Hydroelectric Installations Research Articles

OPERATING MODES OF MICRO-HYDROELECTRIC POWER PLANT WITH OUTPUT VOLTAGE STABILIZATION USING INVERTER CONTROL

Link for citation: Lukutin B.B., Shandarova E.B., Popov M. M. Operating modes of micro-hydroelectric power plant with output voltage stabilization using inverter control. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 51-58. In Rus. The relevance. The use of Russia's hydroelectric potential for electricity generation is one of the cleanest and environmentally friendly methods as it does not result in the emission of harmful substances and carbon dioxide into the atmosphere. Moreover, it is a reliable and efficient source of energy as water is a constant source of energy. Hydro turbines are used to convert the energy of water flow into electrical energy, which effectively ensures more reliable and stable production capacity for hydroelectric installations. However, micro-hydroelectric power plants have some drawbacks related to difficulties in ensuring the high quality of produced electricity of autonomous power supply systems. This is due to the fact that the load on the autonomous power supply system can vary not only in magnitude but also in nature, which makes it difficult to maintain a stable level of electricity production. The main goal of the research is to determine the ranges of variation of the output electrical parameters of a non-regulated hydrogenerator operating as part of an inverter-based micro-hydroelectric power station for rural domestic consumers. Additionally, the task is to formulate requirements for the hydrogenerator and power conversion devices in static and dynamic operating modes of the autonomous power supply system. Object: inverter-based micro-hydroelectric power station. Methods: simulation modeling, and programming in Matlab Simulink. Results. A simulation model of an electric power supply system with an inverter microelectric power station was developed. The structure of microelectric power station is proposed, as well as the ranges of voltage changes of the microelectric power station generator are obtained.

A new method for regulating Pelton turbine based on ejection of discharged flow

Hydropower plants (HPPs) contribute a significant share of Russia’s electricity generation. With the prospects of developing this sector and harnessing the hydroenergy potential, it is necessary to consider methods for modernizing hydroelectric installations. This article examines a new method for regulating active (Pelton) turbines based on modifying the nozzle flow rate through the ejection of spent liquid from the runner using a jet pump. The relevance of this solution lies in the potential to increase the operational duration of high-head pumped-storage hydropower plants (PSHPPs) and improve reliability by eliminating or reducing the intensity of operation of the regulating needle in the guide apparatus. Various structural configurations for incorporating the jet pump into the hydrosystem of HPPs/PSHPPs with Pelton hydro turbines are discussed. Parallel and series configurations offer specific advantages and disadvantages. A methodology for determining the expression to calculate the parameters of the injecting device, depending on the turbine’s characteristics, is presented based on a mathematical model of the jet pump with a central nozzle.

Проекты и проблемы строительства Терской гидроэлектростанции в 1909–1912 гг.

In the early decades of electricity development, water flows were the most powerful and economi-cally viable source of energy for large industrial facilities and power systems. Mountainous areas provided convenient conditions for the construction of hydroelectric installations without flooding of territories and relatively low capital costs. Therefore, the North Caucasus was one of the first regions in Russia to be targeted by hydroelectric power. The article deals with the problems of de-signing the first high-head Terskaya hydropower station in the Caucasus, and with the clash of in-terests of several groups of entrepreneurs who fought for the right to build it with the support of various pressure groups in high places in the Russian Empire and foreign countries. In this strug-gle, the interests of the railways and power engineers clashed with those of the political and mili-tary authorities, and as a result, the project was delayed for over 100 years.

New way to dampen the energy of medium- and high-pressure flows

The current practice of hydraulic engineering construction applies four methods for damping extra energy of excess water discharge: throwing out the stream into the tailwater; using twisting of the stream in the water passageway, in a water-well, and on a multistage drop; and energy damping in a vertical shaft. The cheapest method is energy damping by throwing the jet into the downstream reservoir. The main disadvantages limiting the use of this method include the need for appropriate topographic conditions in the tailrace basin, strong rocks in the river channel, and the possibility of water throwing at a large distance from the hydropower project, which restricts the use of this method. Extra energy damping with the use of twisting flow in the water passageway requires complex structures, providing for a rotational movement of water and forming a deep vacuum in the outlet conduit. The breaking of vacuum requires a large amount of air, which causes dynamic modes, and its removal complicates the design of energy damping structures. The most reliable way of energy damping is damping in a stilling well. But the disadvantages of water-sucking wells are low efficiency accompanied by an uneven distribution of specific discharges in the inlet section and a sharp increase in the cost at high-pressure hydroelectric installations. The use of multistage cross-fall drastically facilitates the operation of a stilling well and serves as its supplement. Energy damping in a vertical shaft is easy to use. Still, it results in trapping a large amount of air at all operating modes, which has limited its practical use in hydraulic engineering construction. However, the damping of flow energy in a vertical shaft except for possible air supply has shown high efficiency of operation in combination with a diversion water pipe with a reverse slope. A variant of such design of flow energy damping in a vacuum vertical shaft has been developed and studied as applied to conditions of the Rogun hydropower project. Model studies of the design on the scale of 1:100 showed high efficiency and reliability in all possible ranges of discharged flow rates.

НАБЛИЖЕНА ЗАСТУПНА ЕЛЕКТРИЧНА СХЕМА СИНХРОННОГО ЯВНОПОЛЮСНОГО ГЕНЕРАТОРА ДЛЯ АНАЛІЗУ НАВАНТАЖУВАЛЬНИХ РЕЖИМІВ РОБОТИ АВТОНОМНИХ ВІТРО- ТА ГІДРОЕЛЕКТРИЧНИХ УСТАНОВОК

Синхронні явнополюсні генератори знаходять широке застосування в складі вітро- та гідроелектричних установок малої потужності. На сьогодні набуває актуальності задача застосування потужних автономних вітроелектричних установок з синхронними генераторами для накопичення частини генерованої ними енергії на гідроакумулювальних електростанціях. Розроблення раціональних схемо-технічних рішень реалізації даної технології для багатоагрегатних вітроелектростанцій потребує аналізу навантажувальних режимів роботи всіх складових в широкому діапазоні робочих швидкостей вітру і частоти обертання. Ефективне моделювання та проведення розрахункових досліджень перебігу електромеханічних процесів в даних системах може бути реалізовано шляхом застосування заступних електричних схем генераторів та двигунів, проте для явнополюсного синхронного генератора неможливо побудувати точну заступну електричну схему для електрорушійної сили обмотки якоря. В рамках цього дослідження розроблено наближену заступну електричну схему фази явнополюсного синхронного генератора та виконано оцінку можливих похибок результатів розрахунку параметрів навантажувального режиму схеми за різних значень частоти обертання ротора. Схема базується на послідовному ввімкненні активного опору обмотки якоря та індуктивних опорів розсіювання і поперекової реакції якоря, а також індуктивного опору, зумовленого сумісною дією поперекової та повздовжньої реакцій якоря. Очікувані похибки визначення розрахункових параметрів напруги споживачів автономної системи електроживлення на основі вітро- та гідроелектричних установок з синхронними явнополюсними генераторами за використання розробленої заступної електричної схеми не перевищують 2,5% по модулю та 1,5 електричних градусів по фазі для довільного значення частоти обертання ротора генератора в діапазоні 0,6...1,2 номінального значення. Застосування розробленої заступної електричної схеми явнополюсного синхронного генератора надає можливості проведення автоматизованих багатоваріантних розрахункових досліджень електромеханічних перехідних процесів в системах електроживлення на основі вітро- та гідроелектричних установок з урахуванням пульсацій швидкості вітру, зміни витрат та напорів води, зміни навантаження. Бібл. 24, табл. 3, рис. 3.

COMMUNITIES OF AQUATIC INVERTEBRATES IN THE OLDEST STORAGE RESERVOIR IN THE KOMI REPUBLIC

The species composition and structure of zooplankton and zoobenthos were studied in the Komi Republic’s oldest small storage reservoir, which has operated continuously since 1758. Over the period from 2007 to 2017, 85 species and forms of zooplankton and 21 taxonomic groups of benthic invertebrates were identified. At the initial stage of the research, as the water level in the reservoir was stable and the growth of aquatic macrophytes was minor, the reservoir’s planktic and benthic communities was stable in the species composition and quantities. Lowering of the water level promoted the reservoir’s water trophicity, triggered a rise in the taxonomic abundance and quantities of zooplankton and zoobenthos, a change of the communities’ leading groups, and a reduction in the composition of the dominant complexes. When the water level was boosted up after the restoration of the Kazhimsky hydroelectric installations was over, a vast shore area was flooded, modifying the reservoir’s ecological status. Changes in aquatic invertebrate communities included a decrease in the quantitative indicators of development, a reduction in the number of taxa and species diversity, alteration of the dominant complexes.

Renewable Energy: Volume 1: Requirements and Sources

This book reviews the past and present energy use of society and its future needs. A breakdown of current energy sources shows that approximately 80% of the world's primary energy comes from fossil fuels. The book provides an assessment of the needs to change the way in which energy is produced and utilized. The reasons for change fall into two broad categories; diminishing resources and environmental impact. The Hubbert model is described as a means of projecting availability of fossil fuel energy resources in the future. The environmental impact of fossil fuel use is described, with particular emphasis on global climate change. The major options for carbon-free energy are presented. These options include hydroelectric energy and solar energy for both thermal applications and the production of electricity, wind energy, and biofuels. Renewable energy options that range from residential wind turbines and photovoltaics for electricity and solar thermal heating systems to grid scale facilities, such as off-shore wind farms and hydroelectric installations, are discussed. The production of biofuels as a replacement for fossil fuels used for transportation is also presented. The book also provides evidence for the need to develop energy storage technologies. Energy storage is essential for most forms of renewable energy because the thermal or electrical energy produced by such sources is generally not available when it is needed, nor is it sufficiently portable for transportation applications.

Rational arrangement of direct plummets in concrete dams

Introduction. The design and construction of high hydroelectric installations are closely related to in-situ observations and studies over their condition and operation, which are the most reliable and effective means of verifying the reliability of calculation methods and design solutions. According to the results of the in-situ observations and studies during the construction and operation of dams, to monitor their condition by means of measurement systems, laboratory tests and calculation methods, unified methods can be developed for equipping the installations with devices on a unified principle. Currently, there is quite a lot of experience in the development and application of methods of in-situ research. New-type devices for measuring displacements, stresses in concrete, filtration flows and piezometric levels are developed. Automated systems for monitoring the behavior of hydraulic structures during the construction, filling of the reservoir and operation are installed. Modern satellite systems GLONASS and GPS are used. Materials and methods. The research was carried out on the arch dam of Inguri HEPS by means of 2177 measuring systems, 46 of which are direct and opposite plummets. The body of the dam has three direct plummets and one in each of the rocky bank abutments. Displacements relative to the plummets were measured with an optical coordinate-measuring apparatus. Statistical analysis methods were used to process the measurement data. Results. A technique of rational direct plummet arrangement in concrete dams was fine-tuned using statistical analysis methods and Barlow-Hunter-Proshan mathematical model based on the modern experience of in-situ observations and research. The type of distribution law of dam horizontal displacements was determined by means of analyzing the histograms of the measured indicators of the static state of the installation. The required number of plummets for the key console of the Inguri arch dam was specified. This technique was used in practice for designing high concrete dams. Conclusions. Munlti-year experience in the research and operation of the Inguri HEPS arch dam allowed assessing the compliance of the mounted measuring systems with special control requirements and allocating the necessary amount of them for monitoring the strength and stability of the installation. The proposed methods of in-situ research data analysis based on the theory of probability, statistics and reliability were used in the design of the Hudoni HEPS dam.

Réévaluation des apports moyens de matières en suspension de l'Arve au Rhône

L'Arve est le principal contributeur au flux de matières en suspension (MES) du Rhône entre le lac Léman et Lyon. Une évaluation fiable des apports moyens de MES de l'Arve est cruciale pour la connaissance et la gestion des flux sédimentaires sur ce secteur du Rhône et à travers ses aménagements hydroélectriques. Cette étude vise à réévaluer les flux moyens de l'Arve en suspension fine, en croisant les données historiques avec les flux de MES de référence pour les années 2012 à 2017 issus du suivi turbidimétrique en continu à la station de Genève Bout-du-Monde de l'Observatoire des sédiments du Rhône. Ce jeu de données a permis d'évaluer les deux méthodes de calcul des flux mises en œuvre par le Service hydrologique national suisse pour les périodes avec des mesures discontinues des MES : la méthode des débits classés et la courbe de tarage sédimentaire à deux segments. En combinant au mieux ces méthodes, le flux moyen interannuel entre 1965 et 2017 est estimé à 0,68 Mt/an avec un écart-type de 0,29 Mt/an. Cette valeur est cohérente avec le flux moyen mesuré par la station turbidimétrique entre 2012 et 2017 (0,63 Mt) et avec un suivi historique pour l'année 1890 (0,71 Mt) ; en revanche, elle est nettement inférieure à l'estimation précédemment proposée par l'étude globale Rhône (2000), comprise entre 1,0 et 3,6 Mt/an, qui inclut sans doute la suspension graduée de sables et limons grossiers, très mal connue. À partir de relevés bathymétriques et granulométrique des dépôts, nous avons estimé que la retenue de Verbois intercepte approximativement 0,1 Mt/an de particules grossières issues de l'Arve et environ la moitié des apports de MES.

Experimental Study of Screw Turbine Performance based on Different Angle of Inclination

Abstract Potential energy from fluid flow of small rivers or irrigations could be extracted become electricity by using screw turbine. This turbine is promising because the advantages of ultra-low head and fish friendly.Experimental performance of screw turbine for ultra-low head hydro resource is presented in this paper. The screw turbine with anoutside diameter of 142 mm and the water flowrate of 1.2 l/s with the head of 0.25 m, can produce maximum power 1.4 W with 49% efficiency at 22 o angle of inclination. This turbine has one blade screw and screw turbine experiment apparatus is made by using locally available materials. The screw turbine has shown good potential to be used for low head micro hydro-electric installations. This paper reports on a performance analysis based on the experimental data collected from different performance tests carried out on some inclination angle position of screw turbine prototype.

Application of molecular tools for microbial source tracking and public health risk assessment of a Microcystis bloom traversing 300 km of the Klamath River

Microcystis is a globally distributed cyanobacterium that forms dense surface scums in eutrophic freshwater bodies and is also capable of producing potent liver toxins (microcystins). Although it is not commonly observed in riverine environments, high concentrations of Microcystis cells – and microcystins – have been observed on a recurring basis in recent years throughout the Klamath River system (Oregon/California). In this study, a variety of genetic approaches were used to assess the connectivity of Microcystis populations found throughout the Klamath River. In 2012, samples were collected bi-weekly from 16 sites spanning the entire system, including all five reservoirs and Upper Klamath Lake. A newly designed QPCR assay targeting a conserved region within the c-phycocyanin β-subunit gene (cpcB) was used along with a microcystin synthetase gene (mcyE) targeting QPCR assay to quantify the spatiotemporal patterns of total and toxigenic Microcystis. These data were compared with traditional metrics, such as microscopic cell counts and analytical toxin measurements, and the public health implications are discussed. Overall, Microcystis was a minor constituent of the phytoplankton community above Copco and Iron Gate Reservoirs, although it was highly prolific within these reservoirs and our data indicate that most of these populations originate internally. Spatiotemporal variations in the proportional abundances of a single nucleotide polymorphism (SNP), identified by 454 deep sequencing of the cpcBA genes, was used to fingerprint Iron Gate Reservoir as the source of downriver Microcystis assemblages. Throughout the study period, the Microcystis populations remained highly toxic, with total microcystin concentrations ranging from 165μg/L in Copco Reservoir to 3.6μg/L within the lower estuary (0.8km from the Pacific Ocean). These results demonstrate that large quantities of intact and toxic Microcystis cells can withstand passage through hydroelectric installations and transport over distances exceeding 300km. This finding emphasizes that public health risk assessments should consider the impact of cyanobacterial blooms even when they originate in distant upstream locations within a watershed.

A critical view on the eco-friendliness of small hydroelectric installations

Renewable energy sources are widely perceived as ‘clean’, ‘green’, and ‘inexhaustible’. In recent years the spectre of global warming and ocean acidification, which has been primarily attributed to fossil fuel burning, has brought renewable energy at the forefront of most climate change mitigation strategies. There is strong advocacy for large-scale substitution of conventional energy sources with the renewables on the premise that such a move would substantially reduce environmental degradation and global warming. These sentiments are being echoed by scientists and policy makers as well as environmental activists all over the world.‘Small hydro’, which generally represents hydroelectric power projects of capacities 25MW or lower, is one of the renewable energy options which is believed to be clean and sustainable even as its bigger version, large hydro, is known to cause several strongly adverse environmental impacts.This paper brings out that the prevailing perception of ‘eco-friendliness’ of small hydro is mainly due to the fact that it has only been used to a very small extent so far. But once it is deployed at a scale comparable to fossil fuel use, the resulting impacts would be quite substantially adverse.The purpose is not to denegrade small hydro, less so to advocate use of fossil fuels. It, rather, is to bring home the point that a much more realistic and elaborate assessment of the likely direct as well as indirect impacts of extensive utilization of this energy source than has been done hitherto is necessary.

Underwater acoustic measurements of an ultrasonic barrier for guidance of American Shad in front of hydroelectric installations

This article presents the results of ultrasonic underwater acoustic measurements in a project guide shads during their downstream migration. Biological issues will be explained to allow the context, but the focus will be on the acoustic problems. In the spring, thousands of shad ascend the St. Lawrence River to spawn downstream of the Central Carillon. After spawning, adults return to sea heading toward the dam Rivière-des-Prairies. The configurations of the installed barriers at the Rivière-des-Prairies dam and at the ile Bizard site will be presented. A design of a signal amplifier was performed to optimize the barrier. A series of simulations and acoustic measurements have been conducted for the evaluation of the emission level of the barrier. The measurement strategy must take into account aspects such as high frequency signal (125 kHz) and geolocation measurement to allow achieving a mapping program of the barrier. The paper will describe: The issue biological; The deployment sites; The mechanism of hearing ultrasonic shad; Configuration of the barrier; The measurement system and the analysis of the results; Typical results obtained for mapping acoustic; Future directions in terms of signal measurements of the acoustic barrier.

De l’atelier au laboratoire: Recherche et innovation dans l’industrie électrique, XIX e –XX e siècles (review)

Reviewed by: De l’atelier au laboratoire: Recherche et innovation dans l’industrie électrique, XIXe–XXe siècles Andrew Butrica (bio) De l’atelier au laboratoire: Recherche et innovation dans l’industrie électrique, XIXe–XXe siècles. Edited by Yves Bouvier et al. Frankfurt am Main: Peter Lang, 2011. Pp. 141. $38.95. The goal of this slim installment in Peter Lang’s History of Energy series is to explore the nature and loci of electrical industry invention, innovation, research, and development and to challenge the accepted view of nineteenth-century lone inventor-geniuses and twentieth-century richly endowed corporate laboratories. It substantively broadens and deepens the work of Robert Fox and Anna Guagnini’s Laboratories, Workshops, and Sites: Concepts and Practices of Research in Industrial Europe, 1800–1914 (1999). The contributions represent revisions of half the papers read at a [End Page 933] December 2005 conference in Mulhouse, France, the other half appearing in a 2007 issue of Annales historiques de l’électricité. The authors of the six articles succeed superbly in relocating and redefining industrial research. W. Bernard Carlson, in a study of Nikola Tesla’s AC motor and wireless transmission of high-frequency power, argues the case for the inventor’s advantages over big firms, advantages that arise from being unhampered by the constraints of production and marketing. Tesla exemplified Joseph Schumpeter’s separation of invention and development by allying himself with promoters and selling or licensing his patents rather than establishing manufacturing plants. Alain Cortat analyzes Swiss cable-making firms in the context of a national (eventually international) cartel. Research and quality control evolved side-by-side until their separation during the 1930s. The firms overcame their small size and limited finances to innovate by purchasing patents from industrial groups (Bell, Siemens, Philips), collaborating with universities and technical schools, and contracting research with the Battelle Institute (1960s). Serge Paquier reminds the reader in a study of long-distance electrical power transmission that not all research took place indoors. Building up to the Frankfurt electrical exposition of 1891 (and so accenting the importance of these expositions for technological advance), Paquier focuses on hydroelectric installations as laboratories “hors les murs.” In an inquiry on the Toulouse electrical engineering laboratory (LGET), Marie-Pierre Bès calls attention to the critical role played by government policy and sponsorship in France between 1955 and 1985. The research carried out legitimated a nascent discipline in applied science and served the needs of industry (chiefly the electric monopoly EDF) with public underwriting largely from the Ministry of Industry and Research, the CNRS, and research agencies in the critical space, telecommunications, and nuclear sectors. The research never led to patents or the conception of new products or processes, but did fulfill the electrical industry’s strategic needs. Graeme Gooday revisits Marie Sklodowska Curie’s original contribution to the science and fabrication of permanent steel magnets (which too often proved to lack permanence), underwritten by the Société d’encouragement pour l’industrie nationale in the 1890s and carried out in the Sorbonne and École de physique et de chimie. His main attention is on the received notion in “narrow folklore” (p. 107) that Sydney Evershed in 1920 and 1925 solved the permanent magnet problem and established their manufacture on a scientific basis through decades of designing and redesigning electrical instruments. Here British trade secrecy collided with (and obscured) the results of Curie’s science-based open and systematic approach that relied on an assortment of samples donated by industry. Gabriel Galvez-Behar tackles Clément Ader, a telegraph, telephone, and automobile innovator too often associated solely with aeronautics. He [End Page 934] focuses on Ader’s changing contractual relationships with the Société générale des téléphones and the Société industrielle des téléphones to provide patentable inventions on demand. Ader successfully and simultaneously performed aeronautical research for the army because he operated as an “inventor entrepreneur” (like Edison) acting as both inventor (and insisting that his name be on all patents) and an entrepreneur who managed multiple research teams working on different problems (telephony, air transport, automobiles) at separate locations. A firm’s lack...

Examining the Potential of Split Reaction Water Turbine for Ultra-Low Head Hydro Resources

Theoretical performance analysis of a split reaction water turbine for ultra-low head hydro resource is presented in this paper. The spilt reaction water turbine has shown good potential to be used for low head micro hydro-electric installations. The main advantage of this turbine is its simplicity to manufacture and reasonable energy conversion efficiency of about 65-70% (hydro to mechanical energy). Theoretical investigation has also shown a simple reaction water turbine would perform better when it spins faster. And for the simple reaction water turbine to spin faster under constant water head, its diameter should be smaller. This paper reports on a performance analysis based on the experimental data collected from different performance tests carried out on two simple reaction water turbine prototypes. Further parametric analysis of split reaction water turbine has been discussed in relation to the supply head, turbine diameter and its rotational speed. Finally this paper investigates the power production potential of an ultra-low head hydro site on a vine farm in Taggerty, Victoria, Australia. The methods used for hydro site survey are briefly discussed with the survey results over the driest period of the year. Optimum layout design of hydro system for this site is presented with the estimations of the maximum net head that is available for power production.

Stochastic optimisation of Hydro-Quebec hydropower installations : a statistical comparison between SDP and SSDP methods

Cet article etudie le probleme de trouver une politique optimale d'exploitation des centrales hydroelectriques d'Hydro-Quebec sur les rivieres Manicouagan et aux Outardes. La methode de resolution est basee sur l'algorithme de programmation dynamique stochastique par echantillonnage (SSDP — sampling stochastic dynamic programming). Nous utilisons une nouvelle variable de l'etat hydrologique pour saisir les debits entrants; cette variable est donnee par une combinaison lineaire de l'equivalent en eau de la neige et de l'eau dans le sol. Dans une exploitation en temps reel, cette variable est calculee par un modele hydrologique et incorporee dans la politique d'exploitation afin de calculer la quantite d'eau liberee par chaque centrale. L'algorithme est compare a la programmation dynamique stochastique (SDP — stochastic dynamic programming) lag-1 deja utilise a Hydro-Quebec par le truchement d'une analyse statistique d'un ensemble de 40 scenarios historiques de debits entrants obtenus par modelisation hydrologique utilisant une temperature et une precipitation artificielles produites par un generateur meteorologique stochastique. Les resultats de l'analyse montrent que la politique d'exploitation SSDP est superieure d'un point de vue statistique a la politique d'exploitation du modele SDP lag-1. Contrairement au SDP, la politique d'exploitation SSDP ne sous-estime pas le volume de ruissellement printanier. Ainsi, il y a reduction des hm 3 d'eau deverses tout en augmentant la moyenne annuelle produite.

Long‐term simulations of the dynamics of trout populations on river reaches bypassed by hydroelectric installations—analysis of the impact of different hydrological scenarios

AbstractChanges in a brown trout (Salmo trutta L.) population result from interaction among various mechanisms which are dependent on environmental conditions and biotic processes. In reaches influenced by the presence of dams, the instream flow in the bypassed section is not the only parameter which affects the population. Flood episodes, the general connectivity of the bypassed section, and the characteristics of the substrate which define the availability and quality of spawning grounds may also have a crucial impact. The design and fine‐tuning of tools which take environmental parameters into account can improve our understanding of the dynamics of such influenced populations. In this perspective, a deterministic model (MODYPOP) has been developed in an attempt to integrate all these factors and to test the effect of different long‐term scenarios of influenced flow regimes on the structure of trout populations. MODYPOP was applied to three populations and three reaches (on the Roizonne, Neste d'Aure and Lignon du Forez rivers in France). For each stream, experiments were carried out on a bypassed section downstream of a hydropower station, before and after an increase in the minimum instream flow due to relicensing. These experiments allowed integrating into MODYPOP local phenomena (impact of flood episodes, impact of flushing, impact of downstream migration of juveniles and adults) affecting the populations during the study period and then calibrating them. To estimate the change in the population due to the increase in minimum instream flow, different long‐term simulations were run, selecting discharge patterns at random. These scenarios help to evaluate the time required for the population to return to a range close to habitat saturation after an improvement in the hydraulic habitat or following a flood event. These applications have enabled determining the relative importance of changes in population density due to different types of events. Copyright © 2008 John Wiley & Sons, Ltd.

Size and composition of inorganic colloids in a peri-alpine, glacial flour-rich lake

From June 2004 to October 2005, particle size distributions (PSD) and the mineralogy of inorganic colloids in Lake Brienz, a glacial flour-rich Swiss lake, and in its tributaries (the Aare and Lütschine rivers), were quantified by single particle counting based on light scattering (0.1–2 μm) combined with transmission electronic microscopy coupled with energy dispersive spectroscopy and selected area electron diffraction. The two lake tributaries differ in terms of the geology of their catchment area and in their hydrology: the River Lütschine’s glacial regime is unperturbed, while the River Aare has been significantly modified by hydroelectric installations. The dependence of the colloid concentration numbers on colloid diameters can be described by a power-law distribution in all cases. The power-law slopes in the River Aare were consistently smaller, and the total colloid number concentrations consistently higher, (mean values: −3.89 and 6.2 × 10 8 mL −1, respectively) than in the River Lütschine (−3.61 and 1.7 × 10 8 mL −1). The measured PSD in the lake were dependent on season and depth: homogenous in the whole epilimnion in winter and modified by river intrusions in summer. In this season, the presence of a river turbid plume above the thermocline is a significant source of colloids in the epilimnion, where their concentration was high (mean value: 5.1 × 10 7 mL −1). The same main mineral types were found in the different systems: 2:1 minerals, feldspars, chlorite and quartz; with a few particles of oxides. Differences in their relative concentrations in the rivers, essentially reflecting the geological differences of the respective catchment areas, made it possible to trace the origin of the mineral colloids present in lake surface waters throughout the year. The relationship between colloid size and mineralogy was assessed, showing that different minerals have distinct size distributions. In the rivers, where almost no aggregates were observed, PSD would essentially be the result of the nature (particle formation and mineralogy) of the colloids, whereas in the lake, aggregation and sedimentation processes would also play a role, particularly in summer.

Numerical simulation of atomized flow diffusion in deep and narrow goeges

Abstract Atomized flow is an unnatural two-phase flow produced while water discharges in water release structures. This flow might threaten the normal operation of hydraulic and hydroelectric installations owing to the unnatural and high-density rain as well as the unnatural and dirty mist. In this paper two dimensional mathematical model based on thickness-averaging is established for the atomized flow to consider the effect of downstream topography on the atomized flow diffusion, and orthogonal curvilinear coordinate system is used to simulate the atomized flow. The prototype observation data for the atomized flow in Dongjiang Hydropower Station is used to verify the model suggested.

Rain intensity distribution in the splash region of atomized flow

Atomized flow is an unnatural two-phase flow produced while water discharges in water release structures. This flow might threaten the normal operation of hydraulic and hydroelectric installations owing to the unnatural and high-density rain as well as the unnatural and dirty mist. The splash region, the region with the highest rain intensity, hence should receive much attention during the design and operation of the hydraulic and hydroelectric installations. In this paper rain intensity distribution in the splash region of the atomized flow is investigated experimentally, and the method of random simulation is used to predict the rain intensity distribution in the splash region.