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- Garcia-Urquia, Elias
(författare)
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Establishing rainfall frequency contour lines as thresholds for rainfall-induced landslides in Tegucigalpa, Honduras, 1980-2005
- 2016
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Ingår i: Natural Hazards. - : Springer Science and Business Media LLC. - 0921-030X .- 1573-0840. ; 82:3, s. 2107-2132
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Tidskriftsartikel (refereegranskat)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.
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- Garcia-Urquia, Elias, 1982-
(författare)
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The Use of Press Archives in the Temporal and Spatial Analysis of Rainfall-Induced Landslides in Tegucigalpa, Honduras, 1980-2005
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The scarcity of data poses a challenging obstacle for the study of natural disasters, especially in developing countries where the social vulnerability plays as important a role as the physical vulnerability. The work presented in this thesis is oriented towards the demonstration of the usefulness of press archives as a data source for the temporal and spatial analysis of landslides in Tegucigalpa, Honduras for the period between 1980 and 2005. In the last four decades, Tegucigalpa has been characterized by a disorganized urban growth that has significantly contributed to the destabilization of the city’s slopes. In the first part of the thesis, a description of the database compilation procedure is provided. The limitations of using data derived from press archives have also been addressed to indicate how these affect the subsequent landslide analyses. In the second part, the temporal richness offered by press archives has allowed the establishment of rainfall thresholds for landslide occurrence. Through the use of the critical rainfall intensity method, the analysis of rainfall thresholds for 7, 15, 30 and 60 antecedent days shows that the number of yielded false alarms increases with the threshold duration. A new method based on the rainfall frequency contour lines was proposed to improve the distinction between days with and without landslides. This method also offers the possibility to identify the landslides that may only occur with a major contribution of anthropogenic disturbances as well as those landslides induced by high-magnitude rainfall events. In the third part, the matrix method has been employed to construct two landslide susceptibility maps: one based on the multi-temporal press-based landslide inventory and a second one based on the landslide inventory derived from an aerial photograph interpretation carried out in 2014. Despite the low spatial accuracy provided by the press archives in locating the landslides, both maps exhibit 69% of consistency in the susceptibility classes and a good agreement in the areas with the highest propensity to landslides. Finally, the integration of these studies with major actions required to improve the process of landslide data collection is proposed to prepare Tegucigalpa for future landslides.
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- Garcia-Urquia, Elias, et al.
(författare)
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The use of press data in the development of a database for rainfall-induced landslides in Tegucigalpa, Honduras, 1980–2005
- 2014
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Ingår i: Natural Hazards. - : Springer Science and Business Media LLC. - 0921-030X .- 1573-0840. ; 73:2, s. 237-258
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Tidskriftsartikel (refereegranskat)abstract
- The capital city of Honduras, Tegucigalpa, suffers from the occurrence of destructive landslides on a yearly basis. During the rainy season, damages to infrastructure as well as injuries, casualties and homeless individuals resulting from landslides are reported in the press. This paper presents the development of a database for rainfall-induced landslides for the period 1980–2005, based on the news reported by two local newspapers. The editions comprehended during the study period have been scrutinized, and articles focusing on landslides, tropical storms, hurricanes, floods and vulnerability of the city have been collected. The interpretation of these archives has allowed the compilation of valuable data of approximately 400 landslides. The analyses of monthly and annual precipitation during the study period show how extreme rainfall events like Hurricane Mitch in October of 1998 have significantly contributed to the initiation of landslides. In addition, the assessment of the slums and neighborhoods affected by landslides during the study period reveals an evident link between the social and physical vulnerability of Tegucigalpa. In order to estimate the reliability of this press-based database, the set of landslides that have been reported as a result of Hurricane Mitch in the press archives has been compared with two inventories based on the interpretation of aerial photographs taken in 1999 and 2001. It is shown that the analysis of the landslide damage left after the hurricane can be enriched with the detailed temporal data provided in the archives and the precise location of these events determined by the aerial photographs. Despite the difficulties faced in the compilation of this database, a good comprehension of the temporal and spatial distribution of landslides in Tegucigalpa has been achieved.
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