Selecting criteria for urban basin delineation based on UAV photogrammetry: a case study in Culiacan, Mexico

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Urban storm drainage is essential for the large part of the population living in cities with torrential rains to protect public urban infrastructure, private property, and human lives from flooding. The most important design parameter for urban storm drainage is the flow discharge, which is normally calculated with the area, runoff coefficient, and rainfall intensity depending on basin delineation. This requires highly accurate topographic information on the urbanized terrain that digital elevation models sometimes do not meet due to the lack of resolution. This study proposes criteria for delineating urban basins considering urbanization without requiring the usual topographic surveys. The proposed basin delineation is based on a high-resolution digital elevation model obtained from an unmanned aerial vehicle (UAV) and field verification of flow directions. As a result, the delineation of two urban basins was obtained: an urban basin within an area that drains exclusively to a sinkhole and another basin that additionally drains out through other points of the divide. The latter basin does not comply with the traditional concept of a hydrological basin because it has more than one outlet. In addition, this basin has an area that is 38% of the total area draining into the sinkhole.