Abstract

CASTILLO RUALES, Antonio et al. Rainfall thresholds based on intensity for flash floods in the Manizales River, Colombia. Rev.EIA.Esc.Ing.Antioq [online]. 2020, vol.17, n.33, pp.27-42. ISSN 1794-1237.  https://doi.org/10.24050/reia.v17i33.1302.

Where the traditional approach in establish alert thresholds for Early Warning Systems (EWS) relies on rainfall depth-duration curves, in the context of watersheds characterised by short runoff response time and in the absence of weather radar data, such practise cannot be implemented effectively. Hence, this research establishes alert threshold based on real-time rainfall measurement correlation over a catchment between headwaters and stages observed downstream in absence of rainfall depth-duration data. The Manizales River catchment (Caldas, Colombia) has presented flash flood events that have been aggravated by urbanization of the area. The distributed hydrological model TETIS was implemented using local rainfall distribution patterns to establish overland flow. The 2DH hydraulic flow model was based on IBER that determined 3 risk levels. The study suggests that then catchment response is highly sensitive to rainfall intensity changes rather than precipitation depth over time. Hence a specific methodology based on 10 minute cumulative mobile rainfall depth over time was used to establish rainfall thresholds for the EWS of the Manizales watershed.

Keywords : Rainfall thresholds; flash floods; Risk flood; Early warning system.

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