Flooding in the United States has been increasing over the past century due to changing hydrological conditions as well as increased human manipulation of the waterways. People continue to live in these high hazard areas, even with increasing risk levels. Flood hazard mitigation has increasingly become a primary goal of floodplain managers with buyouts, insurance, and other nonstructural approaches becoming more prevalent over the past two decades. Whole town relocations have become one flood mitigation option. This study explores which community factors affect a town's decision to relocate. Three study areas in the Midwestern U.S. were analyzed: Valmeyer, IL, Rhineland, MO, and Pattonsburg, MO. Each of these three towns underwent a buyout and town relocation after the flood of 1993. Data was gathered using personal interviews with community members, specifically elected officials and relocation committee members. Analysis of interview responses identified community sense of place as the primary factor influencing relocation decisions including leadership, cost, people, and landscape. Leadership included town incorporation, relocation decision and committees, handling of legal issues, and site selection criteria. Cost involved the relocation cost, post-disaster development and tourism, and the business community of the study areas. People included the town heritage, community type, and the various community organizations. Landscape includes the types of relocation completed, the speed of the relocation event, and the amount of pre-disaster planning. Maps created show the pre and post-relocation municipal boundary of the study sites in relation to the 500-year floodplain boundary.

This thesis explores the impact that the petrochemical industry has had on the built environment of Norco, St. Charles Parish, Louisiana. Previous scholars have suggested that heavy industry in Norco consumes a majority of the Mississippi River's natural levee, which is the most elevated and flood resistant land in the town. In order to test these observations, the author of this thesis has collected parcel-level land use data in Norco to determine the flood hazard and topographical characteristics of these various land uses. Spatial calculations, run using Geographic Information System software, have determined that heavy industrial land uses in Norco consume a vast majority of the Mississippi River's natural levee.

Loss prevention and distribution must begin well before a flood event at multiple levels. However, the benchmarks and terminology we use to manage and communicate flood risk may be working against this goal. U.S. flood policy is based upon a flood with a one percent chance of occurring in any year. Commonly called the "hundred year flood," it has been upheld as a policy criterion, but many have questioned the effectiveness of hundred year flood terminology in public communication. This research examined public perceptions of the hundred year flood and evaluated the comparative effectiveness of this term and two other methods used to frame the benchmark flood: a flood with a one percent chance of occurring in any year and a flood with a 26 percent chance of occurring in thirty years. This research also explored how flooding and flood risk messages fit into the larger context of people's lives by modeling the relationships between flood related understanding, attitude and behavior and the situational and cognitive contexts in which these factors are embedded. The final goal was to come up with locally based suggestions for improving flood risk communication. Data were collected in the Towns of Union and Vestal, New York. Participants were adult residents of single family homes living in one of two FEMA designated floodplains. Face to face surveys and focus groups were used to gather information on respondents' flood experience and loss mitigation activities; general perception of flood risk and cause; flood information infrastructure; perceptions associated with specific flood risk descriptions; and basic demographic data. Focus groups were also asked to suggest improvements to flood risk communication. Results indicated that experience was the most influential factor in perception and behavior. Additionally, there was little evidence that understanding led to "appropriate" behavior. The 26 percent chance description was the most effective when both understanding and persuasion were included, but interpretations of probabilistic flood risk messages were highly individualized. Finally, regulatory practice likely influences attitude and behavior and may emphasize the likelihood of a particular flood at the expense of the possibility of flooding in general.

In response to the rising costs of floods, the United States has adopted sophisticated programs to mitigate the loss of life and property. However, the efficient implementation of certain aspects of flood policy has taken precedence over effective communication. The scope of the National Flood Insurance Program and the efficient coding of "the 100 year flood" have led to a pervasive use of the term in both formal and informal risk communication. When officials began consciously communicating flood policy to the public, they assumed a narrow "engineering" model and did not fully anticipate the influence of informal communication on the perception of flood risk. The effectiveness of the "100 year flood" as a means to change attitudes or motivate behaviors was not assessed. Nor was its utility in increasing public understanding of flood risk. New explanatory methods have been introduced, but they, too, have yet to be tested. This project evaluated the effectiveness of four methods commonly used to communicate the risk associated with policy's benchmark flood. These include: a 100 year flood; a flood with a 1 percent chance of occurring in any year; a flood with a 26 percent chance of occurring in 30 years; and a flood risk map available through Project Impact. Data were collected using a structured face to face questionnaire survey of residents living in Wimberley, Texas. Respondents included individuals who lived inside the boundaries of official flood plains, as well as those who did not. Comparable questions regarding uncertainty, perceived need for protection, and levels of concern were asked using each of the four methods of description. Qualitative observations were made during both the interviews and the collection of secondary data. Results showed a significant disjuncture of understanding and persuasion with each method; potentially serious problems with the 26 percent chance method; and a preference for concrete references in describing risk. It is recommended that use of the 26 percent chance method be discontinued. Both the 100 year flood and the map performed better than expected; these descriptions are recommended with reservations in lieu of more contextually appropriate methods of communication and policy formation.

<p>Syftet med denna uppsats är att ge en forskningsöversikt kring begreppet social sårbarhet i relation till naturkatastrofer i allmänhet. Sårbarhet i relation till naturkatastrofer har kartlagts och studerats vetenskapligt under en kortare period, medan social sårbarhet, som är en undergrupp till sårbarhetsfältet, har studerats förhållandevis lite. Genom att ta reda på vilka människor/grupper av människor som är mest utsatta för naturkatastrofer finns det en möjlighet för beslutsfattare att fatta välgrundade beslut om var förebyggande insatser bör göras, såväl som akuta insatser i händelse av en naturkatastrof. Tanken är att denna uppsats skall ligga till grund för en lokal studie 2009-2010 av social sårbarhet i en utvald kommun vid Vänerns strand. Vänern är som känt hotad av ökad översvämningsrisk i samband med klimatförändringar och vikten av att undersöka social sårbarhet där är stor. Det huvudsakliga resultatet är att social sårbarhet i relation till naturkatastrofer är bristfälligt kartlagt i vetenskaplig litteratur. Den metodik som har utarbetats för att mäta och hantera social sårbarhet i olika samhällen är fortfarande på ett experimentellt stadium. Att mäta och analysera social sårbarhet i Sverige är möjligt, om än med tydliga begränsningar, men det är av största betydelse att hänsyn tas till de unika förhållanden som råder på den plats som skall studeras. De variabler som används i utländska studier för att mäta social sårbarhet är förmodligen annorlunda från vilka variabler som är lämpliga att använda i Sverige. De studier som undersökts i rapporten använder sig av variabler som är lätta att kvantifiera. Kvalitativa variabler skulle sannolikt vara mer intressanta att mäta i en studie om social sårbarhet i Sverige.</p>

Syftet med denna uppsats är att ge en forskningsöversikt kring begreppet social sårbarhet i relation till naturkatastrofer i allmänhet. Sårbarhet i relation till naturkatastrofer har kartlagts och studerats vetenskapligt under en kortare period, medan social sårbarhet, som är en undergrupp till sårbarhetsfältet, har studerats förhållandevis lite. Genom att ta reda på vilka människor/grupper av människor som är mest utsatta för naturkatastrofer finns det en möjlighet för beslutsfattare att fatta välgrundade beslut om var förebyggande insatser bör göras, såväl som akuta insatser i händelse av en naturkatastrof. Tanken är att denna uppsats skall ligga till grund för en lokal studie 2009-2010 av social sårbarhet i en utvald kommun vid Vänerns strand. Vänern är som känt hotad av ökad översvämningsrisk i samband med klimatförändringar och vikten av att undersöka social sårbarhet där är stor. Det huvudsakliga resultatet är att social sårbarhet i relation till naturkatastrofer är bristfälligt kartlagt i vetenskaplig litteratur. Den metodik som har utarbetats för att mäta och hantera social sårbarhet i olika samhällen är fortfarande på ett experimentellt stadium. Att mäta och analysera social sårbarhet i Sverige är möjligt, om än med tydliga begränsningar, men det är av största betydelse att hänsyn tas till de unika förhållanden som råder på den plats som skall studeras. De variabler som används i utländska studier för att mäta social sårbarhet är förmodligen annorlunda från vilka variabler som är lämpliga att använda i Sverige. De studier som undersökts i rapporten använder sig av variabler som är lätta att kvantifiera. Kvalitativa variabler skulle sannolikt vara mer intressanta att mäta i en studie om social sårbarhet i Sverige.

Natural and human-induced environmental changes have been altering the earth's surface and hydrological processes, and thus directly contribute to the severity of flood hazards. To understand these changes and their impacts, this research developed a GISbased hydrological and hydraulic modeling system, which incorporates state-of-the-art remote sensing data to simulate flood under various scenarios. The conceptual framework and technical issues of incorporating multi-scale remote sensing data have been addressed. This research develops an object-oriented hydrological modeling framework. Compared with traditional lumped or cell-based distributed hydrological modeling frameworks, the object-oriented framework allows basic spatial hydrologic units to have various size and irregular shape. This framework is capable of assimilating various GIS and remotely-sensed data with different spatial resolutions. It ensures the computational efficiency, while preserving sufficient spatial details of input data and model outputs. Sensitivity analysis and comparison of high resolution LIDAR DEM with traditional USGS 30m resolution DEM suggests that the use of LIDAR DEMs can greatly reduce uncertainty in calibration of flow parameters in the hydrologic model and hence increase the reliability of modeling results. In addition, subtle topographic features and hydrologic objects like surface depressions and detention basins can be extracted from the high resolution LiDAR DEMs. An innovative algorithm has been developed to efficiently delineate surface depressions and detention basins from LiDAR DEMs. Using a time series of Landsat images, a retrospective analysis of surface imperviousness has been conducted to assess the hydrologic impact of urbanization. The analysis reveals that with rapid urbanization the impervious surface has been increased from 10.1% to 38.4% for the case study area during 1974 - 2002. As a result, the peak flow for a 100-year flood event has increased by 20% and the floodplain extent has expanded by about 21.6%. The quantitative analysis suggests that the large regional detentions basins have effectively offset the adverse effect of increased impervious surface during the urbanization process. Based on the simulation and scenario analyses of land subsidence and potential climate changes, some planning measures and policy implications have been derived for guiding smart urban growth and sustainable resource development and management to minimize flood hazards.

A model that emphasizes possible alternative sequences of events that occur over time is presented in paper 1 (chapter 2) of this dissertation. Representing alternative or branching events captures additional semantics unrealized by linear or non-branching approaches. Two basic elements of branching, divergence and convergence are discussed. From these elements, many complex branching models can be built capturing a perspective of events that take place in the future or have occurred in the past. This produces likely sequences of events that a user may compare and analyze using spatial or temporal criteria. The branching events model is especially useful for spatiotemporal decision support systems, as decision-makers are able to identify alternative locations and times of events and, depending on the context, also identify regions of multiple possible events. Based on the formal model, a conceptual framework for a branching events model for flood disasters is presented. The framework has five parts, an event handler, a query engine, data assimilator, web interface, and event database. A branching events viewer application is presented illustrating a case study based on a flood response scenario. A spatiotemporal framework for building evacuation events is developed to forecast building content evacuation events and building vulnerabilities and is presented in paper 2 (chapter 3) of this dissertation. This work investigates the spatiotemporal properties required to trigger building evacuation events in the floodplain during a flood disaster. The spatial properties for building risks are based on topography, flood inundation, building location, building elevation, and road access to determine five categories of vulnerability, vulnerable basement, flooded basement, vulnerable first-floor, flooded first-floor, and road access. The amount of time needed to evacuate each building is determined by the number of vulnerable floors, the number of movers, the mover rate, and the weight of the contents to be moved. Based upon these properties, six possible evacuation profiles are created. Using this framework, a model designed to track the spatiotemporal patterns of building evacuation events is presented. The model is based upon flood forecast predictions that are linked with building properties to create a model that captures the spatiotemporal ordering of building vulnerabilities and building content evacuation events. Applicable to different communities at risk from flooding, the evacuation model is applied a historical flood for a university campus, demonstrating how the defined elements are used to derive a pattern of vulnerability and evacuation for a campus threatened by severe flooding. Paper 3 (Chapter 4) of this dissertation presents a modeling approach for representing event-based response risk. Surveys were sent to emergency managers in six states to determine the priorities of decision makers during the response phase of flood disasters. Based on these surveys, nine response events were determined to be the most important during a flood response, flooded roads, bridges closed, residential evacuations, residential flooding, commercial flooding, agricultural damage, power outage, sheltering, sandbagging. Survey participants were asked to complete pairwise comparisons of these nine events. An analytic hierarchy process analysis was completed to weight the response events for each decision-maker. A k-means clustering analysis was then completed to form 4 distinct profiles, mixed rural and urban, rural, urban, and high population - low population density. The average weights from each profile were calculated. The weights for each profile were then assigned to geospatial layers that identify the locations of these events. These layers are combined to form a map representing the event-based response risk for an area. The maps are then compared against the response events that actually occurred during a flood disaster in June 2008 in two communities.

Pågående klimatförändringar med påföljande ökad nederbörd ger förhöjd risk för översvämningar. Det är därför viktigt att kunna göra förutsägelser för var översvämning riskerar att ske. Förutsättningarna att göra sådana prediktioner med geografiska informationssystem ökar då Sveriges geografi karteras i allt större utsträckning. Syftet med uppsatsen är att utföra och analysera en modell för kartering av översvämningsrisk av väg. Det görs genom GIS-analys av geografiska data, baserade på platsspecifika egenskaper i landskapet, för ett område i Östersunds kommun där två vägavsnitt översvämmades 2008. De platsspecifika egenskaperna kvantifieras i s.k. fysikaliska avrinningsområdesegenskaper (FAE). Vidare syftar uppsatsen till att undersöka hur dessa FAE kan kopplas till översvämningsrisk, på vilket sätt vägen inverkat på risken för att översvämning uppstår och hur modellen kan användas i ett allmänt syfte att kartera översvämningsrisk. Resultatet visar att det finns en korrelation mellan ett flertal FAE och risken för översvämning. Det kan dock göras gällande från resultatet att dessa inte är så entydiga att det med användning av FAE går att allmänt förutsäga översvämningsrisk och riskkarteringen indikerar inte heller att det förelåg större risk i de områden där översvämning dokumenterades. Slutsatsen gällande om det går att applicera den här metoden allmänt för att kartera översvämningsrisk för andra områden är att det i dagsläget är komplicerat och osäkert att göra den här typen av kartering. Med förfinade metoder och noggrannare kartering av geografin kan den här typen av modellering få större träffsäkerhet då sambanden mellan platsspecifika egenskaper i landskapet och översvämningsrisken är vetenskapligt belagd. / Ongoing climate change with increasing levels of precipitation elevates the risk of flooding. It is therefore important to be able to make predictions of when and where such flooding events will occur. The conditions for making such predictions in geographic information systems is increasing at pace with the mapping of the geography of Sweden. The purpose of this paper is to conduct and analyze a planning model for flood hazard by GIS-analysis for an area located in Östersund municipality where two road sections were flooded in 2008. The analysis is based on site specific properties in the terrain. The site specific properties are quantified as Physical Catchment Descriptors. The purpose is furthermore to investigate how these FAE can be linked to the risk of flooding, which role the road plays in causing flooding and in what way the planning model can be used to map flood hazard. The result shows that there is a correlation between several of the FAE and the risk of flooding. These findings are however not that unambiguous to make use of the FAE as general indicators of flood hazard. The mapping of flood hazard in the studied area did not implicate a clear correlation between flood hazard and the flooding events. The conclusion regarding if it is possible to apply this method for mapping probability of flood hazards is that it is uncertain and complicated. With more sophisticated models and more detailed geographical data this type of modelling can get more accurate, since the relation between FAE and flood hazard has been verified.