Enhanced DEM-based flow path delineation methods for urban flood modelling

Abstract

In order to simulate surface runoff and flooding, one-dimensional (1D) overland flow networks can be automatically delineated using digital elevation models (DEM). The resulting network comprises flow paths and terrain depressions/ponds and is essential to reliably model pluvial (surface) flooding events in urban areas by so-called ID/ID models. Conventional automatic DEM-based flow path delineation methods have problems in producing realistic overland flow paths when detailed highresolution DEMs of urban areas are used. The aim of this paper is to present the results of research and development of three enhanced DEM-based overland flow path delineation methods; these methods are triggered when the conventional flow path delineation process stops due to a flow obstacle. Two of the methods, the 'bouncing ball and buildings' and 'bouncing ball and A*' methods, are based on the conventional 'bouncing ball' concept; the third proposed method, the 'sliding ball' method, is based on the physical water accumulation concept. These enhanced methods were tested and their results were compared with results obtained using two conventional flow path delineation methods using a semi-synthetic test DEM. The results showed significant improvements in terms of the reliability of the delineated overland flow paths when using these enhanced methods.

A Modified Digital Elevation Modeling for Stormwater Management Planning in Segmentalized Micro-catchment Areas

“…This study also presents the process required to add vertical geo-information data to a DEM. The results from the DEM combined with the vertical data could then be applied to development planning within a catchment area based on the rolling ball method (RBM) (Boonya-Aroonnet et al, 2007;Jenson and Domingue, 1988;Leitao, 2013;Maksimović et al, 2009;Prodanović, 1999;van Dijk et al, 2014;Zhou et al, 2010). In addition, the morphological differences of the catchment area in this study were shown by comparing the results from the DEM with and without the vertical data.…”

“…The addition of urban vertical data-such as curb heights, buildings, and walls-to a high-resolution DEM increases the precision of any analysis of overland flow and catchment areas. As artificial vertical structures are elements that affect overland flow in urban areas, urban vertical data are needed to fill the data gaps (Leitao et al, 2008;Leitao, 2013). This research is conducted in order to discover areas vulnerable to flooding by analyzing surface water flow associated with micro-sub catchments and altered topography, both of which are the result of urbanization.…”

Identifying the best locations to install flow control devices in sewer networks to enable in-sewer storage

“…Two highly urbanised catchments (Figure 3) have reported severe pluvial flooding in recent years (Leitão et al, 2016;Leitão, 2009). The Zona Central catchment with approximately 1.5 km 2 is located in Coimbra (Portugal).…”

Semi- vs. Fully-Distributed Urban Stormwater Models: Model Set Up and Comparison with Two Real Case Studies

“…Examples of important advancements are: increase of available data (e.g., digital map [18], advanced collaborative sources of information [19], weather radar data [20]); advances in technology (e.g., remote sensing [21], computing techniques [22]); and improvements of numerical methods (e.g., reduction in simulation times in 2D overland modeling [23], new mathematical approaches [24][25][26]). These improvements are opening the discussion for the application of FD urban stormwater models.…”