With the ever increasing reliance on hydropower in the world, it is important that its effects on riparian vegetation is well understood. This study aimed to explore the effects of different forms of hydropeaking, which results from the rapid and frequent opening and closure of hydroturbines, on different species groups of riparian species native to northern Sweden. Thirteen riparian species belonging to three different species groups, forbs, graminoids and woody species, were subjected to three different watering treatments simulating water stress, rapid fluctuation and prolonged flooding, which often correspond to different hydropeaking conditions. A fourth treatment maintained individuals under controlled conditions and simulated a non-regulated stream. The treatments were carried out over seven weeks. The results showed that the treatments affect the three tested species groups differently. Woody species responded to all treatments with lower germination, higher mortality and lower root elongation, while forbs and graminoids responded to flooding and fluctuation with increased germination but higher mortality and lower root elongation. Fluctuation and flooding had in general positive effects on germination and short term growth but also increased mortality, particularly fluctuation. There were no significant results regarding change in number of leaves for any treatment or species group. As this study only covered seven weeks it can only account for short-term trends, but it still provides interesting information about general expected trends for a wide variety of species native to northern Sweden and belonging to the main three species groups. Such information is key for river management.

The kinetic energy in river streams, tidal currents, or other artificial water channels has been used as a feasible source of renewable power through different conversion systems. Thus, hydrokinetic energy conversion systems are attracting worldwide interest as another form of distributed alternative energy. Because these systems are still in early stages of development, the basic approaches need significant research. The main challenges are not only to have efficient systems, but also to convert energy more economically so that the cost-benefit analysis drives the growth of this alternative energy form. One way to view this analysis is in terms of the energy conversion efficiency per unit cost. This study presents a detailed assessment of a prototype hydrokinetic energy system along with power output costs. This experimental study was performed using commercial low-cost blades of 20 in diameter inside a tank with water flow speed up to 1.3 m/s. The work was divided into two stages: (a) a fixed-pitch blade configuration, using a radial permanent magnet generator (PMG), and (b) the same hydrokinetic turbine, with a variable-pitch blade and an axial-flux PMG. The results indicate that even though the efficiency of a simple blade configuration is not high, the power coefficient is in the range of other, more complicated designs/prototypes. Additionally, the low manufacturing and operation costs of this system offer an option for low-cost distributed power applications.

The interest in sports fishing and the number of enterprises involved is a growing phenomenon in Sweden. According to statistics from Statistics Sweden, about 1.6 million of all Swedish residents has an interest in fishing and about 10 percent of all international trips are related to fishing tourism. This indicates that there is a potential to develop fishing tourism in Swedish rivers. The aim of this study was to explore the fishing tourism around the salmon fishery and to identify any action that has been taken to improve conditions for the salmon in the river Göta älv, in the area of the Lilla Edet and Trollhättan municipalities. The information in this study has been collected from literature and interviews with SFK Laxen and Trollhättan Municipality. Göta älv is, among other rivers, regulated for hydropower production with four hydropower dams blocking the migration routes for the salmon. The main measurements that have been taken to facilitate salmon migration and improve conditions for salmon fishing are fish ladders at the power stations, and the addition of gravel to create spawning grounds. However, many projects that would improve the potential for fishing tourism are still waiting to be approved or has been denied. The result of this study has clarified the current situation for salmon and salmon fishing in Göta älv, and make some suggestions for further development of fishing tourism in the river.

No Brasil, cerca de dois terços da capacidade total instalada de geração de energia elétrica e, em média nos últimos quinze anos, aproximadamente 90% da geração efetiva provêm das hidrelétricas. Este sistema inclui 170 usinas hidrelétricas de médio e grande porte existentes ou previstas até 2023, aproximadamente dois terços delas com capacidade de regularizar vazões e todas operando de maneira interligada. Restrições ambientais, técnicas, sociais e econômicas tem dificultado cada vez mais a implantação de empreendimentos hidráulicos contendo reservatórios de grande porte, tornando a maioria dos novos empreendimentos a fio d´água. Para compreender melhor o processo, este trabalho apresenta um levantamento da evolução anual da capacidade instalada e de armazenamento do sistema desde 1950 até a expansão prevista nos próximos 8 anos, em 2023. Os dados da década de 2000 e a previsão até 2023 de forma ainda mais acentuada indicam uma redução continua e significativa da capacidade relativa de regularização, com impacto direto nas decisões de operação e de expansão do sistema térmico complementar. A fim de avaliar as possíveis consequências da redução da capacidade de regularização, simulações foram realizadas no modelo HIDROTERM (ZAMBON et al. 2012); os resultados apontam para uma necessidade de ser complementar continuamente a energia hídrica, não só em períodos hidrologicamente desfavoráveis. / In Brazil, about two-thirds of electricity installed capacity and over the last fifteen years, on average 90% of energy consumed has come from hydropower generation. The hydro system includes 170 medium and large hydropower plants in integrated operation today or planned to be operational by the end of 2023, about two-thirds of them have large storage capacities to regulate flows. Environmental, technical, social and economic constraints have made it increasingly difficult to project and build new reservoirs with large storage capacities. As a result, newly built hydropower plants are mostly the run-of-river type. To better understand the process, this paper presents a historical survey of the installed capacity of hydropower and storage capacity of the system since 1950 and extends to the planned expansion over the next eight years, through 2023. Data from 2000 and projections through 2023 indicate a significant reduction of relative regulating capacity, which has a direct impact on decisions regarding operation and expansion of the complementary thermal system. In order to assess the possible consequences of the reduction in regulating capacity, simulations were performed on HIDROTERM model (ZAMBON et al. 2012); the simulation results point to a continuous need for complementing the hydropower generation, not only on hydrologically unfavorable years.

No Brasil, cerca de dois terços da capacidade total instalada de geração de energia elétrica e, em média nos últimos quinze anos, aproximadamente 90% da geração efetiva provêm das hidrelétricas. Este sistema inclui 170 usinas hidrelétricas de médio e grande porte existentes ou previstas até 2023, aproximadamente dois terços delas com capacidade de regularizar vazões e todas operando de maneira interligada. Restrições ambientais, técnicas, sociais e econômicas tem dificultado cada vez mais a implantação de empreendimentos hidráulicos contendo reservatórios de grande porte, tornando a maioria dos novos empreendimentos a fio d´água. Para compreender melhor o processo, este trabalho apresenta um levantamento da evolução anual da capacidade instalada e de armazenamento do sistema desde 1950 até a expansão prevista nos próximos 8 anos, em 2023. Os dados da década de 2000 e a previsão até 2023 de forma ainda mais acentuada indicam uma redução continua e significativa da capacidade relativa de regularização, com impacto direto nas decisões de operação e de expansão do sistema térmico complementar. A fim de avaliar as possíveis consequências da redução da capacidade de regularização, simulações foram realizadas no modelo HIDROTERM (ZAMBON et al. 2012); os resultados apontam para uma necessidade de ser complementar continuamente a energia hídrica, não só em períodos hidrologicamente desfavoráveis. / In Brazil, about two-thirds of electricity installed capacity and over the last fifteen years, on average 90% of energy consumed has come from hydropower generation. The hydro system includes 170 medium and large hydropower plants in integrated operation today or planned to be operational by the end of 2023, about two-thirds of them have large storage capacities to regulate flows. Environmental, technical, social and economic constraints have made it increasingly difficult to project and build new reservoirs with large storage capacities. As a result, newly built hydropower plants are mostly the run-of-river type. To better understand the process, this paper presents a historical survey of the installed capacity of hydropower and storage capacity of the system since 1950 and extends to the planned expansion over the next eight years, through 2023. Data from 2000 and projections through 2023 indicate a significant reduction of relative regulating capacity, which has a direct impact on decisions regarding operation and expansion of the complementary thermal system. In order to assess the possible consequences of the reduction in regulating capacity, simulations were performed on HIDROTERM model (ZAMBON et al. 2012); the simulation results point to a continuous need for complementing the hydropower generation, not only on hydrologically unfavorable years.

This paper sets out: How river resources can be used towards a sustainable development of Tanzania, the case ofthe Rufiji River Basin. The study focuses on the role of hydropower at present and in the future, in the context ofeconomic growth and sustainability and meeting the energy demand in Tanzania.Take into consideration that hydropower is still the major source of electricity that Tanzania relies on. Tanzaniahas been struggling with one of the lowest electricity rates in sub-Saharan Africa where on average less than 15percent of the Tanzanian population has access to electricity.Tanzania faces a major challenge to provide more than 85 percent of the remaining population with electricity,which will require big investment and expertise. Electricity and energy in general seem to take fore debate andnews spots in the country because it reaches a point where even those accessing electricity still suffer withsevere energy rationing. In this project, different development implications regarding hydropower production inthe country were addressed through in depth literature review from different academic sources, and a surveywhich was conducted through questionnaires, a field trip and interviews to identify not only people’s opinionsand feelings concerning the situation, but also to find out if they propose any optimal sustainable solution forremedying the problem, which hinders the socio-economic development of the country. The analysis shows thatTanzania can produce enough hydropower to meet the energy demand if hydropower was improved as one of thesources of energy. The clear picture shows that the potential of the Rufiji River basin is not fully exploited due tothe lack of an integrated approach on achieving the best solutions for Tanzanian energy, inappropriatetechnology and poor allocation of funds.Moreover the indication illustrates that hydropower has an important role to play in the future if the potentialtapped in an area was endowed with considerable benefits to an integrated electric system. For that case, thepaper attributes that hydropower production can contribute to the energy security in Tanzania. On the other handthe paper argues that other renewable options such as solar and wind power in a country like Tanzania shouldn’tbe separated but rather go hand in hand in research and consideration. The theory derived in this project statesthat ‘‘River Basins remain a largely untapped resource for poverty alleviation in Tanzania’’.

This work helps increasing our general understanding of how plants behave under altered hydrological conditions which occur along rivers regulated by hydropower dams. Usually, natural-real environments are highly unpredictable. Consequently, research based on field data becomes challenging and results may contain uncertainty. Here, an experimental design in a greenhouse is developed. Several measured attributes of selected plant species related to germinability, performance and survival were used as indicators of the impact of watering treatments which mimic hydrological regime spilled through hydropower dams. Specifically, direct effect<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /><img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> of water availability changes, water fluctuation and water flooding, and indirect effect<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> through derived erosion, were tested. Results benefitted from indoors controlled conditions. They showed significant different responses depending on species and hydrological changes. In general, Helianthus annuus was slightly affected. It deal well flooding conditions, and was comparatively more affected by water fluctuation and stress. Carex and Filipendula species showed the highest sensitivities to flow. They hardly germinated under any water treatment (few germinations under flooding for Carex and few under water fluctuation for Filipendula) and performance was very low for germinates. Betula pubescens was in between. Contrarily to Helianthus, it was severely affected by flooding, and also for water fluctuation. It survived water stress better than Helianthus, but looked unhealthy. All species seeds but Helianthus were highly eroded. However, erosion resulting<img src="https://cdncache-a.akamaihd.net/items/it/img/arrow-10x10.png" /> from water fluctuation was relatively higher than from prolonged flooding. Differing responses are the result of morphological and physiological characteristics of the species which enable them to success under certain stressful conditions, such as water scarcity and anoxia. These results objectively inform about tolerance limits of selected species to key hydrological conditions and are useful for riparian areas management and environmental flows designs.

The frequency control in the Nordic grid is to a large extent delivered by hydropower plants. The hydropower plants deliver frequency control of varying quality, meaning that a remuneration method based on more than just the static gain of the power plant is called for. This thesis has examined how three remuneration methods based on the hydropower plant output and the grid frequency deviation affects the grid stability. Using frequency data, the remunerated work along with the bandwidth and phase-crossover frequency was plotted and compared for varying governor settings. The results show that all three remuneration methods examined need constructive technical specifications (for example based on the frequency response) to not decrease the grid stability. The first remuneration method, where the power plant is remunerated for being on the right side of the power set point value as the grid frequency deviates, gave incentives for increased bandwidth, but no particular incentives regarding the phase-crossover frequency. The second remuneration method, where the power plant is remunerated for how well it matches the output power from a plant with no dynamics using a proportional controller, gave incentives for moderately high bandwidth and phase-crossover frequency. The third remuneration method, which remunerates how well the plant power output matches the load disturbance that gave rise to the grid frequency deviation, needs to be investigated further, but the initial analysis show that it did neither give incentives for increased bandwidth nor phase-crossover frequency.

Currently, Statkraft knows that they have oil spills from their hydraulic system, but the problem is that the amount of the oil spilled is not clear. Furthermore, Statkraft is missing a tool that can be used when decisions need to be made on what power plants that should be prioritized to be renovated next or which oil system that they should be switched to. In order to answer these points a look has been taken onto the environmental effects and the amount of oil spilled from hydropower plants, the general oil system inside a power plant, and in Kaplan turbines. Furthermore, two maps were developed: one presenting areas of interest for humans and environment around the hydropower plants and a second map about the river shorelines sensitivity to oil spills represented in form of an ESI ranked river shoreline. The maps give a general overview and can be used as a starting point to include environmental aspects into the planning and decision making process. The outcomes of the study are that more detailed information about the amount of oil spills released in small amounts from the turbines is needed. The catchment areas, where Statkraft Sverige AB has hydropower plants, which are most sensitive to oil spills, are Moälven and Nätraån. The hydropower plant with the most sensitive river shoreline is the Stennäs power plant due to a large wetland close by. Those areas should therefore be prioritized in projects about reducing the amount of oil inside Statkraft`s hydropower plants.

The aim of this research is to investigate the application of nonlinear programming techniques to multipurpose reservoir systems. A multipurpose multiple reservoir operation problem is a typical nonlinear large scale optimization problem. The currently applied techniques overcome the nonlinearity and dimensionality problems through simplification. To model the problem more closely, a successful trial is made in this study to apply the most efficient and suitable nonlinear programming techniques. Although research in large scale nonlinear optimization has been in recent'years a major subject of interest within the mathematical programming community, its application to reservoir systems is very limited. As a result of these activities software packages, as Lancelot, have been developed. Lancelot is a general purpose software package designed for solving large-scale nonlinear optimization problems. It uses Augmented Lagrangian and Conjugate Gradient methods. This software is used here successfully to solve an optimization problem formulated for a major river system, the Blue Nile in Sudan. The system has two in series reservoirs used for hydropower generation, maintaining minimum downstream flows and irrigation. For optimization, some features of the system have been modelled. These are sedimentation, evaporation, demand and flow. To represent the effect of sedimentation a model is fitted and verified. To include the effect of evaporation a model that estimates the total evaporation losses is fitted using Penman approach and verified using water balance. To cope with flow uncertainty the Blue Nile flow has been modelled. ARMA(1,1) has given the best fitting. Irrigation requirements have been estimated using Penman- Monteith approach. Efficiency of water use has been investigated and other possible demand scenarios resulting from efficient water use are obtained. The results of flow and demand modelling are used as direct input to the optimization model while sedimentation and evaporation models are incorporated in the model. The objective of this model is to maximise power benefits on condition that certain irrigation and downstream requirements be met. To solve this problem a double precision version of Lancelot was installed in a hp-UNIX system. For the problem a specification and a standard input format, SEF, files were written and put under the same directory with Lancelot to run the program. The problem was solved successfully in few minutes. The solution includes values for the objective function, decision variables (releases and storage volumes), penalty parameter, Lagrange multipliers and slack variables. The optimization output is affected by reservoir sedimentation. Therefore the developed optimization and sedimentation models have been linked to investigate sedimentation effect on optimization on output along the course of reservoir operation. Results have shown that this approach can be used to investigate the effect of sedimentation on reservoir optimum output. In, a multipurpose reservoir system, the optimization output for one purpose is affected by the efficiency of water use for other purposes. Therefore the effect of efficient water use in irrigation on power benefits is investigated. Results have shown an increment in benefits due to using irrigation water efficiently. This approach can be applied to systems where priority is given for one purpose over the others.