Abstract
Flood simulation and hydrodynamic modeling of river flow require a dense sequence of river cross-sections. These cross-sections should be perpendicular to the flow path and are usually obtained through an in-field survey that is both a costly and time-consuming procedure. An alternative way to get these river cross-sections is to extract them from Digital Elevation Models (DEM). The accuracy achieved, though, depends on the quality and the resolution of the DEM available. Although there are specialized computer programs available for this process, the entire work must be mainly done manually. Some researchers have presented methods for the automatic extraction, but the cross-sections “produced” are restricted to be planar. This restriction does not ensure that they are perpendicular to the flow at all positions and does not allow them to be close to each other. In this paper, a new method is presented that, along with the algorithm developed, is fully parametric and allows non-planar (or dog-legged) river cross-sections to be extracted. These cross-sections offer two important advantages: (a) they are perpendicular to the flow at each subsection; and (b) they allow a much denser sequence to be formed. Moreover, as the proposed procedure is fully parametric, it can be repeated as many times as necessary, simply by altering any of the specified parameters, until the desirable result is achieved.
Highlights
Flood simulation and river flow one or two-dimensional hydrodynamic modeling require the availability of geometric data describing the morphology of the riverbed as precisely as possible.A significant number of river cross-sections perpendicular to the flow is absolutely necessary though.These cross-sections usually result from field measurements using special measuring equipment, such as theodolites and geographical location devices (GPS—Global Positioning System)
The results showed that the lidar Digital Elevation Models (DEM) had the lowest root mean square error (RMSE), followed by the contour DEM and the SRTM
DEMs used(resolutions derived from the SRTM1 project
Summary
Flood simulation and river flow one or two-dimensional hydrodynamic modeling require the availability of geometric data describing the morphology of the riverbed as precisely as possible. Radar Topography Mission) [3] project, in which the elevations of the water surface remain for the sea and the lakes but have been replaced for the rivers in a manner that they ensure correct calculation of the flow directions and, correct delineation of the river network and drainage basins Despite its drawbacks, this alternative remains attractive since it allows a quick and costless application, especially in the case of a preliminary study. The usual procedure to extract cross-sections from DEMs is mainly done in a manual way and is both time consuming and difficult to apply, while its results are not that accurate. If the DEMs of a fully automatic procedure These cross-sections will depend on a set of specified result is not the expected one, entire one, procedure canentire be repeated as many as necessary by parameters.
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