Abstract
Abstract. Flash floods are a recurrent hazard for many developing Latin American regions due to their complex mountainous terrain and the rainfall characteristics in the tropics. These regions often lack the timely and high-quality information needed to assess, in real time, the threats to the vulnerable communities due to extreme hydrometeorological events. The systematic assessment of past extreme events allows us to improve our prediction capabilities of flash floods. In May 2015, a flash flood in the La Liboriana basin, municipality of Salgar, Colombia, caused more than 100 casualties and significant infrastructure damage. Despite the data scarcity, the climatological aspects, meteorological conditions, and first-order hydrometeorological mechanisms associated with the La Liboriana flash flood, including orographic intensification and the spatial distribution of the rainfall intensity relative to the basin's geomorphological features, are studied using precipitation information obtained using a weather radar quantitative precipitation estimation (QPE) technique, as well as from satellite products, in situ rain gauges from neighboring basins, quantitative precipitation forecasts (QPFs) from an operational Weather Research and Forecasting Model (WRF) application, and data from reanalysis products. The La Liboriana flash flood took place during a period with negative precipitation anomalies over most of the country as a result of an El Niño event. However, during May 2015, moist easterly flow towards the upper part of La Liboriana caused significant orographic rainfall enhancement. The overall evidence shows an important role of successive precipitation events in a relatively short period and of orography in the spatial distribution of rainfall and its intensification as convective cores approached the steepest topography. There were three consecutive events generating significant rainfall within the La Liboriana basin, and no single precipitation event was exceptionally large enough to generate the flash flood, but rather the combined role of precedent rainfall and the extreme hourly precipitation triggered the event. The results point to key lessons for improving local risk reduction strategies in vulnerable regions with complex terrain.
Highlights
On the morning of 18 May 2015, at around 02:40 LT (UTC−5), a deadly flash flood in the La Liboriana river basin inundated the town of Salgar, in the Department of Antioquia, Colombia, killing more than 100 people, leaving around 535 houses destroyed, and causing significant public infrastructure damage1
The La Liboriana flash flood occurred during May 2015, a month with multiannual average cumulative precipitation between 350 and 400 mm in the nearby region according to IDEAM records
The probabilities presented in this paragraph are not robust as they have been estimated based on a 5-year radar record, which is not enough for assessing extreme event recurrence as mentioned previously; the practical implications are important as the results suggest that the La Liboriana event was, exceptional compared to all events in the 5-year radar record, but in particular in the upper part of the basin, implying that for optimal risk management it is necessary to consider the spatial distribution of cumulative rainfall relative to the geomorphological features of the basin
Summary
On the morning of 18 May 2015, at around 02:40 LT (local time) (UTC−5), a deadly flash flood in the La Liboriana river basin inundated the town of Salgar, in the Department of Antioquia, Colombia (see Fig. 1), killing more than 100 people, leaving around 535 houses destroyed, and causing significant public infrastructure damage. Salgar, founded in 1903, and according to the national government with a population of around 17 600 people in 2015, of which 8800 reside in the urban area, is a typical complexterrain South American town settled in the Andes Cordillera, erected on the river margins of the main channel of the La Liboriana watershed, near the confluence with the El Barroso river, in a flash-flood-susceptible region from a geomorphological perspective
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
