Climate change effects are getting more evident year by year. Athens is specially affected by climate change related shocks, especially by poor air quality, flooding and heat waves. Every year climate shocks threatens and worsens the situation in the city. The municipality of Athens, together with the European Investment Bank and EQO-NIXUS (consulting company) have undertaken a project in order to increase the resilience and the mitigation and adaptation measures of the city, taking as case study 5 public buildings located in different areas of the centre of the city. This project is in line with the Athens Resilience Strategy drawn by the Municipality of Athens in order to integrate new ways to prepare and protect the city from future shocks and stresses. This study aims to investigate and propose mitigation and adaptation measures that could be potentially applied into the 5 selected public buildings in order to improve the energy efficiency and the resilience towards heat waves, flooding and pollution of the air. A literature review study has been performed in order to look for good practices worldwide in terms of energy efficiency and climate mitigation and adaptation in order to find the best measures that could be applied in the 5 selected buildings. Finally, a multi-criteria decision analysis has been executed to prioritise which measures result to be more relevant for each specific building. The study shows that, in overall, energy efficiency and raise of public awareness are the most relevant measures that can be potentially applied in the buildings in order to tackle the climate shocks that threatens Athens. Finally, if the measures are applied into the buildings and the resilience and energy efficiency measures are improved, this study could be replicated to other buildings of Athens in order to achieve the 2030 strategy plan set by the municipality of Athens. / Effekterna av klimatförändringen blir alltmer tydliga. Greklands huvudstad Aten påverkas exempelvis av försämrad luftkvalitet, översvämningar och värmeböljor och extrema klimatrelaterade händelser förvärrar situationen i staden. Atens kommun har tillsammans med Europeiska investeringsbanken och EQO-NIXUS (ett privat konsultföretag) genomfört ett projekt för att öka motståndskraften mot klimatförändringens effekter, genom anpassningsåtgärder, där fem offentliga byggnader i olika delar av Atens centrum studeras. Projektet är relaterat till Atens resiliensstrategi som handlar om hur staden ska integrera nya sätt förbereda och skydda staden och dess invånare från framtida extrema händelser och påfrestningar. Denna studie syftar till att undersöka och föreslå anpassningsåtgärder som potentiellt kan tillämpas i de fem olika offentliga byggnaderna för att förbättra energieffektiviteten och resiliensen mot värmeböljor, översvämningar och luftföroreningar. En litteraturstudie har genomförts för att identifiera globala, goda exempel när det gäller energieffektivitet och anpassning till ett förändrat klimat som potentiellt kan tillämpas i de fem byggnaderna. Slutligen har en multikriterieanalys med flera kriterier genomförts för att prioritera vilka åtgärder som är mest relevanta för varje specifik byggnad. Studien visar att energieffektivitet och ökning av allmänhetens medvetenhet totalt sett är de mest relevanta åtgärderna som potentiellt kan tillämpas i byggnaderna för att hantera klimatförändringar. Slutligen, om dessa åtgärder tillämpas och resiliensen och energieffektivitetsåtgärderna förbättras, skulle denna studie kunna vara relevant även för andra byggnader i Aten och därmed bidra till uppfyllelsen av stadens 2030-strategi.

Floods are becoming more frequent and the magnitude of direct consequences, relating to destruction of critical infrastructure and loss of life, has highlighted the importance of flood management. This thesis proposes a new methodology to quantify the impact of predicted and historic flooding events on emergency services. The approach moves beyond simple flood inundation mapping by accounting for the relationship between flood depth and vehicular speed. A case study was presented for Calgary Alberta, where the depths of a predicted 100-year flood and an historic 2013 flood event were modelled. The methodology applied geographic information systems (GIS) to flood depth mapping, utilizing digital elevation models (DEMs), flood extents, and hydrological data. Flood depths were then assigned to links comprising the road network, where the maximum vehicle speed was calculated as a function of the standing depth of water on a link. The flooded network was used to derive service areas for several types of emergency services (emergency medical services (EMS), fire, and police), following targeted response times. The results quantified and located the residential and work populations that no longer meet the targeted response times. During both flood scenarios, EMS were found to have the greatest reduction in accessibility, with 23% to 47% of residents and workers, respectively, not served. Fire services were seen to be more resilient with only 3% to 9% of residents and workers, respectively, not served. The results for police services were similar to fire services. However, the former have a greater range of response times, meaning these areas represent those that are completely isolated during both flood events. Overall, the proposed methodology quantified vulnerable populations on a partially degraded network, which can be used to develop evacuation plans and emergency response strategies, minimizing disturbances in the network and the number of people affected. / Thesis / Master of Science (MSc)

Soybean and wheat are important crop species due to their significance for human consumption, animal feed, and industrial use. However, increasing global population and worsening climate change have put a major strain on the production system of these crops. Natural disasters such as flooding and drought can severely impact growth and productivity of these crops. In addition, increased application of synthetic nitrogenous fertilizers to meet the global food demand has led to environment related issues. Therefore, with a goal of understanding mechanisms of flooding and drought tolerance in soybean and nitrogen-use-efficiency in wheat, we explored their physiological and transcriptomic regulation. We characterized the fundamental acclimation responses of soybean to flooding and drought and compared the metabolic and transcriptomic regulation during the stresses in a tissue-specific manner. We demonstrated the dynamic reconfiguration of gene expression and metabolism during flooding, drought, and recovery from these stresses. Our study displayed that flooding triggers more dramatic adjustments than drought at the transcriptional level. We also identified that the soybean genome encodes nine members of group VII ERF genes and characterized their responses in leaves and roots under flooding and drought. Based on the expression patterns, it is estimated that two of the nine genes are promising candidate genes regulating tolerance to submergence and drought. In addition, our genome-scale expression analysis discovered commonly induced ERFs and MAPKs across both stresses (flooding and drought) and tissues (leaves and roots), which might play key roles in soybean survival of flooding and drought. In wheat, we evaluated the effect of three different nitrogen rates on yield and its components across four diverse soft red winter wheat genotypes. The cultivar Sisson displayed superior performance in grain yield and nitrogen use efficiency at low nitrogen levels. Our results suggested that improvement of nitrogen use efficiency in low nitrogen environments can be achieved through the selection of three components: grain number/spike, 1000-seed weight, and harvest index. Overall, this study has advanced our understanding of how plants respond to abiotic stresses such as flooding, drought, and nutrient limitation conditions. / Ph. D.

Flooding has always been and is still today a disastrous event with agricultural, infrastructural, economical and not least humanitarian ramifications. Understanding the behaviour of floods is crucial to be able to prevent or mitigate future catastrophes, a task which can be accomplished by modelling the water flow. In this thesis the finite element method is employed to solve the shallow water equations, which govern water flow in shallow environments such as rivers, lakes and dams, a methodology that has been widely used for flooding simulations. Alternative approaches to model floods are however also briefly discussed. Since the finite element method suffers from numerical instabilities when solving nonlinear conservation laws, the shallow water equations are stabilised by introducing a high-order nonlinear artificial viscosity, constructed using a multi-mesh strategy. The accuracy, robustness and well-balancedness of the solution are examined through a variety of benchmark tests. Finally, the equations are extended to include a friction term, after which the effectiveness of the method in a real-life scenario is verified by a prolonged simulation of the Malpasset dam break.

Nuclear power is a foundational part of our electrical grid in the present and through our transition towards more sustainable and renewable alternatives. However, given the serious consequences of reckless and/or dangerous operation of nuclear power plants, they are subject to strict regulation and supervision by the Swedish radiation protection authority (SSM) and other regulating bodies (e.g. IAEA). In order to prove that a nuclear power plant is operating in a safe and accident preventative manner, the “Safety Analysis Report” (SAR) is created and submitted. The SAR categorizes and ranks all possible incidents and operation affecting events in terms of risk and available countermeasures to ensure that the radioactive release from the power plant and impact on a third party from any event is at acceptable levels. This projects limits its analysis to flooding of the reactor building or “internal flooding events” as described in the SAR. To determine the affected areas and impacted systems of any flooding event, deterministic safety analyses (DSA) are employed. The goal of this project is to develop a comprehensive thermohydraulic model of the Forsmark 2 reactor building and evaluate its performance with respect to the previously used MATLAB model. The model  should allow for a detailed nodalisation of the reactor building as well as realistic modelling of structural components such as doors, hatches, stairwells and drainage systems. The resulting thermohydraulic model  can be used to evaluate different flooding incidents dynamically and follow the spread of water and/or steam throughout the reactor building. Furthermore, the resulting pressure changes and heat generation in the reactor building can also be evaluated. The model allows for the possibility to couple the thermohydraulic reactor building model with the existing power plant systems model to holistically evaluate the power plant response to flooding related incidents. / Kärnkraft är en grundläggande del av vårt elnät i nuläget och under vår övergång mot mer hållbara och förnybara alternativ. Men med tanke på de allvarliga konsekvenserna av vårdslös och/eller farlig drift av kärnkraftverk, är de föremål för strikt reglering och tillsyn av Strålsäkerhetsmyndigheten (SSM) och andra reglerande organ (t.ex. IAEA). För att bevisa att ett kärnkraftverk drivs på ett säkert och olycksförebyggande sätt, upprättas och inlämnas "Strålsäkerhetsanalysrapport" (SAR). SAR kategoriserar och rangordnar alla möjliga incidenter och händelser som påverkar driften i termer av risk och tillgängliga motåtgärder för att säkerställa att radioaktiva utsläpp från kraftverket och påverkan på tredje person från någon händelse är på acceptabla nivåer. Detta projekt begränsar sin analys till översvämning av reaktorbyggnaden eller "interna översvämningshändelser" enligt beskrivningen i SAR. För att fastställa de påverkade områdena och drabbade systemen vid en översvämningshändelse, används deterministiska säkerhetsanalyser (DSA). Målet med detta projekt är att utveckla en omfattande termohydraulisk modell av Forsmark 2 reaktorbyggnad och utvärdera dess prestanda i förhållande till den tidigare använda MATLAB-modellen. Modellen ska möjliggöra en detaljerad nodalisering av reaktorbyggnaden samt realistisk modellering av strukturella komponenter som dörrar, luckor, trapphus och dräneringssystem. Den resulterande termohydrauliska modellen kan användas för att dynamiskt utvärdera olika översvämningsincidenter och följa spridningen av vatten och/eller ånga genom reaktorbyggnaden. Dessutom kan de resulterande tryckförändringarna och värmegenereringen i reaktorbyggnaden också utvärderas. Modellen möjliggör koppling av den termohydrauliska reaktorbyggnadsmodellen med den befintliga kraftverkssystemmodellen för att holistiskt utvärdera kraftverkets respons på översvämningsrelaterade händelser.

Utbyggnation av städer och allt större andel hårdgjorda ytor leder till problem med dagvattenhanteringen. Flödena blir snabbare samtidigt som större mängder än tidigare bildar avrinning och då är det viktigt att de befintliga systemen klarar av att hantera dem. Dagvatten från tak och hårdgjorda ytor och dräneringsvatten från källarfastigheter kan vara kopplat till spillvattennätet och leda till att vattenflödena i ledningarna vid stora regn kan bli betydligt större än de är dimensionerade för, med kapacitetsproblem som följd. En lösning som många VA-huvudmän har implementerat är att använda öppna dagvattenlösningar istället för att välja det mer kostnadskrävande alternativet att bygga ut ledningssystemet. Att koppla om stuprör, brunnar och dräneringsledningar och gräva diken för att leda om vattnet är både kostnads- och resurskrävande. Syftet var därför att undersöka om multikriterieanalys kan fungera som ett lämpligt verktyg för att allokera resurserna till de områden som ger mest nytta per satsad krona. Detta genom att ta fram en metodik för detta syfte och testa dess robusthet för att avgöra om den är lämplig att applicera eller om osäkerheterna i parametervärdena blir för stora för att några slutsatser ska kunna dras. Metodiken som togs fram testades på Bjursås, ett litet samhälle två mil utanför Falun, eftersom omfattande utredningar gjorts i området tidigare, vilket innebar att mycket data fanns att tillgå. Undersökningar gjordes av var mängderna kunde förväntas bli stora, var det fanns stor risk för källaröversvämningar och vilka områden som bidrog mest till bräddningar. Detta utvärderades tillsammans med förväntade åtgärdskostnader och en samlad bedömning gjordes av var nyttan per satsad krona bör bli störst. Stora osäkerheter återfanns i bedömningen. Slutsatsen blev att metoden kan fungera som stöd vid beslutsunderlag, men att den inte är tillräckligt robust för att kunna användas uteslutande utan att efterföljande utvärderingar och kritisk granskning av resultaten måste göras. Detta kan lämpligtvis ske genom en känslighetsanalys. För att resultaten ska utgöra ett användbart verktyg för VA-huvudmannen måste också kostnaderna utvärderas noggrannare än de har gjorts i den här studien. / Urbanization along with a greater amount of hardened surfaces affects the storm water management. When the flows get faster and larger amounts create runoff, it is crucial that the available systems are able to handle the water. Storm water from roofs and asphalt surfaces and drainage water can be connected to the sewage water pipelines and make the flows in the conduits at rainfall much greater than they are designed for, leading to capacity issues. Many municipalities have implemented open storm water solutions instead of choosing the more cost-ineffective way of expanding the conduit system. Reconnecting downspouts, wells and drainage pipelines and digging trenches to lead the water is both cost and resource demanding. Therefore the aim of this study was to investigate whether multi criteria analysis can be used as an appropriate tool in order to allocate the resources to the most beneficial areas. This was done by developing a method for this aim and testing its robustness in order to determine if it is suitable to use in this context or if the uncertainties make the method too unreliable. The robustness in the method developed can be questioned since the uncertainties can be substantial. To be able to use this method, a lot of data is needed and the method needs to be updated relatively often in order to contain relevant information. It is recommended that a sensitivity analysis is performed along with the method, since the use of only one set of parameters can make the result relatively arbitrary. Using a Monte Carlo procedure with the uncertainties defined can reduce the time needed to measure and identify the values. The sensitivity analysis showed that the parameters that have the largest impact on the results are the number of residents living in every real estate with a basement, the catchment areas, the roughness parameters of the pipelines and the use of energy and chemicals in the system. In the future, the urbanization is expected to increase as well as the amount of rainfall and problems related to inflow and infiltration are expected to become more common. The hope is that the method used and its results will be useful for the municipalities’ future planning and to inspire to more studies on this topic.

Flooding is a global challenge that has plagued mankind throughout history, affecting over 164 million people worldwide in 2007 alone. As the frequency of flooding increases in England and Wales coupled with an increase in the number of properties at risk of flooding and the attendant huge (insured) economic costs of flooding, the services received by homeowners during flood damage repair works, have not been spared criticism, Both the Welsh Consumer Council report and the Warwickshire Trading Standards report raised serious questions about the level of service in insurance claims for the repair of flood-damaged domestic property. This research project was therefore aimed at investigating the level of service quality and determinants of homeowners’ satisfaction in England and Wales with respect to flood damage repair works during insurance claims. A comprehensive literature review was conducted on customers’ needs, satisfaction and service quality, flooding and related issues, and the repair of flood damaged domestic property, in order to set the framework for the research and shape the development of the research questions/hypotheses. The study employed a two-phased sequential mixed methods approach, commencing with 20 in-depth interviews with homeowners, repairers, insurers and loss adjusters. Findings from the initial exploratory study (and from the literature review) informed the development of a questionnaire instrument, which incorporated elements of SERVQUAL, the generic service quality measurement instrument. Survey data were collected for the quantitative phase of the study from a sample of 126 homeowners, which was then analysed to test the hypotheses put forward in the study. The data did not yield a set of reliable and interpretable factors of service quality from the three service quality scales used to measure homeowners’ perceptions of the performance of insurers, loss adjusters and contractors. However, of the three key service providers, the contractor’s performance was the best predictor of homeowners’ overall satisfaction during flood damage reinstatement claims, accounting for seven times the combined unique contribution of insurance and loss adjusting firms. In addition, satisfaction levels were significantly different for homeowners whose claims for repair works were completed within six months compared to those repairs exceeded twelve months. The thesis concludes with implications of the findings for practice as well as recommendations for further research. It is argued that knowledge of the determinants of homeowners’ satisfaction with services during the repair of flood damaged property, is beneficial not only to insurers, loss adjusters and repairers but to homeowners as well.

Summary: Floristic, Ecological and Phytosociological, Study of the Forests of the Mbiye Island at Kisangani, DR Congo The Mbiye Island is situated on the Congo River, in the Eastern part of Kisangani. It is located upstream of the Wagenia Falls, between latitude 0º31’ North and longitude 25º11’ East, with 376 m of altitude. It adjoins the town of Kisangani, and it is 14 km long and 4 km wide. All around Kisangani, the Mbiye Island is the only ecosystem which has a dense forest that is relatively well preserved. This Island has an area of 1,400 ha, and it comprises three types of forest: dry land forest, periodically flooded forest and swampy forest. The main purpose of this study has been to make a qualitative and quantitative analysis of the physiognomy and structure of these three types of forest. I relied on two methods in data collecting: the Phytosociological plotting method with a sampling equal to 100 individuals for the higher strata and 100 m² grass strata, associated with dbh measure for trees whose diameter is ≥ 10 cm. In total, out of the 80 plottings, 67 multi strata and structurals each of which has been decomposed in 4 sub-plottings fit together. Based on the presence-absence criterion, the other 13 multi strata and structurals have been made into Chablis, and all the data have been globally analyzed. An inventory of 33991 individuals has been made in this study. After their identification, it has been found out that there 470 species belonging to 297 types and 90 families. Rubiaceae, Caesalpiniaceae and euphorbiaceae families have been found out to be the most important in Genus and species. In the raw spectra of biological types, the phanerophyts (83.0%) are the most predominant, and within which the mesophanerophyts (trees 10 to 30 m tall in their old age) are the most predominant (39.0%). The Phytogeographical spectra have more omni-guineo-congolese (35%) elements; and amongst the diaspore types, the sarcochores (69%) are the most predominant. 58 endemic species (12.3%) of the central forest sector have been found out at the Mbiye Island. After the classification and ordination of the 80 plottings by Twinspan and DCA, three Phytosociological groupings have been found out in the dry land forest: (1) grouping of Funtumia elastica and Albizia ealaensis, (2) grouping of Nesogordonia leplaei and Antiaris toxicaria, (3) prouping of Olyra latifolia and Campylospermum elongatum; two others for floodable forests (1) grouping of Rinorea oblongifolia and Byrsocarpus coccineus, (2) grouping of Pachystela seretii, Dracaena kindtiana and Culcasia yangambiensis, and three others for swampy forests: (1) grouping of Strombosia grandifolia, Calamus deerratus, Culcasia angolensis and Elaeis guineensis, (2) grouping of Cleistopholis patens and Pterygota bequaertii, (3) grouping of Diospyros bipendensis, Strychnos icaja and Palisota barteri and then two groupings for the Chablis plottings (1) grouping of Palisota schweinfurthii, Eremospatha haullevilleana, Thomandersia hensii and Pycnocoma insularis and (2) grouping of Nephrolepis biserrata and Scaphopetalum thonneri. The coelocaryon botryoides has shown a uniform spatial distribution in the in the forest periodically flooded, whereas Gilbertiodendron dewevrei has shown an aggregated distribution. Comparison of richness in different taxa within the sampling has given high values as far as the numbers of species is concerned and genus of the same family in the phytosociological sampling. Out of all the species listed, 189 have been considered to be common species with regard to the three forest types, other 144 belonged to two types. 90 species have been listed only on solid land, 27 on periodically flooded forest 20 on swampy forest. Euphorbiaceae, Rubiaceae and Caesalpiniaceae families were the best represented in species and genus. With regard to richness in each forest type, the forest of solid soil was the only one to have high values both in species and genus, and the swampy forest was less represented. With reference to richness according to strata, the herbaceous and under-shrub stratum (H) was the richest whereas the stratum of dominant trees (E+A1) was the poorest. Mbiye island forest is the nearest one of Kisangani for which it plays the most important role with regards to supplies in different forest products and non-ligneous forest products. In total, 12.3% endemic species of Central forest sector have been listed there, but due to frequent use by man this time, all these endemic species may disappear from this island. It is therefore urgent that particular attention be paid on it. Actions of conservation and lasting exploitation must be started in order to block their extinction. Key words: DRCongo, Flora, Ecology, Phytosociology, insularity, flooding, spatial distribution, biodiversity, synusie, Mbiye Island, Kisangani./Résumé : Etude floristique, écologique et phytosociologique des forêts de l'île Mbiye, Kisangani, RDCongo. L'île Mbiye est une île du fleuve Congo située dans la partie Est de la ville de Kisangani, en amont des chutes Wagenia, entre 0° 31' de latitude Nord et 25° 11' de longitude Est, avec une altitude de 376 m. Elle jouxte la ville de Kisangani et sa longueur maximale est de 14 km sur 4 km de largeur. Elle est le seul écosystème à proximité de la ville, possédant encore une forêt dense relativement bien conservée et formant un îlot de 1400 ha comprenant trois types forestiers : la forêt de terre ferme, la forêt périodiquement inondée et la forêt marécageuse. L’objectif principal de cette étude a été de faire une analyse quantitative et qualitative de la physionomie et la structure de ces trois types forestiers. Deux méthodes ont permis la récolte de données ; la méthode de relevés phytosociologiques à effort d’échantillonnage égal à 100 individus pour les strates supérieures et 100 m² pour la strate herbacée, associée à celle de mesure de D130, pour les arbres à diamètre ≥ 10 cm. Au total, 80 relevés dont 67 multistrates et structurels, décomposés chacun en 4 sous-relevés emboîtés, ont été mis en place. 13 autres ont été faits dans les chablis avec l’appréciation basée sur le critère de présence-absence et toutes les données ont été analysées globalement. A l’issue de cette étude, 33991 individus ont été recensés. Après leur identification, au total 470 espèces appartenant à 297 genres et 90 familles ont été obtenues. Les familles des Rubiaceae, des Caesalpiniaceae et des Euphorbiaceae sont les plus importantes, tant en genres qu’en espèces. Dans les spectres bruts de types biologiques, les phanérophytes (83,0 %) sont les plus abondants et au sein desquels les mésophanérophytes (arbres de 10 à 30 m au stade adulte) sont les plus dominants (39,0 %). Les spectres phytogéographiques ont montré une prédominance d’éléments omni-guinéo-congolais (35 %) alors que parmi les types de diaspores, les sarcochores (69 %) sont les plus dominants. 58 espèces endémiques du Secteur forestier central (soit 12,3 %) ont été recensées à l’île Mbiye. Après classification et ordination de ces 80 relevés par Twinspan et DCA, trois groupements phytosociologiques ont été obtenus dans la forêt de terre ferme: (1) groupement à Funtumia elastica et Albizia ealaensis, (2) groupement à Nesogordonia leplaei et Antiaris toxicaria, (3) groupement à Olyra latifolia et Campylospermum elongatum ; deux autres pour les forêts inondables (1) groupement à Rinorea oblongifolia et Byrsocarpus coccineus, (2) groupement à Pachystela seretii, Dracaena kindtiana et Culcasia yangambiensis ; trois autres encore pour les forêts marécageuses : (1) groupement à Strombosia grandifolia, Calamus deerratus, Culcasia angolensis et Elaeis guineensis, (2) groupement à Cleistopholis patens et Pterygota bequaertii, (3) groupement à Diospyros bipendensis, Strychnos icaja et Palisota barteri, et enfin, deux groupements pour les relevés de chablis (1) groupement à Palisota schweinfurthii, Eremospatha haullevilleana, Thomandersia hensii et Pycnocoma insularum et (2) groupement à Nephrolepis biserrata et Scaphopetalum thonneri. L’espèce Coelocaryon botryoides a montré une répartition spatiale uniforme dans la forêt périodiquement inondée alors que Gilbertiodendron dewevrei y a montré une répartition agrégée. La comparaison de la richesse en différents taxa au sein de relevés et de placettes a donné de valeurs supérieures en nombre d’espèces, de genres et même de familles, dans les relevés phytociologiques. Sur le total des espèces recensées, 189 ont été considérées comme espèces communes aux trois types forestiers, 144 autres appartenaient aux deux types. 90 espèces n’ont été recensées qu’en forêt de terre ferme, 27 en forêt périodiquement inondée et 20 dans la forêt marécageuse. Les familles des Euphorbiaceae, des Rubiaceae et celle des Caesalpiniaceae ont été les mieux représentées en espèces et en genres. En ce qui concerne la richesse dans chaque type forestier, la forêt de terre ferme était la seule à avoir des valeurs supérieures tant en espèces qu’en genres et la forêt marécageuse était la moins représentée. Quant à la richesse spécifique selon les strates, la strate herbacée et sous-arbustive (H) était la plus riche alors que la strate des arbres dominants (E+A1) était la plus pauvre. La forêt de l’île Mbiye est la seule forêt proche de la ville de Kisangani pour laquelle elle joue un rôle de premier plan en ce qui concerne le ravitaillement en différents produits forestiers et forestiers non ligneux. Au total, 12,3% d’espèces endémiques du Secteur forestier Central y ont été recensées, mais vue l’action anthropique qu’elle connaît ce dernier temps, toutes ces espèces endémiques risquent de disparaître de cette île. Il est alors urgent qu’une attention particulière, soit tournée vers elle. Des actions de conservation et d’exploitation durable doivent être amorcées en vue contrecarrer l’extinction des celles-ci. Mots clés : RDCongo, flore, écologie, phytosociologie, insularité, inondation, répartition spatiale, biodiversité, synusie, île Mbiye, Kisangani.

Models of climate change predict that temperature will increase during the 21th century and the largest warming will take place at high northern latitudes. In addition to warming, predictions for northern Europe include increased annual precipitation and a higher proportion of the precipitation during winter falling as rain instead of snow. These changes will substantially alter the hydrology of rivers and streams and change the conditions for riverine communities. The warming is also expected to result in species adjusting their geographic ranges to stay within their climatic tolerances. Riparian zones and wetlands are areas where excess water determines the community composition. It is therefore likely that these systems will be highly responsive to alterations in precipitation and temperature patterns. In this thesis we have tested the predicted responses of riparian vegetation to climate-driven hydrologic change with a six year long transplant experiment (I). Turfs of vegetation were moved to a new elevation with shorter or longer flood durations. The results demonstrate that riparian species will respond to hydrologic changes, and that without rare events such as unusually large floods or droughts, full adjustment to the new hydrological regime may take at least 10 years. Moreover, we quantified potential effects of a changed hydrology on riparian plant species richness (II) and individual species responses (III) under different climate scenarios along the Vindel River in northern Sweden. Despite relatively small changes in hydrology, the results imply that many species will become less frequent than today, with stochastic extinctions along some reaches. Climate change may threaten riparian vegetation along some of the last pristine or near-natural river ecosystems in Europe. More extensive loss of species than predicted for the Vindel River is expected along rivers in the southern boreal zone, where snow-melt fed hydrographs are expected to be largely replaced by rain-fed ones. With a seed sowing experiment, we tested the differences in invasibility between open wetlands, forested wetlands and riparian zones (IV). All six species introduced were able to germinate and survive in all habitats and disturbance levels, indicating that the tested wetlands are generally invisible. Germination was highest in open wetlands and riparian zones. Increasing seed sowing density increased invasion success, but the disturbance treatments had little effect. The fact that seeds germinated and survived for 2 to 3 years in all wetland habitats indicates that wetland species with sufficiently high dispersal capacity and propagule pressure would be able to germinate and establish here in their respective wetland type. Our results clearly demonstrate that a changed climate will result in substantial changes to functioning, structure and diversity of boreal wetland and riparian ecosystems. To preserve species rich habitats still unaffected by dams and other human stressors, additional protection and management actions may have to be considered.

Reflecting on fieldwork carried out in the UK insurance sector, the thesis explores the role played by various types of actuarial and hydrological expertise in the performance of flooding as a matter of sustained public concern. In doing so, the question is raised: what analytical status to give the concept of risk when accounting for the epistemic doings involved in bringing yet unrealised future floods to bear on the present? Contrary to most other European countries the provision of flood insurance in the UK is left to the market and organised via an agreement under which insurers pledge to provide cover in areas protected by the Government to a standard of 1:75 years (the average return period between floods). What should be taken into account when mapping out this 1:75 year flood zone is subject to debates constantly revitalised by flood events with changing characteristics as well as new ways of modelling and anticipating what has yet to take place. How should we understand the knowledge claims hardwired into these debates through the involvement of actuarial and hydrological expertise? The thesis will argue that a reorientation of flood risk away from a status as the (multiple) object of these claims towards a status as an event in which a diverse variety of other things are brought into being (maps, futures, frequencies, anxieties, publics, geographies, things which are not necessarily very well understood as risk per se), will give rise to more productive and eventful questions. In the terminology of Isabelle Stengers, to risk is to create the possibility of bringing new things to life – the risking of floods seems to be constantly exciting such creativities.