A Novel Method for the Automatic Extraction of Quality Non-Planar River Cross-Sections from Digital Elevation Models

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.