A multilayered approach to two-dimensional urban flood modelling
PublisherUniversity of Exeter
MetadataShow full item record
With urbanisation continuing to encroach upon flood plains, the constant replacement ofpermeable land with impermeable surfaces and with the changes in global climate, theneed for improved flood modelling is ever more apparent. A wide range of methodsexist that simulate surface flow; most commonly in one-dimensional (1D) or twodimensional(2D), and more recently on smaller scales in three-dimensional (3D)models. In urban flood modelling, 2D models are often the preferred choice as they cansimulate surface flow more accurately than their 1D model counterparts; they are,however, more computationally demanding and thereby usually require greatersimulation time. With the vast amount of information used in flood modelling,generalisation techniques are often employed to reduce the computational load within asimulation.The objective of this thesis is to improve 2D flood modelling in urban environments byintroducing a new and novel approach of representing fine scale building features withincoarse grids. This is achieved by creating an automated approach that data-mines keyfeatures such as buildings and represents their effects numerically within a multiplelayer grid format. This new approach is tested in comparison to two other, alreadyestablished generalising techniques which are single layer based. The effectiveness ofeach model is assessed by its ability to accurately represent surface flow at different gridresolutions and how each copes with varying building orientations and distributionswithin the test datasets. The performance of each generalising approach is determinedtherefore by its accuracy in relation to the fine scale model and the difference in thecomputational time required complete the simulation. Finally the multilayeredmethodology is applied to a real case scenario to test its applicability further. Overall itrevealed, as predicted, that the multilayered approach enables far greater accuracies atrouting surface flow within coarse grids whilst still greatly reducing computationaltime.As a further benefit in urban flood modelling, this thesis shows that using a multilayereddata format it is possible to simulate the influence of features that have a grid resolutionfiner than the initial terrain topology data, thus enabling, for example, the routing ofsurface water through alleyways between buildings that have a width less than onemeter.