Author(s): Maria Elvira Guevara Alvarez, Juan Camilo Rojas

Linked Author(s): Maria Elvira Guevara Alvarez

Keywords: Floods; Hydraulic modeling; Rivers; Digital Elevation Model (DEM); Land survey;

Abstract: The purpose of this research is to analyze the difficulties and conveniences of three different digital elevation models constructed from official digital cartography, common ground-based surveys (topo-bathymetry) and drones and to make a relative comparison of the results of river flood areas in Popayán, located in Southwestern Colombia. Different flow rates were examined to assess the consistency of the results. In general, the superimposition of the modeling results of flooding obtained from the two first models, illustrates the critical places where broader flood areas are generated, reveals large discrepancies in the width of the flood, flow depths, and velocity, and it indicates how differences become less noticeable as channels increase in size. This first analysis allowed choosing the reach of the river where most flooding problems were detected in order to take images using drones. The results, among other findings, show that the use of drones is promising to replace conventional land surveys only in the case of riverbanks clear of vegetation, but with a substantial reduction in costs and risks. The drone serves to speed up field work, although, it is always expedient to also use conventional ground-based survey to characterize the river banks in areas where there is vegetation in order to obtain more accurate river profiles and cross sections. Unless we have excellent data, digital mapping can be used in preliminary studies as an approximation of the flooding areas while reducing the cost of the studies when compared to the conventional land surveys.

DOI: https://doi.org/10.3850/38WC092019-0828

Year: 2019