UAV Photogrammetry–Based Flood Early Warning System Applied to Migok-cheon Stream, South Korea

Flood-induced damages have increased due to increased frequency of extreme rainfall events owing to climate change and continued development in flood-prone areas. Among the flood mitigation measures, flood early warning systems (FEWS) have been popular due to their low cost and easy installation, and have been found to be highly effective. A FEWS provides warning and alarm signals according to the water level of a river. Water-level measurements are often made at bridges because of easy access to the middle of a river and concrete ground. However, a measurement site is often not related to the earliest flooded site. A thorough investigation and ground surveying are therefore required to select the site. Therefore, the current study tried to resolve this problem with a newly developed unmanned aerial vehicles (UAV) photogrammetry technique and proposed a novel UAV-based approach to establish the water-level standards for the FEWS. The digital surface model (DSM) obtained from UAV photogrammetry provides useful three-dimensional (3D) information and allows one to determine the earliest embankment site. The approach was applied to the Migok-cheon Stream, South Korea. Results showed that the proposed approach can be a useful alternative for establishing a water-level standard for the FEWS. The proposed alternative can be further developed with advancing UAV and 3D photogrammetry technologies.