Linking paleochannel evidence and physical vulnerability to urban flooding: a spatial analysis in Ibarra, Ecuador 

Urban flooding is a recurrent hazard in Ibarra city, northern Ecuador, where intense rainfall frequently triggers the overflow of streams draining the slopes of the Imbabura volcano. Recent flood events reported at local and provincial scales highlight the increasing relevance of flood-related hazards in the city (El Universo, 2023; La Hora, 2023). Previous research has demonstrated a strong spatial correspondence between flood occurrence and paleochannel networks and has characterized urban flood hazard using historical records and geospatial analyses (Torres-Ramírez, 2024a; Torres-Ramírez, 2024b). However, the physical vulnerability of neighborhoods located within these flood-prone areas has not yet been systematically evaluated. This research builds on previous studies by integrating paleochannel geomorphological evidence with general indicators of physical vulnerability to evaluate urban flood risk in Ibarra. Areas susceptible to flooding were identified based on existing interpretations of paleochannel remnants and documented historical flood events. In parallel, information related to urban exposure was compiled from collaborative geospatial sources and analyzed within a GIS environment to explore spatial relationships between flood-prone zones and the built environment. These datasets were then jointly examined to characterize patterns of physical vulnerability across the city. The results indicate that urban areas located within or near zones influenced by paleochannel landforms tend to present higher levels of flood vulnerability. This pattern is particularly evident in low-lying sectors affected by recent urban growth and limited drainage capacity, where geomorphological conditions favor the concentration of surface flows. By integrating inherited fluvial morphology with present-day urban characteristics, this approach provides a more comprehensive understanding of urban floods in Ibarra. In this way, the study provides relevant information linking paleochannels to support flood analysis and urban planning in rapidly growing Andean cities, based on the case of Ibarra.  References  El Universo. (2023, february ). Lluvias afectan a varios sectores de Ibarra. https://www.eluniverso.com/noticias/ecuador/lluvias-ibarra-febrero-2023-nota/La Hora. (2023, february ). Las calles de Ibarra se llenaron de lodo por inundaciones. https://www.lahora.com.ec/imbaburacarchi/Las-calles-de-Ibarra-se-llenaron-de-lodo-por-inundaciones-20230223-0020.htmlTorres-Ramírez, R. (2024, a). Hazard and Risk Assessment of Secondary flows (lahars) in Ibarra city, Imbabura – Ecuador. Université de Genève, Switzerland. Torres-Ramírez, R. (2024, b). Paleochannels and their correspondence with floods in the 21st century. Case study of Ibarra city, Imbabura, Ecuador., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14423, https://doi.org/10.5194/egusphere-egu24-14423.