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| Titel |
Quantitative estimation of landslide risk from rapid debris slides on natural slopes in the Nilgiri hills, India |
| VerfasserIn |
P. Jaiswal, C. J. Westen, V. Jetten |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 11, no. 6 ; Nr. 11, no. 6 (2011-06-21), S.1723-1743 |
| Datensatznummer |
250009492
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| Publikation (Nr.) |
 copernicus.org/nhess-11-1723-2011.pdf |
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| Zusammenfassung |
A quantitative procedure for estimating landslide risk to life and property
is presented and applied in a mountainous area in the Nilgiri hills of
southern India. Risk is estimated for elements at risk located in both
initiation zones and run-out paths of potential landslides. Loss of life is
expressed as individual risk and as societal risk using F-N curves, whereas
the direct loss of properties is expressed in monetary terms.
An inventory of 1084 landslides was prepared from historical records
available for the period between 1987 and 2009. A substantially complete
inventory was obtained for landslides on cut slopes (1042 landslides), while
for natural slopes information on only 42 landslides was available. Most
landslides were shallow translational debris slides and debris flowslides
triggered by rainfall. On natural slopes most landslides occurred as
first-time failures.
For landslide hazard assessment the following information was derived: (1)
landslides on natural slopes grouped into three landslide magnitude classes,
based on landslide volumes, (2) the number of future landslides on natural
slopes, obtained by establishing a relationship between the number of
landslides on natural slopes and cut slopes for different return periods
using a Gumbel distribution model, (3) landslide susceptible zones, obtained
using a logistic regression model, and (4) distribution of landslides in the
susceptible zones, obtained from the model fitting performance (success rate
curve). The run-out distance of landslides was assessed empirically using
landslide volumes, and the vulnerability of elements at risk was
subjectively assessed based on limited historic incidents.
Direct specific risk was estimated individually for tea/coffee and
horticulture plantations, transport infrastructures, buildings, and people
both in initiation and run-out areas. Risks were calculated by considering
the minimum, average, and maximum landslide volumes in each magnitude class
and the corresponding minimum, average, and maximum run-out distances and
vulnerability values, thus obtaining a range of risk values per return
period. The results indicate that the total annual minimum, average, and
maximum losses are about US$ 44 000, US$ 136 000 and US$ 268 000,
respectively. The maximum risk to population varies from 2.1 × 10−1 for one or more lives lost to 6.0 × 10−2 yr−1 for 100
or more lives lost. The obtained results will provide a basis for planning
risk reduction strategies in the Nilgiri area. |
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