This thesis deals with the solution of numerical modeling. Consequently problems associated with the flow of the water over spillway of the specific water structure. In this case numerical modeling means modeling of fluid movement, which is described by mathematical means. Especially nowadays, when a lot of spillways need to be recalculated, whether it meets the capacity demands, or there is no need to tackle reconstruction. With today's software capabilities there is a wide range of commercial and freeware resources. The numerical model, compared to physical model is less accurate which is, on the otherhand, physical model is usually financially and time-consuming. The following work simulates the behavior of water on the edge of the spillway, in the trough and then behind the trough. The result is a comparison of the water depth in the trough calculated by the numerical and the physical model.

Comprehensive rehabilitation projects of dam spillways are made in Sweden, due to stricter dam safety guidelines for their discharge capacity. The Piano Key Weir (PKW) is an innovative design which has proven effective through several renovation projects made in many countries including France. In this study we investigate the flow patterns around a prototype PKW, located in Escouloubre dam in southern France, with numerical simulations through three different flow cases in Ansys Fluent. A computational domain containing the PKW is created in the CAD software Ansys SpaceClaim for the simulations. Three polyhexcore meshes are further generated using Ansys Fluent Meshing. The three flow cases are then simulated with a Reynolds-averaged Navier-Stokes (RANS) model, coupled with realizable k-epsilon and volume of fluid models. Through an assessment of the discretization error between three meshes, a relative error of one percent is obtained for the discharge rate. The numerical results are qualitatively compared with results from previously conducted physical experiments on this PKW. The RANS model does not capture the water surface undulations (due to turbulence) around the PKW. The effects from under modelled surface undulations are alleviated by inserting an air vent to the PKW, which results in a flow behaviour in good agreement with the physical experiments. Through this alteration, water discharge rates are computed with a maximum discrepancy of five percent compared with the corresponding experimental values. A large eddy simulation should be conducted in the future, to bring further light on air exchange and water interaction phenomena present in the PKW flow pattern.

Det Jämtländska fjällområdet Frostviken har under den senare delen av Weichsel haft ett komplicerat deglaciationsförlopp. Glacialfluviala landformer som ansamlingar av morän, lineationer och laterala smältvattenrännor är tydliga i landskapet. Vid glacialfluviala studier av postglaciala områden förstärks kunskapen om sedimenttransport som förändrat jordlagerföljder och format om landskapet. Den vetskapen kan vidare användas i samhällsplanering och jordbruk för att anpassa utbyggnad eller ombyggnad av befintlig miljö. Under deglaciationen bildades den omfattande issjön Frostviksissjön, en issjö vars tappningsränna inte kunnat lokaliseras i tidigare studier. Arbetet har utgått från en historisk kronologisk litteraturstudie tillsammans med en analys av LiDAR-data för att säkerställa och ifrågasätta den glacialfluviala transporten i landskapet. I detta arbete presenteras en möjlig tappningsränna för Frostviksissjön vid Storbergets östra sida och issjön är rekonstruerad med hjälp av strandnivåkarta från SGU. Landformerna i området har undersökts för att härleda om de härrör från den senaste nedisningen under Weichsel eller från tidigare nedisningar. / The mountain area in the most northwest part of Jämtland is Frostviken, which during the latter part of the Weichsel had a complicated deglaciation process. Glaciofluvial landforms such as accumulations of moraine, lineations and lateral meltwater channels are evident in the landscape. Glaciofluvial studies of postglacial areas emphasize knowledge about sediment transport that has changed soil layer sequences and reshaped the landscape. This knowledge can also be used in community planning and agriculture to adapt the expansion or rebuilding of the existing environment. During the deglaciation, the extensive ice lake Frostviksissjön was formed, an ice lake where the main spillway has not been interpreted in previous studies. The work has been based on a historical chronological literature study together with an analysis of LiDAR data to ensure and question the glaciofluvial transport in the landscape. In this study, a possible main spillway has been presented for Frostviksissjön on the eastern side of Storberget. The ice lake has been reconstructed using a shore level map from SGU. The landforms in the area have been studied in accordance with whether they originate from the most recent glaciation during the Weichsel period or derives from previous glaciations.

The theme of this diploma thesis is to restore the existing small reservoir in the village Žďárná. A new safety spillway and bottom outlet will be built, the flood will be shaped according to the cross-sections and the dam of the water reservoir will be fortified. The designed objects will be hydraulically verified. Using the HEC-HMS program, a hydrological model of the river basin is created and subsequently a derived flood wave PV20.

This diploma thesis, called „Reconstruction of the small water reservoir Hradisko in the cadastral area of Radslavice“, focuses on the complex process of a reconstruction of the small water reservoir Hradisko. This work follows up on the bachelor’s thesis, in which the current state of the Hradisko reservoir was described in detail. Based on the survey of the dam and the flood using a GPS device, detailed project documentation was prepared. Within the solution for the reconstruction of Hradisko reservoir, a repair of the dam and the increase of the crown of the dam is proposed, new functional objects are dimensioned, the bottom is cleared of mud, including modifications in the flood, and other necessary steps for proper functioning of the crumbling no longer compliant reservoir are described. Functional objects are processed for two variants of the solution. The first option consists of the design of a bottom outlet and a safety spillway, and the second alternative involves the design of a combined functional block. In the end, the total costs of both options are quantified and compared on the basis of an indicative item budget.

The subject of the thesis is to develop a simplified documentation of multipurpose reservoirs in the cadastral territory Třebařov. This thesis consists of the text, graphic and hydraulic calculations.

Die jüngst beobachteten Hochwasserereignisse zogen eine Überarbeitung der hydrologischen Daten zahlreicher Talsperren nach sich. Im Ergebnis wiesen viele der Anlagen nicht die erforderliche Hochwassersicherheit auf. Aus diesem Grund ist auch für die in Sachsen gelegene Talsperre Lehnmühle eine Ertüchtigung der Hochwasserentlastungsanlage geplant. Die Vorzugsvariante zur Wiederherstellung der Überflutungssicherheit sieht die Absenkung der Wehrkrone einzelner Überlauffelder vor. Die damit verbundene Leistungssteigerung erfordert eine Überprüfung der Abflussverhältnisse im nachgeschalteten Tosbecken. Im Rahmen der Arbeit werden die Strömungsverhältnisse im bestehenden Tosbecken mit Hilfe dreidimensionaler numerischer Modellierungen abgebildet. Mit dem Ziel einer verbesserten Energieumwandlung wird darüber hinaus die Wirksamkeit von Prallblöcken untersucht und bewertet.:1 Einleitung 2 Grundlagen der numerischen Strömungsberechnung 2.1 Numerische Modellierung im Vergleich 2.1.1 Prinzip der numerischen Strömungsberechnung 2.1.2 Exkurs: Physikalische Modellierung 2.1.3 Vor- und Nachteile der numerischen und physikalischen Modellierung 2.2 Vollständige Navier-Stokes-Gleichungen 2.3 Berechnungsmethoden 2.4 Turbulenzmodellierung 2.4.1 k-ε-Modell 2.4.2 k-ω-Modell 2.4.3 SST-Modell 2.5 Diskretisierung 2.5.1 Definieren der Geometrie 2.5.2 Berechnungsnetze 2.5.2.1 Strukturierte Netze 2.5.2.2 Unstrukturierte Netze 2.5.2.3 Hybride Netze 2.5.3 Räumliche Diskretisierung 2.5.4 Zeitliche Diskretisierung 2.5.5 Anfangs- und Randbedingungen 2.6 Wichtige Eigenschaften numerischer Berechnungsverfahren 3 Hochwasserentlastungsanlagen 3.1 Funktion 3.2 Begrifflichkeiten und Regelwerke 3.3 Aufbau 3.3.1 Einlaufbauwerk 3.3.2 Transportbauwerk 3.3.3 Energieumwandlungsanlagen 3.3.3.1 Der Prozess der Energieumwandlung 3.3.3.2 Konstruktionsmöglichkeiten 3.4 Hydraulische Bemessung 3.4.1 Hochwasserbemessungsfälle 3.4.2 Bemessungsabflüsse und Überschreitungswahrscheinlichkeiten 3.4.3 Freibordbemessung 4 Methodik 4.1Die Talsperre Lehnmühle 4.2Hydrologie 4.3Untersuchungsumfang 4.4Erstellung der numerischen Modelle 4.4.1Geometrie 4.4.1.1Wehrüberfall 4.4.1.2Tosbecken 4.4.1.3Tosbeckeneinbauten 4.4.2Numerische Modelle 4.4.2.1Modell des Wehrüberfalls 4.4.2.2Modell des Tosbeckens 4.4.3Berechnungsnetze 4.4.4Modellkonfiguration 5Ergebnisse der numerischen Berechnungen 5.1Numerik versus Physik 5.2Überfallmodellierungen 5.2.1Sensitivitätsuntersuchungen 5.2.2Ermittlung der Eingangsbedingungen für die Tosbeckenmodellierung 5.3Szenario 1 - Modellierung des bestehenden Tosbeckens 5.3.1Ergebnisse 5.3.2Sensitivitätsuntersuchungen 5.3.2.1Plausibilisierung der Randbedingung für die überströmte Tosbeckenwand 5.3.2.2Einfluss der Turbulenzmodellierung 5.3.2.3Einfluss der Rauigkeit 5.4Tosbeckenoptimierung 5.4.1Grundlegende Aussagen 5.4.2Wasserspiegellagen 5.4.3Fließgeschwindigkeiten 5.4.4Abfluss über die Tosbeckenwand 5.4.5Schubspannungen / Recent flood events called for a revision of hydrological data for numerous dams. As a result, many constructions have been found to not possess necessary flood safety. On this account, the flood spillway of the Saxon Lehnmühle dam is designated to be upgraded. In order to ensure an overflow-proof construction, the favored solution is to lower the crest of several weir fields. The resulting increased performance requires a revision of the runoff characteristics in the stilling basin. Firstly, this thesis shows the flow conditions of the existing stilling basin, using 3D numerical modeling. Secondly, with the goal of enhanced energy dissipation the effectiveness of baffle blocks will be examined and evaluated.:1 Einleitung 2 Grundlagen der numerischen Strömungsberechnung 2.1 Numerische Modellierung im Vergleich 2.1.1 Prinzip der numerischen Strömungsberechnung 2.1.2 Exkurs: Physikalische Modellierung 2.1.3 Vor- und Nachteile der numerischen und physikalischen Modellierung 2.2 Vollständige Navier-Stokes-Gleichungen 2.3 Berechnungsmethoden 2.4 Turbulenzmodellierung 2.4.1 k-ε-Modell 2.4.2 k-ω-Modell 2.4.3 SST-Modell 2.5 Diskretisierung 2.5.1 Definieren der Geometrie 2.5.2 Berechnungsnetze 2.5.2.1 Strukturierte Netze 2.5.2.2 Unstrukturierte Netze 2.5.2.3 Hybride Netze 2.5.3 Räumliche Diskretisierung 2.5.4 Zeitliche Diskretisierung 2.5.5 Anfangs- und Randbedingungen 2.6 Wichtige Eigenschaften numerischer Berechnungsverfahren 3 Hochwasserentlastungsanlagen 3.1 Funktion 3.2 Begrifflichkeiten und Regelwerke 3.3 Aufbau 3.3.1 Einlaufbauwerk 3.3.2 Transportbauwerk 3.3.3 Energieumwandlungsanlagen 3.3.3.1 Der Prozess der Energieumwandlung 3.3.3.2 Konstruktionsmöglichkeiten 3.4 Hydraulische Bemessung 3.4.1 Hochwasserbemessungsfälle 3.4.2 Bemessungsabflüsse und Überschreitungswahrscheinlichkeiten 3.4.3 Freibordbemessung 4 Methodik 4.1Die Talsperre Lehnmühle 4.2Hydrologie 4.3Untersuchungsumfang 4.4Erstellung der numerischen Modelle 4.4.1Geometrie 4.4.1.1Wehrüberfall 4.4.1.2Tosbecken 4.4.1.3Tosbeckeneinbauten 4.4.2Numerische Modelle 4.4.2.1Modell des Wehrüberfalls 4.4.2.2Modell des Tosbeckens 4.4.3Berechnungsnetze 4.4.4Modellkonfiguration 5Ergebnisse der numerischen Berechnungen 5.1Numerik versus Physik 5.2Überfallmodellierungen 5.2.1Sensitivitätsuntersuchungen 5.2.2Ermittlung der Eingangsbedingungen für die Tosbeckenmodellierung 5.3Szenario 1 - Modellierung des bestehenden Tosbeckens 5.3.1Ergebnisse 5.3.2Sensitivitätsuntersuchungen 5.3.2.1Plausibilisierung der Randbedingung für die überströmte Tosbeckenwand 5.3.2.2Einfluss der Turbulenzmodellierung 5.3.2.3Einfluss der Rauigkeit 5.4Tosbeckenoptimierung 5.4.1Grundlegende Aussagen 5.4.2Wasserspiegellagen 5.4.3Fließgeschwindigkeiten 5.4.4Abfluss über die Tosbeckenwand 5.4.5Schubspannungen

A spillway is an important component of a dam and serves as a flood release structure. It achieves controlled discharge of water and protects the dam from overtopping. The majority of the hydropower dams were built before the 1980s, and many spillways are undersized in light of the present design flood guidelines. Another issue that arises in connection with the high design floods is the energy dissipation capacity. Many existing energy-dissipating arrangements are insufficient or construed only for a design flood standard at the time of dam construction. The increment in the flood discharges requires that the energy dissipation should be improved to obtain sufficient capacity or higher efficiency. In addition, the high-velocity flow is a major concern in the design of spillways. If the flow velocity exceeds approximately 20 m/s, the risk of cavitation may arise. In Sweden, many dams belong to this category. To address these issues, an assessment of their discharge behaviours is required. Innovative engineering solutions for better energy dissipation and cavitation mitigation are also necessary for safe operation. This thesis presents machine learning based methods for discharge estimation. Three data-driven models are developed to study the discharge behaviours of the overflow weirs. Their reliability is validated through the comparison with the experimental and empirical results. These models are capable of giving accurate predictions and show superiority over the conventional approaches. With high accuracy and adaptability, data-driven models are an effective and fast alternative for spillway discharge prediction. This research also focuses on the hydraulic design of stepped spillways, aiming to devise innovative engineering solutions to enhance energy dissipation and reduce cavitation risks. Consequently, several unconventional step layouts are conceived and their hydraulic behaviours are investigated. The modified configurations include steps with chamfers and cavity blockages, non-linear steps and inclined steps. This part attempts to gain insight into the effects of the step geometries on the spillway hydraulics via computational fluid dynamics, which provides references for engineering applications. / Ett utskov är en viktig komponent i en damm och fungerar som ett skydd mot översvämning. Det avbördar vatten på ett kontrollerat sätt och skyddar dammen från överströmning. Majoriteten av vattenkraftsdammarna byggdes före 1980-talet och många utskov är underdimensionerade i förhållande till de nuvarande riktlinjerna för utformning med avseende på dimensionerande flöden. En annan fråga som uppstår i samband med höga flöden är energiomvandlingskapaciteten. Många befintliga arrangemang för reducering omvandling av vattnets rörelseenergi är otillräckliga eller endast anpassade för det dimensionerande flöde som gällde vid tidpunkten för dammens uppförande. En avbördningsökning kräver i sin tur att energiomvandlingsförmågan förbättras för att uppnå tillräcklig kapacitet eller högre effektivitet. Dessutom är höghastighetsflödet ett stort bekymmer vid utformningen av utskov. Om flödeshastigheten överstiger t.ex. 20 m/s uppstår risk för kavitation i vattenvägar. I Sverige hör många dammar till denna kategori. För att lösa dessa problemställningar behöver en utvärdering av avbördningsanordningar göras. Innovativa tekniska lösningar som syftar till effektiv hantering av flödesenergi och kavitationsreducering, vilka utgör nödvändiga förutsättningar för säker drift av anläggningar. Denna uppsats presenterar maskininlärningsbaserade metoder för att prognostisera avbördning i dammar. Tre datadrivna modeller har utvecklats för att studera avbördningsegenskaper hos överfallsdammarna. Deras tillförlitlighet valideras genom jämförelse med experimentella och empiriska resultat. Modellerna kan ge noggrann uppskattning, som kan användas som ett tillförlitligt alternativ för bestämning av avbördning. Forskningen fokuserar också på den hydrauliska utformningen av stegade bräddavlopp (s.k. stepped spillway), i syfte att utveckla innovativa tekniska lösningar för att åstadkomma hög energiförlust och minska kavitationsrisker. Flera okonventionella stegformade geometrier föreslås och deras hydrauliska egenskaper undersöks. Denna del syftar till att, via numerisk simulering, ge en inblick i vilka effekter olika steggeometrier har på avbördningshydrauliken, vilken tillhandahåller referens för tekniska applikationer. / <p>QC 20210205</p>

No Abstract Provided / Thesis / Bachelor of Arts (BA)

Sabe-se que a formação de reservatórios altera a qualidade e a quantidade da água de montante e jusante e que a direção e a magnitude das alterações dependem de suas características construtivas, operacionais, morfométricas, bem como do regime hidrológico e climático da região. Porém, a maior parte deste conhecimento foi fundamentada em pesquisas de reservatórios com grande capacidade de regularização, que fazem parte da realidade do Pantanal, uma região que vem sendo impactada por um número cada vez maior de reservatórios com pequena capacidade de regularização, levantando questionamentos sobre seus possíveis efeitos no funcionamento da planície de inundação. Sendo assim, este trabalho procurou (i) identificar qual o fator chave determinante no processo de estratificação e mistura vertical do reservatório e se este pode influenciar na qualidade da água; (ii) avaliar os efeitos da formação e operação do reservatório na alteração da qualidade da água de montante e jusante e (iii) avaliar os efeitos da operação do reservatório na alteração do regime hidrológico de jusante, além de propor os limites preventivos para a sustentabilidade. O estudo foi desenvolvido no reservatório de Ponte de Pedra, localizado no rio Correntes, divisa dos estados de Mato Grasso e Mato Grosso do Sul (Centro Oeste do Brail), na fronteira entre o Pantanal e o Planalto. O reservatório apresentou prolongado período de estratificação vertical (mistura no inverno) dos parâmetros físicos e químicos da água nas partes médias e profundas, mantendo-se homogêneo na parte superior, onde se encontra a captação, não alterando as características da água de jusante. Entre os fatores analisados, o vento foi o único fator que influenciou significativamente a estrutura vertical da qualidade da água sendo beneficiada pelas características morfométricas e construtivas do reservatório. Longitudinalmente, a formação do reservatório alterou significativamente quatro dos dez parâmetros analisados, com redução média de 38% da turbidez, 28% do fósforo total, 23% dos sólidos totais e 14% do nitrato. Destes, apenas a turbidez e o nitrato foram afetados pelo controle operacional do tempo de retenção hidráulica. Em relação à alteração dos parâmetros do regime hidrológico anual, dos 31 analisados, os parâmetros de vazões mínimas de curta duração (1, 3 e 7 dias), vazões máximas de 90 dias e o número de pulsos baixos e altos foram significativamente alterados pela operação do reservatório. Destes, a vazão máxima de 90 dias e o número de pulsos altos resumem os impactos, e podem ser utilizados como parâmetros alvos para restauração e conservação do regime hidrológico. As vazões sazonais também foram significativamente alteradas, com maior impacto na estação seca (inverno). Com base na variabilidade natural do rio, foram propostos os limites preventivos para a sustentabilidade, com alterações diárias permitidas de ±18% no inverno, ±24% na primavera e ±22% no verão e outono, aplicados sobre a vazão natural. De maneira geral, as alterações na qualidade da água e no regime hidrológico provocado pela formação e operação do reservatório foram consideradas baixas, tanto em número de parâmetros alterados quanto nas magnitudes das alterações, e estas foram atribuídas às baixas concentrações de partículas e nutrientes na bacia, ao sistema de captação superficial, o curto tempo de retenção hidráulica, pequena capacidade de regularização associadas à sazonalidade no regime de chuvas e ventos na região, que limitam manobras operacionais para a maximização da eficiência energética. / The formation of reservoirs changes the quality and quantity of water, both upstream and downstream, and the direction and magnitude of such changes depend on their characteristics of construction, operation, morphometry, as well as hydrological regime and climate of the region. However, much of this knowledge was based on large reservoirs, which is not the reality of the Pantanal, an area that is being impacted by a growing number of reservoirs with low capacity for regularization, raising questions about possible effects on the floodplain functioning. In this way, this study aimed (i) to identify the key factor in the process of stratification and vertical mixing of the reservoir, and whether this can influence the water quality, (ii) to evaluate the effects of the reservoir formation and operation on the quality of water upstream and downstream of the reservoir, and (iii) to examine the effects of the reservoir operation on the downstream hydrological regime, in addition to propose preventive limits for sustainability. The study was conducted at Ponte de Pedra Reservoir, located on the Correntes river, the motto between the states of Mato Grasso and Mato Grosso do Sul (Central West Brazil), on the border between the Plateau and the Pantanal. The reservoir had an extended period of vertical stratification (mixture in the winter) of physical and chemical water parameters in the medium and deep parts of the water column, being homogeneous in the upper part where the water is capitation, without changing the characteristics of the downstream water. Among the factors analyzed, the wind was the only factor that significantly influenced the vertical structure of the water quality, favored by morphometric and constructive characteristics of the reservoir. Along the longitudinal axis, the reservoir formation significantly altered the turbidity and concentrations of total phosphorus, total solids, and nitrate, with mean reduction of 38, 28, 23 and 14% of their values. Among these, only turbidity and nitrate were affected by the operational control of the hydraulic retention time. In relation to the change in parameters of the annual hydrological regime, parameters of short-term minimum flows (1, 3 and 7 days), maximum flows of 90 days and the number of low and high pulses were significantly modified by the reservoir operation. Of these, the maximum flow of 90 days and the number of high pulses have summarized the impacts, and can be used as target parameters for restoration and conservation of the hydrological regime. Seasonal flows were also significantly altered, with the greatest impact in the dry season (winter). Based on the natural variability of the river, it was proposed preventive limits for sustainability, with permitted daily changes of ±18% in winter, ±24% in spring and ±22% in summer and autumn applied on the natural flow. In general, changes in water quality and hydrological regime caused by the reservoir formation and operation were considered low, both in number of altered parameters as magnitudes of such changes, and these characteristics were ascribed to low concentrations of particles and nutrients in the basin, to the surface capitation system, short hydraulic retention time, low capacity of regularization associated with the seasonality of the regime of rainfall and wind in the region, limiting operational maneuvers for maximizing the energy efficiency.