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Monitoring and maintaining the health of coastal wetlands is a global concern. The greatest threat to coastal wetlands in the Great Lakes Basin are anthropogenic removal and enrichment. The coastal wetlands in Georgian Bay are relatively undisturbed by humans, but face disturbance caused by reduced annual water-level fluctuations. Since these wetlands are critical habitat for many fish, bird, amphibian, and reptile species, many efforts to accurately monitor and maintain their health have been put into place. Recently, these wetlands have been experiencing an abrupt (~1 m) transition to higher water levels, following 14 years of sustained lows, which allowed trees and shrubs to invade the meadow vegetation zone. This sustained water-level pattern has never occurred in this region before, offering the unique opportunity to study wetlands undergoing a transition, where areas of 10+ years of upland plant species growth was inundated and became part of the wetland habitat. This thesis first investigates how this change in water level affects the distribution of meadow, emergent, floating, and submerged vegetation both in physical space and area. The second chapter of this thesis presents long-term water quality, macrophyte, and fish community monitoring using ecological indices. Water quality and macrophyte indices are robust enough to monitor wetlands undergoing a transition; however, issues arise in the calculation of the wetland fish index, as the changes in macrophyte distribution described in Chapter 1 impact the ability to replicate community sampling using fyke nets. The research done throughout this thesis is highly beneficial in adding to the limited knowledge of key factors impacting macrophyte community shifting. This work also identifies water-level scenarios where managers must adjust sampling protocols to succeed in effectively sampling wetland fish communities. / Thesis / Master of Science (MSc) / The coastal wetlands in the Georgian Bay area are primarily threatened by human development and the removal of annual water-level fluctuations. From 1999-2013, the water level decreased and remained low. In 2014, the water level rose about 1 m, causing flooding of grass and trees that had grown in the meadow zone during the 14 years when the water level was low. The first goal of this thesis is to explain how and why all wetland plants are relocating during this period. The second goal is to make sure that common indicators of wetland health (water quality, plants, and fish) can still be used during a time when flooding of grasses and trees was occurring in wetlands. The findings in this thesis contribute to the ability to predict and understand how the plants will shift within a wetland during a time of flooding, as well as informing managers on appropriate sampling protocols.

The Diploma thesis deals with the safety assesment of the small water reservoir Bartošovice III during the floods, according to requirments of TNV 75 2935 (technical standard). First two chapters are devoted to the description of the dam purpose. Following chapter deals with the summary of basic information and documentation, including hydraulic analysis. In the following section maximum permissible safe water level is determined together with the maximum check flood water level in reservoir which reflects the flood wave transformation. In the final evaluation the comparison of the maximum permissible safe water level with maximum check flood level is carried out. At the end of the thesis recommendations leading to ensuring of reliability and safety of water reservoir are listed.

Warmer air temperatures projected for the mid-21st century under climate change are expected to translate to increased evaporation and a re-distribution of precipitation around the world, including in the mid-latitude, continental Athabasca River region in northern Alberta, Canada. This study examines how these projected changes will affect the water balance of various lake sizes. A thermodynamic lake model, MyLake, is used to determine evaporation over three theoretical lake basins – a shallow lake, representative of perched basins in the Peace-Athabasca Delta near Fort Chipewyan; an intermediate-depth lake representative of industrial water storage near Fort McMurray; and a deep lake representative of future off-stream storage of water by industry, also near Fort McMurray. Bias-corrected climate data from an ensemble of Regional Climate Models are incorporated in MyLake, and the water balance is completed by calculating the change in storage as the difference between precipitation and evaporation. Results indicate that evaporation and precipitation are projected to increase in the future by similar magnitudes, thus not significantly changing the long-term water balance of the lakes. However, intra-annual precipitation and evaporation patterns are projected to shift within the year, changing seasonal water level cycles, and the magnitudes and frequencies of extreme 1-, 3- and 5-day weather events are projected to increase. These results demonstrate that future climate change adaptation and mitigation strategies should take into account increases in intra-annual variability and extreme events on water levels of lakes in mid-latitude, interior hydroclimatic regimes. / Graduate / 0368 / walkerg@uvic.ca

<p>The discharge from Lake Mälaren is regulated to keep the lake water level within limits set by a water decree. Despite this, in the year 2000 the lake water level rose above the upper limit. Studies conducted at the climate modeling unit Rossby Centre at the Swedish Meteorological and Hydrological Institute (SMHI) indicate that the inflow to the lake may increase in the future. A flood in the area will, among other things, strike infrastructure and residential districts.</p><p>The aim of this study was to investigate the water levels of Lake Mälaren in future climates. In addition to this possible future expansion of the lake discharge though the sluice gates in order to keep water levels below limits set by the water decree and to prevent flooding of the shoreline were discussed. This was done by examining past lake and sea water level data and by using a discharge model to simulate future lake water levels resulting from high future inflow. The study was commissioned by SMHI.</p><p>High lake water levels were reproduced fairly well by the discharge model, whereas it was more difficult to draw any coclusions concerning low lake water levels. The examination of data on past lake water levels demonstrated that the regulation of the lake discharge caused a reduction of the highest lake water levels, but above all an increase of low lake water levels. Data on past sea levels in the Baltic Sea showed high values during wintertime. In combination with future high inflow to Lake Mälaren during this season, this indicates that the greatest future flood risk may prevail during wintertime. The conclusion from the simulated future lake water levels was that the lake discharge needs to be expanded to prevent flood in the area. In all scenarios examined in this study, the lake water level will not rise above the upper limit set by the water decree if the discharge is increased to 1 370 m3/s, which almost corresponds to a doubling of the existing discharge of 710 m3/s.</p> / <p>Mälarens utlopp är reglerat för att kunna hålla vattenståndet inom acceptabla gränser. Trots regleringen översteg vattenståndet under vintern 2000/01 den högsta föreskrivna nivån i regleringsbestämmelserna. Studier som bedrivs på klimatforskningsavdelningen Rossby Centre på SMHI pekar på att det framtida inflödet till Mälaren kan komma att bli högre än vad det är idag, något som skulle innebära ännu högre vattennivåer i Mälaren.</p><p>En omfattande översvämning av Mälarens stränder går bland annat ut över infrastruktur och bostäder. Problemet idag är att avbördningen genom sjöns utskov är för liten för att förhindra att översvämning uppstår. Att försöka skydda Stockholm mot vattnet med hjälp av skyddsmurar och invallning skulle bli alltför kostsamt. Ett bättre alternativ är istället att öka avtappningskapaciteten genom slussarna.</p><p>Syftet med det här arbetet var att undersöka hur vattennivån i Mälaren kan komma att bli i ett framtida förändrat klimat. I samband med detta gavs ett underlag för diskussioner om kommande utbyggnader av Mälarens utlopp för att kunna hålla vattennivån under vattendomens högsta föreskrivna nivå även vid ett högre framtida inflöde. Detta uppnåddes genom att genomföra analyser med historiska vattenståndsdata och genom att använda en beräkningsmodell för avtappning, Mälarmodellen, för simulering av ett antal framtida inflödessituationer. Arbetet har genomförts på uppdrag av SMHI.</p><p>Avtappningsmodellen återskapade de höga vattenstånden förhållandevis väl, medan det var svårare att bedöma hur precist den beräknade de allra lägsta vattennivåerna. Ett viktigt resultat från analysen med historiska data var att införandet av regleringen av Mälarens utlopp bidrog till att sänka de höga vattenstånden, men framförallt till att höja de låga. Ett annat resultat från studierna av historiska data var att vattenståndet i Östersjön antar högst nivåer under vintern. Detta i kombination med ett framtida högre inflöde till Mälaren under denna årstid indikerar att störst risk för översvämning kan komma att föreligga under vintern. För att säkert kunna hålla Mälarens vattennivå inom acceptabla gränser måste sjöns utlopp byggas ut. I alla scenarier som har undersökts i det här arbetet kan vattennivån hållas under den högsta föreskrivna nivån om avbördningen utökas till 1 370 m3/s. Det krävs alltså nästan en fördubbling av dagens avbördningskapacitet på 710 m3/s.</p>

Le fonctionnement des milieux aquatiques d’origine anthropique est étroitement dépendant des usages ; l’environnement des communautés biologiques est donc généralement fluctuant. L’étude du lien entre environnement et organisme est alors plus complexe que dans les environnements stables. Ce travail de thèse vise à mieux comprendre comment l’ichtyofaune réagit face aux changements des conditions environnementales dans une retenue soumise à marnage, la retenue des Bariousses, située sur la Vézère.Une approche multi-échelle à la fois biologique (communauté et individus) et temporelle (cycles annuel et journalier) a été adoptée. Une attention particulière a été donnée à la zone littorale car elle joue un rôle crucial pour les communautés piscicoles des milieux lacustres et constitue la première zone affectée par les variations du niveau de l’eau. L’étude se décompose en quatre parties. La première présente les caractéristiques du site d’étude et la seconde décrit l’impact des variations du niveau de l’eau sur les habitats à partir d’une analyse cartographique de la zone littorale. Les conséquences de la contrainte hydrologique via les modifications des conditions d’habitats ont été ensuite analysées en parallèle des effets de la température de l’eau et de la photopériode. Ensuite, la troisième partie présente l’effet de la variabilité temporelle des conditions environnementales, induites par les variations du niveau de l’eau, sur la composition de la communauté littorale (échantillonnage par pêche électrique). Un système innovant de positionnement par télémétrie acoustique (Vemco Positioning System) a finalement permis dans une quatrième partie d’étudier cet impact à un niveau individuel en analysant le comportement de 90 individus de trois espèces différentes (sandre, brochet et perche commune) avec une précision satisfaisante (erreur moyenne de 3.3 m après filtration). Nous avons mis en évidence que les fluctuations du niveau de l’eau induisent une variabilité temporelle de la surface et du volume occupés par la zone littorale. De plus, une diminution progressive de la complexité structurelle des habitats littoraux avec une tendance à l’homogénéisation (dominance des substrats fins et de l’absence de végétation) est observée suite à un abaissement du niveau de l’eau. Malgré ces changements des conditions d’habitats induites par les variations du niveau de l’eau, la communauté piscicole littorale n’a pas montré de nets changements de composition. Une forte variabilité inter individuelle des réponses comportementales aux fluctuations environnementales est notée mais, la température et la photopériode représentent deux paramètres structurant majeurs de l’activité et du choix des habitats. Le niveau d’eau affecte une partie du peuplement, certains individus fréquentent davantage la zone littorale et sont moins mobiles lorsque les habitats accessibles en bordure sont plus complexes (niveau d’eau élevé). Ces résultats ont permis de proposer quelques pistes de réflexion sur la gestion des niveaux d’eau sur cette retenue, en lien avec le peuplement de poissons. / Aquatic ecosystem functioning in human-impacted environments is highly dependent of its uses; in consequence, the environment of biological communities is generally fluctuating. Studying the link between environment and organism in fluctuating environments is generally more complex compared to steady environments. The main objective of this work was to better understand how fish populations respond to environmental modifications in a reservoir affected with water level fluctuations (WLF), the Bariousses’s reservoir located on the Vézère River.A multiscale approach was used with different biological (community and individual) and temporal (annual and daily cycles) scales. A special attention was given to the littoral zone as it plays a key role for lake fish communities and since it is strongly affected by WLF. This work is divided in 4 parts. The first part presents the characteristics of the study site and the second part describes the impact of WLF on the studied habitats using a mapping of the littoral zone. The consequences of hydrological stress through the changes in habitat conditions were also analyzed as well as the effects of water temperature and photoperiod. The third part shows the effect of the temporal variability of environmental conditions induced by WLF on the composition of the littoral fish community (sampled by electrofishing). The fourth part presents an innovative positioning system acoustic telemetry (Vemco Positioning System) that was used to study the impact of WLF at the individual scale by analyzing the behavior of 90 individuals from three different fish species (pikeperch, pike and perch) with a satisfactory accuracy (average error of 3.3 m after filtration).The results of this work showed that WLF induced a temporal variability of the littoral zone surface and volume. In addition, a gradual decrease of the structural complexity of littoral habitats was associated with lower water level inducing a trend to homogenization (dominance of thinner substrates without vegetation). Despite these changes in habitats conditions induced by WLF, littoral fish community did not show any clear change in composition. High inter-individual variability of behavioral responses was observed in response to environmental fluctuations, but the temperature and photoperiod were the two major structural parameters controlling fish activity and spatial distribution. Water level affected a part of the fish population since more individuals attended the littoral zone and were less mobile when available habitats were more complex (with a high water level). These results allowed us to suggest some ideas for the management of water levels in the studied reservoir focused on the fish population.

Submitted by (edna.saturno@ufrpe.br) on 2017-02-15T15:31:59Z No. of bitstreams: 1 Lucas Brainer de Carvalho.pdf: 2127247 bytes, checksum: 494ab9eb5e7aefab43af3c982cc03d23 (MD5) / Made available in DSpace on 2017-02-15T15:31:59Z (GMT). No. of bitstreams: 1 Lucas Brainer de Carvalho.pdf: 2127247 bytes, checksum: 494ab9eb5e7aefab43af3c982cc03d23 (MD5) Previous issue date: 2010-05-03 / Variations in water physical and chemical characteristics are more frequent in reservoirs located in semi-arid regions where rainfall is seasonal, as the Pedra reservoir. This study evaluated the influence of multi-annual inflow of the Contas River on limnological variables of Pedra reservoir and its relation with reservoir´s water level. Quarterly samples were taken in eleven stations between 2005 and 2007, during the wet and dry seasons and significant differences were analyzed using the Kruskal-Wallis test for variables (pH, conductivity, dissolved oxygen, temperature, euphotic zone, nitrate, nitrite, turbidity, inorganic phosphate, total phosphate, total phosphorus, water level, rainfall and inflow). All variables showed significant differences (p <0.05), with the exception of nitrite, turbidity, and inorganic phosphate. A principal component analysis (PCA) was performed for each month, including data for the three years. Nutrients´ concentrations showed higher values, when water level presented lower values. The PCA showed that variables presented no similar seasonal pattern, but formed distinct monthly clusters for each year, with different determining variables, such as nutrients in 2005, euphotic zone, pH and conductivity in 2006, and water level, rainfall and inflow in 2007. / Variações nas características físicas e químicas da água são mais freqüentes em reservatórios localizados em regiões semi-áridas, onde o período de chuvas é sazonal, como no reservatório de Pedra. Este trabalho avaliou plurianualmente a influência da vazão afluente do rio de Contas sobre variáveis limnológicas do reservatório de Pedra e sua relação com a cota do reservatório. Foram realizadas coletas trimestrais em onze estações de coletas, entre 2005 e 2007, durante os períodos seco e chuvoso, e as diferenças significativas foram analisadas através do teste de Kruskal-Wallis para as variáveis (pH, condutividade elétrica, oxigênio dissolvido, temperatura, zona eufótica, nitrato, nitrito, turbidez, fosfato inorgânico, fosfato total, fósforo total, cota, chuva e afluência) As variáveis apresentaram diferença significativa (p < 0,05), com exceção do nitrito, turbidez e fosfato inorgânico. Uma análise de componentes principais (ACP) foi realizada para cada mês, envolvendo os três anos. As concentrações dos nutrientes apresentaram valores elevados quando o reservatório apresentava as menores cotas. A ACP mostrou não existir um padrão sazonal semelhante para as variáveis, geralmente apresentando agrupamentos distintos para cada ano, com variáveis determinantes distintas, sendo nutrientes em 2005, zona eufótica, pH e condutividade em 2006, e cota, afluência e chuva em 2007.

In this study, the factors influencing zooplankton community structure in Turkish shallow lakes were elucidated with four main approaches: (i) space-for-time substitution for shallow lakes using snap-shot sampling in 31 lakes along a latitudinal gradient / (ii) in-situ mesocosm experiments in eleven lakes along a latitudinal gradient using three sets of artificial plants systems / (iii)&lsquo / Habitat Choice&rsquo / laboratory experiments mimicking a &lsquo / shallow littoral&rsquo / zone with plants and a &lsquo / deeper pelagic&rsquo / zone with sediments testing the response of Daphnia magna to predation cues / and (iv) long-term monitoring data (1997-2011) from two interconnected lakes. Snap-shot and long-term monitoring showed that eutrophication has a strong influence on the zooplankton community via increased fish predation, nutrient loading and salinization. Here too the zooplankton community shifted towards a smaller sized profile, especially in lakes located at lower latitudes. Moreover, The laboratory and in-situ mesocosm experiments revealed that under predation risk Daphnia preferred to hide near sediment instead of using submerged plants as a refuge. Accordingly, in-situ mesocosm experiments revealed a predation pressure induced size structure shift towards small-medium sized zooplankton and calanoid copepods. The long-term monitored lakes experienced (i) drought-induced water level drop, leading to increased salinity and eutrophication, and consequent anoxic conditions and fish kill / as well as (ii) biomanipulation in the downstream. Both conditions resulted in major reduction in the top-down control of fish and ultimate predomination by large sized Daphnia spp. Nevertheless, the excessive exploitation of lakes and ongoing warming entail Turkish shallow lakes to become more eutrophic, making this study indicative for the Mediterranean region.

Darbe nagrinėjama nusausintų pelkių degradavimas, jų hidrologinio rėžimo būklė, jo atstatymo galimybės ir pasiūlymai. Analizuojami ir įvertinami pelkių renovacijos būdai. Pelkių tyrimams buvo panaudota specializuota šiems darbams technika ir įprasta mokslinių tyrimų metodika. Geologiniams tyrimams naudotasi pelkių zondu, hidrologiniams – plonasieniai skydai, aukščių ir vietų nustatymui – nivelyras ir GPS įranga. Atlikus tyrimus ir išanalizavus gautus duomenis, buvo atliktas rezultatų įvertinimas. Didžiausią įtaką aukštapelkių būklei turi sausinimo poveikis. Visų trijų nagrinėjamų pelkių hidrologinis rėžimas yra pažeistas, degraduoja aukštapelkinė ekosistema, nyksta durpių klodai, kyla gaisrai, gresia pelkinės bioįvairovės rūšių išnykimas. Hidrologinio rėžimo atkūrimas būtų geriausia priemonė sustabdyti pelkių degradavimą. Todėl būtina sustabdyti pelkių sausinimą. Grioviuose įrengti užtvankas, kurios sudarytų sąlygas pakelti vandens lygį aukštapelkėse. / The study researches into the degradation of drained bogs, the status of their hydrological regime, possibilities and proposals concerning its restoration. The methods of bog renovation are analysed and evaluated. In the bog research, specialized technical means of this area and the usual scientific research methodology were employed. The following equipment was used: bog probe in geological research, thin-walled screens in hydrological research, levelling instrument and GPS equipment for the determination of altitudes and location. After research and analysis of the data obtained, the evaluation of results was carried out. The effect of draining has the biggest impact on upland bogs. The hydrological regime of all three bogs considered in the study is affected negatively, the upland bog ecosystem is under degradation, peat layers are diminishing, fires emerge, there is a threat of extinction of various species making up the bog biological diversity. The restoration of the hydrological regime would be the best measure to stop bog degradation. Therefore, bog drainage has to be stopped. Dikes should be constructed in trenches in order to form conditions to lift the water level in upland bogs.

The aim of this thesis is to evaluate developement of selected lakes in area Základna in upper Lužnice basin. The area of interest is located in nature reservation Horní Lužnice, which extends from state border with Austria to Suchdol nad Lužnicí. This part of the river is very preserved almost without any anthropogenic influence. Eventhough it is the middle part of the river, it has developed floodplain with meandering belt, which is typical for lower parts of rivers. Because of its conditions, this area is very convenient for observing natural spills and studying fluvial lakes, which occure here in huge amount. First part of this work describes characteristic of the study area, fluvial lakes and natural spills and floods in the area. The main second part focuses on research of selected lakes and their developement. During several field researches the lakes were mapped and measured and soil samples were taken from the lake beds. Furthermore flow in floodplain during river spill was measured and data from automatic surface level sensors were evaluated, which show mutual connections of fluctuations of the lakes and the river. In conclusion the results of measurement were compared with previous theses regarding this area. Main results are that common spills cause clogging of lakes but intense floods...