Uncertainty propagation through a numerical model of storm surge flooding
Brown, J. D.
PublisherUniversity of Cambridge
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This research focuses on the uncertainties associated with numerical modelling of extreme coastal flooding. It uses Canvey Island in the Thames estuary (UK) as a case study, where a linked storm surge and flood inundation model is developed and applied within an uncertainty framework. The case study is used to illustrate and evaluate the propagation of uncertainties from model inputs to model outputs as a function of the ‘boundary conditions’ encountered (input data, geography of the case study). The thesis is separated into six chapters, of which two provide an introduction to the research (Chapters 1 and 2), two focus on model development (Chapters 3 and 4) and two address model application and evaluation (Chapters 5 and 6). Chapter 1 provides a theoretical context for the research and outlines the aims and objectives of the thesis. The research adopts a ‘critical realist’ perspective on the value of models as tools for probing understanding about uncertain coastal flood hazards. Chapter 2 provides a description of the case study site and discusses its illustrative value from a flood risk perspective. Chapter 3 describes the development of a storm surge model for predicting water levels at Canvey Island in response to meteorological and tidal forcing of the North Sea. The storm surge model is based on four nested models, which provide a consistent increase in spatial resolution towards the case study site. The predicted water levels are used to drive a flood inundation model of Canvey Island, which is described in Chapter 4. The flood model is based on a 2-D, shock capturing, numerical scheme, and resolves the terrain and buildings of the study area with high-resolution topographic data. Chapter 5 describes the application of these models within an uncertainty framework where model sensitivities and uncertainties are evaluated for a range of storm forcing conditions over the North Sea and sea defence failures at Canvey Island.