scholarly journals Snow–avalanche history reconstructed with tree rings in Parâng Mountains (Southern Carpathians, Romania)

2020 ◽  
Vol 22 (1) ◽  
pp. 73-85
Author(s):  
Corina TODEA ◽  
Olimpiu Traian Pop ◽  
Daniel GERMAIN
Keyword(s):  
Tree Rings ◽  
Past History ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Average Return ◽  
Historical Archives ◽  
Prone Area ◽  
Forested Areas ◽  
Pertinent Information ◽  
Southern Carpathians

Snow avalanches are a common phenomenon in Parâng Mountains (Southern Carpathians, Romania) perturbing tourism activities and associated infrastructures, damaging forests, and causing fatalities. Its past history is an es­sential information to gather while assessing the hazard zonation areas. Usually, in Romania snow–avalanche activ­ity occurring in forested areas are neither monitored, nor recorded by historical archives. In these areas, environ­mental archives such as tree rings may provide useful information about the past avalanche activity. The purpose of the present study is to reconstruct snow–avalanche history with tree rings along a path located below Cârja Peak (2405 m a.s.l.), an area where past snow–avalanche activity still remains underestimated. In this sense, 57 Norway spruce (Picea abies (L.) Karst.) trees showing clear signs of disturbance by snow avalanches were sampled and the growth anomalies associated with the mechanical impact produced by snow avalanches on trees were identified within their rings and served to reconstruct past events. The reconstructed chronology covers the period 1994–2018 showing the occurrence of a minimum of 11 major events, with an average return period of 2.1 years. Tree–ring records provided the most consistent avalanche event chronology in the study area. Although the lim­ited extension of the chronology back in time, a better understanding of snow–avalanche history which may be gained through dendro­chronological reconstructions represent nonetheless useful and pertinent information to consider before the imple­mentation and development of infrastructure in this mountain avalanche–prone area.

Tree-ring reconstruction of snow avalanches in Şureanu Mountains (Southern Carpathians, Romania)

2021 ◽  
Author(s):  
Corina Todea ◽  
Olimpiu Pop
Keyword(s):  
Tree Ring ◽  
Tree Rings ◽  
Spatial Extent ◽  
Snow Avalanches ◽  
Historical Archives ◽  
Hazard Zoning ◽  
Tree Ring Reconstruction ◽  
Natural Archive ◽  
Callus Tissues ◽  
Southern Carpathians

<p>Snow avalanches (SAs) are a widespread natural hazard in the Carpathians, damaging forests and threatening properties, tourism infrastructures and people. In Şureanu Mountains (Southern Carpathians), SA activity is not documented in the historical archives and consequently information regarding the SA frequency and their spatial extent is lacking. Along the forested avalanche paths, disturbed trees record selectively in their annual rings evidence of past events. Tree rings represent therefore a natural archive which can provide valuable information about the past SA activity. The aim of the present study is to reconstruct the occurrence and spatial extent of past SA activity with tree rings in Şureanu Mts. For this purpose, two avalanche paths adjacent to a ski area located in the central part of Şureanu Mts., have been investigated. Samples (cores and discs) collected from 121 and 141 Norway spruce (Picea abies (L.) Karst.) trees damaged by SAs along both paths have been analyzed. Tree-growth anomalies (e.g. scars, callus tissues, onset sequences of tangential rows of traumatic resin ducts, compression wood and growth suppression sequences) associated with the mechanical impact produced by SAs on trees were identified and used to reconstruct the SA history. Within the investigated paths, the reconstructed SA chronology spans the period of the last century. The minimum SA frequency and maximum extent reconstructed served to define the return periods within the two paths investigated. Tree-ring derived records provided the most consistent SA chronology in the study area, and can further be integrated in the avalanche hazard zoning assessment.</p>

Reconstructing snow-avalanche activity with tree rings in Maramureş Mountains (Eastern Carpathians, Romania)

2020 ◽  
Author(s):  
Armelle Decaulne ◽  
Ionela-Georgiana Răchită ◽  
Mihai Hotea ◽  
Vasile Timur Chiş ◽  
Olimpiu Traian Pop
Keyword(s):  
Tree Ring ◽  
Tree Rings ◽  
Climatic Factors ◽  
Climatic Conditions ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Joint Research ◽  
Eastern Carpathians ◽  
Joint Research Project ◽  
Callus Tissues

<p> <span>Snow avalanches </span>represent a common phenomenon <span>in Maramureş Mountains (Eastern Carpathians, Romania)</span> where they <span>occur frequently on higher steep slopes and reach in the runout zones the valley bottoms below 1000 m a.s.l. The presence of particular topo-climatic conditions influences the patterns of avalanche activity in terms of past frequency and spatial extent along the slope valleys. As the past snow-avalanche activity is not documented by written reports in the area, reliable information about avalanche history is missing. </span>However, the slopes are forested, trees repeatedly disturbed by snow avalanches record evidence of past events. <span>For this study we reconstructed the avalanche activity using tree rings as a source of proxy data. To date the snow-avalanche history, dendrochronological investigations have been carried out in two avalanche paths, along which living trees showed clear external signs of past disturbances related to mechanical impacts produced by snow avalanches. In each investigated path, a total number of 52 and respectively 118 trees have been sampled and their spatial position recorded with a GPS device. Tree-growth </span>anomalies (e.g. scars, callus tissues, the onset sequences of tangential rows of traumatic resin ducts, compression wood, growth suppression and release sequences) <span>related to snow avalanche disturbance identified within tree rings served to reconstruct past events with an annual resolution. The results indicate that, apart the 2005 major event witnessed and also confirmed by tree-ring dating, multiple other events have been reconstructed since the beginning of 20</span><sup><span>th</span></sup><span> century. Despite some inherent limitations of tree-ring methods in reconstructing past avalanche events, these dendrochronological investigations confirm their utility in deciphering the patterns of avalanche activity in Maramureş Mountains. Tree-ring studies contribute to a better understanding of the role of topographical and climatic factors which influence the spatio-temporal occurrence of snow avalanches.</span></p><p><span>This study represents a contribution to the joint research project 09-AUF, </span><span>‘‘</span><span><em>Activité des avalanches de neige dans les Carpates Orientales Roumaines et Ukrainiennes - </em></span><span> ACTIVNEIGE</span><span>’’</span><span>, co-funded by the </span><span><em>Agence Universitaire de la Francophonie (AUF)</em></span><span> and </span><span><em>Institutul de Fizică Atomică (IFA), Romania</em></span><span>.</span></p>

Tree-ring dating of snow avalanche history in Parâng Mountains (Southern Carpathians, Romania)

2020 ◽  
Author(s):  
Corina Todea ◽  
Olimpiu Pop
Keyword(s):  
Tree Ring ◽  
Snow Avalanche ◽  
Mountainous Area ◽  
Snow Avalanches ◽  
The Past ◽  
Avalanche Hazard ◽  
Hiking Trails ◽  
Traumatic Resin Ducts ◽  
Tree Ring Data ◽  
Southern Carpathians

<p>In high mountainous areas worldwide, snow avalanches represent one of the main morphodynamic processes which influence the morphology of steep slopes. They usually disturb the forests, and represent a significant natural hazard that may endanger the safety of tourists exposed along the hiking trails crossing the avalanche-prone slopes. In the context of the growing tourism activities in the area where tourist become exposed to snow avalanche hazard, there is need for detailed analysis for documenting the past activity of this geomorphic process, especially in remote areas where historical data is lacking. Such mountainous area without snow avalanche monitoring and archival records is in Parâng Mountains (Southern Carpathians, Romania). On forested slopes, trees disturbed by snow-avalanches may record in their growth rings information about the past event occurrence. The main aim of this study is to improve the knowledge about the past snow avalanche history using tree-rings approach. To this end, 57 disturbed spruce (Picea abies (L.) Karst.) trees growing along an avalanche path located on the western slopes of the Parâng Mountains were sampled and their growth disturbances (scars, traumatic resin ducts, compression wood and growth suppression sequences) served to reconstruct the snow-avalanche history back to 1950. Tree-ring analyses allowed reconstructing a minimum of 14 snow avalanche events which occurred in the past along the investigated path. The tree-ring approach presented in this study proved to be a valuable tool in reconstructing snow avalanche history and compliting the snow avalanche database in Parâng Mountains. The number and spatial extent of documented snow avalanches evidence the potential snow avalanche hazards in the study area. The tree-ring data from the present study, together with those presented by the previous studies in the study area may further contribute to the snow avalanche hazard assessment. </p>

A century-long snow avalanche chronology reconstructed from tree-rings in Parâng Mountains (Southern Carpathians, Romania)

2016 ◽  
Vol 415 ◽  
pp. 230-240 ◽  
Author(s):  
Olimpiu Traian Pop ◽  
Ionela-Georgiana Gavrilă ◽  
Gheorghe Roşian ◽  
Flaviu Meseşan ◽  
Armelle Decaulne ◽  
...  
Keyword(s):  
Tree Rings ◽  
Snow Avalanche ◽  
Southern Carpathians

scholarly journals The mechanical origin of snow avalanche dynamics and flow regime transitions

2020 ◽  
Author(s):  
Xingyue Li ◽  
Betty Sovilla ◽  
Chenfanfu Jiang ◽  
Johan Gaume
Keyword(s):  
Flow Velocity ◽  
Alpha Angle ◽  
Maximum Flow ◽  
Flow Regimes ◽  
Snow Avalanche ◽  
Snow Avalanches ◽  
Deposition Zone ◽  
Avalanche Dynamics ◽  
Maximum Flow Velocity ◽  
Deposit Height

Abstract. Snow avalanches cause fatalities and economic damages. Key to their mitigation entails the understanding of snow avalanche dynamics. This study investigates the dynamic behaviors of snow avalanches, using the Material Point Method (MPM) and an elastoplastic constitutive law for porous cohesive materials. By virtue of the hybrid Eulerian-Lagrangian nature of MPM, we can handle processes involving large deformations, collisions and fractures. Meanwhile, the elastoplastic model enables us to capture the mixed-mode failure of snow, including tensile, shear and compressive failure. Using the proposed numerical approach, distinct behaviors of snow avalanches, from fluid-like to solid-like, are examined with varied snow mechanical properties. In particular, four flow regimes reported from real observations are identified, namely, cold dense, warm shear, warm plug and sliding slab regimes. Moreover, notable surges and roll-waves are observed peculiarly for flows in transition from cold dense to warm shear regimes. Each of the flow regimes shows unique flow characteristics in terms of the evolution of the avalanche front, the free surface shape, and the vertical velocity profile. We further explore the influence of slope geometry on the behaviors of snow avalanches, including the effect of slope angle and path length on the maximum flow velocity, the $\\alpha$ angle and the deposit height. Unified trends are obtained between the normalized maximum flow velocity and the scaled $\\alpha$ angle as well as the scaled deposit height, reflecting analogous rules with different geometry conditions of the slope. It is found the maximum flow velocity is mainly controlled by the friction between the bed and the flow, the geometry of the slope, and the snow properties. In addition to the flow behavior before reaching the deposition zone, which has long been regarded as the key factor governing the $\\alpha$ angle, we reveal the crucial effect of the stopping behavior in the deposition zone. Furthermore, our MPM model is benchmarked with simulations of real snow avalanches. The evolution of the avalanche front position and velocity from the MPM modeling shows reasonable agreement with the measurement data from literature. The MPM approach serves as a novel and promising tool to offer systematic and quantitative analysis for mitigation of gravitational hazards like snow avalanches.

Analysis of snow avalanche potential in Bâlea glacial area – Făgăraş massif (Southern Carpathians – Romanian Carpathians)

2011 ◽  
Vol 55 (3) ◽  
pp. 291-316 ◽  
Author(s):  
Mircea Voiculescu ◽  
Florina Ardelean ◽  
Alexandru Onaca ◽  
Marcel Török-Oance
Keyword(s):  
Snow Avalanche ◽  
Romanian Carpathians ◽  
Southern Carpathians

A numerical approach for simulating two-dimensional dense-snow avalanches in global coordinate systems

2021 ◽  
Author(s):  
Daniel Zugliani ◽  
Giorgio Rosatti ◽  
Stefania Sansone
Keyword(s):  
Coordinate System ◽  
Finite Volume ◽  
Reference System ◽  
Source Term ◽  
Numerical Approach ◽  
The Other ◽  
Snow Avalanche ◽  
Two Dimensional ◽  
Snow Avalanches ◽  
Avalanche Models

<p>Snow avalanche models are commonly based on a continuum fluid scheme, on the assumption of shallow flow in the direction normal to the bed, on a depth-averaged description of the flow quantities and on different assumptions concerning the velocity profile, the friction law, and the pressure in the flow direction (see Bartelt et al, 1999, Barbolini et al., 2000, for an overview). The coordinate reference system is commonly local, i.e., for each point of the domain, one axis is normal to the bed while the other two axes lay in a tangent plane. When the bed is vertical and the flow is not aligned with the steepest direction (e.g., in case of a side wall), the flow depth is no longer defined considering the normal direction and the model based on the local coordinate system is no longer valid. In near-vertical conditions, numerical problems can be expected.</p><p>Another critical point, for numerical models based on finite volume schemes and Godunov fluxes, is the accurate treatment of the source term in case of no-motion conditions (persistence, starting and stopping of the flow) due to the presence of velocity-independent, Coulomb-type terms in the bed shear stress. </p><p>In this work, we provide a numerical approach for a Voellmy-fluid based model, able to overcome the limits depicted above, to accurately simulate analytical solutions and to give reliable solutions in other cases (Zugliani & Rosatti, 2021). Firstly, differently from the other literature models, the chosen coordinate reference system is global (an axis opposite the gravity vector and the other two orthogonal axes lay in the horizontal plane) and therefore, the relevant mass and momentum equations have been derived accordingly. Secondly, these equations have been discretized by using a finite volume method on a Cartesian square grid where the Godunov fluxes has been evaluated by mean of a modified DOT scheme (Zugliani & Rosatti, 2016) while source terms in conditions of motion have been discretized by using an implicit operator-splitting technique. Finally, a specific algorithm has been derived to deal with the source term to determine the no-motion conditions.  Several test cases assess the capabilities of the proposed approach.</p><p> </p><p><strong>References:</strong></p><p>Barbolini, M., Gruber, U., Keylock, C.J., Naaim, M., Savi, F. (2000), <em>Application of statistical and hydraulic-continuum dense-snow avalanche models to five real European sites.</em> Cold Regions Science and Tech. 31, 133–149.</p><p>Bartelt, P., Salm, B., Gruber, U. (1999), <em>Calculating dense-snow avalanche runout using a voellmy-fluid model with active/passive longitudinal straining.</em> Journal of Glaciology 45, 242-254.</p><p>Zugliani D., Rosatti G. (2021), <em>Accurate modeling of two-dimensional dense snow avalanches in global coordinate system: the TRENT2D<sup>❄</sup> approach. </em>Paper under review.</p><p>Zugliani, D., Rosatti, G. (2016), <em>A new Osher Riemann solver for shallow water flow over fixed or mobile bed</em>, Proceedings of the 4th European Congress of the IAHR, pp. 707–713.</p>

Using Tree-Rings to Reconstruct Fire History Information from Forested Areas

10.3791/61698 ◽  
2020 ◽  
Author(s):  
Julián Cerano-Paredes ◽  
Jose M. Iniguez ◽  
José Villanueva-Díaz ◽  
Rosalinda Cervantes-Martínez ◽  
Víctor H. Cambrón-Sandoval ◽  
...  
Keyword(s):  
Tree Rings ◽  
Fire History ◽  
History Information ◽  
Forested Areas

scholarly journals Scale Modeling of Snow–Avalanche Impact on Structures

1980 ◽  
Vol 26 (94) ◽  
pp. 189-196
Author(s):  
T. E. Lang ◽  
J.D. Dent
Keyword(s):  
Froude Number ◽  
Computer Modeling ◽  
Snow Avalanche ◽  
Small Scale ◽  
Snow Avalanches ◽  
Scale Modeling ◽  
Impact Processes ◽  
Model Fluid ◽  
Impact Predictions

AbstractSmall–scale modeling of flow and impact of snow avalanches is demonstrated to be both feasible and accurate. Geometric, kinematic, and force variables are scaled correctly under equivalence of Froude number between prototype and model using sifted snow as the model fluid. Physical and computer–simulated impact processes show correspondence, so that computer modeling is demonstrated to be a viable tool in flow and impact predictions.

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