater desalination plant, incorporates energy storage by storing water at high altitude to be turbined under the right conditions. The new situation with this incorporation will be analysed and the option of integrated operation in the overall energy system of Gran Canaria will be assessed.

From order to reorder: Assessment of the living environment of hydropower resettlement for just energy transition in China

Hydropower projects have contributed significantly to the world’s just energy transition, while at the cost of massive-scale resettlement and displacement. The principles of a just transition ensure that the low-carbon transition process is fair, inclusive and socially responsible. However, since hydropower resettlers are often involuntary, it incurs many socio-environmental disruptions for the affected. Whether the post-resttlement living environment of the resettlers can also be just and sustainable needs to be effectively evaluated. This paper establishes and validates an optimized deep neural network (DNN) approach for predictability and reliability. A comprehensive set of living environment development indicators is then used to assess the just transition in the living environment of resettlers, based on three typical hydropower station resettlement cases in the Wujiang River Basin in Guizhou Province, China. The results indicate that individual living condition, community development, and fairness in market and social participation have important impacts on the just transition of resettlers’ living environments. By summarizing the composite affiliation and score values of each sub-indicator, it is found that the Hongjiadu hydropower station has the lowest composite score of the resettlers’ living environment, ranging from 0.476 to 0.680, followed by the Dongfeng hydropower station, from 0.483 to 0.709. The resettlers of Qianzhong Hydropower Hub have the highest living environment status after resettlement, from 0.497 to 0.794. Although there are differences in the living environment scores of different hydropower stations, it is argued that the transition of the living environment in the stepped power stations along the Wujiang River is just and sustainable in the long term. This paper provides valuable insights into the just transition of hydropower and the living environment of the resettlers, so as to foster sustainable development policymaking.

МОДЕЛЬ ОПТИМАЛЬНОГО РОЗПОДІЛУ ГІДРОРЕСУРСІВ ГЕС З РЕЗЕРВУВАННЯМ ПОТУЖНОСТЕЙ ДЛЯ НАДАННЯ ДОПОМІЖНИХ ПОСЛУГ АВТОМАТИЧНОГО ВІДНОВЛЕННЯ ЧАСТОТИ

The publication is devoted to the development of a mathematical model for the optimal allocation of hydro resources among hydroelectric units of HPPs for the production of electric energy and the provision of automatic frequency res-toration reserves with an asymmetric adjustment range. The concept of building a mathematical model for the optimiza-tion problem is presented. The main goal of the optimization is to maximize the benefit of the power generation com-pany from the use of available hydro resources for the production of electricity and the provision of services for the regulation of IPS of Ukraine modes. Areas of determining the main characteristics of the operation mode of hydro-power units of HPPs were studied and a system of restrictions on the load capacity of hydrounits was formed. A system of restrictions to control the balance of water resources in the reservoir and a system of restrictions to control the val-ues of water runoff for hydroelectric power stations have been defined. For the level of the power generating company, a system of restrictions on the control of the minimum values of the volumes of electricity and ancillary services for the fulfillment of already concluded agreements, as well as a system of restrictions on the control of the volumes of electric-ity and ancillary services within the predicted volumes of market demand, has been formed. The structure is substanti-ated and the components of the target function are described. Approaches to solving the problem of forecasting the amount of electrical energy imbalances on the balancing market of Ukraine are defined. Peculiarities of the process of finding optimal solutions regarding the loading levels of hydropower units with available hydro resources have been studied. The presence of the effects of "economic impracticality of the full use of available water resources" was noted, and the main consequences of the manifestations of this effect were investigated. References 12, figures 3, tables 2.

РАЗВИТИЕ СИСТЕМЫ ВЛАСТИ И УПРАВЛЕНИЯ г. ДИВНОГОРСКА В 1962–1980 гг.

The paper, based on materials from the state archive of the Krasnoyarsk Region, analyzes the development of the system of power and governance in Divnogorsk in the period from 1962 to 1980. Divnogorsk appeared in the Krasnoyarsk Region as a settlement serving the needs and requirements of the Krasnoyarsk hydroelectric power station under construction. In the first years, as a settlement for hydraulic construction workers, it was subordinate to the Kirovsky district of Krasnoyarsk. With the acquisition of city status, the need arose to develop its own administrative governance system. According to the authors, the created administrative governance system generally coincided with that adopted in the country, but with minor features. Thus, the leadership of the city in the Soviet period included the governing bodies of the Krasnoyarsk Hydroelectric Power Station, the city Council of Workers' Deputies (Council of People's Deputies), and the City Committee of the Communist Party. An active role in the life of the city was played by the Komsomol organization, trade unions, bodies of people's control, as well as a wide range of the public, involved in resolving various issues. The most important issues for the city during the period under review were issues of housing and communal services of the city, its improvement, issues of social security of the population, cultural and educational development. Since the city was built primarily to service the construction of a hydroelectric power station, the main task of the authorities and governance was to manage the economic activities of the construction site.

ЭТНИЧЕСКИЙ СОСТАВ НАСЕЛЕНИЯ ДИВНОГОРСКОГО ГОРОДСКОГО ОКРУГА В 1970–1989 гг.

The paper examines the dynamics of changes in the ethnic composition of the population of two settlements of the Divnogorsk urban District: Divnogorsk itself and the workers' village of Ovsyanka in the period from 1970 to 1989 based on census materials of the corresponding years. Divnogorsk and the Divnogorsk urban District appeared in the Krasnoyarsk Region in 1963. Their emergence was associated with the construction of the Krasnoyarsk hydroelectric power station. Its construction was truly of an all-Union nature. The construction of the Krasnoyarsk hydroelectric power station, like Divnogorsk, was called an all-Union project, so it was assumed that specialists from all over the country took part in it. But, despite this, according to the 1970 census, the majority of the population, both in the city of Divnogorsk and in the working-class village of Ovsyanka, considered themselves Russians, followed in number by Ukrainians, Belarusians and Germans. Over the next 26 years, the structure of the local population has undergone virtually no changes. The most noticeable dynamics was the increase in the proportion of Russians in relation to all other ethnic groups, which was a consequence of the development of mixed marriages, the children of which most often identified themselves as Russians, who were perceived in the eyes of society as the titular Soviet nation. Moreover, according to the 1989 census, the proportion of the Russian population in Divnogorsk was even higher than the average for the Krasnoyarsk Region, which destroys the idea of an all-Union construction project.

Geological study of an outburst flood event in the upper Yangtze River and risk of similar extreme events

Outburst flood sediments are studied on the upper course of the Yangtze River (known as the Jinsha River) where is a key region for the development of hydroelectric power. As the history and magnitude of outburst flooding in this stretch of the Jinsha River during historic times has remained largely undocumented, we have endeavored as part of this study to conduct field investigations into, and provide numerical dating (using OSL and 14C dating techniques) of outburst flood evidence found in the First Bend area of the Yangtze River. Carbonized nutshells and charcoal from the ancient settlement yielded 14C ages that precisely pinpointed an outburst flood event ∼1200–1300 cal yr BP, during China's Tang Dynasty (618–907 CE). However, OSL ages using the minimum age model for all outburst flood samples ranged from 9.1 to 1.8 ka, which was ∼0.5–7.8 ka older than the 14C-dated outburst flood. This discrepancy suggests a potential overestimation of quartz age when dating outburst flood sediments from the Holocene period. Furthermore, using 2D hydraulic modeling, we estimated the magnitude of the aforementioned outburst flood, revealing a reconstructed peak flow discharge of 51,000–55,300 m3/s. This discharge was three times greater than the 10,000-year flood for the hydroelectric power station nearest to the study area. Our study underscores the significant role of combining archaeological and geological evidence in enhancing paleoflood hydrology research. Through a multidisciplinary approach, our findings emphasize the importance of paleoflood hydrology studies in comprehending both the latent and catastrophic flood risks in alpine mountain areas amid the context of global warming. Key points•A series of outburst flood sediments was identified in the First Bend area of the Yangtze River, with a maximum flood water surface ∼86 m high above modern river level.•The obtained 14C ages would suggest that the outburst flood occurred at ∼1200–1300 cal yr BP in the Tang Dynasty (618–907 CE) of China.•The reconstructed peak flow discharge (51,000–55,300 m3/s) is larger than the three times of the 10,000-yr flood for the nearest hydropower station to the study site.

Combining InSAR Technology to Uncover the Deformation Factors and Mechanisms of Landslides in the Baihetan Hydropower Station Reservoir Area

With the operation of the world’s second-largest hydropower facility, Baihetan Hydropower Station, the risk of landslide deformation has increased. To address these potential threats, we employed Interferometric Synthetic Aperture Radar (InSAR) technology for a large-scale landslide investigation and comprehensively revealed the deformation mechanisms of landslides near the dam site. Our research indicates that the alternating geological features of soft and hard rock layers are the primary causes of landslides, especially the fracturing phenomena of vast amounts of mudstone upon contact with moisture. This leads to the reservoir’s left bank’s dip-slope being susceptible to slip and tensional failure, while the reservoir’s right bank’s reverse slope is more prone to plastic flow and tensional damage. Rapid water level changes and altered rainfall patterns are key factors that trigger landslide instability. Furthermore, we also explored the relationship between fault zones, seismic activity, and landslides, particularly noting the fully coupled state of the southern end of the Daliangshan fault zone, which might further exacerbate landslide deformation.

The application effect of the optimized scheduling model of virtual power plant participation in the new electric power system

To build a comprehensive framework for virtual power plant (VPP) development aligned with market dynamics and to devise effective strategies to foster its growth, this study undertakes several key steps. Firstly, it constructs a VPP development framework based on market conditions, to drive the evolution of new power systems and facilitating energy transformation. Secondly, through a blend of theoretical analysis and model construction, the fundamental principles of VPP are systematically elucidated, and a decision model for the VPP development framework, focusing on price demand response, is formulated. Lastly, an optimal scheduling model for the new power system is developed, with its efficacy validated across three distinct scenarios. The findings underscore the critical importance of integrating energy storage technologies, particularly pumped storage hydropower systems, for achieving balance and optimization within new power systems. Model verification reveals that the incorporation of energy storage power stations significantly enhances system stability and efficiency, particularly in addressing the volatility associated with renewable energy sources. Additionally, the analysis indicates that while the adoption of energy storage technologies may marginally increase overall power generation costs, the total power generation cost declines with the integration of battery storage and pumped storage hydropower stations. This suggests that leveraging energy storage technologies not only enhances system operational reliability but also contributes to reducing the overall cost of power production to a certain extent. In summary, this study presents an economic and environmentally sustainable scheduling model for new power systems within the context of market trading environments. By offering both theoretical insights and practical guidance, it aims to support sustainable development and energy transformation initiatives. Ultimately, the study is poised to foster the adoption of clean energy, facilitate the establishment of smart grids, and bolster the sustainable utilization of energy resources, thereby advancing environmental conservation efforts.

An integrated analysis of transcriptome and metabolome to reveal the effects of temperature stress on energy metabolism and physiological responses in Schizothorax wangchiachii muscles

The unique hydrological situation of Jinsha River and the construction and operation of large hydropower stations may cause resident Schizothorax wangchiachii to experience acute changes in water temperature. To reveal the response mechanisms of S. wangchiachii to high and low temperature stress, we conducted a stress experiment. Compared with the control group, the activity of antioxidant enzymes (SOD\\CAT) increased first and then decreased at high temperature, while MDA activity in the low temperature group continued to increase slowly. The activities of glycolytic enzymes were increased initially and then decreased including HK and PFK, but PK activity continued to increase throughout the stress period. Transcriptome sequencing showed that a large number of genes in muscle tissues were differentially expressed after high and low temperature stress, and the main enriched pathways included glycosaminoglycan biosynthesis, lysine degradation, glycerolipid metabolism, the PPAR signaling pathway, and the adipocytokine signaling pathway. Significant metabolic pathways were identified as enriched according to the metabolic differences,such as glycerophospholipid metabolism, qRT-PCR was used to verify gene expression. The results suggested that both high temperature and low temperature stress induced physiological responses in S. wangchiachii that maintained homeostasis by regulating glucolipid metabolism and amino acid degradation. This study revealed the response mechanisms of S. wangchiachii to high and low temperature stress, information that may serve as a reference for the study of responses in other fish to environmental changes in the upper reaches of the Yangtze River or where they are displaced by hydropower station construction.

Study on the habitat evolution after dam removal in a habitat-alternative tributary of large hydropower station

The establishment of large hydropower stations in the main stream poses a threat to fish habitats. Selecting suitable tributaries as alternative habitats is a practical measure for ecological environment protection during large hydropower station's construction. The small dams constructed on certain tributaries need to be removed in order to restore river connectivity. The removal of dams will activate hydro-sedimentary dynamics and change the original habitat in terms of topography and hydrodynamics. To explore the evolution of fish habitats following the removal of small dams, a dam-removed reach of a habitat-alternative tributary was selected as the research object, and the model of water-sediment transport and riverbed evolution in strongly disturbed dam-removed reaches and the model of fish habitat suitability evaluation were established. The key parameters calibration and model verification were completed by field monitoring results. The simulation results showed dramatic evolution in the reservoir riverbed in the initial stage after dam removal and during the high discharge period. One year after dam removal, there was a noticeable 4.0 m incision in front of the dam, along with a decrease in channel slope at the dam site from about 4.8% to approximately 1.5%. Downstream of the dam, alterations to the riverbed were mainly concentrated near the dam, and sedimentary bodies with a height of around 2.0 m have formed on the left bank following the high discharge period. The fish habitat in most areas of the dam-removed reach was suitable, except for the downstream high-velocity area. To compare the evolution process of fish habitat under two dam removal periods in wet and dry seasons, two dam removal schemes were implemented in March and June. The results showed that the riverbed evolved more gradually in the March scheme, creating a larger and continuous suitable habitat for fish. Therefore, the March scheme was recommended. By revealing the evolutionary pattern of fish habitat after dam removal, this research provides a reliable model for assessing and restoring habitats in dam-removed reaches, and enjoys significant implications for protecting river ecology in hydropower development reaches.

How does the daily regulation hydropower station reduce the hydrological regime impact? A case study in upper Yellow River

ABSTRACT Human activities, particularly the regulation of hydropower stations, have profoundly altered river flow patterns. While studies have extensively assessed the impact of large or multi-year regulated hydropower stations on hydrological regimes using indicators of hydrological alteration (IHA) and range of variability approach (RVA), the impact of daily regulation hydropower stations has received comparatively less attention. This study aims to evaluate the influence of daily regulation hydropower stations on hydrological regime changes, focusing on the upper Yellow River region in China. Using daily runoff data from 1954 to 2020 at the Guide station, the study compares the impacts of multi-year regulated (Longyangxia) and daily regulation (Laxiwa and Nina) hydropower stations. The Mann-Kendall test showed that 27 out of 32 Indicators of Hydrological Alteration (IHAs) had significant trends under Longyangxia operation, which reduced to 18 IHAs with the inclusion of daily regulation stations. The Range of Variability Approach (RVA) revealed that only 46.87% of IHAs exhibited high alteration from the natural regime when daily regulation was considered, down from 75.00% with Longyangxia alone. This suggests that daily regulation can mitigate the negative impacts of multi-year regulation, potentially enhancing the river's eco-hydrological health.

An effective point cloud registration method for three-dimensional reconstruction of pressure piping

Abstract At present, industrial scenes with sparse features and weak textures are widely encountered, and the three-dimensional reconstruction of such scenes is a recognized problem. Pressure pipelines have a wide range of applications in fields such as petroleum engineering, chemical engineering, and hydropower station engineering. However, there is no mature solution for the three-dimensional reconstruction of pressure pipes. The main reason is that the typical scenes in which pressure pipes are found also have relatively few features and textures. Traditional three-dimensional reconstruction algorithms based on feature extraction are largely ineffective for such scenes that are lacking in features. In view of the above problems, this paper proposes an improved interframe registration algorithm based on point cloud fitting with cylinder axis vector constraints. By incorporating geometric feature parameters of a cylindrical pressure pipeline, specifically the axis vector of the cylinder, to constrain the traditional iterative closest point algorithm, the accuracy of point cloud registration can be improved in scenarios lacking features and textures, and some environmental uncertainties can be overcome. Finally, using actual laser point cloud data collected from pressure pipelines, the proposed fitting-based point cloud registration algorithm with cylinder axis vector constraints is tested. The experimental results show that under the same conditions, compared with other open-source point cloud registration algorithms, the proposed method can achieve higher registration accuracy. Moreover, integrating this algorithm into an open-source three-dimensional reconstruction algorithm framework can lead to better reconstruction results.

Research on power generation prediction of hydropower in river basin based on multi-head attention graph convolutional neural network

For the power generation prediction of traditional hydropower stations, most of them only use time series prediction and neglect to study the spatial topological relationship of hydropower stations in the river basin, so that it is difficult to fully explore the characteristic relationship of space power stations. In this paper, a research method for power generation prediction of hydropower in river basin hydropower stations based on multi-head attention map convolutional neural network is proposed. This method establishes a first-level node neighborhood feature map based on the spatial geographic distribution information of hydropower stations in the basin, and uses the method of graph convolution to carry out node feature mining and feature learning, so as to transform the power generation capacity evaluation problem of the hydropower station in the basin into the node prediction problem in the graph, which is different from the global normalization rule. the multi-head attention mechanism introduced further improves the information aggregation quality of the graph node, and uses the historical temperature, power generation, electricity price, unit status and other data of each hydropower station in the basin for training. The reasoning results show that the proposed method achieves higher accuracy than other schemes, and the power prediction method is conducive to the formulation of power plans of hydropower stations in the basin, and can also play a positive role in guiding the site selection of hydropower plants.

Challenges in downstream dam passage and the effect of dam removal on Atlantic salmon (Salmo salar) smolt migrations.

Migration is critical for life-cycle completion in diadromous fish species. River connectivity is vital in facilitating these large-scale movement events, but the extent of present-day river fragmentation can interfere with these migrations. Fish passage solutions (FPSs) are commonly implemented with the aim of improving river connectivity. In our study, we investigated the performance of two types of FPSs, spill regimes and complete dam removal, on Atlantic salmon (Salmo salar) smolt migrations. We used acoustic telemetry to monitor migration behavior and passage success of 120 wild smolts released in three different groups/sites: one group with two dams to pass to reach the river mouth, a second group with one dam to pass, and a control group without any barriers to pass (upstream of a recently removed hydroelectric dam). Smolt passage probabilities were similar for the two studied dams (87% and 86%) but showed variation in path choice, delay times, and loss rates. Passage success was influenced by several factors, such as body size, diel period, and water temperature, but not flow. Cumulative passage success to the river mouth was 61%, with most individuals being lost within lentic river stretches, either in the forebays of hydroelectric power stations or in naturally wide river stretches. Within the recently rehabilitated river sections (post dam removal), passage speeds were significantly faster than all other sections of the river (post-rehabilitation x¯ = 56.1 km/day) with significantly faster speeds compared to pre-rehabilitation (pre-x¯ = 28.0 km/day). Our findings provide valuable information on the benefits of dam removal and highlight the need for further rehabilitation measures in upriver reaches where barriers still affect downstream passage.