The influence of digital elevation model resolution on overland flow networks for modelling urban pluvial flooding

Abstract

This paper presents the developments towards the next generation of overland flow modelling of urban pluvial flooding. Using a detailed analysis of the Digital Elevation Model (DEM) the developed GIS tools can automatically generate surface drainage networks which consist of temporary ponds (floodable areas) and flow paths and link them with the underground network through inlets. For different commercially-available Rainfall-Runoff simulation models, the tool will generate the overland flow network needed to model the surface runoff and pluvial flooding accurately. In this paper the emphasis is placed on a sensitivity analysis of ponds and preferential overland flow paths creation. Different DEMs for three areas were considered in order to compare the results obtained. The DEMs considered were generated using different acquisition techniques and hence represent terrain with varying levels of resolution and accuracy. The results show that DEMs can be used to generate surface flow networks reliably. As expected, the quality of the surface network generated is highly dependent on the quality and resolution of the DEMs and successful representation of buildings and streets.

Assessing the quality of digital elevation models obtained from mini unmanned aerial vehicles for overland flow modelling in urban areas

“…From the literature, it is clear that a great effort has been made to develop new and improve existing numerical methods for hydraulic models. However, DEMs, as all input data, can also have a significant impact on overland flow modelling results (Fewtrell et al, 2011;Leitão et al, 2009). showed the effect that DEM sources, resolution and accuracy have on the delineation of overland flow paths in urban catchments; fine-resolution DEMs are required to obtain accurate 1-D overland flow networks in urban areas.…”

A rapid urban flood inundation and damage assessment model

“…As the size of IZs increases (the number of IZs decreases), the amount of dry areas increases. This can be improved by finding possible connecting pathways between IZs using the "rolling ball" technique suggested in the literature (CH2M, 2013;Leitão et al, 2009;Maksimović et al, 2009;van Dijk et al, 2014). Water depth in these dry areas were usually smaller than the minimum threshold level in our depth damage curves.…”

A New Method for Urban Storm Flood Inundation Simulation with Fine CD-TIN Surface

“…Using a Triangle Irregular Network (TIN) or a Constrained Delauney Triangle Irregular Network (CD-TIN) for representing urban surface has obvious advantages. (1) Constructing a raster from irregularly spaced data or multiple source data often requires interpolation and possible loss of information [26]; (2) Water flow on a grid is commonly constrained to eight (or even four) neighbor directions for ease of computation, which can produce visible artifacts; (3) The extracted flow networks and water depressions may be unrealistic due to the limited regular arrangement of raster fixed cells, such as plume-parallel-shape flow streams and parallel-discrete-shape depressions [27,28]; (4) Different resolution of raster represented terrain can produce different hydrology elements, e.g., flow networks or depressions [29]. The urban water depressions, defined as watershed of the sink point to which water converges, are of importance to serve as basic unit for urban flood simulation.…”