A manifestação de danos em infraestruturas costeiras decorrente da ação de ondas tem estimulado avaliações de vulnerabilidade para fins de gestão integrada da costa. Os municípios costeiros do Estado de Santa Catarina concentram 28% de sua população e sua interface com o oceano é predominantemente composta por praias arenosas dominadas por ondas. Impactos costeiros relacionados a processos dominados por ondas, sobretudo às escalas local e regional, podem ser ainda mais danosos do que os ocasionados por processos naturais de larga escala (p. ex., a subida do nível do mar). A abordagem utilizada neste estudo consiste na definição de um índice multicritério de vulnerabilidade a ondas de maior frequência de ocorrência e de tempestade para o litoral de Santa Catarina. O índice de vulnerabilidade (IVC) foi obtido a partir da integração entre o índice de capacidade adaptativa, composto por variáveis socioeconômicas e de ocupação (área ocupada, distância entre a ocupação e a linha de costa, número de residentes, renda por residente e número de domicílios de uso ocasional), e o índice de suscetibilidade - composto por variáveis do meio físico (altura significativa de onda, gradiente de deriva litorânea potencial, largura de praia, elevação e declividade). A dinâmica costeira resultante da incidência de ondas sobre as manchas urbanas na área em perigo é analisada através de produtos de modelagem numérica, integrados às demais variáveis em ambiente de Sistema de Informação Geográfica (SIG). A relevância das variáveis na composição do índice foi avaliada pelo método de decisão multicritério AHP (analytic hierarchy process). As variáveis e os índices foram representados em cinco classes de vulnerabilidade (muito baixa, baixa, média, alta e muito alta) nos setores do Plano Estadual de Gerenciamento Costeiro (GERCO/SC). Com base na opinião de especialistas, as variáveis físicas foram consideradas mais relevantes do que as socioeconômicas. Os setores mais suscetíveis e vulneráveis são: centro-sul, sul, norte, centro-norte e centro, respectivamente. Já os setores de menor capacidade adaptativa são: centro-norte, centro, norte, centro-sul e sul, respectivamente. A baixa presença de residentes e ocupações na área em perigo, bem como as maiores distâncias entre a ocupação e a linha de costa - variáveis utilizadas na determinação da capacidade adaptativa e que favorecem a redução da vulnerabilidade - apresentaram um papel secundário na determinação do IVC para os setores centro-sul e sul. Os setores ao norte do Estado são menos suscetíveis e vulneráveis, todavia se encontram intensamente ocupados em praias com menores larguras de faixa de areia, terrenos planos e com baixa declividade (segmentos de maior suscetibilidade). A maior ocorrência de danos por erosão e inundação, atualmente observada ao norte do Estado, pode ser facilmente revertida caso haja a expansão de áreas ocupadas próximo às linhas de costa dos setores centro-sul e sul, tendo em vista a alta suscetibilidade e os baixos valores de renda e de segunda-moradia encontrados ao sul do Estado. / The occurrence of coastal infrastructure damage due to wave action has been promoting vulnerability assessments for integrated coastal management. Santa Catarina\'s coastal municipalities concentrate 28% of the state\'s population and the interface between the coastline and the ocean is predominantly composed by wave-dominated sandy beaches. Coastal impacts related to wave-dominated processes, especially at local and regional scales, can produce more damaging effects than large-scale natural processes (e. g., sea level rise). The approach suggested in this study consists of defining a vulnerability multicriteria index, for Santa Catarina\'s coastline, to waves with higher frequency of occurrence and to storm wave events. The coastal vulnerability index (IVC) was obtained by integrating the adaptive capacity index, composed by socioeconomic and occupational variables (constructed area, distance between human settlements and shoreline, number of residents, income per capita and number of households for occasional use), and the susceptibility index - consisting of environmental variables (significant wave height, potential longshore drift gradient, beach width, coastal elevation and slope). The resulting coastal dynamics from nearshore wave incidence is analyzed through the application of a numerical model, integrated with the other variables by geoprocessing techniques in a Geographic Information System (GIS) environment. The variables\' relevance in the index formula was obtained by the analytic hierarchy process (AHP). Variables and indices were hierarchized in five vulnerability classes (very low, low, medium, high and very high) and represented in the sectors from the State Coastal Management Plan (GERCO/SC): north, center-north, center, center-south and south. Based on specialists\' opinion on the determination of vulnerability, physical/environmental variables were considered more relevant than socioeconomic variables. The most susceptible and vulnerable sectors are: center-south, south, north, center-north and center, respectively. Sectors with the lowest adaptive capacity are: center-north, center, north, center-south and south, respectively. The low number of residents and settlements in the endangered area, as well as the greater distances between occupied area and the shoreline - variables used to determine adaptive capacity and that contribute to reduction of vulnerability - played a secondary role in the CVI\'s determination for the center-south and south sectors. The northern sectors of the state are less susceptible and vulnerable; however, they are intensely occupied in beaches with smaller beach width, lower elevation and slope (segments with higher susceptibility degrees). The highest occurrence of erosion and flood damage, currently observed at the north of the state, can easily be reversed in case of expansion of settlements near the center-south and south sectors, as a function of the higher susceptibility degrees and lower income per capita and number of households of occasional use found at the south of the state.

A manifestação de danos em infraestruturas costeiras decorrente da ação de ondas tem estimulado avaliações de vulnerabilidade para fins de gestão integrada da costa. Os municípios costeiros do Estado de Santa Catarina concentram 28% de sua população e sua interface com o oceano é predominantemente composta por praias arenosas dominadas por ondas. Impactos costeiros relacionados a processos dominados por ondas, sobretudo às escalas local e regional, podem ser ainda mais danosos do que os ocasionados por processos naturais de larga escala (p. ex., a subida do nível do mar). A abordagem utilizada neste estudo consiste na definição de um índice multicritério de vulnerabilidade a ondas de maior frequência de ocorrência e de tempestade para o litoral de Santa Catarina. O índice de vulnerabilidade (IVC) foi obtido a partir da integração entre o índice de capacidade adaptativa, composto por variáveis socioeconômicas e de ocupação (área ocupada, distância entre a ocupação e a linha de costa, número de residentes, renda por residente e número de domicílios de uso ocasional), e o índice de suscetibilidade - composto por variáveis do meio físico (altura significativa de onda, gradiente de deriva litorânea potencial, largura de praia, elevação e declividade). A dinâmica costeira resultante da incidência de ondas sobre as manchas urbanas na área em perigo é analisada através de produtos de modelagem numérica, integrados às demais variáveis em ambiente de Sistema de Informação Geográfica (SIG). A relevância das variáveis na composição do índice foi avaliada pelo método de decisão multicritério AHP (analytic hierarchy process). As variáveis e os índices foram representados em cinco classes de vulnerabilidade (muito baixa, baixa, média, alta e muito alta) nos setores do Plano Estadual de Gerenciamento Costeiro (GERCO/SC). Com base na opinião de especialistas, as variáveis físicas foram consideradas mais relevantes do que as socioeconômicas. Os setores mais suscetíveis e vulneráveis são: centro-sul, sul, norte, centro-norte e centro, respectivamente. Já os setores de menor capacidade adaptativa são: centro-norte, centro, norte, centro-sul e sul, respectivamente. A baixa presença de residentes e ocupações na área em perigo, bem como as maiores distâncias entre a ocupação e a linha de costa - variáveis utilizadas na determinação da capacidade adaptativa e que favorecem a redução da vulnerabilidade - apresentaram um papel secundário na determinação do IVC para os setores centro-sul e sul. Os setores ao norte do Estado são menos suscetíveis e vulneráveis, todavia se encontram intensamente ocupados em praias com menores larguras de faixa de areia, terrenos planos e com baixa declividade (segmentos de maior suscetibilidade). A maior ocorrência de danos por erosão e inundação, atualmente observada ao norte do Estado, pode ser facilmente revertida caso haja a expansão de áreas ocupadas próximo às linhas de costa dos setores centro-sul e sul, tendo em vista a alta suscetibilidade e os baixos valores de renda e de segunda-moradia encontrados ao sul do Estado. / The occurrence of coastal infrastructure damage due to wave action has been promoting vulnerability assessments for integrated coastal management. Santa Catarina\'s coastal municipalities concentrate 28% of the state\'s population and the interface between the coastline and the ocean is predominantly composed by wave-dominated sandy beaches. Coastal impacts related to wave-dominated processes, especially at local and regional scales, can produce more damaging effects than large-scale natural processes (e. g., sea level rise). The approach suggested in this study consists of defining a vulnerability multicriteria index, for Santa Catarina\'s coastline, to waves with higher frequency of occurrence and to storm wave events. The coastal vulnerability index (IVC) was obtained by integrating the adaptive capacity index, composed by socioeconomic and occupational variables (constructed area, distance between human settlements and shoreline, number of residents, income per capita and number of households for occasional use), and the susceptibility index - consisting of environmental variables (significant wave height, potential longshore drift gradient, beach width, coastal elevation and slope). The resulting coastal dynamics from nearshore wave incidence is analyzed through the application of a numerical model, integrated with the other variables by geoprocessing techniques in a Geographic Information System (GIS) environment. The variables\' relevance in the index formula was obtained by the analytic hierarchy process (AHP). Variables and indices were hierarchized in five vulnerability classes (very low, low, medium, high and very high) and represented in the sectors from the State Coastal Management Plan (GERCO/SC): north, center-north, center, center-south and south. Based on specialists\' opinion on the determination of vulnerability, physical/environmental variables were considered more relevant than socioeconomic variables. The most susceptible and vulnerable sectors are: center-south, south, north, center-north and center, respectively. Sectors with the lowest adaptive capacity are: center-north, center, north, center-south and south, respectively. The low number of residents and settlements in the endangered area, as well as the greater distances between occupied area and the shoreline - variables used to determine adaptive capacity and that contribute to reduction of vulnerability - played a secondary role in the CVI\'s determination for the center-south and south sectors. The northern sectors of the state are less susceptible and vulnerable; however, they are intensely occupied in beaches with smaller beach width, lower elevation and slope (segments with higher susceptibility degrees). The highest occurrence of erosion and flood damage, currently observed at the north of the state, can easily be reversed in case of expansion of settlements near the center-south and south sectors, as a function of the higher susceptibility degrees and lower income per capita and number of households of occasional use found at the south of the state.

Floods are the most common natural disaster in the U.S. as reported by the Federal Emergency Management Administration (FEMA), and there is a need to provide advance warning to vulnerable communities on the potential risks of flooding after intense storms. The key drivers of urban hydrological research include climate change impacts and adaption, city resilience to hydrological extremes, and integration with emergency management and city planning disciplines. Significant advances in modeling techniques and computational resources have made real-time flood forecasting tools in urban and rural areas an achievable goal, but there is no universal method for flood modeling. Urban landscapes pose a challenge because of fine-scale features and heterogeneities in the landscape including streets, buildings, pipes, and impervious land cover. A nested regional-local modeling approach was used to evaluate its capabilities to provide useful and accurate flood related information to a small community in Iowa. The advantage of a nested approach is the ability to harness the computational efficiency of the regional model while providing reasonably accurate streamflow boundary conditions to the local model. The nested model incorporates the tools and products maintained at the Iowa Flood Center (IFC) including the streamflow bridge sensors, rain gauges, radar rainfall product, and statewide model. A one-way connection was made between the regional model of the upper Maquoketa Watershed (275 mi2) and the local model of the City of Manchester (5 mi2). The uncalibrated, nested model was validated using photos and streamflow records for flood events that occurred in July 2010 and September 2016. Multiple radar rainfall estimates were used as input to the model to better understand the impacts of the spatial and temporal resolution and variations of rainfall on streamflow predictions. A local storm event analysis was completed to determine the vulnerable areas of the stormwater network in eastern Manchester. The two main sources of flooding in Manchester are from the river and from local runoff. During extreme flood events caused by the river, the hydrologic impacts of the urban catchment are masked and the stormwater network system is overwhelmed. The coarse, regional model is limited in producing streamflow results for the small tributaries draining the eastern areas of Manchester. In the case of localized rainfall, a fine resolution model that takes into account the stormwater network and rainfall-runoff dynamics are crucial to capturing the hydrologic response of the urban area. Overall, the nested model showed skill in reproducing the hydrographs and the flood extents. Using an ensemble of rainfall input, the multiple model realizations envelope the observed streamflow indicating that the uncertainty of the rainfall is implicitly captured in the model results. The simulated streamflow at the outlet varies significantly depending on the spatial resolution of the rainfall but shows small sensitivity to the temporal resolution of the rainfall input. However, the local rainfall-runoff volumes vary significantly depending on the spatial and temporal resolution of the rainfall input. Recommendations are given to Manchester to highlight areas at risk to flooding. Recommendations are given to the IFC on the capabilities of the nested regional-local modeling approach along with suggestions for future work to incorporate urban areas into the statewide flood forecasting system.

The low-lying topographic nature of salt marshes makes plants in these communities particularly vulnerable to increased salinity and inundation exposure associated with sea level rise. Both increased salinity and inundation have been cited as major causes of reduced plant performance and survival in marsh and areas fringing marsh. In addition to limitations imposed by physical stress, interspecific interactions have also been shown to mediate the performance and survival of salt marsh and salt marsh fringing species. The Stress Gradient Hypothesis (SGH) postulates that species interactions shift from competitive to facilitative as stress levels increase and predicts that (a) the frequency and intensity of facilitative interactions increase as conditions become more stressful for plants and (b) the strength of competitive interactions increases as abiotic stress levels diminish. The SGH has been rigorously tested to examine how both the frequency and intensity of species interactions change under varying physical stress levels. Studies conducted in salt marsh systems have shown facilitation to be as strong of a driving force as competition in influencing plant performance and survival and have shown that while competition appears to be the pervasive force in the less physically stressful terrestrial zones fringing salt marshes, facilitation influences the performance and survival of species in harsher marsh areas. Under conditions of sea level rise, it remains unclear if the nature of interspecific interactions would shift as stress levels change. This research endeavors to examine the interplay between abiotic stresses and biotic interactions under conditions of increased salinity and inundation exposure. The first study presented here investigated the effects of increased inundation and soil salinity associated with sea level rise on four salt marsh fringing species, and assesses how competition and facilitation impact survival of salt marsh fringing plant survival under these changing conditions. All plant species experienced reduced growth and photosynthetic inhibition below their current distributional positions, both in the presence and absence of neighboring above ground vegetation. The findings also signal a potential shift in the nature of interspecific interactions from competition to facilitation to neutral as plants begin to experience increased salt and inundation exposure. The second study aimed to disentangle the effects of increased soil salinity and increased soil moisture on four salt marsh fringing species, and to examine the effects of plant neighbors. The results showed that fringe plants exposed to increased inundation experienced a two-fold reduction in performance and survival over 750 g pure salt addition, suggesting that inundation may be a more important limiting factor than salinity with rising sea levels. Landward transplants at the forest-fringe margin exposed to lower soil salinity and decreased inundation exhibited a three-fold increase in performance and survival when compared to controls. Neighbor manipulation studies, which consisted of trimming neighboring vegetation to ground level, again suggested that interspecific interactions in salt marsh fringing species may shift from competitive to facilitative with climate-induced sea level rise. Overall, our findings suggest that salt marsh fringing species may not be able to tolerate changing conditions associated with sea level rise and their survival may hinge on their ability to migrate towards higher elevations. The final experiment tested the Stress Gradient Hypothesis and investigated the relative importance of facilitation and competition in a salt marsh system under varying stress levels. This study also ascertained whether salt or inundation exposure is the primary influence on salt marsh plant performance and survival. As in previous studies, our findings suggest that many salt marsh plants don't require, but merely tolerate harsher abiotic conditions. The results showed that plants at higher elevations were depressed by strong competitive pressure from neighboring fringe species while plants at lower elevations benefited from the presence of neighbors. Collectively, the results of these studies indicate that species interactions are an integral driver of plant distribution in salt marsh communities. Furthermore, our findings indicate that changing stress levels may not always result in a shift in the nature of interspecific interactions. These studies have endeavored to show that the interplay between competition and facilitation interacts with physical processes to determine the growth and performance of both fringe and marsh plant species. The paucity of studies examining the roles of species interactions and changing abiotic stress levels on multiple salt marsh and salt marsh fringing species warrants the need for additional research. The responses of salt marsh and salt marsh fringing species to sea level rise can not only serve as very valuable and sensitive indictors of climate change, but will also aid in predicting the future location of the marsh-fringe-forest ecotone, which is predicted to shift inland as sea levels continue to rise.

Using a multi-scale experimental approach, the research undertaken in this thesis investigated the role of the flood pulse in ephemeral floodplain wetlands of the River Murray, in order to better understand the impact of river regulation (and permanent inundation) on these wetlands. An ecosystem-based experiment was conducted on the River Murray floodplain, to compare changes in nutrient availability and phytoplankton productivity in three ephemeral wetlands (over a drying/reflooding cycle) with three permanently inundated wetlands. In the ephemeral wetlands, both drying and re-flooding phases were associated with significant increases in nutrient availability and, in some cases, phytoplankton productivity. It was demonstrated that the ?flood pulse?, as described by the Flood Pulse Concept (FPC), can occur in ephemeral wetlands in dryland river-floodplain systems, although considerable variation in the nature of the pulse existed amongst these wetlands. Results of this experiment suggest that factors such as the degree of drying and length of isolation during the dry phase, the rate of re-filling, timing of re-flooding and the number of drying/re-flooding cycles may be potentially important in producing the variation observed. Permanent inundation of ephemeral wetlands effectively removed these periods of peak nutrient availability and phytoplankton productivity, resulting in continuously low levels (of nutrient availability and phytoplankton productivity). It was concluded that alteration of the natural hydrological cycle in this way can significantly reduce nutrient availability, primary production and secondary production, essentially changing the structure and function, the ecology, of these wetlands. Equally, the results of this experiment indicate that some of the changes resulting from river regulation and permanent inundation can be somewhat reversed, within a relatively short period of time, given re-instatement of a more natural hydrological regime. A mesocosm experiment was used to examine the influence of the dry phase, specifically the effect of the degree of wetland drying, on patterns of nutrient availability and primary productivity comprising the flood pulse. Compared to permanent inundation, re-flooding of completely desiccated sediments increased carbon (C) and nitrogen (N) availability while partial drying generally decreased, or had little effect on, C and N availability after re-flooding. However, degree of drying had little effect on phosphorus availability or rates of primary production measured after re-flooding, and it is possible that these two factors are related. Partial drying reduced rates of community respiration after reflooding, possibly a reflection of the reduced carbon concentrations measured in these mesocosms in this phase of the experiment. Degree of drying also influenced the macrophyte community (measured after three months of flooding), with plant biomass generally decreasing and species diversity increasing as the degree of drying increased (with the exception of complete sediment desiccation which had lasting negative effects on both macrophyte biomass and species diversity). The results of the ecosystem and mesocosm experiments were utilised, in addition to results collected from the same experiment conducted at two smaller scales (minicosms and microcosms), to assess whether the effects of hydrological regime on nutrient availability at the ?wetland? scale could be replicated in smaller-scale experiments. None of the smaller-scaled experiments included in this investigation were able to replicate the specific response to hydrological regime recorded at the ecosystem scale, however the mesocosm experiment did produce results that were more similar to those at the ecosystem scale than those produced by the mini and microcosm experiments. The results of this study indicated that extrapolation of results from small-scale experiments should be undertaken with caution, and confirmed that a multi-scale approach to ecological research is wise, where large-scale field experimentation and/or monitoring provides a check on the accuracy, and hence relevance, of conclusions reached via mesocosm experiments.

<p>A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.</p><p> </p><p>In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.</p><p> </p><p>Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.</p><p> </p><p>With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s <em>n</em> for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.</p><p> </p><p>Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.</p><p> </p><p>Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.</p>

Performance-based measures are used to validate and quantify how likely the system’s results resemble that of the actual data. Its application in inundation studies is performed by comparing the extents of the predicted flood to the real event by measuring their overlap size and getting the percentage of this size to the union of both data. In this study, performances of 1- and 2-dimensional flow models were assessed when used with different topographic data sources, rasterisation cell sizes, mesh resolution and Manning’s values with the help of Geographic Information Systems (GIS). The Generalised Likelihood Uncertainty Estimation (GLUE) was also implemented to evaluate the behaviour and the uncertainties of the Hydrologic Engineering Center-River Analysis System (HEC-RAS) steady-flow model in delineating the inundation extents when various sets of friction coefficients for floodplain and channel were utilised as inputs. Although it was not possible to perform the GLUE procedure with Telemac-2D due to the simulation time, Manning’s n performances’ effects were evaluated using ten randomly selected sets of friction for the channel and floodplain. The LiDAR data, which had the highest resolution, performed well in all simulations, followed by Lantmäteriet data at 50 m resolution. The lowest resolution Digital Terrain Elevation Data (DTED) showed poor resemblance to the actual event and big misrepresentations of flooded areas. Rasterisation cell sizes in HEC-RAS showed minimal effect to the inundation limits when used between 1 m and 5 m, but performance started to deteriorate at 10 m (Lantmäteriet) and 20 m (LiDAR). The 10 m mesh resolution used for LiDAR behaved poorer than the 20 m mesh, which performed well in the different 2D simulations. For HEC-RAS, =0.033 to 0.05 performed well when paired with =0.02 to 0.10. It was apparent, therefore, that the channel’s Manning’s n affected the performances of the floodplain’s . Furthermore, the study also showed that using heterogeneous roughness values corresponding to the different land use classes is not as effective as using single channel and floodplain’s Manning. The dependence of the floodplain’s roughness to the channel’s friction values had also been manifested by Telemac, even though it required lower values than the 1D simulator. = 0.007 to 0.019   and =0.01 to 0.04 gave good performance to the 2D system. In terms of the overall model performance, HEC-RAS 1D exhibited good results for Testeboån. Even when the average distances to the actual data were estimated, the breadths were shorter compared to the most optimal output of the two-dimensional simulator, which showed more overestimated areas, despite the fact that the overlap size with the 1977 actual event was better than HEC-RAS. It could be because the measures-of-fit took into consideration the areal sizes that were over- and under-predicted aside from the overlap sizes between the observed and modelled results. This could be the same reason with the mean distances produced, wherein higher values were computed for Telemac-2D due to its bigger gap from the actual flood as brought by the enlargement in the flood extents. But it was also made known in the study that such ambiguities in the model performance were further contributed by the characteristics of the floodplain’s topography of being flat. Testeboån’s inclination to the banks was averaged at 0.027 m/m, with the central portion at 0.002 m/m. The middle portion of the floodplain was illustrated to contain more uncertain regions, where water extents changed easily as the parameters were altered. Distances greater than 200 m were also mostly located within these inclination values or within 0.005 to 0.006 m/m. The response of distance to the floodplain’s gradient improved when the slope value became higher, and this had been particularly noticed between 0 to 50 m.

In this thesis, detailed tsunami numerical modeling study was applied to the selected case studies, Fethiye town (Turkey) and Kiparissia-Zakintos-Pylos (Greece) in Mediterranean, using rupture-specific tsunami sources which can generate tsunamis in Mediterranean. As a first step of the study, the general database of Fethiye and Kiparissia-Zakintos-Pylos were integrated to GIS-based environment to organize, analyze and display reliable data from different sources. Secondly, for each earthquake scenario, the tsunami propagation and coastal amplifications were computed by TUNAMI N3 to evaluate the coastal amplifications of tsunamis and understand the tsunami propagation for the cases. As the final step, a study of inundation areas of probable tsunamis in these regions was performed. Available results were used to understand the effects of tsunamis and assist in developing mitigation strategies. Methods and results were presented and discussed.

Abstract Accurate measurement of the hydroperiod in isolated wetlands currently relies upon the installation and frequent monitoring of devices such as piezometers and staff gauges. Observations of biological indicators of the hydroperiod may be able to supplement data collected from these devices and could potentially replace them as a means of accurately determining this hydrologic interval. The study objective was to determine whether adventitious root formation and maturation on buttonbush (Cephalanthus occidentalis) could be used as a viable indicator of the hydroperiod in isolated wetlands. Buttonbush seedlings were flooded in a controlled environment over a three month period in the summer of 2011. During this time, the length and complexity of adventitious roots observed were recorded. When average lengths of primary roots were regressed against time of inundation, a linear regression (r2) of 0.94 was calculated. The structure of these roots was then compared to adventitious roots observed in a natural wetland with a hydroperiod of 12 months. This was undertaken to allow a comparison of the observed lengths and complexity of adventitious roots in the controlled experiment with roots in the natural environment. The regression of both sets of observations yielded an r2 value of 0.99. Consequently, the results of this study found that the length of adventitious roots on buttonbush can help determine the hydroperiods of isolated wetland systems.

A big responsibility lies in the hand of local authorities to exercise measures in preventing fatalities and damages during flood occurrences. However, the problem is how flooding can be prevented if nobody knows when and where it will be occurring, and how much water is expected. Therefore, the utilisation of flood models in such studies can be helpful in simulating what is anticipated to occur.   In this study, the HEC-RAS steady flow model was used in calibrating different flood events in Testeboån river, which is situated in the municipality of Gävle in Sweden. The purpose is to provide inundation maps that show the water surface profiles for the various flood events that can help authorities in planning within the area. Moreover, the study would try to address certain issues, which concern one-dimensional models like HEC-RAS in terms of the effects of topographic data and the parameters used for friction coefficient.   Various flood maps were produced to visualise the extents of the floods. In Oppala and Norra Åbyggeby, the big water extents for both the 100-year and the highest probable floods were visible in the forested areas and grasslands, although a few houses were within the predicted flooded areas. In Södra Åbyggeby, Varva, Forsby, and in the northern parts of Strömsbro and Stigslund, the majority of the residential places were not inundated during the 100-year flood calibration, but became flooded during the maximum probable flood. The southern portions of Strömsbro and Stigslund had lesser flood extents and houses were situated within the boundaries of the highest flood. In Näringen, there were also some areas close to the estuary that were flooded for both events.   With the other calibrations performed, two factors that greatly affect the flood extents in the floodplain, particularly in flatter areas were topographic data and the parameters used as friction coefficient.  The use of high resolution topographic data was important in improving the performance of the software. Nevertheless, it must be emphasised that in areas characterised by gentler slopes that bounded the channel and the floodplain, data completeness became significant whereby both ground data and bathymetric points must be present to avoid overestimation of the inundation extent. The water extents also varied with the use of the various Manning’s n for the overbanks, with the bigger value showing greater water extents. Else, in areas with steeper slopes and where the water was confined to the banks, the effect was minimal.   Despite these shortcomings of one-dimensional models, HEC-RAS provided good inundation extents that were comparable to the actual extent of the 1977 flooding.   Modelling real floods has its own difficulties due to the unpredictability of real-life flood behaviours, and more especially, there are time dependent factors that are involved.  Although calibrating a flood event will not exactly determine what is to arise as they might either under- or overestimate such flooding occurrences, still, they give a standpoint of what is more or less to anticipate, and from this,  planning measures can be undertaken.