Avalanche Site Research Articles

Predisposing, triggering and runout processes at a permafrost‐affected rock avalanche site in the French Alps (Étache, June 2020)

AbstractAlthough numerous recent studies have explored the relationship between permafrost degradation and rock slope failure, there is still a need for in‐depth investigations to develop relevant hazard assessment approaches. We investigate the predisposing, triggering and propagation processes of a rock avalanche (c. 225,000 m3) that occurred in Vallon d'Étache (France) on 18 June 2020, whose scar was coated by ice and water. Weather records and energy balance models show that the rock avalanche occurred right after the warmest spring and winter since at least 1985, but also right after the spring with the highest water supply anomaly (snowmelt and rainfall). Measured ground surface temperature and geoelectrical surveys reveal that relatively ice‐rich permafrost could exist in the NW face (release area) while it is inexistent below the SE face, contradicting certain permafrost maps. Heat transfer simulations suggest that the rock avalanche occurred during a transition from cold to warm permafrost conditions at failure depth (30 m), with a temperature increase of up to 0.6°C per decade since 2012 (when considering potential snow cover effect), and current temperature ranging between −3 and −1°C, depending on the applied model forcing. This warming certainly contributed to predispose slope to failure. In addition, the shift towards warm permafrost and water infiltration potentially enhancing permafrost degradation along fractures through heat advection or favouring the development of high hydrostatic pressures may have played as triggering factors. Finally, propagation simulations show that the rock avalanche involved several phases with different rheological properties due to the incorporation of snow and material segregation within the deposit. These new insights at various scales highlight the complexity of the triggering and propagation processes of rock slope failure occurring in high mountains, a significant part of which can be linked to snow effects on ground temperature, water supply and rheological properties.

Frequency of Post Traumatic Stress Disorder and Associated Factors Among Survivors of Van Avalanche: 6-Month Follow-up Study.

We aimed to evaluate the frequency of Post Traumatic Stress Disorder (PTSD), to determine the risk factors, and to monitor the change of symptoms after 6 months among individuals who survived the avalanche disaster in Van. Face-to-face interviews were conducted with 35 people who were rescued from two consecutive avalanche disasters in Van 2 months and 6 months after the avalanche disaster. The socio-demographic and clinical data of the cases were evaluated. The Post Traumatic Stress Disorder Symptom Scale-Self Report version (PSS-SR) and clinical interviews were used for PTSD diagnosis. The level of trauma was assessed by using the Impact of Event Scale (IES). All participants were rescuers who went to the avalanche site for rescue mission. Of the cases, 16 were volunteers from the local community and 19 were professional rescuers. The frequency of PTSD was 71.4% in the early assessment, and 57.1% in the long term. Staying in avalanche for more than 30 minutes, the absence of a history of disaster exposure and being in the group of volunteers were found to increase the risk for PTSD development. There is a high risk of developing PTSD as a result of an avalanche. People who will intervene with the disasters should be educated and prepared in terms of preventing negative psychological consequences of the disaster. The relationship between the severity of trauma and PTSD was replicated in our study.

Reconstruction and Characterisation of Past and the Most Recent Slope Failure Events at the 2021 Rock-Ice Avalanche Site in Chamoli, Indian Himalaya

Frequent ice avalanche events are being reported across the globe in recent years. On the 7 February 2021, a flash flood triggered by a rock-ice avalanche with an unusually long runout distance, caused significant damage of life and property in the Tapovan region of the Indian Himalaya. Using multi-temporal satellite datasets, digital terrain models (DTMs) and simulations, here we report the pre-event and during-event flow characteristics of two large-scale avalanches within a 5-year interval at the slope failure site. Prior to both the events, we observed short-term and long-term changes in surface velocity (SV) with maximum SVs increasing up to over 5 times the normal values. We further simulated the events to understand their mechanical characteristics leading to long runouts. In addition to its massive volume, the extraordinary magnitude of the 2021 event can partly be attributed to the possible remobilisation and entrainment of the colluvial deposits from previous ice and snow avalanches. The anomalous SVs should be explored further for their suitability as a possible remotely observable precursor of ice avalanches from hanging glaciers. This sequence of events highlights that there is a need to take into account the antecedent conditions, while making a holistic assessment of the hazard.

7 February Chamoli (Uttarakhand, India) Rock-Ice Avalanche Disaster: Model-Simulated Prevailing Meteorological Conditions

The present study aims to analyze the high-resolution model-simulated meteorological conditions during the Chamoli rock-ice avalanche event, which occurred on 7 February 2021 in the Chamoli district of Uttarakhand, India (30.37° N, 79.73° E). The Weather Research and Forecasting (WRF) model is used to simulate the spatiotemporal distribution of meteorological variables pre- and post-event. The numerical simulations are carried out over two fine resolution nested model domains covering the Uttarakhand region over a period of 2 weeks (2 February to 13 February 2021). The model-simulated meteorological variables, e.g., air temperature, surface temperature, turbulent heat flux, radiative fluxes, heat and momentum transfer coefficients, specific humidity and upper wind patterns, were found to show significant departures from their usual patterns starting from 72 h until a few hours before the rock-ice avalanche event. The average 2 m air and surface temperatures near the avalanche site during the 48 h before the event were found to be much lower than the average temperatures post-event. In-situ observations and the ERA5-Land dataset also confirm these findings. The total turbulent heat flux mostly remained downward (negative) in the 72 h before the event and was found to have an exceptionally large negative value a few hours before the rock-ice avalanche event. The model-simulated rainfall and Global Precipitation Measurement (GPM, IMERG)-derived rainfall suggest that the part of the Himalayan region falling in the simulation domain received a significant amount of rainfall on 4 February, around 48 h prior to the event, while the rest of the days pre- and post-event were mostly dry. The results presented here might be helpful in further studies to identify the possible trigger factors of this event.

Simulation and Analysis of a Snow Avalanche Accident in Lower Western Himalaya, India

In Western Himalaya, an average 49 person die every year due to snow avalanche activities and this death rate is very high as compared to other Asian countries. A snow avalanche accident was observed on 5 January 2018 on Chowkibal–Tangdhar (CT) road axis at avalanche site number CT-8 located near Chowkibal village in Kupwara district, union territory Jammu and Kashmir, India. In the present paper, we discuss snow avalanche simulation, the climatic condition, avalanche debris height and length, and suggested solutions to handle avalanche situations. Rapid Mass MovementS numerical model in combination with digital elevation model and potential release area has been used to simulate avalanche accident occurred on 5 January 2018 at CT-8. The analysis demonstrates maximum snow avalanche velocity, impact of pressure and height of flow to be ~ 25 ms−1, ~ 9.39 × 104 kgm−1 s−2, and ~ 3.0 m respectively on 5 January 2018 at CT-8. Further simulated avalanche debris height and length form road has been validated with ground observed data. Ground reconnaissance of the location was conducted by a team of Snow and Avalanche Study Establishment, Chandigarh and it has been observed that lack of ‘avalanche awareness and Standard Operating Procedures during movement in avalanche prone areas’ among the travellers on the road cause accident . The present paper seems to be first to investigate snow avalanche accident in Western Himalaya and recommend that proper campaigning of avalanche awareness among the people residing in avalanche prone areas of Himalaya could reduce such accidents significantly.

Integration of terrain and AVHRR-derived multi-temporal snow cover data for statistical assessment of avalanches: case study of a part of NW Himalaya

In this paper, the data of Advanced Very High Resolution Radiometer (AVHRR) 1 km resolution of daily time series is used to extract the distribution of seasonal snow in the Chowkibal-Tangdhar (CT) area. Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM) at 90-m resolution has been used to delineate the terrain characteristics such as aspect, slope, and altitude. The study is focused on two major objectives, first is to assess the snow cover variation with a time series analysis and second one is the snow cover changes with respect to the changes in terrain parameters mainly at avalanche prone regions. Study area has 60 registered avalanche sites; most of these avalanches trigger during the winter months when snow deposition takes place in the steep slopes due to successive snowfall spells. Normalized Difference Snow Index (NDSI) method is used to monitor the snow cover of the study area from the satellite image. The multi-temporal analysis of the snow cover derived from the AVHRR data shows that the binary snow cover in the study area increases with time from November to March due to successive snowfalls. After that, the snow cover starts to deplete from the mid-March onwards due to rise in temperature. Maximum snow cover area (SCA) has been found 85.67% and minimum is at 14.33% respectively. An attempt has been made to understand the influence of terrain parameters by extracting the major terrain and snow parameters for each of the avalanche site and correlating it with occurrences of the avalanches. The study suggests that the sites having terrain characteristics of slope 25–45°, aspect 26.45%, and altitude 2500–3500 m has more occurrences of avalanches.

Ground thermal and geomechanical conditions in a permafrost-affected high-latitude rock avalanche site (Polvartinden, northern Norway)

Abstract. On 26 June 2008, a rock avalanche detached in the northeast facing slope of Polvartinden, a high-alpine mountain in Signaldalen, northern Norway. Here, we report on the observed and modelled past and present near-surface temperature regime close to the failure zone, as well as on a subsequent simulation of the subsurface temperature regime, and on initial geomechanical mapping based on laser scanning. The volume of the rock avalanche was estimated to be approximately 500 000 m3. The depth to the actual failure surface was found to range from 40 m at the back of the failure zone to 0 m at its toe. Visible in situ ice was observed in the failure zone just after the rock avalanche. Between September 2009 and August 2013, ground surface temperatures were measured with miniature temperature data loggers at 14 different localities, close to the original failure zone along the northern ridge of Polvartinden and on the valley floor. The results from these measurements and from a basic three-dimensional heat conduction model suggest that the lower altitudinal limit of permafrost at present is at 600–650 m a.s.l., which corresponds to the upper limit of the failure zone. A coupling of our in situ data with regional climate data since 1958 suggests a general gradual warming and that the period with highest mean near surface temperatures on record ended four months before the Signaldalen rock avalanche detached. A comparison with a transient permafrost model run at 10 m depth, representative for areas where snow accumulates, strengthen these findings, which are also in congruence with measurements in nearby permafrost boreholes. It is likely that permafrost in and near the failure zone is presently subject to degradation. This degradation, in combination with the extreme warm year antecedent to the rock failure, is seen to have played an important role in the detaching of the Signaldalen rock avalanche.

Calibration of snow avalanche mathematical models using the data of real avalanches in the Ile (Zailiyskiy) Alatau Range

The calibration of the dry friction and turbulent friction coefficients is necessary for computer simulation of avalanches. The method of back calculation based on data on actual avalanches is used for this purpose. The article presents the results of the calibration of the Eglit’s and RAMMS models for Ile Alatau range condi‑ tions. The range is located in Kazakhstan. The data on six avalanches in the same avalanche site were used. Five avalanches were dry, and one avalanche was wet. Avalanches volume varied from 2000 to 12000 m3. Maximum speed avalanches were between 15 and 30 m/s, the flow height – from 3 to 10 m. Series of back calculations with different values of the friction coefficients was made to obtain the calibrated coeffi‑ cients. The calibrated coefficients were chosen under condition of the best fit with real avalanches. The cal‑ ibrated coefficients were following. For the Eglit’s model for dry avalanches of the volume 2000–5000 m3 μ = 0.46÷0.48, k = 0.005–0.006, and the volume 8000–12000 m3 μ = 0.38÷0.42, k = 0.002÷0.003. For RAMMS model for dry avalanches of the volume of 2000–5000 m3 μ (dry friction coefficient) = 0.35÷0.4, ξ (viscous friction coefficient) = 1500÷2000 m/s2, and the volume 8,000–12,000 m3 μ = 0.3÷0.35, ξ = 2000÷3000 m/s2. For wet avalanches of the volume 12,000 m3 μ = 0.35, ξ = 1500 m/s2. The work on the calibration will be con‑ tinued to obtain the friction coefficients for the Eglit’s and RAMMS models. The additional data on real ava‑ lanches will be needed for this purpose.

Short-term spatial and temporal forecast of dry snow avalanches of sublimation recrystallization and mixed origin

A possibility of space-temporary short-term forecast-diagnosis of dry sublimative recrystallization and mixed (recrystallization plus fresh snow) avalanches is under consideration. The special discriminate analog–macrophysical models of the short-term background forecast is verified on correlation degree with probabilistic zoning of avalanche site № 22 in Khibiny. Аs a result we have correlation coefficients of order –(0.6÷0.7). The statistical significance of correlation coefficients (an order of 0.02–0.07) are checked and a conclusion on likelihood of assumed hypothesis is made. So by the current and predicted meteorological data such kind of forecast for such genetic avalanche types release in concrete sites becomes possible. The short-term forecast function transformation of the examined in the article avalanche types into long-term ones by averaging perennial realized forecast function values on slipping optimal 5-years intervals shows avalanche activity trend with probable 8–10 and 32-years harmonics during selected observation period. But in comparison with purely dry and wet fresh snow avalanches forecast analysed before the examined here above types are less precisely predicted. So it is needed an improvement of correspondent forecast functions on the base of theory contribution and future observations by increasing their series

The compressibility and shear characteristics of soils associated with landslides in geologically different localities—case examples from Nigeria

Field and Shuttle Radar Topographic Mission data were used to create Digital Elevation Model and geologic maps to study the roles of geology, discontinuities, elevation, steep slopes, deep valleys, and drainage patterns on the frequent occurrence of long-travel landslides along the Nigeria–Cameroon border. The undrained shear behaviors of sandy specimens from two localities with different mode and magnitude of landslides were analyzed at different stress levels and related directly to their compressibility and permeability characteristics. The weathered granitic-sandy specimens from Kwande debris avalanche showed significant change in bulk permeability and sample height, and exhibited the greatest evidence of grain crushing. This behavior correlates well with their shear response which manifested in considerable increase in excess pore pressure and drastic reduction of shear resistance. Due to grain crushing, finer grains that lowered permeability were formed at the shear zone. It is likely that the decrease in permeability facilitated the generation of high excess pore pressures leading to significant reduction of shear resistance to low values at steady state. Contrastingly, the reduction in sample height and permeability of Iva valley sands was not as significant, which also correlates with the generation of low excess pore pressure and higher steady state strengths; conditions that may be responsible for the predominance of short-travel slides in the area. The behavior of silica sands, however, which suffered higher grain crushing and reduction in sample height and permeability, appeared closer to that of the samples from the avalanche site.

Hazard investigation of the Portillo Rock Avalanche site, central Andes, Chile, using an integrated field mapping and numerical modelling approach

This paper reports a detailed rock slope hazard investigation of the Portillo Rock Avalanche site located in the rugged mountains of the Andean Cordillera of central Chile. The site is important as it lies along the International Santiago–Mendoza Highway Corridor connecting Chile and Argentina, and a major ski resort is located on its deposits. A number of large lobate-shaped diamicton deposits were mapped and dated by cosmogenic nuclides ( 36Cl), with the results showing that they correspond to two significant prehistoric rockslide events. An integrated field mapping and numerical modelling investigation was subsequently carried out to assess the threat posed to the area by further rocksliding activity. Distinct-element modelling was used to back analyze the failure mechanism and identify the geological model that best reproduced the Portillo Rock Avalanche failure surface. Results show that a stress-controlled failure at the toe of the slope followed by sliding along volcaniclastic bedding was the likely failure mechanism. A 3-D dynamic runout analysis was carried out to back analyze which combinations of rheologies, material properties and rockslide sequencing were best able to reproduce the current distribution of rockslide deposits. Results indicate that two separate sliding events originating from different sources had occurred, with each involving different combinations of frictional and Voellmy rheologies depending on the level of entrainment that occurred along each travel path. Insights gained from the back analysis were then used to carry out a forward analysis to assess the potential for a recurring major rockslide under several different triggering scenarios. Results suggest that a low probability M 7.8 earthquake would be required to trigger another rockslide from the original source area. The rock slope was otherwise found to be stable, even following high precipitation events. Nevertheless, runout simulations for the estimated large-magnitude earthquake-triggered rockslide volume showed that for both a highly frictional and non-saturated path (i.e. dry season) and a snow covered path (winter), the leading edge of the flow would override part of the International Santiago–Mendoza Corridor with the debris coming to rest in a flat-lying area in the upper part of the valley. Overall, the results from this integrated hazard assessment suggest that the hazard level is low.

Implementation of Structural Control Measures to Mitigate Avalanche Hazard along Transportation Corridors

Avalanche hazards along transportation corridors in the United States have traditionally been addressed by forecasting their potential and actively controlling them through explosive release while the roadway is closed. This approach reduces the threat of avalanches cascading onto the roadway and thus reduces danger to the traveling public. However, active control methods cannot always be implemented in a timely fashion, can be ineffective, and can have large associated economic impacts. An alternative to active control is passive, structural avalanche defenses. They are passive in that they do not require maintenance during winter storm periods. Structural defense measures include snow sails, snow-supporting structures, and snow sheds. Despite their extensive use in Europe and their potential for effectively reducing avalanche hazards, few examples are found in the United States. The potential for negative impacts to the visual attributes of the landscape has been a significant reason for their lack of domestic use. This paper discusses several types of structural defense measures, criteria for their selection at a given site, and their relative effectiveness. Passive structural defense measures designed for implementation at the Milepost 151 avalanche on US Route 89/191 near Jackson, Wyoming, are described. Details are given on important collaborations between landscape architects and engineers that led to successfully addressing National Environmental Policy Act requirements for retention of visual attributes at the Milepost 151 avalanche site in the presence of snow support structures deployed for the purpose of avalanche hazard reduction.

Application of a regional approach for hazard mapping at an avalanche site in northern Italy

Abstract. The currently adopted approach to avalanche hazard mapping in northern Italy includes avalanche dynamic modelling, coupled with statistical analysis of snow depth at avalanche start. The 30-years and 300-years return period avalanches at a given site are modelled and their run out zone and pressure are evaluated. The snow depth in the avalanche release zone is assumed to coincide with the three days snow fall depth H72 featuring a return period of 30 years and 300 years, respectively. In the Italian alps only short series of observed snow depth are available, covering a period of 20 years or so, thus requiring a regional approach, or index value approach for the purpose of high return period quantile estimation. Based of former studies, here we apply the index value approach developed for the Lombardia region, in northern Italy, for hazard mapping in a particular avalanche site. A dynamic avalanche model is tuned using the runout data for two major observed avalanche events. Then, the 30-years and 300-years runout zone and dynamic pressure are calculated. It is then shown that the obtained hazard maps are more accurate than those obtained using the evaluation of H72 as deduced from distribution fitting in a single site.

Modelling of snow avalanche dynamics: influence of model parameters

AbstractThe three-parameter hydraulic model of snow avalanche dynamics including the coefficients of dry and turbulent friction and the coefficient of new-snow-mass entrainment was investigated. The ‘Domestic’ avalanche site in Elbrus region, Caucasus, Russia, was chosen as the model avalanche range. According to the model, the fixed avalanche run-out can be achieved with various combinations of model parameters. At the fixed value of the coefficient of entrainment me , we have a curve on a plane of the coefficients of dry and turbulent friction. It was found that the family of curves ( me is a parameter) are crossed at the single point. The value of the coefficient of turbulent friction at the cross-point remained practically constant for the maximum and average avalanche run-outs. The conclusions obtained are confirmed by the results of modelling for six arbitrarily chosen avalanche sites: three in the Khibiny mountains, Kola Peninsula, Russia, two in the Elbrus region and one idealized site with an exponential longitudinal profile. The dependences of run-out on the coefficient of dry friction are constructed for all the investigated avalanche sites. The results are important for the statistical simulation of avalanche dynamics since they suggest the possibility of using only one random model parameter, namely, the coefficient of dry friction, in the model. The histograms and distribution functions of the coefficient of dry friction are constructed and presented for avalanche sites Nos 22 and 43 (Khibiny mountains) and ‘Domestic’, with the available series of field data.

Structural Measures for Controlling Avalanches in Formation Zone

Jammu-Srinagar national highway (NH-1A), a lifeline of the Kashmir valley, gains considerable importance as being the only link between the Kashmir valley and the rest of the country. A stretch of 15 km is marred by 15 major avalanche sites, out of that D-10 avalanche site takes a heavy toll of life and property, besides bringing the busiest highway to a standstill for days together, year after year. Therefore, this avalanche site was selected for installation of avalanchecontrol structures in formation zone and demonstration of technology thereof. A combination of wind-control structures, supporting structures, and controlled release of avalanches using explosive, has been adopted to mitigate avalanche hazard. As a result, the D-10 site can boast of having become a school for live demonstration of the avalanche-control methods on the mighty Pir Panjal range at more than 3200 m above the sea level. This paper deals with the methods used for control of avalanches in formation zone of D-10 avalanche site and brings out their effectiveness and site-specific applications.

The Monte Carlo simulation of avalanche-type processes

AbstractThe statistical modelling of gravitational avalanche-type processes is carried out using the Monte Carlo method. The process of snow avalanche origin is described with the model of stress state and stability of snow cover on a slope. The statistical simulation of the stress state of a snow slab is performed for avalanche site No. 22 (Khibiny, Russia). The strength characteristics of the snow slab are considered as randomvariables.The influence of the first moments of the distributions of the slab-strength parameters on the probability of avalanche release is studied. Using a hydraulic model of a dense flow avalanche, the statistical modelling of avalanche dynamics for the avalanche site “Domestic” (Elbrus region, Russia) is carried out. The coefficients of dry and turbulent friction and snow entrainment are considered as random parameters of the model. The histograms and distribution functions of the run-out distance, thickness and volume of avalanche depositions are obtained. The model and empirical distribution functions of the avalanche run-out distance are compared. Statistical simulation of slushflow dynamics (basin of Bear brook, Khibiny, Russia) is performed. The two-layer deterministic model of slushflow is used. The random parameters of the model assumed are: the water inflow on the “tail”of the flow and the coefficient of dry friction for slush. The histograms and distribution functions of dynamic characteristics of flow are obtained. The model outcomes are compared with field data.

Flexible Retaining Barriers for Prevention of Avalanches on National Highway NH-1A

An avalanche hazard Call be reduced by active and passive methods. In an active method, which is a very effective, avalanche control structures are used to mitigate the avalanche danger. These structures can be installed in any of the three zones of an avalanche, viz., formation zone, middle zone and run-out zone. In the formation zone, avalanche can be controlled by supporting structures/retaining barriers, which are installed in the formation zone with a view to prevent formation of an avalanche. Their placement in the formation zone with proper arrangement and layout helps in preventing fracture in the snow mass. The basic concept lies in converting the shear and tensile stresses in snow into compressive stresses which can be conveniently sustained by the snowcover. Such supporting structures/retaining barriers can be categorised into rigid and flexible types of structures. Snow rakes and snow bridges are categorised as rigid structures, whereas wire rope nets are categorised as flexible structures. The Snow & Avalanche Study Establishment, Chandigarh, had developed snow nets in 1988-89, which were installed at D-10 avalanche site on north portal of Jawahar tunnel, Jammu-Srinagar Highway (NH-1A). These nets were designed considering the snow forces acting in the direction parallel to the slope only. Hence, the movement of the swivel post was restricted in one direction only. However, detailed scientific studies carried out for retaining barriers over the last seven year's have revealed that two types of failures occur in these nets. First, a major failure was noticed in hinge joint of swivel post, and second, a failure was noticed in the foundation of the uphill anchor. To overcome these failures, the swivel post joint has been redesigned as articulated ball and socket joint to cater for omni directional movement to the swivel post, and the uphill anchor foundation has been strengthened by providing the reinforcement. This paper deals with the concept of flexible retaining barriers, including criteria for height of structures, their layout, terrain investigation required and also considers the snow pressure for designing various components of snow nets.

北海道北部の雪崩発生地における森林造成

北海道北部の雪崩発生地における森林造成

Quelques réflexions autour de la classification des avalanches / Some thoughts on a classification of avalanches

Abstract : This paper attempts to provide a reliable classification of avalanches. After outlining the development of current terminology, the authors draw attention to the fact that usual classifications, which divide avalanches into slab, powder and loose-snow avalanches are rather inconvenient to use and crude. A number of proposals are therefore made for a more reliable classification. Three main groups of avalanches are identified based on the type of flow : aerosol, dense, and mixed avalanches. Analysis of avalanche starting and stopping phases and consideration of the avalanche site provide further criteria for subdividing groups into sub-groups. Genetic factors are found to be helpful in completing descriptions but are to use in classifications.

Field measurements and model calibration in avalanche dynamics

A short summary of the evolution of the computational models and of the data acquisition techniques in this field is made in order to give a proper frame to the problem. The description of data from a recently realised experimental avalanche site and the attempt of their reproduction through a finite difference numerical model based on the 1D shallow water equations is then proposed as hint for a critical discussion over the open questions related with the calibration and the application of such numerical algorithms for practical purposes on the basis of the available experimental data. An effort is made in order to underline the major uncertainties in relation to the physical assumptions made in the models and to the accuracy and completeness of the field data. A final discussion and proposal of criteria for experimental data collection in relation with model validation is made according to the experience acquired on the specific site and on data of other authors.