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The impact of landslide dam on a Mediterranean small basin: the case of extinct Costantino lake (Calabria, Southern Italy)
No full textLarge landslides, triggered by earthquakes or heavy rainfall, often obstruct the river’s path to form landslide dams.
These phenomena can become very dangerous causing flooding both upstream, because of dam filling, and downstream,
due to dam failure. In Italy, landslide dams are rather widespread along Alps and Apennines: although the identification
of past events is a complex task, recently 300 landslide dams in a new open database were detected and collected (Tacconi
Stefanelli et al., 2015).
The present work is focused on the landslide occurred on the Bonamico River basin giving life to the Costantino Lake,
nowadays completely extinct. The basin is located in the Aspromonte mountain massif (Calabria, Southern Italy) covering
an area of 136 km2. The length of the main river channel is about 30 km with a mean gradient of 6% (Ergenzinger, 1992).
During the night of 3 to 4 January 1973 a large landslide occurred on the slopes of Mount Costantino, in the middle
of the Buonamico's mountain valley. The volume was estimated to be approximately 10-16 million m3. The mass
movement caused river damming and creation of Costantino Lake. The event occurred in response to heavy rainfalls
registered in 1972-1973 period, when several mass movements and widespread flooding in the regional area were counted.
According to some local reports (Petrucci et al., 1996), the heavy precipitation events occurred in 1972-1973 can be
considered as the exceptional weather phenomena within 1970-1980 decade, both for extreme values registered and for
damages caused.
The Costantino Lake, arisen immediately after landslide failure, has reached 2,400 m in length on the river bed, with
a perimeter of about 5,000 m and a maximum depth of 18 m. The total volume of the lake was estimated in 7,000,000 m3.
Since the river damming the water volume has steadily decreased, due to the load deposited by the river in the lake, which
has raised the bottom. Due to further heavy rainfalls during 2008-2009, the Costantine Lake became extinct, 36 years
after, on January 2009.
The purpose of the study is to increase the knowledge on the investigated site and update the data on the evolution of
the entire phenomenon taking into account information gathered both through field visits and remote sensing techniques
(aerial and satellite images).
Ergenzinger P. 1992. A conceptual geomorphological model for the development of a Mediterranean river basin under neotectonic stress (Buonamico
basin, Calabria, Italy). In: Walling D.E., Davies T.R. & Hasholt B., Eds., Erosion, debris flows and environment in mountain regions. IAHS 209,
51-60.
Petrucci O., Chiodo G. & Caloiero D. 1996. Eventi alluvionali in Calabria nel decennio 1971-1980. CNR- IRPI Cosenza.
Tacconi Stefanelli C., Catani F. & Casagli N. 2015. Geomorphological investigations on landslide dams. Geoenvironmental Disasters, 2, 21
Site-specific landslide assessment in Alpine area using a reliable integrated monitoring system
No full textRockfalls are one of major cause of landslide fatalities around the world. The present work discusses the relia-
bility of integrated monitoring of displacements in a rockfall within the Alpine region (Salzburg Land – Austria),
taking into account also the effect of the ongoing climate change. Due to the unpredictability of the frequency
and magnitude, that threatens human lives and infrastructure, frequently it is necessary to implement an efficient
monitoring system. For this reason, during the last decades, integrated monitoring systems of unstable slopes
were widely developed and used (e.g., extensometers, cameras, remote sensing, etc.). In this framework, Remote
Sensing techniques, such as GBInSAR technique (Groung-Based Interferometric Synthetic Aperture Radar), have
emerged as efficient and powerful tools for deformation monitoring. GBInSAR measurements can be useful to
achieve an early warning system using surface deformation parameters as ground displacement or inverse velocity
(for semi-empirical forecasting methods). In order to check the reliability of GBInSAR and to monitor the evo-
lution of landslide, it is very important to integrate different techniques. Indeed, a multi-instrumental approach is
essential to investigate movements both in surface and in depth and the use of different monitoring techniques
allows to perform a cross analysis of the data and to minimize errors, to check the data quality and to improve the
monitoring system.
During 2013, an intense and complete monitoring campaign has been conducted on the Ingelsberg landslide. By
analyzing both historical temperature series (HISTALP) recorded during the last century and those from local
weather stations, temperature values (Autumn-Winter, Winter and Spring) are clearly increased in Bad Hofgastein
area as well as in Alpine region. As consequence, in the last decades the rockfall events have been shifted from
spring to summer due to warmer winters. It is interesting to point out that temperature values recorded in the val-
ley and on the slope show a good relationship indicating that the climatic monitoring is reliable. In addition, the
landslide displacement monitoring is reliable as well: the comparison between displacements in depth by exten-
someters and in surface by GBInSAR - referred to March-December 2013 - shows ad high reliability as confirmed
by the inter-rater reliability analysis (Pearson correlation coefficient higher than 0.9). In conclusion, the reliability
of the monitoring system confirms that data can be useful to improve the knowledge on rockfall kinematic and to
develop an accurate early warning system useful for civil protection issues
Rock fall analysis in an Alpine area by using a reliable integrated monitoring system: results from the Ingelsberg slope (Salzburg Land, Austria)
No full textThe present work illustrates the monitoring
system of the Ingelsberg slope (Bad Hofgastein, Austria),
which hosts one of the most dangerous landslides in the
Salzburg Land. It is a rock fall, which can be considered as
representative of landslides commonly occurring in the
Alpine area. During the monitoring campaign (March
2013–July 2014), a rock fall occurred at the end of April,
2013 that involved 20–40 m3 of rocks. The comparison of
surface measurements (by Ground-Based Interferometric
Synthetic Aperture Radar—GB-InSAR) with measurements
in depth (by extensometers) allowed the understanding
of the failure process of the rock mass. Data are
discussed taking into account meteorological conditions
antecedent to the landslide triggering, indicating that factors
such as rapid snow melting (added to first spring
rainfall events) and rock thermal dilatation are very
important in slopes located far below the permafrost line
The Ingelsberg landslide (Bad Hofgastein, Austria): description and first results of monitoring system (GBInSAR technique)
No full textThe present work shows the first results of a monitoring campaign performed at the Ingelsberg slope in Bad Hofgastein (Austria). The Groung-Based Interferometric Synthetic Aperture Radar (GBInSAR) was used to create displacement maps, providing information on the location and magnitude of the phenomena studied.
These information provide a significant support to decision makers during landslide emergencies, allowing the civil protection authorities to assess the risk and to manage an efficacious emergencies response. In detail, the landslide assessment and the correlation of the GBInSAR data with meteorological data and those obtained by other monitoring instruments are discussed highlighting the open problems related to data acquisition, processing and analysis
Rockfall in Alpine climatic area: Remarks from multi-instrumental monitoring on a landslide in Salzburg Land
No full textThis work provides some remarks on results from multi-instrumental
monitoring for the Ingelsberg landslide (Bad Hofgastein – Austria), that is
one of the most dangerous landslide of Salzburg Land. The unstable area
is located very close to the village of Bad Hofgastein within the Gastein
Valley. It is a rockfall that cover an area of about 4 hectares, which is
characterized by the outcropping of anti-dip stratified green and calc-mica
schists. The monitoring campaign was implemented from March 2013 to
December 2013 using several monitoring instrument such as terrestrial
interferometry, meteorological data, extensometers and cameras. The
present work shows some results about the reliability of entire monitoring
system, through a statistical comparison of surface displacement recorded
by GBInSAR and displacement in depth given by extensometers, during
one of the most large rockfall events registered during the campaign.
Moreover the main landslide events are discussed by analyzing both
historical temperature time series (HISTALP) and those from local
weather stations, recorded during the last century
Reliability of GBInSAR Monitoring in Ingelsberg Landslide Area (Bad Hofgastein, Austria)
No full textThe present work shows and discusses the GBInSAR measurements for the Ingelsberg area, where one of most
dangerous landslide of Salzburg region is located (Bad Hofgastein – Austria). It is a rockfalls developing on an area of about
40000 m2 which is characterized by the outcropping of anti-dip stratified green and calc-mica schists. The GBInSAR monitoring
campaign started on March, 2013 (scan time of about 5 minutes): data acquired by the radar instrument were integrated with
those from other traditional monitoring systems consisting in 3 cameras placed near the slope and 5 extensometers placed in the
landslide Head Area. In order to evaluate the reliability of GBInSAR monitoring, a comparison with displacement data from
extensometers was made. During March-December 2013 at least 5 events were observed, the main of which occurred during
April-May-June period (3 events), representing a key period for the landslides occurrence in this region. Taking as reference this
period, the comparison of the two monitoring techniques showed a good correlation, indicating that the monitoring system of the
Ingelsberg landslide is reliable and useful for further analysis, such as the application and checking of the techniques to predict
the time to slope failure (TSF)
Effect of laboratory repeatability of direct shear test on slope stability
No full textThe present work quantified the laboratory geotechnical variability by repeatability direct shear test (DS) on alluvial fine-grained soils. The effect of laboratory variability of geotechnical parameters (cohesion c’ and friction angle φ’) on slope stability was investigated. A mixture of compacted fine sand (40%) and clayey silt (60%) taken from a quarry fines stockpile was used: these soils are commonly used to backfill exhausted quarries located in the River Paglia alluvial plain (Central Italy). As knew in the literature, the dry density achieved by a given degree of compaction controls the shear strength parameters affecting the performance of compacted soil. Four direct shear tests were conducted following the ASTM D 3080-72 procedure on samples having a dry density of about 16.5 kN/m3, corresponding to 95 % of maximum dry density. Combining four DS tests yielded 256 pairs of shear strength parameters in terms of effective stresses, φ’ and c’ parameters show normal distribution with φ’= 27.0 ± 0.8° and c’= 19.22 ± 4.08 kPa, for the stress range 100÷250 kPa. In most of the 256 combinations, the friction angle decreased as the cohesion increased. It is generally accepted that the strength parameters (c’ and φ’) have a negative correlation, although it is appreciated this is not always the case and different cohesion values can be obtained for the same friction angle (i.e., for the same slope of Coulomb failure envelope). The effect of the uncontrolled experimental variability of shear strength parameters on the long-term stability of a single homogeneous slope whose geometry can vary was investigated. Analyzing the factor of safety obtained using all the 256 combinations of shear strength parameters, the probability of having safety factors lower than 1.30 for the different slope heights was calculated. Such analyses demonstrate not only that direct shear testing is reliable, but also that the stability of a slope can be assessed with greater accuracy
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Combining ground based remote sensing tools for rockfalls assessment and monitoring. The Poggio Baldi landslide natural laboratory
Full text linkNowadays the use of remote monitoring sensors is a standard practice in landslide characterization and monitoring. In the last decades, technologies such as LiDAR, terrestrial and satellite SAR interferometry (InSAR) and photogrammetry demonstrated a great potential for rock slope assessment while limited studies and applications are still available for ArcSAR Interferometry, Gigapixel imaging and Acoustic sensing. Taking advantage of the facilities located at the Poggio Baldi Landslide Natural Laboratory, an intensive monitoring campaign was carried out on May 2019 using simultaneously the HYDRA-G ArcSAR for radar monitoring, the Gigapan robotic system equipped with a DSLR camera for photo-monitoring purposes and the DUO Smart Noise Monitor for acoustic measurements. The aim of this study was to evaluate the potential of each monitoring sensor and to investigate the ongoing gravitational processes at the Poggio Baldi landslide. Analysis of multi-temporal Gigapixel-images revealed the occurrence of 84 failures of various sizes between 14–17 May 2019. This allowed us to understand the short-term evolution of the rock cliff that is characterized by several impulsive rockfall events and continuous debris production. Radar displacement maps revealed a constant movement of the debris talus at the toe of the main rock scarp, while acoustic records proved the capability of this technique to identify rockfall events as well as their spectral content in a narrow range of frequencies between 200 Hz to 1000 Hz. This work demonstrates the great potential of the combined use of a variety of remote sensors to achieve high spatial and temporal resolution data in the field of landslide characterization and monitoring
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