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| Titel |
Regional debris flow susceptibility analysis in mountainous peri-urban areas through morphometric and land cover indicators |
| VerfasserIn |
M. C. Rogelis, M. Werner |
| 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 Sciences ; 14, no. 11 ; Nr. 14, no. 11 (2014-11-19), S.3043-3064 |
| Datensatznummer |
250118753
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| Publikation (Nr.) |
 copernicus.org/nhess-14-3043-2014.pdf |
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| Zusammenfassung |
| A method for assessing regional debris flow susceptibility at the watershed
scale, based on an index composed of a morphometric indicator and a land
cover indicator, is proposed and applied in 106 peri-urban mountainous
watersheds in Bogotá, Colombia. The indicator of debris flow
susceptibility is obtained from readily available information common to most
peri-urban mountainous areas and can be used to prioritise watersheds that
can subsequently be subjected to detailed hazard analysis. Susceptibility is
considered to increase with flashiness and the possibility of debris flows
occurring. Morphological variables recognised in the literature to significantly
influence flashiness and occurrence of debris flows are used to construct the
morphometric indicator by applying principal component analysis.
Subsequently, this indicator is compared with the results of debris flow
propagation to assess its capacity in identifying the morphological
conditions of a watershed that make it able to transport debris flows.
Propagation of debris flows was carried out using the Modified Single Flow
Direction algorithm, following identification of source areas by applying
thresholds identified in the slope–area curve of the watersheds. Results show
that the morphometric variables can be grouped into four indicators: size,
shape, hypsometry and (potential) energy, with energy being the component
that best explains the capability of a watershed to transport debris flows.
However, the morphometric indicator was found to not sufficiently explain the
records of past floods in the study area. Combining the morphometric
indicator with land cover indicators improved the agreement and provided a
more reliable assessment of debris flow susceptibility in the study area. The
analysis shows that, even if morphometric parameters identify a high
disposition to the occurrence of debris flow, improving land cover can reduce
the susceptibility. However, if favourable morphometric conditions
are present but deterioration of the land cover in the watershed takes place,
then the susceptibility to debris flow events increases. The indicator of
debris flow susceptibility is useful in the identification of flood type,
which is a crucial step in flood risk assessment especially in mountainous
environments, and it can be used as input for prioritisation of flood risk
management strategies at regional level and for the prioritisation and
identification of detailed flood hazard analysis. The indicator is regional
in scope, and therefore it is not intended to constitute a detailed assessment
but to highlight watersheds that could potentially be more susceptible to
damaging floods than others in the same region. |
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