Physically based and distributed rainfall intensity and duration thresholds for shallow landslides

For landslide assessment in a specific small area of interest, regional thresholds may not be applicable and the application of empirical-statistical methodologies could be limited due to a lack of required databases (landslide inventories and triggering rainfall events). Rainfall thresholds for lan...

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Bibliographic Details
Published in:Landslides 2020-12, Vol.17 (12), p.2907-2917
Main Author: Marin, Roberto J.
Format: Article
Language:English
Subjects:
Agriculture
Civil Engineering
Duration
Early warning systems
Earth and Environmental Science
Earth Sciences
Empirical analysis
Extreme weather
Geography
Landslide warnings
Landslides
Landslides & mudslides
Mechanical properties
Mountains
Natural Hazards
Power law
Rain
Rainfall
Rainfall intensity
Sandy soils
Silt loam
Soil
Soil mechanics
Soil properties
Statistical methods
Technical Note
Thresholds
Tropical climate
Warning systems
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Description
Summary:For landslide assessment in a specific small area of interest, regional thresholds may not be applicable and the application of empirical-statistical methodologies could be limited due to a lack of required databases (landslide inventories and triggering rainfall events). Rainfall thresholds for landslides have been recently derived from the implementation of physically based methodologies that usually provide a power-law equation for the study area (e.g. region or a specific basin). In this work, a new methodology for defining rainfall intensity and duration thresholds using a physically based model (TRIGRS) is presented and implemented in a tropical mountain basin of the Colombian Andes. Multiple calculations of the factor of safety for different (synthetic) rainfall events permitted the fitting of power-law equations to the sets of critical intensity and duration conditions, causing failure in each grid cell. Maps of the equation parameters (scale and shape) and the range of applicability (initial and final duration) of the grid cell thresholds were analysed. The results show that the hydraulic and mechanical properties of the soil affected the threshold curve characteristics, comparing sandy soil with silty loam; the higher strength characteristics of sandy soil meant that most extreme rainfall conditions are required to reach their thresholds. This methodology could improve landslide early warning systems in terms of analysing the specific (local) areas that are highly susceptible to landslide occurrence.
ISSN:1612-510X
1612-5118
DOI:10.1007/s10346-020-01481-9