REDUNDANCIA DE LOS UMBRALES DEL SISTEMA DE ALERTA TEMPRANA PARA AVENIDAS TORRENCIALES DE MOCOA, PUTUMAYO, COLOMBIA

The study explores a novel methodology to determine ‘thresholds’ associated with debris flows in the municipality of Mocoa, Putumayo, Colombia. Thresholds are proposed in function of precipitation, water level elevation, and flow rate. Results were obtained with a debris flow physics-based modeling and damage produced on homes near the riverbed. Rainfall-Landslide thresholds were also determined based on the probabilistic analysis of curves reported in the literature and their comparison with two previous events that occurred in Mocoa. Findings show the need for advancing redundancy of the thresholds for several reasons: the high epistemic and random uncertainty included in the physical modeling process, the complexity of the process in the occurrence of the debris flow and its subsequent impact on the protection of life (main objective of disaster risk management) in case the early warning system does not function properly. For the very first time in Colombia, a procedure for determining thresholds for an Early Warning System of debris flow is presented, coming from an integrated physical analysis with probabilistic analyzes of available information.