Annually, tropical cyclones do tremendous damage and are agents of long-term coastal change. To test this idea of different tropical cyclones delivering consistent coastal change, a landform with such evolution is needed. One such landform is a spit. What contributions do tropical cyclones give toward the evolution of a spit, and do tropical cyclones give the same kinds of impacts? To determine if tropical cyclones have similar impacts, shoreline and volumetric change from four storms impacting Bolivar Peninsula are considered. Being a southwest-trended spit at a length of 33.5 kilometers, storm impacts are measured in the form of one dimensional shoreline and two dimensional volumetric change. These impacts are abstracted into shoreline change and volumetric change patterns. These patterns are identified and compared for differences between each storm and similarity among all storms. Results indicate that shoreline accretionary zones vary alongshore. Results from Hurricane Ike indicate an accretionary zone ten kilometers from the distal end. Shoreline change patterns for Hurricane Rita show an unstable accretionary zone at four kilometers from the distal end. Results for Tropical Storm Fay indicate an unstable accretionary zone that begins at the distal end and continues to the middle of the spit. In terms of similarity for shoreline change, all patterns from storms demonstrated erosion near Rollover Fish Pass. One dimensional volumetric change patterns were entirely erosive for Hurricanes Rita and Ike, and Tropical Storm Fay had by small zones of accretion near the distal portion of the spit. Tropical Storm Josephine demonstrated an accretion zone between the middle and distal portion of the spit. Results from two dimensional volumetric change patterns suggest a threshold for inland penetration. Tropical Storm Fay showed a ten to twenty meter wide pattern of erosion around five kilometers from the distal end and near the proximal end of the spit, and Hurricane Rita demonstrated a twenty meter wide pattern of erosion near the distal end. Hurricane Ike had erosive penetration of up to 200 meters around fifteen kilometers from the distal end. Results suggest that certain storms reinforce the standard spit growth model, and others work against it.

published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

No description available.

A fast catchment response usually leads to a shorter lag time, and under these conditions the forecast lead time obtained from a rainfall-runoff model or correlation between upstream and downstream flows may be infeasible for flood warning purposes. Additional lead time can be obtained from short-term quantitative rainfall forecasts that extend the flood warning time and increase the economic viability of a flood forecasting system. For this purpose algorithms which forecasts the quantitative rainfall amounts up to six hours ahead have been developed, based on lumped and distributed approaches. The lumped forecasting algorithm includes the essential features of storm dynamics such as rainband and raincell movements which are represented within the framework of a linear transfer function model. The dynamics of a storm are readily captured by radar data. A space-time rainfall model is used to generate synthetic radar data with known features, e.g. rainband and raincell velocities. This enables the algorithm to be assessed under ideal conditions, as errors are present in observed radar data. The transfer function algorithm can be summarised as follows. The dynamics of the rainbands and raincells are incorporated as inputs into the transfer function model. The algorithm employs simple spatial cross-correlation techniques to estimate the rainband and raincell velocities. The translated rainbands and raincells then form the auxiliary inputs to the transfer function. An optimal predictor based on minimum square error is then derived from the transfer function model, and its parameters are estimated from the auxiliary inputs and observed radar data in real-time using a recursive least squares algorithm. While the transfer-function algorithm forecasts areal rainfalls, a distributed approach which performs rainfall forecasting at a fine spatial resolution (referred to as the advection equation algorithm) is also evaluated in this thesis. The algorithm expresses the space-time rainfall on a Cartesian coordinate system via a partial differential advection equation. A simple explicit finite difference solution scheme is applied to the equation. A comparison of model parameter estimates is undertaken using a square root information filter data processing algorithm, and single-input single-output and multiple-input multiple-output least squares algorithms.

No description available.

Greater environmental considerations and the desire to reduce pollution overflows to watercourses are requiring engineers to develop a better understanding of the processes involved in pollution transport through sewer networks. Furthermore, developments in modelling techniques and computer power are allowing urban drainage modellers to increase the complexity of their software and so demand additional data that can be incorporated. Presently, an important aspect is quantifying the retention time and dispersion of pollutants entering an urban drainage system. Manholes provide a means of sewer access for maintenance and inspection. Under storm flow conditions they are liable to surcharge above the level of the pipe soffit. This creates a storage volume that has an impact on the longitudinal dispersion and travel time of soluble pollutants in sewer systems. A laboratory investigation has been completed to quantify these effects for various manhole configurations. These include step heights between the inlet and outlet pipes, benching and extreme high surcharge conditions. In addition, re·analysis of previously acquired data has allowed variations in manhole diameter to be considered. Numerical modelling using computational fluid dynamics, combined with laser light sheet visualisation of the flow structures within manholes, has provided greater insight into the processes causing longitudinal dispersion. The coefficients required for two existing longitudinal dispersion models, the advection dispersion equation and the aggregated dead zone model, have been determined by means of an optimisation process. This has been undertaken with computer software specifically written for the purpose. The technique adopted for optimisation is fully detailed. Final conclusions regarding the longitudinal dispersion due to surcharged manholes are presented.

The purpose of this report was to investigate how municipals in the county of Västra Götaland work with climate adaptation of storm water management and to identify problems that occur in the work. As with the rest of the world, Sweden will be affected by expected climate changes and it is therefore important that Swedish municipalities work with climate adaptation and to help them make the work manageable. The method used was semi-structural qualitative interviews where 13 municipalities were interviewed in April 2016. The result of the interviews shows that there is an ambition to work with climate adaptation of storm water management but that there are different problems associated with the work that have made it difficult to start. 69% of the municipalities include climate adaptation to some extent when they work with master plans and 5 out of 8 municipalities are or will be including climate adaptation strategies in their storm water management document. A majority of the municipalities don’t prioritize climate adaptation and could be doing more to include climate adaptation in their work. The most common problems reported by the municipalities were too little resources/lack of finance, undecided responsibility and not clear enough laws regarding the subject.

A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg in partial fulfillment of the requirements for the degree of Master of Science in Engineering. / Urban stormwater drainage designers and planners are having to deal with the dramatic effect that urbanization has on the hydrological regime. To cope economically with the increases in runoff volumes and peaks due to urbanization, more sophisticated approaches are required for the design and planning of stormwater drainage systems. [Abbreviated abstract. Open document to view full version] / AC2017

Este estudo tem como objetivo a previsão de impactos gerados por tempestades sobre os sistemas praial e de dunas frontais nas costas Leste (praias expostas) e Norte (praias abrigadas) da Ilha de Santa Catarina. A área de estudo abrange as praias entre a Barra da Lagoa e a Praia da Daniela. As respostas da costa frente aos eventos de tempestades foram classificadas em quatro diferentes regimes: Espraiamento (Swash), Colisão (Collision), Sobrelavagem (Overwash) e Inundação (Inundation). A delimitação entre cada regime é baseada na mais alta e mais baixa elevação vertical do nível d’água em relação às características morfológicas da duna frontal (base e crista). Para a Costa Leste, onde as praias são expostas à incidência de ondas, a máxima elevação do nível do mar foi definida pela soma do wave runup, maré astronômica e maré meteorológica, calculada para quatro distintos períodos de retornos (5, 10, 25 e 50 anos). A mais baixa elevação do mar foi definida como sendo a elevação na qual a praia é, na maior parte do tempo, continuamente submersa. Enquanto que para a Costa Norte, onde as praias são abrigadas da incidência das ondas, a máxima elevação do nível do mar durante eventos de tempestades foi calculada levando-se em consideração a soma das marés astronômica e meteorológicas para cada período de retorno analisado; enquanto que a mínima elevação foi representada pelo nível mais alto da maré astronômica. Em ambas as costas, foram adicionados os valores de elevação do nível do mar baseados nas previsões de pior caso do relatório do Painel Intergovernamental de Mudanças Climáticas. De acordo com este estudo a elevação do nível médio do mar vem ocorrendo em uma taxa de 4 mm/ano com uma aceleração anual de 0,019 mm/ano². Os resultados mostram que para a maioria das praias expostas não houve mudança de regime entre os períodos de retorno analisados. As exceções foram a porção central da praia dos Ingleses que apresentou passagem do regime de sobrelavagem (5 e 10 anos) para o regime de inundação (25 e 50 anos) e a Praia Brava que foi classificada como sujeita ao regime de colisão para o período de retorno de 5 anos passando a ser classificada como submetida ao regime de sobrelavagem para os demais períodos. O regime de sobrelavagem foi predominante para as praias abrigadas, sendo este o único regime registrado em toda a Costa Norte para o período de 50 anos. / This study aims to forecast the impacts of storms on the beache and foredune system along the East (exposed beaches) and North (sheltered beaches) coast of Santa Catarina Island. The study area covers the beaches between Barra da Lagoa and Daniela Beach. The coastal storm response were classified into four different regimes: Swash, Collision, Overwash and Inundation. The limits between regimes are based on the highest and lowest vertical elevation of the water level in relation to the elevation of geomorphic features of the foredune (base and crest). To the East Coast the maximum rise in sea level was defined as the sum of the wave runup, astronomical tide and storm surge, calculated for four different return periods (5, 10, 25 and 50 years). The lowest elevation of the sea is defined as the elevation at below which the beach is, most of the time, continuously subaqueous. On the North Coast the maximum rise in sea level during storm events was calculated taking into account the sum of astronomical and meteorological tides; the minimum level was defined as the maximum vertical range of astronomical tide for each return period. On both coasts the sea level rise (SLR) based on worst-case of the Climate Change Intergovernmental Panel report predictions was added to the maximun and minimum sea level elevation. According to this study the increase on the mean sea level has been occurring at a rate of 4 mm/year with an annual acceleration of 0.019 mm/ano². The results show that most of the exposed beaches did not change their regimes between the return periods analyzed. The exceptions being the Central-North portion of Ingleses, that went from overwash (RP 5 and 10 years) to inundation (RP 25 and 50 years) and Brava which changed from collision (RP 5 years) to overwash regime (RP 10, 25 and 50 years). Overwash was the predominant regime on sheltered beaches, being the only recorded regime for the 50-year return period.