Definition of Rainfall Thresholds for Shallow Landslides in Colombian Tropical Mountainous Catchments as Debris Flow Triggering Mechanism

Abstract

As a cascade precursor of the Debris Flow phenomenon, landslides generate economic losses and human fatalities worldwide, especially in mountainous and tropical countries like Colombia. This work proposes two different methodologies of defining rainfall thresholds as a tool for Early Warning Systems for Debris Flow occurrence in Colombian urban and mountainous catchments: Empirical-Statistical and Physically based. Empirical-Statistical rainfall thresholds are defined using several data sources such as rain gauges (pluviometers), radar, and satellite data allowing a different timing and spatial resolution in the definition. The definition of physically based rainfall thresholds the TRIGRS software is used in mountainous catchments with rainfall data from rain gauges, with the information from the safety factor map resulting in the simulations calculated as the cumulative density function from the histogram of the distributed safety factor allowing the understanding of how the instability varies in a catchment during different storms events