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 1D/1D 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.
