In the event of hypothetical accident scenarios in PWR, emergency strategies have to be mapped out, in order to guarantee the reliable removal of decay heat from the reactor core, also in case of component breakdown. One essential passive heat removal mechanism is the reflux condensation cooling mode. This mode can appear for instance during a small break loss-of-coolant-accident (LOCA) or because of loss of residual heat removal (RHR) system during mid loop operation at plant outage after the reactor shutdown. In the scenario of a loss-of-coolant-accident (LOCA), which is caused by the leakage at any location in the primary circuit, it is considered that the reactor will be depressurized and vaporization will take place, thereby creating steam in the PWR primary side. Should this lead to ¿reflux condensation¿, which may be a favorable event progression, the generated steam will flow to the steam generator through the hot leg. This steam will condense in the steam generator and the condensate will flow back through the hot leg to the reactor, resulting in counter-current steam/water flow. In some scenarios, the success of core cooling depends on the behaviour of this counter-current flow. Over several decades, a number of experimental and theoretical studies of counter-current gas¿liquid two-phase flow have been carried out to understand the fundamental aspect of the flooding mechanism and to prove practical knowledge for the safety design of nuclear reactors. Starting from the pioneering paper of Wallis (1961), extensive CCFL data have been accumulated from experimental studies dealing with a diverse array of conditions A one-dimensional two field model was developed in order to predict the counter-current steam and liquid flow that results under certain conditions in the cold leg of a PWR when a SBLOCA (small break loss of coolant accident) in the hot leg is produced. The counter-current model that has been developed can predict the pressure, temperature, velocity profiles for both phases, also by taking into account the HPI injection system in the cold leg under a counter-current flow scenario in the cold leg. This computer code predicts this scenario by solving the mass, momentum and energy conservation equations for the liquid and for the steam separately, and linking them by using the interfacial and at the steam wall condensation and heat transfer, and the interfacial friction as the closure relations. The convective terms which appear in the discretization of the mass and energy conservation equations, were evaluated using the ULTIMATE-SOU (second order upwinding) method. For the momentum equation convective terms the ULTIMATE-QUICKEST method was used. The steam-water counter-current developed code has been validated using some experimental data extracted from some previously published articles about the direct condensation phenomenon for stratified two-phase flow and experimental data from the LAOKOON experimental facility at the Technical University of Munich. / Romero Hamers, A. (2014). STUDY OF THE THERMAL STRATIFICATION IN PWR REACTORS AND THE PTS (PRESSURIZED THERMAL SHOCK) PHENOMENON [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/36536 / Alfresco

The environment has become the center of attention in recent years. The world is at the brink of several interrelated ‘green’ crises: environmental degradation, climate change, peak oil, food crisis, and various natural disasters. Hence, there is a viable threat to society. This essay aims to explore the significance of the environment for societal collapse—with a Western world city focus. The method of choice is a literature-based critical instance case study. In this thesis, the environmentally focused collapse theories of Jared Diamond and Clive Ponting are tested on the empirical example of the city of New Orleans, USA. In 2005, New Orleans was wrecked by Hurricane Katrina. As a result, 80% of New Orleans was flooded, almost 1,800 people lost their lives, and the infrastructural systems suffered lengthy breakdowns. Consequently, the supply of basic services such as water, food, sewage, electricity, heating, communications, transportation and shelter was severely compromised.   The study shows that in the specific case of New Orleans, the underlying reasons for collapse cannot be explained by ‘green’ collapse theories alone. In fact, poor wetlands management was the only environmental issue of importance. Contributing causes were various managerial flaws (including lack of financing) on all levels in terms of emergency prevention, preparedness and response, as well as long-term structural implications for social justice. Thus, the environmentally related theories of Diamond and Ponting do not prove a perfect match. Instead, the collapse of New Orleans had better been explained by a ‘root cause mix’ theory, which takes political, economic, social and environmental aspects into consideration. / Miljöfrågor har hamnat allt mer i fokus de senaste åren. Världen står på tröskeln till ett flertal miljörelaterade kriser: miljöförstöring, klimatförändring, peak oil (oljeproduktionstoppen), global matkris samt diverse naturkatastrofer. Detta medför sammantaget ett allvarligt hot mot samhället. Examensarbetet syftar till att belysa miljöns betydelse för samhällskollaps – med fokus på den västerländska staden. Den metod som tillämpas är en litteraturbaserad fallstudie. I uppsatsen testas Jared Diamonds och Clive Pontings miljöinriktade teorier om samhällskollaps på det empiriska exemplet New Orleans, USA. År 2005 ödelades New Orleans av orkanen Katrina. Så mycket som 80 % av staden drabbades av översvämning, 1 800 invånare omkom och hela infrastrukturen bröt samman. Katastrofen fick därmed allvarliga konsekvenser för grundläggande samhällsfunktioner som försörjningen av vatten, livsmedel, avlopp, elektricitet, värme, kommunikationer, transporter samt boende.   Studien visar att miljöorienterade teorier om samhällskollaps inte fullt ut kan förklara grundorsakerna till det sammanbrott som skedde i New Orleans. Den enda miljörelaterade orsaken av betydelse var inadekvat skötsel av våtmarkerna. Bidragande faktorer var istället bristande politisk styrning (inklusive otillräcklig finansiering) på alla nivåer vad gäller förebyggande, beredskap och hantering av kriser, samt långvariga strukturella hinder för social rättvisa. Slutsatsen blir därför att varken Diamonds eller Pontings miljöinriktade teorier träffar helt rätt. För större träffsäkerhet, borde New Orleans’ sammanbrott förklaras med en teori som förutom miljöfaktorer även innefattar politiska, ekonomiska och sociala aspekter.

Der Werkstatttag für Bestandserhaltung fand am 20. September 2012 in Tharandt statt, am Standort Forstwissenschaften der TU Dresden und der SLUB, der 2002 von den Regenfluten aus dem Erzgebirge besonders stark betroffen war. Zur Fortbildung „Kultureinrichtungen nach der Jahrhundertflut im Jahr 2002 – Rückblicke und Schlussfolgerungen“ kamen 45 Teilnehmer aus Sachsen, Berlin und Brandenburg, darunter Vertreter aus damals betroffenen Einrichtungen und den seither gegründeten Notfallverbünden, aber auch aus der vom Neiße-Hochwasser 2010 heimgesuchten Lausitz mit großen Schäden in Zittau, in Görlitz und im Kloster St. Marienthal.

With an intensification of heavy rain events in a changing climate and a rapid urbanization the risk for pluvial flooding is increasing in our societies. Pluvial flooding, which is formed when the rainfall rate exceeds the infiltration or drainage rate, can occur rapidly and cause great damages, large economic losses and possibly risk human lives. This kind of flooding is difficult to predict since it is caused by short-term and often local processes, but preventive measures and more robust infrastructure developed over the last decades have decreased the risk of the most severe damages. One way to prevent damage is to map risk areas and take measures by performing a cloudburst modelling, which can be done as a 2D hydraulic modelling. Common practice in cloudburst modelling today is to use a uniform design storm, often the Chicago Design Storm (CDS), with the same hyetograph applied evenly over the whole model area. Even though rain is not spatially uniform this assumption might be valid for more stratiform frontal rain. Intense rain events however have a higher spatial variation in rain intensity, and an assumption like this might significantly affect the results. This study aimed to investigate the effect of the spatial variation in rain intensity on the modelled hydraulic response from an intense rain event. It was performed through a case study of the cloudburst in Gävle, Sweden, in August 2021. A 2D hydraulic model of the city was prepared in the software MIKE 21 Flow Model FM and the cloudburst event was simulated with a spatially varied rainfall input, based on radar data from the event with a 2x2 km resolution, and with spatially uniform rainfall input both with the temporal variation in rain intensity from the event and with a Chicago Design Storm, all with the same total volume. The scenarios were evaluated in terms of proportion of the model area being flooded, the average maximum flooding depth and by mapping the difference in flooding depth over the whole area. The results showed that the spatial variation of rainfall input had a significant effect on the hydraulic response in the city and that assuming a uniform rainfall might lead to an underestimation of the flooding depths in parts of the model area compared to a varied one. The average flooding depth was only a few percent higher for the spatially varied rain compared to the uniform rain with a similar time variation, but in large central areas of the city the model with the uniform rain underestimated the maximum flooding depth by 5-35%. The uniform CDS rain was seen to both over- and underestimate the flooding depth, but in the central and flooded parts of the city underestimation dominated. This points out a risk of using uniform design storms in cloudburst modelling, since a spatially varied rain of the same volume could give more severe effects than the simulated response and that using a uniform design storm potentially introduces an uncertainty in the modelled results that could be important to point out and further quantify. / Med en intensifiering av häftiga regnväder i ett förändrat klimat och en allt snabbare urbanisering ökar risken för pluviala översvämningar i våra samhällen. Pluviala översvämningar, som skapas av att regnintensiteten är högre än infiltrations- eller dräneringshastigheten, kan uppstå plötsligt och orsaka stora skador, ekonomiska förluster och även i värsta fall riskera människoliv. Denna typ av översvämning är svår att förutse eftersom den orsakas av snabba och ofta lokala processer, men förebyggande åtgärder och mer robust infrastruktur som har utvecklats de senaste decennierna har minskat risken för de allvarligaste skadorna. Ett sätt att förebygga skador är att kartera riskområden genom skyfallsmodellering, till exempel med en tvådimensionell hydraulisk modell. Praxis idag är att använda spatialt uniforma typregn vid skyfallsmodellering, där samma hyetograf appliceras jämnt över hela modellområdet. Detta antagande kan ge giltiga resultat för mer stratiforma frontregn, men intensiva regn, skyfall, har generellt sett en hög spatial variation i intensiteten vilket gör att antagandet skulle kunna påverka resultatet signifikant. Denna studie syftade till att undersöka effekten av den spatiala variationen i regnintensitet på den simulerade hydrauliska responsen från ett intensivt regn och den utfördes som en fallstudie av skyfallet i Gävle 17-18 augusti 2021. En 2D hydraulisk modell av Gävle förbereddes i programmet MIKE 21 Flow Model FM och simuleringar utfördes med en spatialt varierad regnindata, baserad på radardata från tillfället med en 2x2 km upplösning, och med spatialt uniforma regnindata både med den verkliga tidsvariationen och med en Chicago Design Storm (CDS), alla med samma totala volym. Skillnaden mellan scenarierna utvärderades genom att jämföra andel översvämmat modellområde, medel av maximala översvämningsdjupet och en kartering av skillnaden i översvämningsdjup över hela modellområdet. Resultaten visade att den spatiala variationen i regnindatan hade en signifikant effekt på den simulerade hydrauliska responsen i staden och att antagande om uniform regnintensitet kan leda till en underskattning av översvämningsdjupen i modellområdet jämfört med ett varierat regn. Medelvärdet av översvämningsdjupet var endast några procent högre  för det spatialt varierade regnet, men i stora centrala områden underskattade modellen med det uniforma regnet det maximala översvämningsdjupet med 5-35 %. Det uniforma CDS-regnet både under- och överskattade översvämningsdjupet, men i centrala och översvämmade områden var det större delar som underskattades. Detta visar på en risk med att använda uniforma typregn i skyfallsmodellering, då ett spatialt varierat regn med samma volym skulle kunna ge betydligt allvarligare effekter än de som modellen har visat och att användandet av uniforma testregn potentiellt inför en osäkerhet i resultaten som är viktig att poängtera och även att vidare undersöka och kvantifiera.

I avhandlingen analyseras möjligheter och hinder för samnyttjande av mark utifrån en fallstudie av skyfallsanpassning i Malmö och Köpenhamn. Som bakgrund står de klimatutmaningar i form av ökad framtida nederbörd och risk för översvämningar som städerna ställs inför, tillsammans med en tilltagande konkurrens om marken från allt fler behov. Fallstudien jämför hur de båda städerna planerat för och tagit sig an skyfallsanpassningen av befintliga stadsmiljöer. Fallstudiens huvudsakliga intresse utgörs dock inte av skyfallsanpassning som sådan, utan denna nyttjas främst för att ta reda på kommunernas inställning till möjligheten att samnyttja mark, samt vilka reella svårigheter samnyttjandet medför. Analysen av fallstudien sker med hjälp av governance-teorier där ett flertal institutionella hinder belyses såväl på strukturell nivå som inom det praktiknära genomförandet. Jämförelsen mellan städerna gör det tydligt att de institutionella förutsättningarna för samnyttjande ser olika ut, men att olikheten också förstärks av kommunernas förmåga att nyttja styrmedel för att möjliggöra skyfallsanpassning genom samnyttjande av mark. Analysen använder även teorier om allmänningar och urbana allmänningar för att belysa institutionella strukturer för samnyttjande av mark utan äganderättsliga anspråk. Avhandlingen har resulterat i att kunna beskriva två olika former av samnyttjande i termer av urban allmänning. Den första formen beskriver allmänningen som ett objekt och belyser i synnerhet materiella och institutionella aspekter. I samband med att ett stort antal markområden inom såväl kvartersmark som allmän platsmark anpassas att avlasta det allmänna va-ledningsnätet vid skyfall, bildas ett nätverk som kan besk- 14 rivas som en urban allmänning. Denna form av urban allmänning utgör ett objekt som sammanfogas genom dess funktionella samband men bibehåller ett diversifierat ägande och förvaltning. Den andra formen beskriver den urbana allmänningen som en process där möjligheten till samnyttjande inom allmän platsmark föranleder inkluderande invånarmedverkan. Genom invånardeltagande och uppmuntran till initiativtagande i den egna stadsdelen tillför samnyttjandet sociala värden till stadsrummet i form av trivsel, trygghet, tillhörighet och andra uttryck för livskvalitet. Denna invånarmedverkan utgör tydliga uttryck för den urbana allmänningen som process samtidigt som själva objektet, stadsrummet, kan fortsätta att räknas som endera en offentlig resurs under kommunal förvaltning eller en gemensam resurs under privat förvaltning. Avhandlingens slutsatser beskriver samnyttjandets möjligheter som en till stora delar outforskad potential att finna synergier och funktionell integration mellan olika markanvändningar och funktioner i stadsrummet. Med ett resursbaserat synsätt ses samnyttjande av mark som ett verktyg att överbrygga fastighetsindelning och de planerade användningsgränserna utan att äventyra egendomsrätten eller planinstrumentets intentioner. Det resursbaserade synsättet ger också samnyttjande möjlighet att låta såväl allmän platsmark som kvartersmark bidra med kvaliteter till staden genom positiva externa effekter. Samnyttjandets huvudsakliga hinder utifrån fallstudierna beskrivs från ett kommunalt institutionellt perspektiv med de tre faktorerna: ett snävt sektorsperspektiv, en strikt uppdelning mellan offentlig och privat mark samt betydelsen av styrmedel. Slutsatsen är att det finns goda möjligheter att berika städernas stadsrum med fler och mer integrerade funktioner genom att utveckla samnyttjande av mark. Denna omställning ställer emellertid krav på ett förhållningssätt av tvärsektoriell samverkan och institutionell förändring. / Based on a case study, comparing the municipal storm water adaptation plans and its recent implementation in the twin cities of Malmö and Copenhagen, the dissertation analyse the possibilities and practical challenges of combined use of urban land. The continuing process of urban densification, where urban land is seen as a strictly limited and often contentious resource, accompanied by the challenge of climate change through an expected increase of precipitation and risk of urban flooding, provides the background for this study. The ultimate concern, however, is not on storm water adaptation as such, but on the opportunities and obstacles to combine different uses of land within the same area, and how local governments approach this issue. In the analysis, governance theories are used to elucidate obstacles to combined use of land on structural level as well as within its practical realisation. A comparison between the cities demonstrates that the institutional preconditions for combined land use differ, but also, that the difference is reinforced by the ability of the local governments to make use of public policy instruments in order to implement storm water adaptation through combined use of land. The analysis also draws upon commons theory and theories of urban commons. These fields of research have similarities with combined use of land regarding the need of institutional structures to govern land management without claiming ownership. Furthermore, the dissertation describes two forms of combined use of land in terms of urban commons. The first form views the urban commons as an object highlighting its material and institutional aspects. 16 Here, the urban commons forms a network of both public and private property, each one adapted to bring relief to the common sewage system, in order to avoid it from being flooded in case of cloudbursts. This form of urban commons constitutes an object where its parts are associated through its functional relatedness, but keeps its diverse ownership and management. The second form describes the urban commons as a process, where the opportunity to combine different land uses opens up for inclusive participation from the citizens. Through initiatives from citizens and encouragement from the municipality for citizens to participate in the planning of public space, social values are created and added to the local community. Values such as well-being, sense of security and belonging as well as other aspects of liveability. This citizen participation produces expressions of the urban commons as a process, while the object itself, the physical urban space, will continue to be regarded either as a municipally owned public resource, or as a common resource within private ownership. The opportunities of combined use of land is described in the dissertation as a largely uncharted potential to seek synergies and functional integration between land uses and functions in the urban space. Looking from a resource-based perspective, combined use of land is seen as a tool to bridge boundaries in the urban space. Both boundaries that are created through planning, and those created through division into property units, although, without challenging the rights of ownership nor the intentions of physical planning. Through the resource-based perspective, combined use of land is able to equip both public space and private property with opportunities to contribute with qualities to the city, that is, positive external effects. The main obstacles, as extracted from the case studies, are explained from a municipal institutional perspective and contains three main elements: a narrow sectional perspective, a strict division between public and private land, and the importance of public policy instruments. The dissertation concludes by indicating rich opportunities for both local governments and private property owners to develop urban space through developing combined use of land. This requires institutional 17 change towards collaboration and cooperation, not the least within the municipal organisation itself, where land can be considered the scarce resource it is, and therefore needs to be shared and used as beneficially as possible.

Från om med 1 januari 2024 ska alla kommuner ha en vattentjänstplan. En vattentjänstplan ska innehålla varje kommuns långsiktiga plan för att tillgodose allmänna vattentjänster i framtiden samt åtgärder som behöver vidtas vid skyfall för att skydda VA-anläggningar. Lagändringen infördes 1 januari 2023 vilket har gett kommuner en snäv tidsplan att ta fram denna plan. Arbetet har undersökt vad vattentjänstplanen i Västerås kommun behöver innehålla för att uppfylla kravet om åtgärder vid skyfall, identifiera punkter i spill- och dagvattennätet som potentiellt är sårbara för skyfall och ge förslag på skyfallsåtgärder. För att uppfylla syftet har en risk- och sårbarhetsanalys utförts för att identifiera punkter i spill- och dagvattennätet som är sårbara för skyfall. Analysen inkluderade en workshop med nyckelpersoner på Mälarenergi Vatten AB och en riskmatris som användes som bedömningsunderlag. Från riskmatrisen identifierades punkter som var potentiellt sårbara för skyfall och en lågpunktskartering utfördes i SCALGO Live på utvalda punkter. De regnhändelser som utfördes i karteringen var 10-, 20- och 100-årsregn. Lågpunktskarteringen jämfördes även med en skyfallskartering med markavrinning och ledningsnät, vilket är en kartering av hög detaljeringsgrad, för att undersöka ifall lågpunktskartering kan vara lämpligt underlag till en vattentjänstplan. Resultatet av risk- och sårbarhetsanalysen var att sju punkter, som gavs som förslag under workshopen, hade höga riskvärden och var potentiellt sårbara för skyfall. Tre av sju punkter valdes till vidare analys: Branthovda, Skiljebo och Önsta-Gryta, alla belägna i Västerås tätort. Samtliga av dessa tre punkter var i dagvattennätet. Lågpunktskarteringen i SCALGO Live som utfördes över dessa tre punkter visade stora översvämningar vid ett 100-årsregn. Skyfallsåtgärder som föreslogs för platserna var magasinerings ytor och skyfallsled. Vid jämförelse av lågpunktskartering och skyfallskartering med markavrinning och ledningsnät visade skyfallskarteringen en mindre översvämning för Branthovda och Skiljebo. I Önsta-Gryta var skillnaden mellan karteringarna minimal. Detta var då skyfallskarteringens resultat visar på att dagvattenledningarna i området var överbelastade redan vid ett 10-årsregn, vilket liknade villkoret i lågpunktskarteringen att dagvattenledningarna antas vara fulla. Med detta kan endast en lågpunktskartering visa ett områdes potential till att var sårbara för skyfall, men säger inget om hur spill- eller dagvattennätet påverkas. Dock kan en lågpunktskartering hjälpa till att identifiera områden i tätorter som skulle kunna vara sårbara för översvämningar. / As of January 1st, 2024, all municipalities must have a water service plan. A water service plan must contain each municipality's long-term plan to provide public water services in the future and solutions that need to be taken in the event of a cloudburst to protect water and sewage facilities. The change in law was introduced on January 1st, 2023, which has given municipalities a tight timetable to develop this plan. The study has investigated what the water service plan in Västerås municipality needs to contain in order to fulfill the requirement for solutions in the event of cloudbursts, identify points in the waste and stormwater network that are potentially vulnerable to cloudbursts, and provide suggestions for torrential rain measures. In order to fulfill the purpose, a risk and vulnerability analysis has been carried out to identify points in the waste and stormwater network that are potentially vulnerable to cloudbursts. The analysis included a workshop, with key individuals at Mälarenergi Vatten AB, and a risk matrix that was used as an assessment basis. From the risk matrix, points that were potentially vulnerable to cloudbursts were identified and a low-point mapping was performed in SCALGO Live at the selected points. The rain events performed in the mapping were 10-, 20- and 100-year rainfalls. The low-point mapping was compared with a cloudburst mapping with land runoff and conduit network, which is a mapping with a high degree of detail, to investigate whether low-point mapping can be a suitable basis for a water service plan. The result of the risk and vulnerability analysis was that seven points, which were given as suggestions during the workshop, had high-risk values and were potentially vulnerable to cloudbursts. Three out of the seven points were selected for further analysis: Branthovda, Skiljebo, and Önsta-Gryta, all of them located in Västerås city. All of these sensitive points were in the stormwater network. The low-point mapping in SCALGO Live performed over these three points showed major flooding during a 100-year rainfall event. The proposed cloudburst solutions for the sites were storage areas and cloudburst roads. When comparing low-point mapping and cloudburst mapping with ground runoff and conduit networks, the cloudburst mapping showed a minor flood for Branthovda and Skiljebo. In Önsta-Gryta, the difference between the mappings was minimal. This was due to the results of the cloudburst mapping showing that the stormwater pipes in the area were overloaded even with a 10-year rain, which was similar to the condition in the low-point mapping that the stormwater pipes are assumed to be filled. With this, only a low point mapping can show an area's potential for being vulnerable to cloudbursts but does not say anything about how the waste or stormwater network is affected. However, low point mapping can help identify areas in built-up areas that could be vulnerable to flooding.

[pt] Devido ao seu comportamento físico-químico, os polímeros solúveis em água são utilizados em várias fases de perfuração, completação, e produção de poços de petróleo. Portanto, é fundamental prever e controlar o comportamento em meio poroso para entender o desempenho do polímero. Experimentos foram conduzidos para estudar a degradação de uma solução aquosa semi-diluída de PEO, usando dois capilares com diâmetros de entrada diferentes (100 micrômetros e 200 micrômetros) ambos com constrição de 50 micrômetros, criando fluxos transientes rápidos em seu centro. Diferentes vazões foram impostas a fim de observar diferentes taxas de cisalhamento e de alongamento no sistema. O efluente do fluxo foi coletado e reinjetado, e suas propriedades reológicas foram utilizadas como proxies para a degradação. Observamos que, para a contração mais abrupta, a vazão mínima necessária para degradar a solução é menor. Este resultado, analisado apenas sob a perspectiva da taxa de cisalhamento, não é razoável, já que a taxa de cisalhamento na constrição a que o polímero é submetido é igual em ambos os capilares. Portanto, inferimos que a brusquidão da contração desempenha um papel na degradação, o que significa que a taxa de alongamento pode ser responsável pela menor taxa de fluxo crítico. Também foi observado um padrão de como ocorre a degradação com as injeções subsequentes. Podemos inferir que injeções subsequentes causam degradação incremental antes de se aproximar de um patamar de estabilização e que vazões mais altas geram patamares de degradação mais baixos. / [en] Due to their physical-chemical behavior, water-soluble polymers are used extensively in various phases of drilling, completion, workover, and production of oil and gas wells. Therefore, it is fundamental to predict and to control in-situ porous medium behavior in order to understand polymer performance. Experiments were conducted to study the degradation of a semi diluted (2000 ppm) aqueous solution of PEO, using two capillaries with different entrance diameter (100 micrometers and 200 micrometers) both with 50 micrometers radius constriction, creating Fast-Transient Flows in their center. Different injection rates were imposed in order to observe different shear and extensional rates in the system. The effluent of the flow was collected, and reinjected, and rheological properties of the fluids were used as proxies for the degradation of the solution. We observed that for the more abrupt contraction, the minimum flow rate needed for degrading the polymer solution is lower. This result, when analyzed purely under shear rate perspective, is not reasonable, since the constriction shear rates to which the polymer is subjected are equal at both capillaries. Therefore, we inferred that the abruptness of the contraction plays a role in the degradation, which means elongational rate may be responsible for the lower critical flow rate. It was also observed a pattern for how the degradation occurs with subsequent injections. We could infer that subsequent injections cause incremental degradation before approaching a stabilization plateau and that higher flow rates generated lower degradation plateaus.

No description available.

Hydrogeological hazards are quite diffuse rainfall-induced phenomena that affect mountain regions and can severely impact these territories, producing damages and sometimes casualties. For this reason, hydrogeological risk reduction is crucial. Mitigation strategies aim to reduce hydrogeological risk to an acceptable level and can be classified into structural and non-structural measures. This work focuses on enhancing some non-structural risk mitigation measures for mountain areas: debris-flow rainfall thresholds, as a part of an Early Warning System (EWS), multivariate rainfall scenarios with multi-hazard mapping purpose and public awareness. Regarding debris-flow rainfall thresholds, an innovative calibration method, a suitable uncertainty analysis and a proper validation process are developed. The Backward Dynamical Approach (BDA), a physical-based calibration method, is introduced and a threshold is obtained for a study area. The BDA robustness is then tested by assessing the uncertainty in the threshold estimate. Finally, the calibrated threshold's reliability and its possible forecast use are assessed using a proper validation process. The findings set the stage for using the BDA approach to calibrate debris-flow rainfall thresholds usable in operational EWS. Regarding hazard mapping, a multivariate statistical model is developed to construct multivariate rainfall scenarios with a multi-hazards mapping purpose. A confluence between a debris-flow-prone creek and a flood-prone river is considered. The multivariate statistical model is built by combining the Simplified Metastatistical Extreme Value approach and a copula approach. The obtained rainfall scenarios are promising to be used to build multi-hazard maps. Finally, the public awareness within the LIFE FRANCA (Flood Risk ANticipation and Communication in the Alps) European project is briefly considered. The project action considered in this work focuses on training and communication activities aimed at providing a multidisciplinary view of hydrogeological risk through the holding of courses and seminars.

No description available.