<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>

<p>Housing construction very close to the lake Mälaren has become very popular today. One potential problem with these houses is the influence of the sea climate. Unprotected buildings are affected by strong winds and precipitation. So for that reason, it is very important to make an accurate climate investigation and use it for decision-making during the planning of the new settlement.</p><p>It is very important with a good moisture protection regarding pelting rain, that is the combination of wind and rain. This is more important for buildings close to a lake, as this location normally means a higher exposure to wind. The location of the main bodies of the houses has an effect on the wind force between the houses. Some house parts are affected more than other, for instance curtain walls, bays, balconies and so on. These are problematic because of water and moisture that are moving in into joints and cavities in connections.</p><p>Bigger efforts than climate investigations are needed to get rid of the moisture problem.</p><p>The different actors that are involved in the construction project need to cooperate and focus on potential moisture problems during the complete construction process, not only during the production phase. It is also important that the construction workers have the knowledge on how to construct buildings that are moisture safe in practice.</p><p>According to investigations made, it appears that many of the moisture damages in buildings originate from the production phase because of incorrect construction components that are moisture-sensitive. But approximately 50% of the moisture problems derive from the planning process. The reasons are mainly lack of easily available tools, (for instance descriptions of moisture protection), insufficient knowledge, lack of time and lack of interest. These early mistakes results in later problems during the production phase. It is of great importance that the project members have good communication with the building contractors. They need to inform them on how to calculate dry times for different construction components and what type of inspections that shall be performed.</p>

<p>The aim of this thesis was to determine whether there has been a trend of increasing or decreasing water colour, absorbance, in Lake Mälaren during the last 35 years and whether it could be correlated with water discharge. The discharge was accounted for using regression analysis. The data material was analyzed for trends using a nonparametric test, the so-called seasonal Mann- Kendall test. The regression model could only account for a small (maximum of 24%) variation due to discharge. Thisindicates that discharge single-handedly can not explain the variation in absorbance. The trend analysis indicated a significant yearly increase in absorbance of 0.93% - 2.43% yr-¹ for three out of four investigated sub-basins, namely, Galten, Ekoln and Skarven. This strongly implies that there has been an increase of absorbance and a change in the amount of organic material in Lake Mälaren during the last 35 years.</p>

The former Viking settlement Birka is located on Björkö Island in Lake Mälaren, the third largest lake in Sweden. Birka is a well-known archeological site that onshore has been carefully examined. The lake floor of the waters surrounding the island has been less investigated but has a great potential to host not yet discovered archeological objects from this former hub for seafarers. Therefore, a geophysical survey including multibeam sonar mapping and subbottom profiling was carried out mainly along the shores of western Björkö Island. Processing and analysis of these collected data form the basis of this thesis. The main aims of this study are to produce a suite of geological maps and stratigraphic profiles that are used to geologically interpret the uppermost sediment stratigraphy and the bathymetry of the area. In addition, the processed data are investigated for archeological objects. The result shows that the acoustic records of the sediment stratigraphy reaches back to glacial clay formed as a consequence of the retreat of the Late Weichselian ice sheet, and that the uppermost sediment units probably are from the time after the isolation of Lake Mälaren from the Baltic Sea. The bathymetry and backscatter results have revealed that this relatively shallow study area contains several objects that potentially could be of interest from an archeological point of view. These objects include several unidentified objects in the Björkö strait and two unregistered shipwrecks where ground truthing data need to be collected to determine their respective origin.

Housing construction very close to the lake Mälaren has become very popular today. One potential problem with these houses is the influence of the sea climate. Unprotected buildings are affected by strong winds and precipitation. So for that reason, it is very important to make an accurate climate investigation and use it for decision-making during the planning of the new settlement. It is very important with a good moisture protection regarding pelting rain, that is the combination of wind and rain. This is more important for buildings close to a lake, as this location normally means a higher exposure to wind. The location of the main bodies of the houses has an effect on the wind force between the houses. Some house parts are affected more than other, for instance curtain walls, bays, balconies and so on. These are problematic because of water and moisture that are moving in into joints and cavities in connections. Bigger efforts than climate investigations are needed to get rid of the moisture problem. The different actors that are involved in the construction project need to cooperate and focus on potential moisture problems during the complete construction process, not only during the production phase. It is also important that the construction workers have the knowledge on how to construct buildings that are moisture safe in practice. According to investigations made, it appears that many of the moisture damages in buildings originate from the production phase because of incorrect construction components that are moisture-sensitive. But approximately 50% of the moisture problems derive from the planning process. The reasons are mainly lack of easily available tools, (for instance descriptions of moisture protection), insufficient knowledge, lack of time and lack of interest. These early mistakes results in later problems during the production phase. It is of great importance that the project members have good communication with the building contractors. They need to inform them on how to calculate dry times for different construction components and what type of inspections that shall be performed.

This study starts from the perspective of a future increase availability of water quality data at the water treatment facility at Lovön and aims to use the existing data to identify a pattern in the role of the different sub-basin that constitute the Mälaren basin. The data are analyzed with the graphical tool of the scatterplot and a Non-linear Canonical Correlation Analysis, a variation of the classical multivariate method, that by using a neural network model is able to handle not linear relationships. From the data analysis, it is possible to identify that different areas have different contribution in shaping the water quality at the facility of Lovön, but also that this pattern of contribution is strongly affected by the season inside the analyzed year.

The aim of this thesis was to determine whether there has been a trend of increasing or decreasing water colour, absorbance, in Lake Mälaren during the last 35 years and whether it could be correlated with water discharge. The discharge was accounted for using regression analysis. The data material was analyzed for trends using a nonparametric test, the so-called seasonal Mann- Kendall test. The regression model could only account for a small (maximum of 24%) variation due to discharge. Thisindicates that discharge single-handedly can not explain the variation in absorbance. The trend analysis indicated a significant yearly increase in absorbance of 0.93% - 2.43% yr-1 for three out of four investigated sub-basins, namely, Galten, Ekoln and Skarven. This strongly implies that there has been an increase of absorbance and a change in the amount of organic material in Lake Mälaren during the last 35 years.

Klimatförändringarnas påverkan på östra Mälaren undersöktes för att bättre kunna förstå framtida risker för dricksvattenproduktionen i Görväln. Genom att analysera tidigare forskning och vattenkvalitetsdata mellan åren 1968 och 2024, identifierades olika trender med avseende på bland annat temperatur, istäckta dagar, syrgashalt, näringsämnen, växtplankton och olika miljögifter. Utmaningarna är många där varmare klimat kan leda till bland annat tidigare skiktning, syrebrist, isfria vintrar och tillväxt av växtplankton. Även en prognosticerad befolkningsökning runt Mälaren kan bland annat leda till ökande mängd miljöföroreningar och övergödning på höst och vår. Klimatförändringarna förväntas öka yttemperaturen i Görväln men dess påverkan på temperaturen i djupet är inte lika tydlig. En starkare skiktning har observerats, vilket kan leda till låga syrgashalter vid botten, men på grund av Görvälns korta omsättningstid (0,4 år) kan det tänkas att dess påverkan på vattenkvaliteten är marginell. Växtplanktonbiomassan har varierat över tid i Görväln, med en minskning mellan 1968 och 1997 följt av en ökning, som sammanfaller med en höjd vattenmedeltemperatur. Generellt är biomassan högre i Ekoln än i Görväln och Prästfjärden, men även cyanobakteriermängden och totalfosfor är högre för Ekoln. Miljöföroreningarna arsenik, bly och benso(a)pyren visar nästan inga signifikanta trender på grund av begränsad data, men halterna borde ha minskat enligt nationella trender. Framtidens klimatförändringar har påverkat och kan komma att påverka Mälarens vattenkvalitet och därmed utmana dricksvattenreningen för befolkningen runt Mälaren.

In this ethnographic study, I explore the ways, in which the engagement of Polish Catholics with Swedish society generates both adaptation and resistance. The thesis begins with an overview of the history of the Swedish Catholic Church and notes how Poles became one of the most numerous immigrant groups in Sweden during past decades. I then make use of fifteen in-depth interviews along with more than twenty sessions of observation in a Polish milieu in the Mälaren Valley. Polish Catholics often consider themselves, as one put it, as "weird creatures" in Sweden, not only for being a religious minority, but also due to conflicts between Catholic moral teachings and prevailing modern liberal views in Swedish society. Also, interviewees tend to blame Sweden for weakening the religiosity of their compatriots. Catholicism often presents particular challenges for the adaptation and integration of Poles, especially teenagers, who are, as one out it, seen "like freaks here". Also notable is the controversial stance of parishioners and the clergy on gender questions. While many laity see feminism as a threat, some priests assert that "feminism and Catholicism have so much in common". Among other challenges for the religious life of Poles in Sweden are consumerism, which leads to the formulation "prosperity destroys people" and is seen as a competitor to the church; and the Swedish language, which divides first and second generations. Interviewees also express shared interests with Muslims and solidarity with Orthodox Christians.

Future climate in temperate regions is projected to get warmer and in many cases wetter. This poses questions about how phytoplankton in our lakes will respond. A dynamic modeling approach based on an allometric description of phytoplankton characteristics was used to investigate how the biomass of different functional groups of phytoplankton will respond to a changed future climate. Simulations based on a warmer future climate scenario suggest that we will experience an increase in phytoplankton biomass in northern temperate lakes. Moreover, phytoplankton groups are projected to shift towards a dominance of cyanobacteria at the expense of diatoms. Climate may affect phytoplankton, either via in-lake changes in temperature and stratification, or due to altered processes at the watershed level, which influence rates of nutrient export and water discharge. This study found that changes in lake temperature and stratification are the major causes of the projected increase in phytoplankton biomass, but that changes in the timing of nutrient export did influence the succession of diatoms. Variation in SPIM (suspended particulate inorganic matter) can have an important role in influencing the depth of the euphotic zone in a turbid lake, and hence the light climate experienced by phytoplankton. Wind and river discharge were found to regulate SPIM in this study, not only wind as in many other studies. Variations in SPIM could be adequately described by a few governing equations. This thesis suggests that, as a result of climate change, lakes close to the limit of becoming eutrophied may be pushed past a threshold beyond which water quality problems will become more prevalent. Finally it is important to bear in mind that all models are simplifications of the reality as we understand it. Still, the use of models can often give a good indication as to what might be expected in the future.