Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence

Nikolopoulos, Efthymios I.; Crema, Stefano; Marchi, Lorenzo; Guzzetti, Fausto; Borga, Marco

doi:10.1016/j.geomorph.2014.06.015

Cited by 160 publications

(98 citation statements)

References 43 publications

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“…Similar effects have been found as a consequence of rainfall measurement uncertainty on thresholds (Nikolopoulos et al, 2014a). Just these two sources of errors -always present in observed datasets -are enough to generate an uncertainty in thresholds assessment that is of significant magnitude.…”

Section: Discussionsupporting

confidence: 63%

Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

Peres¹,

Cancelliere²,

Greco³

et al. 2017

Preprint

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Uncertainty in rainfall datasets and landslide inventories is known to have negative impacts on the assessment of landslidetriggering thresholds. In this paper, we perform a quantitative analysis of the impacts that the uncertain knowledge of landslide initiation instants have on the assessment of landslide intensity-duration early warning thresholds. The analysis is based on an ideal synthetic database of rainfall and landslide data, generated by coupling a stochastic rainfall generator and a physically 15 based hydrological and slope stability model. This dataset is then perturbed according to hypothetical "reporting scenarios", that allow to simulate possible errors in landslide triggering instants, as derived from historical archives. The impact of these errors is analysed by combining different criteria to single-out rainfall events from a continuous series and different temporal aggregations of rainfall (hourly and daily). The analysis shows that the impacts of the above uncertainty sources can be significant. Errors influence thresholds in a way that they are generally underestimated. Potentially, the amount of the 20 underestimation can be enough to induce an excessive number of false positives, hence limiting possible landslide mitigation benefits. Moreover, the uncertain knowledge of triggering rainfall, limits the possibility to set up links between thresholds and physio-geographical factors.

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Section: Discussionsupporting

confidence: 63%

Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

Peres¹,

Cancelliere²,

Greco³

et al. 2017

Preprint

View full text Add to dashboard Cite

show abstract

“…Valéry et al, 2010;Nikolopoulos et al, 2014;Marra et al, 2017) and which is further exacerbated by complex, mountainous terrain (e.g. Hrachowitz and Weiler, 2011).…”

Section: Complementary Trigger Contributionsmentioning

confidence: 99%

The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow dominated system: the compound trigger concept

Mostbauer

Kaitna

Prenner

et al. 2017

Preprint

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Abstract. Debris flows represent a severe hazard in mountain regions. Though significant effort has been made to predict such events, the trigger conditions as well as the hydrologic disposition of a watershed at the time of debris flow occurrence are not well understood. Traditional intensity-duration threshold techniques to establish trigger conditions generally do not 10 account for distinct influences of rainfall, snowmelt, and antecedent moisture. To improve our knowledge on the connection between debris flow initiation and the hydrologic system and to overcome the above limitations, this study explores the use of a semi-distributed conceptual rainfall-runoff model, linking different system variables such as soil moisture, snowmelt, or runoff with documented debris flow events in the inner Pitztal watershed, western Austria. The model was run on a daily basis between 1953 and 2012. Analyzing a range of modelled system state and flux variables at days on which debris flows 15 occurred, three distinct dominant trigger mechanisms could be clearly identified. While the results suggest that for 68% (17 out of 25) of the observed debris flow events during the study period high-intensity rainfall was the dominant trigger, snowmelt was identified as dominant trigger for 24% (6 out of 25) of the observed debris flow events. In addition, 8% (2 out of 25) of the debris flow events could be attributed to the combined effects of low-intensity, long-lasting rainfall and transient storage of this water, causing elevated antecedent soil moisture conditions. The results also suggest a relatively 20 clear temporal separation between the distinct trigger mechanisms, with high-intensity rainfall as trigger being limited to mid-and late summer. The dominant trigger in late spring/early summer is snowmelt. Based on the discrimination between different modelled system states and fluxes and more specifically, their temporally varying importance relative to each other, rather than their absolute values, this exploratory study demonstrates that already the use of a relatively simple hydrological model can prove useful to gain some more insight into the importance of distinct debris flow trigger mechanisms in a 25 compound trigger concept, highlighting in particular the relevance of snowmelt contributions and the switch between mechanisms in early-to mid-summer in snow dominated systems.

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“…Indisputably, rainfall is the predominant factor controlling debrisflow triggering. Hence, most of the work so far on the prediction of debris-flow occurrence is focused on the identification of relevant rainfall conditions (Guzzetti et al, 2008 and references therein; Nikolopoulos et al, 2014;Segoni et al, 2014). However, the vast majority of the literature on identification of debris-flow-triggering rainfall conditions deals primarily with the estimation of rainfall properties (e.g.…”

Section: Introductionmentioning

confidence: 99%

Debris flows in the eastern Italian Alps: seasonality and atmospheric circulation patterns

Nikolopoulos

Borga

Marra

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. The work examines the seasonality and large-scale atmospheric circulation patterns associated with debris-flow occurrence in the Trentino-Alto Adige region (eastern Italian Alps). Analysis is based on classification algorithms applied to a uniquely dense archive of debris flows and hourly rain gauge precipitation series covering the period 2000-2009. Results highlight the seasonal and synoptic forcing patterns linked to debris flows in the study area. Summer and fall season account for 92 % of the debris flows in the record, while atmospheric circulation characterized by zonal west, mixed and meridional south and southeast (SE-S) patterns account for 80 %. Both seasonal and circulation patterns exhibit geographical preference. In the case of seasonality, there is a strong north-south separation of summer-fall dominance, while spatial distribution of dominant circulation patterns exhibits clustering, with both zonal west and mixed patterns prevailing in the northwest and central east part of the region, while the southern part relates to meridional south and southeast pattern. Seasonal and synoptic pattern dependence is pronounced also on the debris-flow-triggering rainfall properties. Examination of rainfall intensity-duration thresholds derived for different data classes (according to season and synoptic pattern) revealed a distinct variability in estimated thresholds. These findings imply a certain control on debrisflow events and can therefore be used to improve existing alert systems.

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Impact of uncertainty in rainfall estimation on the identification of rainfall thresholds for debris flow occurrence

Cited by 160 publications

References 43 publications

Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

Influence of uncertain identification of triggering rainfall on the assessment of landslide early warning thresholds

The temporally varying roles of rainfall, snowmelt and soil moisture for debris flow initiation in a snow dominated system: the compound trigger concept

Debris flows in the eastern Italian Alps: seasonality and atmospheric circulation patterns

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