scholarly journals Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

2011 ◽  
Vol 11 (5) ◽  
pp. 1247-1257 ◽  
Author(s):  
J. Lopez Saez ◽  
C. Corona ◽  
M. Stoffel ◽  
A. Gotteland ◽  
F. Berger ◽  
...  
Keyword(s):  
Debris Flow ◽  
Tree Ring ◽  
Debris Flows ◽  
Temporal Distribution ◽  
Alluvial Fan ◽  
Tree Ring Data ◽  
Pine Trees ◽  
Spatio Temporal ◽  
Flow Activity ◽  
Abandoned Channels

Abstract. Hydrogeomorphic processes are a major threat in many parts of the Alps, where they periodically damage infrastructure, disrupt transportation corridors or even cause loss of life. Nonetheless, past torrential activity and the analysis of areas affected during particular events remain often imprecise. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris-flow activity in abandoned channels on the forested cone of the Manival torrent (Massif de la Chartreuse, French Prealps). A Light Detecting and Ranging (LiDAR) generated Digital Elevation Model (DEM) was used to identify five abandoned channels and related depositional forms (lobes, lateral levees) in the proximal alluvial fan of the torrent. A total of 156 Scots pine trees (Pinus sylvestris L.) with clear signs of debris flow events was analyzed and growth disturbances (GD) assessed, such as callus tissue, the onset of compression wood or abrupt growth suppression. In total, 375 GD were identified in the tree-ring samples, pointing to 13 debris-flow events for the period 1931–2008. While debris flows appear to be very common at Manival, they have only rarely propagated outside the main channel over the past 80 years. Furthermore, analysis of the spatial distribution of disturbed trees contributed to the identification of four patterns of debris-flow routing and led to the determination of three preferential breakout locations. Finally, the results of this study demonstrate that the temporal distribution of debris flows did not exhibit significant variations since the beginning of the 20th century.

scholarly journals Spatio-temporal variability in debris-flow activity: a tree-ring study at Geisstriftbach (Swiss Alps) extending back to AD 1736

2010 ◽  
Vol 103 (2) ◽  
pp. 283-292 ◽  
Author(s):  
Markus Stoffel ◽  
Michelle Bollschweiler ◽  
Susanne Widmer ◽  
Annina Sorg
Keyword(s):  
Debris Flow ◽  
Tree Ring ◽  
Temporal Variability ◽  
Swiss Alps ◽  
Spatio Temporal ◽  
Flow Activity

scholarly journals Debris flows on forested cones – reconstruction and comparison of frequencies in two catchments in Val Ferret, Switzerland

2007 ◽  
Vol 7 (2) ◽  
pp. 207-218 ◽  
Author(s):  
M. Bollschweiler ◽  
M. Stoffel
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Historical Knowledge ◽  
Study Region ◽  
Sampling Height ◽  
The Alps ◽  
Recurrence Intervals ◽  
Study Sites ◽  
Flow Activity ◽  
Different Characteristics

Abstract. Debris flows represent a major threat to infrastructure in many regions of the Alps. Since systematic acquisition of data on debris-flow events in Switzerland only started after the events of 1987, there is a lack of historical knowledge on earlier debris-flow events for most torrents. It is therefore the aim of this study to reconstruct the debris-flow activity for the Reuse de Saleinaz and the La Fouly torrents in Val Ferret (Valais, Switzerland). In total, 556 increment cores from 278 heavily affected Larix decidua Mill., Picea abies (L.) Karst. and Pinus sylvestris L. trees were sampled. Trees on the cone of Reuse de Saleinaz show an average age of 123 years at sampling height, with the oldest tree aged 325 years. Two periods of intense colonization (the 1850s–1880s and the 1930s–1950s) are observed, probably following high-magnitude events that would have eliminated the former forest stand. Trees on the cone of Torrent de la Fouly indicate an average age of 119 years. As a whole, tree-ring analyses allowed assessment of 333 growth disturbances belonging to 69 debris-flow events. While the frequency for the Reuse de Saleinaz study site comprises 39 events between AD 1743 and 2003, 30 events could be reconstructed at the Torrent de la Fouly for the period 1862–2003. Even though the two study sites evince considerably different characteristics in geology, debris-flow material and catchment morphology, they apparently produce debris flows at similar recurrence intervals. We suppose that, in the study region, the triggering and occurrence of events is transport-limited rather than weathering-limited.

scholarly journals Debris-flow activity in five adjacent gullies in a limestone mountain range

2015 ◽  
Vol 42 (1) ◽  
Author(s):  
Klaus Schraml ◽  
Markus Oismüller ◽  
Markus Stoffel ◽  
Johannes Hübl ◽  
Roland Kaitna
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
National Park ◽  
Regional Scale ◽  
Field Investigation ◽  
Mountain Range ◽  
Sediment Sources ◽  
Aerial Vehicle ◽  
Flow Activity ◽  
Local Variability

Abstract Debris-flows are infrequent geomorphic phenomena that shape steep valleys and can repre-sent a severe hazard for human settlements and infrastructure. In this study, a debris-flow event chro-nology has been derived at the regional scale within the Gesäuse National Park (Styria, Austria) using dendrogeomorphic techniques. Sediment sources and deposition areas were mapped by combined field investigation and aerial photography using an Unmanned Aerial Vehicle (UAV). Through the analysis of 384 trees, a total of 47 debris-flows occurring in 19 years between AD 1903 and 2008 were identified in five adjacent gullies. Our results highlight the local variability of debris-flow activi-ty as a result of local thunderstorms and the variable availability of sediment sources.

scholarly journals REFINEMENT OF CONIFER GROWTH MODELS BASED ON TREE-RING CHRONOLOGIES OF THE NORTH OF WESTERN SIBERIA

2020 ◽  
pp. 41-48
Author(s):  
V. R. Tsibulsky ◽  
I. G. Solovyev ◽  
D. A. Govorkov
Keyword(s):  
Time Series ◽  
Tree Ring ◽  
Growth Model ◽  
Western Siberia ◽  
Growth Function ◽  
Climate Conditions ◽  
The North ◽  
Tree Ring Data ◽  
Model Update ◽  
Pine Trees

The subject of this research is conifer growth model based on time-series of annual rings width. The article addresses processing of data and model update in respect of forest dendrology. The purpose of study is to update the conifer growth model due to expansion of time-series of tree-rings width in regards to conifer forests in Western Siberia. The method represents expansion of time-series due to the fact that some growth phases had not been taken into account. When measurements were taken at the height of 1.3 meters, the following phases were not considered: seedling, juvenile, immature and beginning of virginile phase. The authors carried out examination of a number of scans and core samples, as well as time-series received by other scientists and which are contained in the International Tree-Ring Data Bank. Based on the results of field studies, the authors recommend to add some zeroes to the beginning of time-series within the range of 10-15 years for pine-trees in the south of Western Siberia, depending on growth conditions; the range of 15-30 years in the north for larch-trees and pine-trees depending on soil and climate conditions and latitude. The sequence of data pre-processing operations for time-series, received by means of core sampling, is as follows: averaging out of radius gain in 2 (3) mutually perpendicular directions for one specimen, graphing of radius gain curve, adding to the beginning of time-series, its normalization, approximation by specified growth function. It is possible to build area growth function for the scans. For averaging out a group of model trees, the sequence of operations is as follows: synchronization of time-series by cross-correlation method, approximation by specified growth function. Methods and results of studies can be applied in forest sectors and oil and gas industries for monitoring of forest health conditions. The proposed method of curve growth model update will allow to define more precisely time intervals for efficient forest exploitation as well as to reconstruct digital models of conifer populations in the north of Western Siberia.

scholarly journals Periglacial preconditioning of debris flows in the Southern Alps, New Zealand

2021 ◽  
Author(s):  
◽  
Katrin Sattler
Keyword(s):  
New Zealand ◽  
Debris Flow ◽  
Debris Flows ◽  
Southern Alps ◽  
Ice Growth ◽  
Frost Weathering ◽  
Flow Formation ◽  
Flow Systems ◽  
Spatially Distributed ◽  
Flow Activity

<p>The lower boundary of alpine permafrost extent is considered to be especially sensitive to climate change. Ice loss within permanently frozen debris and bedrock as a consequence of rising temperature is expected to increase the magnitude and frequency of potentially hazardous mass wasting processes such as debris flows. Previous research in this field has been generally limited by an insufficient understanding of the controls on debris flow formation. A particular area of uncertainty is the role of environmental preconditioning factors in the spatial and temporal distribution of debris flow initiation in high-alpine areas. This thesis aims to contribute by investigating the influence of permafrost and intensive frost weathering on debris flow activity in the New Zealand Southern Alps. By analysing a range of potential factors, this study explores whether debris flow systems subjected to periglacial influence are more active than systems outside of the periglacial domain.   A comprehensive debris flow inventory was established for thirteen study areas in the Southern Alps. The inventory comprises 1534 debris flow systems and 404 regolith-supplying contribution areas. Analysis of historical aerial photographs, spanning six decades, identified 240 debris flow events. Frequency ratios and logistic regression models were used to explore the influence of preconditioning factors on the distribution of debris flows as well as their effect on sediment reaccumulation in supply-limited systems. The preconditioning factors considered included slope, aspect, altitude, lithology, Quaternary sediment presence, neo-tectonic uplift rates (as a proxy for bedrock fracturing), permafrost occurrence, and frost-weathering intensity. Topographic and geologic information was available in the form of published datasets or was derived from digital elevation models. The potential extent of contemporary permafrost in the Southern Alps was estimated based on the statistical evaluation of 280 rock glaciers in the Canterbury region. Statistical relationships between permafrost presence, mean annual air temperature, and potential incoming solar radiation were used to calculate the spatially distributed probability of permafrost occurrence. Spatially distributed frost-weathering intensities were estimated by calculating the number of annual freeze-thaw cycles as well as frost-cracking intensities, considering the competing frost-weathering hypotheses of volumetric ice expansion and segregation ice growth.  Results suggest that the periglacial influence on debris flow activity is present at high altitudes where intense frost weathering enhances regolith production. Frost-induced debris production appears to be more efficient in sun-avert than sun-facing locations, supporting segregation ice growth as the dominant bedrock-weathering mechanism in alpine environments. No indication was found that permafrost within sediment reservoirs increases slope instability. Similarly, the presence of permanently frozen bedrock within the debris flow contribution areas does not appear to increase regolith production rates and hence debris flow activity. Catchment topography and the availability of unconsolidated Quaternary deposits appeared to be the cardinal non-periglacial controls on debris flow distribution.   This thesis contributes towards a better understanding of the controls on debris flow formation by providing empirical evidence in support of the promoting effect of intense frost weathering on debris flow development. It further demonstrates the potential and limitations of debris flow inventories for identifying preconditioning debris flow controls. The informative value of regional-scale datasets was identified as a limitation in this research. Improvement in the spatial parameterisation of potential controls is needed in order to advance understanding of debris flow preconditioning factors.</p>

scholarly journals Quantitative Analysis of the Debris Flow Societal Risk to People Inside Buildings at Different Times: A Case Study of Luomo Village, Sichuan, Southwest China

2021 ◽  
Vol 8 ◽  
Author(s):  
Li Wei ◽  
Kaiheng Hu ◽  
Jin Liu
Keyword(s):  
Quantitative Analysis ◽  
Debris Flow ◽  
Debris Flows ◽  
Evaluation Model ◽  
Alluvial Fan ◽  
Economic Losses ◽  
Rural Settlements ◽  
Societal Risk ◽  
Flow Intensity ◽  
The Village

Debris flows, which cause massive economic losses and tragic losses of life every year, represent serious threats to settlements in mountainous areas. Most deaths caused by debris flows in China occur in buildings, and the death toll is strongly dependent on the time people spend indoors. However, the role of time spent indoors in the quantitative analysis of debris flow risk has been studied only scarcely. We chose Luomo village in Sichuan atop a debris flow alluvial fan to study the influence of the temporal variation in the presence of people inside buildings on the societal risk. Two types of days (holidays vs. workdays) and two diurnal periods (daytime vs. nighttime) were considered in our risk evaluation model. A questionnaire survey was conducted for each family in the village, and the probability of the temporal impact of a debris flow on every household was calculated based on the average amount of time each member spent in the house. The debris flow hazard was simulated with FLO-2D to obtain the debris flow intensity and run-out map with return periods of 2, 10, 50, and 100 years. The risk to buildings and societal risk to residents were calculated quantitatively based on the probabilities of debris flow occurrence, the probability of the spatial impact, and the vulnerabilities of buildings and people. The results indicated that societal risk on holidays is always higher than that on weekdays, and societal risk at night is also much higher than that in the daytime, suggesting that the risk to life on holidays and at night is an important consideration. The proposed method permits us to obtain estimates of the probable economic losses and societal risk to people by debris flows in rural settlements and provides a basis for decision-making in the planning of mitigation countermeasures.

scholarly journals Sedimentology, dynamics and debris flow potential of Champadevi River, southwest Kathmandu, Nepal

1970 ◽  
Vol 10 ◽  
pp. 9-20
Author(s):  
Naresh Kazi Tamrakar ◽  
Achut Prajapati ◽  
Suman Manandhar
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Alluvial Fan ◽  
Shear Stresses ◽  
Stream Power ◽  
Huge Amount ◽  
Sedimentary Characteristics ◽  
Unconsolidated Material ◽  
Flow Potential ◽  
Headward Erosion

Mountainous and hilly regions are potential for debris flows, one of the major forms of natural disasters, which cause serious damage in downstream areas. The southwestern region of the Kathmandu Valley experienced catastrophic flows in the Champadevi River and its two tributaries (the Aitabare and the Raute Rivers) in July 2002. These rivers were investigated for morphologic, hydraulic and sedimentary characteristics to evaluate potential of debris flow in the area. The Raute and the Aitabare Rivers have tendency of headward erosion due to abrupt drop of gradient down the scarp of the alluvial fan deposit composed of unconsolidated matrix-supported gravel and mud. Because of this tendency, the rivers erode their substrate and banks, and contribute slope movements by sheding a huge amount of clasts and matrix. Therefore, instability condition of rivers and unconsolidated material available in the river courses potentially contribute for debris flow. The tractive shear stresses in the Aitabare, the Raute and the Champadevi Rivers (1.27, 1.60 and 0.48 KPa, respectively) exceeds twice the critical shear stresses required to transport 90th-percentile fraction of the riverbed material (0.14, 0.18 and 0.11 KPa). The stream powers (10.8, 17.2 and 5.1 m-kN/s/m2) of these rivers also greatly exceed the critical stream powers (0.21, 0.35 and 0.18 m-kN/s/m2) required to initiate traction transport. Because the tractive shear stresses and the stream powers that are achieved during bankfull flow are several times larger than the corresponding critical values, even the flow having stream power exceeding the critical stream power may potentially generate debris flow.   doi: 10.3126/bdg.v10i0.1416 Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 10, 2007, pp. 9-20

Debris Flow Hazards and its Mitigation Works in Xianbuleng Gully, Jinchuan County, Sichuan Province, China

2012 ◽  
Vol 166-169 ◽  
pp. 2769-2773
Author(s):  
Jin Feng Liu ◽  
Yong You ◽  
Xing Chang Chen
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Case Analysis ◽  
Sichuan Province ◽  
Alluvial Fan ◽  
Drainage Canal ◽  
Hydraulic Condition ◽  
Township Government

This paper presented a case analysis of debris flow hazards and its mitigation works. The Xianbuleng Gully which is located in Jinchuan County, Sichuan Province was selected as study area. This gully is an old debris flow gully which once burst out many debris flow disasters in history. If debris flows occur again in this gully, the township government, the center school and 13 village houses nearly 300 persons on the alluvial fan will be exposed to great risk.The environment settings and the hazard characteristics of the Xianbuleng debris flow were introduced first in this paper. Then, mitigation works especially the drainage canal under the optimal hydraulic condition were planned and designed in the gully for decreasing the debris flow hazards.

The geomorphic impact of large landslides: A case-study of the actively moving Alpine Gardens Landslide, Fox Glacier Valley, West Coast, New Zealand.

2020 ◽  
Author(s):  
Saskia de Vilder ◽  
Chris Massey ◽  
Garth Archibald ◽  
Regine Morgenstern
Keyword(s):  
New Zealand ◽  
Debris Flow ◽  
West Coast ◽  
Debris Flows ◽  
Sediment Flux ◽  
Valley Floor ◽  
Aerial Imagery ◽  
Glacier Valley ◽  
Flow Activity

&lt;p&gt;Large landslides can result in significant geomorphic impacts to fluvial systems, via increased sediment input and subsequent changes to channel behaviour. We present a case-study of the actively moving&amp;#160; &amp;#820;65 M m&amp;#179; Alpine Gardens Landslide in the Fox Glacier Valley, West Coast, New Zealand, to analyse the ongoing geomorphic impacts within the valley floor. Debris flows, sourced from the toe of the landslide, travel down Mill&amp;#8217;s Creek and deposit sediment on the debris fan at its confluence with the Fox River. This debris flow activity and associated changes in sediment flux and fluvial behaviour have resulted in re-occurring damage to, and current closure of roads and tracks within the Fox Glacier Valley floor, impacting access to the Westland Tai Poutini National Park, the Fox Glacier, associated tourism, and the Fox Glacier township economy.&lt;/p&gt;&lt;p&gt;Initial movement of the Alpine Gardens landslide was detected in 2015, with aerial imagery analysis between March 2017 and June 2018 indicating that the landslide may be accelerating. This acceleration may potentially result in increased debris flow activity within the landslide complex and sediment flux into the Fox River. To monitor and understand the controls on movement rate, we installed a continuous GPS monitoring station along with rainfall gauges on the landslide in February 2019. On average, the landslide moves at a rate of 0.12 m/day &amp;#177; 0.13 m/day, however this rate of movement of the landslide is closely correlated to and fluctuates with rainfall. Significant accelerations of 0.5 m/day have occurred after heavy rainfall, with these rainfall events also resulting in large debris flows.&lt;/p&gt;&lt;p&gt;We document and investigate the geomorphic impact of the Alpine Gardens landslide on the Mill&amp;#8217;s Creek debris fan and Fox Glacier Valley floor via terrestrial laser scanning, airborne LiDAR, UAV surveys and aerial imagery. From this, we derive a time-series of nine surface change models to document the sediment flux within the Alpine Gardens Landslide and Mill&amp;#8217;s Creek debris fan complex. Our initial results reveal that between March 2017 and June 2019, approximately 14.7 M m&amp;#179; was eroded from the landslide, of which 3.7 M m&amp;#179; was deposited directly on the debris fan. A further 9.6 M m&amp;#179; has been transported downstream into the fluvial system. Upstream aggradation has also occurred, with 1.1 M m&amp;#179; deposited in the river valley immediately upstream of the debris fan between June 2018 and June 2019. Continued monitoring of the Alpine Gardens Landslide and volumetric changes of the landslide complex allows us to understand the controls on the movement and sediment flux within the landslide and the geomorphic impact of large actively moving landslides on the valley floor, particularly within alpine and glacial environments.&amp;#160;&lt;/p&gt;

Climate change impacts on sediment yield and debris-flow activity at the Illgraben, Switzerland

2020 ◽  
Author(s):  
Jacob Hirschberg ◽  
Simone Fatichi ◽  
Georgie Bennett ◽  
Brian McArdell ◽  
Stuart Lane ◽  
...  
Keyword(s):  
Climate Change ◽  
Debris Flow ◽  
Surface Runoff ◽  
Debris Flows ◽  
Cascade Model ◽  
Weather Generator ◽  
Climate Scenarios ◽  
Climate Services ◽  
The Future ◽  
Flow Activity

&lt;p&gt;Debris flows are rapid mass movements composed of a mixture of water and sediments and often pose a danger to humans and infrastructure. In the Alpine environment, they are mostly triggered by intense rainfall, snowmelt or a combination thereof, and conditioned by sediment availability. Their occurrence is expected to increase in a warmer climate due to changes in the hydrological regime (e.g. higher rainfall intensity, lower duration of snow cover). Furthermore, sediment production is likely to accelerate due to permafrost thawing and changes in freeze-thaw cycles, resulting in increased sediment availability. For the purpose of climate change impact assessment on sediment yield and debris-flow activity, interactions and feedbacks of climate and the aforementioned processes need to be considered jointly.&lt;/p&gt;&lt;p&gt;In the study presented here, we address this challenge by forcing a sediment cascade model (SedCas&lt;sup&gt;1&lt;/sup&gt;) with precipitation and temperature from a stochastic weather generator (AWE-GEN&lt;sup&gt;2&lt;/sup&gt;) producing ensembles of possible climate in the present and for the future. The chosen study site is the Illgraben, a debris-flow prone catchment in the Swiss Alps which currently produces 3-4 debris flows yearly on average. SedCas conceptualizes a geomorphic system in which hillslopes produce and store sediments from landslides and eventually deliver them to the channels. From there, sediments can be mobilized by concentrated surface runoff and transferred out of the catchment in form of bedload, hypreconcentrated flow, or debris flows, depending on the surface runoff magnitude and the sediment availability. AWE-GEN operates at the hourly scale and is trained for the current climate with observed data and for the future climate using the newest climate change projections for Switzerland CH2018 developed by the National Center for Climate Services&lt;sup&gt;3&lt;/sup&gt;.&lt;/p&gt;&lt;p&gt;Preliminary results reveal a likely increase in debris-flow occurrence in the Illgraben in the future. Such an increase can be attributed to an extension in the debris-flow seasonal changes in the discharge regime. Furthermore, the number of landslides filling the sediment storage increases because they are affected by a shorter duration of snow cover and thus greater exposure to freeze-thaw weathering. However, projections are subject to large uncertainties, stemming not only from uncertainty in climate scenarios, but also from internal climate variability. Furthermore, the simplified hillslope weathering and debris-flow triggering mechanisms contribute to the overall uncertainty. Nevertheless, the methodology is thought to be transferable to any sediment-cascade-like catchment where dominant processes are driven by climate. Lastly, this work highlights the importance of considering stochasticity in climate and sediment history for projections of magnitudes and frequencies of relative rare events as debris flows. This allows us to explicitly separate climate change signals in geomorphic processes from fluctuations induced by internal natural variability.&lt;/p&gt;&lt;p&gt;REFERENCES&lt;/p&gt;&lt;p&gt;&lt;sup&gt;1&lt;/sup&gt; Bennett, G. L., et al. &quot;A probabilistic sediment cascade model of sediment transfer in the Illgraben.&quot; Water Resources Research 50.2 (2014): 1225-1244. doi: 10.1002/2013WR013806&lt;/p&gt;&lt;p&gt;&lt;sup&gt;2&lt;/sup&gt; Fatichi, S., et al. &quot;Simulation of future climate scenarios with a weather generator.&quot; Advances in Water Resources 34.4 (2011): 448-467. doi: 10.1016/j.advwatres.2010.12.013&lt;/p&gt;&lt;p&gt;&lt;sup&gt;3&lt;/sup&gt; CH2018 - Climate Scenarios for Switzerland. National Centre for Climate Services (2018): doi: 10.18751/Climate/Scenarios/CH2018/1.0&lt;/p&gt;

Sign in / Sign up

Export Citation Format

Share Document