Reconstructing the 2015 Salgar flash flood using radar retrievals and a conceptual modeling framework in an ungauged basin

Abstract

Abstract. On 18 May 2015, a severe rainfall event triggered a flash flood in the municipality of Salgar, located in the northwestern Colombian Andes. This work aims to reconstruct the main hydrological features of the flash flood to better understand the processes modulating the occurrence of the event. Radar quantitative precipitation estimates (QPEs), satellite information, and post-event field visits are used to reconstruct the Salgar flash flood, in an ungauged basin, addressing the relationship among rainfall spatiotemporal structure, soil moisture, and runoff generation during successive rainfall events by using a conceptual modeling framework including landslide and hydraulic submodels. The hydrological model includes virtual tracers to explore the role of runoff and subsurface flow and the relative importance of convective and stratiform precipitation in flash flood generation. Despite potential shortcomings due to the lack of data, the modeling results allow an assessment of the impact of the interactions between runoff, subsurface flow, and convective–stratiform rainfall on the short-term hydrological mechanisms leading to the flash flood event. The overall methodology reproduces the magnitude and timing of the La Liboriana flash flood peak discharge considerably well, as well as the areas of landslide occurrence and flood spots, with limitations due to the spatial resolution of the available digital elevation model. Simulation results indicate that the flash flood and regional landslide features were strongly influenced by the antecedent rainfall, which was associated with a northeasterly stratiform event. The latter recharged the gravitational and capillary storages within the model, moistening the entire basin before the occurrence of the flash flood event and impacting the subsurface–runoff partitioning during the flash flood event. Evidence suggests that the spatial structure of the rainfall is at least as important as the geomorphological features of the basin in regulating the occurrence of flash flood events.

Assessment of Deep Convective Systems in the Colombian Andean Region

“…According to our results, convective systems occur more often in areas with high topographical gradients, where the aspect is opposite to the wind direction. This result coincides with other studies performed in the region around rainfall and topography [55,59]. Moreover, similar results linking topography and convective rainfall have been reported in other regions [60][61][62][63][64].…”

An Overview of Flood Risk Analysis Methods

“…The research was mainly focused on the following three major regions: Continental Europe [22][23][24][25][26] with about 40% of articles, Asia with 28% [27][28][29][30][31], and North America with 20% [32][33][34][35][36]. South America (5%) [37][38][39][40][41] and Africa (4%) [42][43][44][45][46] showed less research interest (Figure 2). Following a detailed analysis of each region, we found that the most researched areas were: the United States, representing 13.19% of the total articles analyzed and 71.72% of the articles located in North America [47][48][49]; the United Kingdom, with 90 articles representing 17.92% of the articles in Europe and 6.78% of the total papers [50][51][52]; Italy and Spain, accounting for 5.27% of the entire articles and 13.94% of the scientific papers published in Europe, respectively [53][54][55]; and China, accounting for 5.27% of the total articles and 20.11% of the articles in Asia [56][57][58].…”

Panorama geral sobre dados hidrológicos com ênfase em eventos hidrológicos extremos

“…De acordo com Vanelli et al, (2020), no Brasil, ainda não existem normativas, como na UE, que incentivam a investigação de eventos passados para apoiar a gestão de risco e de desastres. Esse tipo de estudo, denominado reconstrução por Balasch et al (2010), Barriendos et al (2014) e Vanelli et al (2020, entre outros, refere-se a representar um certo evento ocorrido visando determinar os fatores associados aos processos físicos e avaliar as interações entre as variáveis possibilitando uma melhor compreensão dos mecanismos envolvidos (Fortunato et al 2017;Velásquez et al, 2020). Entretanto, outros termos já foram utilizados com o mesmo propósito: retromodelagem (Remo & Pinter, 2007;Balasch et al, 2011) e reconstituição (Ribeiro Neto et al, 2015).…”