Establishing rainfall frequency contour lines as thresholds for rainfall-induced landslides in Tegucigalpa, Honduras, 1980–2005

Abstract

In this paper, a method to derive rainfall thresholds based on the relationship between daily and the antecedent rainfall up to 6 days prior to landslide occurrence is proposed for the analysis of 134 landslide days in Tegucigalpa, Honduras, during the years 1980-2005. Based on a simple graphical procedure, rainfall frequency contour lines have been drawn in the daily versus antecedent rainfall plots to connect rainfall combinations relatively having the same frequency of occurrence. A two-bound threshold has been established: Below the lower bound, rainfall events are so frequent that any landslide day may only occur due to a significant anthropogenic disturbance, while, above the upper bound, rainfall alone is capable of inducing landslide days. Contour lines originating at the same daily rainfall value in all plots were then grouped together to form a threshold set, for which the number of well-predicted landslide days and false alarms was determined. It has been determined that 16 and 84 landslide days have fallen below the lower bound and above the upper bound, respectively. In addition, this method has been proven effective in the distinction between days with and without landslides, since it has led to a 23 % reduction in the number of false alarms per well-predicted landslide day when compared to a previously established threshold line for Tegucigalpa.

Rainfall-Induced Landslide Thresholds Development by Considering Different Rainfall Parameters: A Review

“…This relation of daily rainfall and antecedent rainfall are expressed in percent or ratio. For instance, Dahal and Hasegawa (2008) carried out the relation of daily rainfall of landslides and the cumulative rainfall before landslides (3,7,10,14,20, and 30 days) to recognise the factor of the antecedent parameter. The diagonal line is plotted on the graph to determine the axis biased of the scattering in between the selected antecedent rainfall and daily rainfall and indicated the rainfall at the same value at the time of failure.…”

Rainfall and weather conditions inducing intense landslide activity in northern Spain (Deba, Guipúzcoa)

“…On the basis of total daily rainfall data at the central point, the amount of previous days was aggregated to each day, that is, accumulating the rainfall of the antecedent days. The number of days to be considered depends on the characteristics of the terrain and climate, which may vary widely depending on the local settings (Wieczorek, 1987;Crozier, 1999;Glade et al, 2000;Aleotti, 2004;Guzzetti et al, 2007;Li et al, 2011;Garcia-Urquía, 2016;Ma et al, 2016). For shallow landslides in slopes covered by permeable colluvium, where the interstitial pressure dissipates rapidly, the antecedent rainfall should not be so important, since the rainfall itself generates the hydrological conditions required for instability (Mateos et al, 2012).…”

Rainfall and weather conditions inducing intense landslide activity in northern Spain (Deba, Guipúzcoa)

“…On the basis of total daily rainfall data in the central point, the amount of previous days was aggregated to each day, that is, accumulating the rainfall of the antecedent days. The number of days to be considered depends on the characteristics of the terrain and climate, which may vary widely depending on the local settings (Wieczorek, 1987;Crozier, 1999;Glade et al, 2000;Aleotti, 2004;Guzzetti et al, 2007;Li et al, 2011;Zêzere et al, 2015;Garcia-Urquía, 2016;Ma et al, 2016). For shallow landslides in slopes covered by permeable colluvium, where the interstitial pressure dissipates rapidly, the antecedent rainfall is not so important, since the rainfall itself generates the hydrological conditions required for instability (Mateos et al, 2012).…”