Fragmentation of rivers due to the rapid expansion of hydropower plants is one of the major factors responsible for the decline in the Atlantic salmon (Salmo salar L.) in the Baltic Sea. Current methods to aid downstream migrating salmon smolt still struggle with effectively stopping the smolt from going through the hydropower turbines, by guiding them towards the available salmon ladders. A promising guiding method is using a barrier of bubbles which may serve as a non-intrusive alternative to conventional guiding structures. This study evaluated the risk of artificial selection caused using bubble barriers and compared the results with an earlier study.  The three hypotheses tested were: i) the salmon display a scototaxis behaviour related to their boldness, ii) temperature, and size of arena affect the scototaxis of the salmon, and iii) the salmons reaction to a bubble barrier is correlated to their boldness. The hypotheses were tested in a controlled laboratory setting by conducting three scototaxis tests and an experiment with several bubble barriers, where the reaction of salmon to bubbles could be assessed. There was significant positive correlation (r = 0,62 & p = 0,012) between the boldness of an individual and the time it took to swim through the bubbles. Even though a significant difference in scototaxis as a result of lowered temperature were discovered, the difference was too small to have a noticeable effect on the overall results. A bubble barrier may therefore put artificial selection pressure on the salmon population.

Degraded rivers and streams caused by disturbances have created a need for reliable tools to assess the ecological status of such ecosystems. Numerous methods and programs have been developed to assess ecological status using biological indicators, benthic macroinvertebrates are the most commonly used biotic indicator. The Hester-Dendy multi-plate sampler is a commonly used tool for sampling benthic macroinvertebrates, but its effectiveness under different environmental conditions has not been adequately tested. The aim of this study was to investigate if HD samplers assess the benthic macroinvertebrate community equally under different flow conditions. I investigated if the colonization of BMI in a constant flow differed from that of a variable flow (simulating a hydropeaking flow regime). This was studied using six aquariums, three as control with constant flows and three with variable flow conditions. One Hester-Dendy sampler and 50 benthic macro invertebrates from five different taxonomic orders were place in each aquarium. After five days of colonization the Hester-Dendy samplers were retrieved and benthic macroinvertebrates colonizing the Hester-Dendy samplers and still remaining in the aquariums were collected, preserved and analysed. Results showed that the mean sampling efficiency did not differ between the two treatments. On the other hand species diversity calculated from Shannon-Wiener index was significantly higher in the control treatment than in the variable flow treatment. The lower species diversity in the variable flow treatment is consistent with previous research on benthic macroinvertebrates affected by hydropeaking powerplants. These results can be seen as an indication of how a variable flow regime might affect the samples collected by HD samplers in a natural environment. As the artificial environments created are greatly different from a natural environment, this result might not therefore be representative in a natural environment. / Vattendrag kraftigt påverkade av antropogena störningarna har skapat ett behov av tillförlitliga verktyg för att kunna bedöma dessa vattendrags ekologiska status. Många olika metoder och program har utvecklats genom att använda olika biologiska indikatorer. Bentiska makroevertebrater är en av de vanligaste biotiska indikatorerna. En vanlig metod för att prov ta bentiska makroevertebrater är Hester-Dendy provtagaren. Syftet med denna studie var således att testa om provtagningseffektiviteten för Hester-Dendy provtagare påverkas olika av ett variabelt vattenflöde jämfört med ett jämnt vattenflöde. Detta studerades i sex akvarium, där tre akvarium agerade kontroll och utsattes för ett jämt flöde samt tre akvarium med variabelt flöde. En Hester-Dendy provtagare och 50 bentiska makroevertebrater från fem olika taxonomiska ordningar placerades i varje akvarium. Efter fem dagars koloniserings tid hämtades Hester-Dendy provtagarna och de bentiska makroevertebrater som koloniserade provtagaren såväl som akvariet bevarades i etanol och analyserades i labbet. Resultaten visade att den genomsnittliga provtagningseffektiviteten inte skilde sig åt mellan de två behandlingarna. Däremot var artdiversiteten beräknad med Shannon-Wiener-index signifikant högre i kontrollbehandlingen. Den lägre artdiversiteten i behandlingen med variabelt flöde stämmer överens med tidigare forskning om bentiska makroevertebrater påverkade av korttidsreglerande vattenkraftverk. Resultaten i denna studie bör ses som en indikation av hur ett varierande flöde kan påverka provtagnings effektiviteten hos en Hester-Dendy-provtagare. Detta med anledning av att den konstgjorda miljön som försöket utfördes i är vitt skilt från organismernas naturliga miljö vilket kan ha påverkat resultatet.

Background: Climate change and the consequences of global warming is probably one of the greatest issues of our time. Among other concerns, global warming is thought to have a great impact on hydrology worldwide. When the atmosphere warms up, river runoff patterns are altered. Nevertheless these future changes are assumed to increase the hydropower potential in some countries. In the public debate it is often referred to a nine year old investigation claiming an increase of 15-20 % in Swedish energy production from hydropower due to the river runoff increase. On the other hand recent research is hinting that the effect of global warming might be masked by climate variability in the nearest future. This study seeks to investigate whether or not the hydropower-intensive company Fortum will benefit from increased future hydropower potential due to climate change. Methods: Using historical data, the impacts of global warming on the future potential power production in different types of hydropower plants are estimated by the statistical approach of probability density functions. Moreover spectral analysis is used to investigate the impacts of climate variability in various Swedish watersheds. The study investigates both the nearest future, represented by the years 2021-2050, and the end of the century, represented by the years 2069-2098. Results: The future hydropower production is shown to be strongly dependent on the geographical location of a power plant and of the specific power plant type. Although all Swedish rivers where Fortum operates is given more river runoff in the future, some hydropower plants might  suffer from lower hydropower potential due to increased runoff variability. However all reservoir-type power plants in the study, with ability to store water, are calculated to benefit from increased river runoff. Only the run-of-river type power plants, operating with unregulated river flow, are not yet proven to benefit from a changing climate. When considering both specific river and type of power plant, this study indicates that the hydropower potential in the rivers where Fortum operates is expected to increase with 4-15 % towards the end of the century. The one exception is the unregulated river Västerdalälven where this study indicates a possibility of decreased hydropower potential due to climate change. The results of the spectral analysis indicates that up to 30 % of the coefficient of variation in the  monthly mean runoff data is explained by low-frequent periodic fluctuations due to natural climate variability, linked to somewhat predictable climate indices. Conclusion: Natural climate variability is likely to be the dominating factor in the nearest future, at least in regulated rivers. Although there are uncertainties about the future potential power production in the run-of-river type power plants, one cannot deny that most of the Swedish rivers where the major hydropower companies operate are strongly regulated. Adding the fact that river runoff will increase as a consequence of global warming, Fortum is likely to gain from an increased hydropower potential. However, this present study highlights the inaccuracies in using the out-of-date estimation of 15-20 % hydropower-potential increase as a forecast of future potential power production in all Fortum-operated hydropower plants.

The format the text is saved as is unreadable, so i retyped it to my best ability.  This master thesis contains my work of studies of a short term planning model, with the time span of one week, or 168 hours. The models are based on the future hydropower system in pjorsa- and Tungnaa- river system, located in the south part of Iceland. The purpose ot this thesis is to formulate and develop one week operation schedules for this future power generation system, which for a given inflow-and load forecast returns a good schedule for each power stations in the system. The planning problem is formulated as a mathematical programming problem. The models used to describe and implement the system under study are a piecewise linear models. For piecewise linear models the breakpoints of the model are the local best-efficiency points. The objective is to return operation plan for each power station in the system, where the the volume of stored water in the end of the planning period is maximized through optimal discharge plans. It is needed to supply contracted load, regulation- and balance power for each hour during the planning period under study. Two test cases are made for each model in this theises. The former case describe winter operation, with high consumptions and lower natural inflow to the reservoirs. In the latter case the consumption is low and river inflow high and is meant to describe summer time operation. Obtained results show that piecewise linear model gives more realistic results when the load consumption is high and the inflow is low. During summer time, with low load and high inflow. The piecewise linear models schedule more often discharge not on local best-efficiency points. This behavior can be decreased by insertion a penalty cost of discharge changes.

The discharge through a river hydropower plant must be controlled such that the water level at a pre-specified point close to the facility is kept within given bounds. The controllers used today have a somewhat demanding tuning and often create too much amplified, unnatural discharge variations resulting in unsatisfactory control performance.This will affect both surrounding nature and imposing problems for river navigation. This thesis will present a new type of controller called Override Selector feedback Control that adds an estimator for the water levels and water flows in the up- and downriver for each hydropower plant on top of the old controller. The objective of the state feedback control is to keep the total variation of the water levels and the waterflows as small as possible. After the linear, discrete time model of the power plant cascade in a river derived from the Saint Venant equations have been developed, the new concept is evaluated. Both the water level sloshing and the amplification of the discharges compared to the structure used today is damped with the new control structure. Other advantages of the proposed controller is that it will be cost efficient to implement because of the add-on approach. This is seen as a very important factor while the actual benefit that can be made by improving the water level control is very limited and thereby also the will to make extensive control investments. The control structure will be easily implemented as the estimators only need the same input data as used today.

With an evolving energy system, an increased flexibility is necessary, placing additional demand on hydropower plants. New technology, in particular full size frequency converters (FSFC) and doubly fed induction machines (DFIM), allows hydropower turbines to run at different speeds than originally designed, thus making the turbine more flexible. The Kaplan turbine is a common turbine with adjustable runner blades. Unfortunately, because of this design, mechanical failures are known to occur and if left untreated it could cause total turbine failure. In the industry, one solution used to avoid this is to lock the runner blades in one position. This master thesis investigates implementation of variable speed technology, in combination with locking the runner blades, thereby converting the turbines to variable speed fixed turbines. Two different Kaplan turbines were investigated, and operation parameters were simulated to determine how to operate the turbines for maximum electricity production. Additionally, for one of the turbines (K1), measurements were done on site to find out how the turbine is currently operated. In the results, combinations of parameters to use for maximum electricity production are presented. The results revealed that for K1, the runner blades should be locked at an angle of 9.5° and combined with variable speed technology to maximize electricity production. When compared to ordinary operation, the annual production increased slightly, from 34.72 GWh to 35.32 GWh.

At the intake of hydropower plants, air-core vortex formation is known to cause severe damage. In order to study how to prevent and reduce the origin of the vortex, Vattenfall has built a scale model of the Akkats hydropower plant dam, where scale testing is possible. This thesis work consists of discerning whether Computational Fluid Dynamics (CFD) in terms of solving the Unsteady Reynolds Average Navier-Stokes equations (URANS) can be used as a complement to scale testing. For this work, the RNG k-epsilon turbulence model is chosen, and the flow field is solved with implicit time discretization using a pressure-based solver, for three different inlet flow conditions. Despite significant differences in the inflow of these three cases, the resulting flow fields are surprisingly similar. A main result is that no vortex is formed in any of the cases. The cause of this is discussed, but the number of possible answers is large. The main purpose of the report has therefore become to lay the foundation for further research. Amongst the top priorities in parameters to investigate lies the choice of turbulence model, the surface height, the pressure discretization scheme and to perform calculations on a more expensive mesh. / Virvlar som uppstår vid intaget i vattenkraftverk kan orsaka stora skador. För att kunna göra studier om hur man bäst motverkar virveln och förhindrar dess uppkomst, har Vattenfall AB byggt en småskalig modell av dammen vid Akkats vattenkraftverk. Det här arbetet behandlar frågeställningen huruvida Computational Fluid Dynamics (CFD) med lösning av ekvationerna för Unsteady Reynolds Average Navier-Stokes (URANS) kan användas som ett komplement till dessa modell-tester. I det här arbetet har turbulensmodellen RNG k−epsilon valts och flödesfältet löses för tre olika tillstånd för flödet vid inloppet, med hjälp av implicit tidsdiskretisering tillsammans med en tryckbaserad ekvationslösare. Trots betydande skillnader för inflödet för dessa tre fall är de resulterande flödesfälten överraskande lika. Ett huvudresultat är att ingen virvel formas för någon av dessa fall. Anledningen till detta har diskuterats, men antalet möjliga anledningar är många. Huvudsyftet med den här rapporten har därför blivit att lägga en grund för framtida efterforskningar på området. Några av de viktigaste parametrarna att undersöka är valet av turbulensmodell, höjden på vattenytan, tryckdiskretiserings-schema samt att genomföra beräkningar för en finare mesh.

This thesis concerns with water, energy, and food (WEF) security in Nepal in relation to hydropower development. Hydropower is challenging to WEF security in three ways: First, the focus is only on energy generation which overlooks the impacts on land, forest, water and biodiversity. Second, the hydropowerprojects are being built in the tributaries of transboundary rivers where local, national and international interests and priorities intersect because these rivers are sources of the economy; water, energy, food commodities; and other ecosystems services. Third, discourses on renewable energy, sustainable development and climate change portray hydropower as a promising renewable energy source as other renewable energy sources hold very less potential in Nepal. In this context, this thesis evaluates if the benefit-sharing approach can be a solution to overcome problems related to the implementation of hydropower which challenges WEF security. Therefore, the study adoptsWEF Nexus Framework and Benefit-sharing Framework to evaluate the challenges and possibilities for rising WEF security minimizing the hydropower-induced trade-offs. The study finds hydropower development in Nepal is rapid and haphazard which merely conceives trade-offs between energy production and other benefits. But benefit-sharing practice, though it is still in its nascent phase, has positively impacted WEF security primarily at the local level, mainly by providing irrigation and drinking water facilities, rural electrification, and agriculture-related livelihood training and support. However, a well-planned benefit-sharing approach as an integral part of hydropower development is lacking which foils equitable distribution of benefits among stakeholders across all levels and smooth implementation o f hydropower projects to enhance the sustainability of hydropower.

Freshwater systems have, during human history, endured large-scale impacts. According to the water framework directive, measures must be developed to create a better environment for species in, and connected to, freshwater systems. Hydropower plants has caused loss of natural disturbance (e.g., floodings). Using already collected data from vegetation inventory in the riparian zone, probable distribution curves were created to find flooding requirements of different plant species, and linear regression analyses were run to see if hours of flooding and elevation above sea level had an effect on species richness and vegetation cover in the riparian zone. A model of Bredforsen 3 was conducted by using modelled values obtained from Vattenfall AB, with the aim to answer the following questions: How is riparian vegetation in mixed alluvial forests in reaches affected by static minimum flow levels structured according to flow dynamics? What would the zonation of riparian vegetation look like in an unregulated situation? How can minimum flow in Bredforsen be designed to better match the flooding regime similar to a natural riparian vegetation? Species richness showed to be dependent on elevation. Furthermore, significant results for species richness and vegetation cover both showed to be dependent on hours of flooding in the riparian zone for two of the three inventoried areas. In the alluvial forest, Picea abies, was not affected by hours of flooding. This might be caused by a low number of replicates available in Bredforsen of P. abies. In contrast, Quercus robur did show a significance towards hours of flooding and a vague negative trend for trees with high inundation distributed on lower elevations, though, it seems more parameters are affecting its distribution. The probable species distribution curves revealed the riparian zone in Bredforsen lack the clear vegetative zones visible along unregulated rivers. However, the model created for Bredforsen 3, following the assumptions of Ström et al. (2012) showed that today two vegetative zones, are apparent in Bredforsen 3 (amphibian zone and upland vegetation). With the modelled flow, a third zone (riparian forest) could appear. Because Bredforsen is a Natura 2000 reserve, the minimum flow needs alteration to mimic a relatively natural flow, which could lead to all vegetative zones to develop (amphibian zone, graminoids, willow shrubs, riparian forest, and upland vegetation). This could be achieved by using the spill water from Söderfors and time the release of spill to natural flow events. The model made from Bredforsen 3 indicates that this could cause positive changes in the riparian zone where a more natural distribution of vegetative zones is in place, meaning that species distribution returns to previous distribution patterns and would help disturbance dependent species.

With limited indigenous conventional energy resources, Mauritius imports over 80% of its energy supply from foreign countries, mostly from the Middle East. Developing independent renewable energy resources is thus of priority concern for the Mauritian government. A tropical island surrounded by the Indian Ocean, Mauritius has enormous potential to develop various renewable energies, such as solar energy, biomass energy, wind power, geothermal energy, hydropower, etc. However, owing to the importance of conventional fossil energy in generating remarkably cheap electricity, renewable energy has not yet fully developed in Mauritius, resulting from a lack of market competition. So, in order to reduce the external dependency of fuel, and also to cut down the expenses involved in the imported fuels, the Mauritius Government introduced attractive policies and invited investors of the homeland and abroad to invest in renewable energy technologies. Consequently, numerous promotional and subsidy programs have recently been proclaimed by the Mauritian government, focused on the development of various renewable energies. Thus, the Government of Mauritius has a long-term vision of transforming Mauritius into a sustainable Island. One important element towards the achievement of this vision is to increase the country’s renewable energy usage and thereby reducing dependence on fossil fuels. Democratisation of energy production is determined to be the way forward. A step in this direction is to transfer citizens the ability and motivation to produce electricity via small-scale distributed generation (SSDG), i.e. wind, photovoltaic, Hydropower. As a stepping stone the Government and the Central Electricity Board, with the help of the UNDP, established a grid code in May 2009 which encompasses tariffs and incentive schemes that have in many countries proved essential in order to achieve any substantial development in renewable electricity production based on SSDG.   In line with the government’s vision on renewable energy, the University of Mauritius is working as a partner with DIREKT team to promote renewable energy infrastructure locally. The DIREKT (Small Developing Island Renewable Energy Knowledge and Technology Transfer Network) is a teamwork scheme that involves the participation and collaboration of various universities from Germany, Fiji, Mauritius, Barbados and Trinidad & Tobago.  The aim of the DIREKT project is to reinforce the science and technology competency in the domain of renewable energy through technology transfer, information exchange and networking, targeting ACP (Africa, Caribbean, Pacific) Small Island developing states. This study was therefore initiated to investigate the main renewable energy technologies that stakeholders, institutions as well as businesses and organizations would like to invest in Mauritius based in the attracting incentive schemes provided by the Government.   From the study it was found that the majority of the Organizations, Institutions, Businesses and stakeholders are ready to accept and invest in the solar photovoltaic technology. Moreover, the economic evaluation for the implementation of the photovoltaic technology revealed that within a period of 4.3 years (payback period), the total capital invested can be recovered and after that, the capital generated from the excess electricity produced will contribute to the profit of the organization, Business or Institution.