The October 1999 Mt Adams rock avalanche and subsequent landslide dam‐break flood and effects in Poerua river, Westland, New Zealand

On 12 May 2008, the mountainous area of Longmenshan, which separates the Tibetan Plateau from the Sichuan Basin, was hit by the 8.0 Ms Wenchuan earthquake which triggered about 200,000 landslides, some of which caused river damming with the formation of temporary lakes. Failures of the landslide dams can induce severe flooding downstream, therefore, it is important to study their structure and mechanical properties in order to evaluate their stability conditions.The present study investigates the landslide dam deposits of a rock avalanche triggered in Yang Jia Gou, in Sichuan Province, using single-station three component recordings of ambient noise, with the aim of obtaining information about thickness and mechanical properties of the deposits from their resonance properties. Three noise measurement campaigns and two ERT surveys were conducted to support data interpretation. The data were analyzed using the traditional Nakamura&#8217;s technique, HVNR, and the innovative technique HVIP, both based on the calculation of ratios between horizontal and vertical amplitude of ground motion. Both methods revealed the presence &#160;of resonance peaks, a major one at lower frequency, and a minor one at higher frequencies, representative of the deposit layering. HVNR showed a considerable instability in terms of amplitude of H/V, likely because this technique analyzes the entire noise wave field recorded, so to be subject to a large variability related to a variable composition of the noise field. This problem does not affect the HVIP method, which is based on the analysis of the ellipticity of Rayleigh waves, isolated from the recording.Rayleigh wave ellipticity curves were used as targets in the inversion phase to obtain the velocity profile of the site. The subsoil model was &#160;constrained by the data derived from the resistivity profiles. The results revealed: &#160;different velocity layers inside the deposit; lateral variations in thickness, in accordance with the higher frequency peak, and in mechanical properties, with an increase of stiffness, probably due to a major portion of rocky blocks; an increase in thickness of the entire deposit, probably because of the irregularities of the substrate.Further investigations are in progress through other kinds of noise analysis exploiting the synchronization of simultaneous recordings. This can provide additional constraints (to be derived from the dispersion of group velocity of Rayleigh waves) and aid resolving interpretation ambiguities.

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Experimental Research on the Dam-Break Mechanisms of the Jiadanwan Landslide Dam Triggered by the Wenchuan Earthquake in China

The Scientific World JOURNAL ◽

10.1155/2013/272363 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 2

Author(s):

Fu-gang Xu ◽

Xing-guo Yang ◽

Jia-wen Zhou ◽

Ming-hui Hao

Keyword(s):

Wenchuan Earthquake ◽

Discharge Channel ◽

Landslide Dam ◽

Dam Break ◽

Experimental Results ◽

Dam Breaks ◽

The Wenchuan Earthquake ◽

Large Numbers ◽

Dam Management ◽

Break Process

Dam breaks of landslide dams are always accompanied by large numbers of casualties, a large loss of property, and negative influences on the downstream ecology and environment. This study uses the Jiadanwan landslide dam, created by the Wenchuan earthquake, as a case study example. Several laboratory experiments are carried out to analyse the dam-break mechanism of the landslide dam. The different factors that impact the dam-break process include upstream flow, the boulder effect, dam size, and channel discharge. The development of the discharge channel and the failure of the landslide dam are monitored by digital video and still cameras. Experimental results show that the upstream inflow and the dam size are the main factors that impact the dam-break process. An excavated discharge channel, especially a trapezoidal discharge channel, has a positive effect on reducing peak flow. The depth of the discharge channel also has a significant impact on the dam-break process. The experimental results are significant for landslide dam management and flood disaster prevention and mitigation.

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Recent research on landslide dams - a literature review with special attention to New Zealand

Progress in Physical Geography Earth and Environment ◽

10.1191/0309133302pp333ra ◽

2002 ◽

Vol 26 (2) ◽

pp. 206-235 ◽

Cited By ~ 133

Author(s):

Oliver Korup

Keyword(s):

New Zealand ◽

Management Strategies ◽

Temporal Distribution ◽

Landslide Dam ◽

Distribution Patterns ◽

Future Research ◽

Case Examples ◽

Mountainous Regions ◽

Landslide Dams ◽

Spatio Temporal

More than a decade has passed since the publication of the benchmark paper of Costa and Schuster (Costa, J.E. and Schuster, R.L. 1988: The formation and failure of natural dams. Geological Society of America Bulletin 100, 1054-68) on the formation and failure of natural dams. This review takes a critical look at recent trends and developments in international and New Zealand-based research on landslide dams. Temporary or permanent stream blockages by mass movements commonly occur in steep terrain, and gradually receive more attention and awareness with increasing population and land use pressure in upland regions. Different approaches in methodology and their relevance and application potential for engineering and mitigative measures are reviewed and several shortcomings outlined, with a view towards possible future research directions. A high percentage of previous work on landslide dams has been mainly descriptive in character, and has produced a multitude of documented case studies. Recent attempts to redress the balance have included the establishment of global and nationwide databases (inventories) of landslide dams, progress in predictive, quantitative and GIS-based modelling. Furthermore, interpretative approaches towards the reconstruction of former stream blockages and their spatio-temporal distribution patterns have been pursued, which may assist assessments of present and future geomorphic hazards. Both such appraisals as well as management strategies in mountainous regions in general, will have to rely on key data efficiently extracted from a plethora of case examples. Further work includes consideration of temporal and permanent landslide-triggered stream impoundments within Quaternary landscape evolution, quantification of sediment budgets and palaeoenvironmental reconstruction. Overall, there is still a considerable lack of understanding of geomorphic forms and processes involved with landslide-dam formation, stability and failure, part of which is inherent in the often ephemeral nature of stream blockages in coupled hillslope-valley systems.

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Organisational Response to the 2007 Ruapehu Crater Lake Dam-Break Lahar in New Zealand: Use of Communication in Creating an Effective Response

Advances in Volcanology - Observing the Volcano World ◽

10.1007/11157_2016_38 ◽

2017 ◽

pp. 253-269 ◽

Cited By ~ 1

Author(s):

Julia S. Becker ◽

Graham S. Leonard ◽

Sally H. Potter ◽

Maureen A. Coomer ◽

Douglas Paton ◽

...

Keyword(s):

New Zealand ◽

Crater Lake ◽

Dam Break ◽

Effective Response

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Influence of runout-path material on emplacement of the Round Top rock avalanche, New Zealand

Earth Surface Processes and Landforms ◽

10.1002/esp.1900 ◽

2009 ◽

pp. n/a-n/a ◽

Cited By ~ 9

Author(s):

A. Dufresne ◽

T.R. Davies ◽

M.J. McSaveney

Keyword(s):

New Zealand ◽

Rock Avalanche

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Dynamic decision making for dam-break emergency management – Part 2: Application to Tangjiashan landslide dam failure

Natural Hazards and Earth System Science ◽

10.5194/nhess-13-439-2013 ◽

2013 ◽

Vol 13 (2) ◽

pp. 439-454 ◽

Cited By ~ 21

Author(s):

M. Peng ◽

L. M. Zhang

Keyword(s):

Decision Making ◽

At Risk ◽

Emergency Management ◽

Landslide Dam ◽

Dam Break ◽

Flood Routing ◽

Dynamic Decision Making ◽

Dam Failure ◽

Population At Risk ◽

Three Stages

Abstract. Tangjiashan landslide dam, which was triggered by the Ms = 8.0 Wenchuan earthquake in 2008 in China, threatened 1.2 million people downstream of the dam. All people in Beichuan Town 3.5 km downstream of the dam and 197 thousand people in Mianyang City 85 km downstream of the dam were evacuated 10 days before the breaching of the dam. Making such an important decision under uncertainty was difficult. This paper applied a dynamic decision-making framework for dam-break emergency management (DYDEM) to help rational decision in the emergency management of the Tangjiashan landslide dam. Three stages are identified with different levels of hydrological, geological and social-economic information along the timeline of the landslide dam failure event. The probability of dam failure is taken as a time series. The dam breaching parameters are predicted with a set of empirical models in stage 1 when no soil property information is known, and a physical model in stages 2 and 3 when knowledge of soil properties has been obtained. The flood routing downstream of the dam in these three stages is analyzed to evaluate the population at risk (PAR). The flood consequences, including evacuation costs, flood damage and monetized loss of life, are evaluated as functions of warning time using a human risk analysis model based on Bayesian networks. Finally, dynamic decision analysis is conducted to find the optimal time to evacuate the population at risk with minimum total loss in each of these three stages.

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