During intensive rainfall, the ground is at risk of flooding if the water has no opportunity to infiltrate into the ground or drain. Cities are most heavily affected by such pluvial floods due to their predominantly solid surfaces. An example of such a city is Umeå, which experienced extensive floods causing up to 40 million Swedish kronor in damages. During the period 1970 to 2020, the population of Umeå has increased from 70,000 to 130,000 inhabitants, which means that both housing demand and thus the proportion of hardened surfaces in the municipality increased rapidly. To avoid future flooding problems, studying intensive precipitation trends as well as factors that affect the risk of pluvial floods is of the utmost importance. The purpose of this research is thus to investigate heavy precipitation trends as well as study how climate change and hardened surfaces affect the risk of flooding in Umeå. This study shows that the frequency of intense rainfall in Umeå has increased compared to the mean of the period 1963-1987 and that climate change could lead to an even higher frequency. Increased frequency of intensive precipitation in combination with an increased proportion of hardened surfaces increases the risk of flooding problems. Furthermore, heavy rainfalls, defined as precipitation above ten millilitres a day, occurred eighteen times a year during the period 1996-2020, which is four days more than the 1963-1987 average. By the end of the twenty-first century, climate change is expected to increase these number of days by a further 20-30% (equivalent to 7-12 days) according to SMHI predictions. Intense rainfall is likely to become more common in the future and population growth in Umeå will likely lead to an increase in the number of paved areas. These changes, in combination, place high demands on Umeå municipality to work efficiently with urban planning and climate adaptation.

Bakgrund: Klimatförändringarnas effekter globalt som på lokal nivå, kan redan noteras. För skyfallsöversvämningar har det ökat och kommer öka än mer framöver. Olika sektorer i ett samhälle påverkas när en stad översvämmas, varav en stor grupp består av samhällets medborgare. Individer upplever skyfall som oförutsägbara och slumpmässiga. Konsekvenserna efter en skyfallsöversvämning har effekt på både de sociotekniska och socioekonomiska dimensionerna för en individ på kort och lång sikt. Med detta perspektiv anses det intressant att undersöka hur individer resonerar kring framtida skyfallsöversvämningar på lokal nivå. Studien avgränsas till privata fastighetsägare, då tidigare forskning pekar på att de som äger sin egen bostad är mer benägna att anta skyddande anpassningar på sina enskilda fastigheter, vilket antas bidra till den totala samhällssäkerheten. Syftet: Syftet med studien var att öka förståelsen för privata fastighetsägares syn på skyfall som leder till översvämning och hur det motiverar dem att vilja skydda sin privata fastighet innan en översvämning sker. Metod: Studiens kvalitativa forskningsinriktning utgick från en hermeneutisk vetenskapsteori med inriktning åt samhälls- och beteendevetenskap. Datainsamlingen genomfördes som semi-strukturerade intervjuer som analyserades utifrån en kvalitativ konventionell innehållsanalysmetod med induktiv ansats. Totalt genomfördes sex kvalitativa intervjuer. Områdesurvalet utgick från ett strategiskt icke-sannolikhetsbaserat urval medan respondenturvalet var ett icke-slumpmässigt bekvämlighetsurval. En testintervju genomfördes innan själva studien påbörjades, för att säkerställa att frågorna var relevanta. Som teoretiskt ramverk valdes Protection motivation theory för att fånga upp likheter och skillnader i individers resonemang kopplat till skyfallsöversvämningar. Resultat: Det induktiva analysförfarandet resulterade i tre huvudkategorier och nio underkategorier. Förmågor, riskhantering och samhällspåverkan belyser olika perspektiv hur privata fastighetsägare resonerar kring sin kapacitet innan en skyfallsöversvämning sker. Kunskapsbrist och individnivån; intra- och interpersonlighet inverkar på individernas förmågor och beslut. Medan valet av anpassningar av fastigheten vägdes mellan kostnaden i relation till tid och nyttovärdet. Vidare pekade resultatet på att samhällspåverkan var bidragande till en känsla av utsatthet, detta främst inom ansvarsfördelning och information hos respondenterna då de upplevde ett beroendesamband till kommunen och försäkringsbolagen. Utmärkande för studien: Respondenterna upplever skyfallsöversvämningar som ett abstrakt fenomen, vilket påvisas av en uttalad kunskapsbrist kopplat till området. Vidare har tidsfaktorn tillsammans med ansvarskostnaden inverkan på hur nyttovärdet av en anpassning upplevs. Mest framträdande är hur den sociala omgivningen tillsammans med individens självförmåga kan påverka riskbedömning och hanteringsförmåga i relation till skyfallsöversvämningar. Slutligen upplever den undersökta populationen privata fastighetsägare samhällspåverkan i form av beroendesamband och utsatthet till både kommun och försäkringsbolag, vilket pekar på att individperspektivet med inriktning på hantering av skyfallsrisker bör inkluderas i framtida forskning. / Background: The effects of climate change globally as well as at the local level can already be noted. Pluvial flood events have increased and will increase even more in the future. Different sectors of a society are affected when a city is flooded, of which a large group consists of the citizens of the society. Individuals experience extreme rains as unpredictable and random. The consequences after pluvial floods have an effect on both the socio-technical and socio-economic dimensions of an individual in the short and long term. With this perspective it is considered interesting to do research, to capture how individuals reason about future pluvial floods, at the local level. The study is limited to private property owners, as previous research indicates that those who own their home are more aware and prone to adopt protective adaptations to protect their property, which is assumed to contribute to overall social security. Purpose: The aim of the study was to increase the understanding of private property owners´ views on pluvial floods that lead to flooding and how it motivates them to want to protect their private property before a flood occurs. Method: The qualitative research was based on a hermeneutic theory of science with a focus on social and behavioural sciences. The data collection was conducted as semi-structured interviews. The collected data material was analyzed by applying a qualitative conventional content analysis method with an inductive approach. A total of six qualitative interviews were conducted. The area of the sample was based on a strategic non-probability sample, while the respondent sample was a non-random convenience sample. A test interview was conducted before the actual study began, to ensure that the questions were relevant. The Protection Motivation Theory, was chosen as the theoretical framework to capture similarities and differences in the individuals´ reasoning, linked to pluvial floods. Results: The inductive analysis procedure resulted in three main categories and nine sub-categories. Abilities, risk management and societal impact shed light on perspectives on how private property owners’ reason about their abilities before a pluvial flood occurs. Lack of knowledge and the level of the individual; intra- and interpersonal levels affect individuals´ inner abilities and decisions. While the choice of adaptations of the property was weighed between the cost in relation to time and utility value. Furthermore, the results indicated that social impact was contributing to a feeling of vulnerability, mainly within the division of responsibilities and information among the respondents when they experienced a dependency relationship with the municipality and the insurance companies. Characteristic of the study: The respondents experience pluvial floods as an abstract phenomenon, which is expressed as a lack of knowledge linked to the area of research. Furthermore, the time factor together with the cost of liability has an impact on how the utility value of the adaptation measure is perceived. Most prominent is how the social environment together with the individual´s self-efficacy can affect risk assessment and coping ability in relation to pluvial floods. Finally, the surveyed population of private property owners’ experiences societal impact in the form of dependency and vulnerability to both municipality and insurance companies, which indicates that the individual perspective with a focus on managing pluvial flood risks, should be included in future research.