1,720,996 research outputs found
Rainfall thresholds for the initiation of landslides in central Italy using remote sensing precipitation data.
No full textWe used remote sensing data to define new rainfall thresholds for the possible occurrence of landslides in Marche and Umbria regions, central Ital y. Remote sensing data are provided b y NASA and the estimated rainfall is cumulated every three hours in a regular grid of 0.25° × 0.25°. We exploited a catalogue of temporal and spatial information on landslides triggered by rainfall in the study area in the period 2002-2010. For each slope failure in the catalogue, we calculated the cumulated rainfall E (mm) and the duration D (h) of each rainfall event that triggered one or more landslide, using both remote sensing data and measurements obtained from a rain-gauge network. The rain-gauge network in the study area includes 123 stations and the rainfall is cumulated every hour. Finally, we obtained two data sets of empirical rainfall conditions (D, E) that triggered landslides and we defined the corresponding rainfall thresholds for remote sensing data and for rain gauge data. We used a Frequentist method and assumed that the threshold curve is a power law E =alfax D^gamma, where alfa is a scaling constant (the intercept) and gamma is the shape parameter that defines the slope of the power law curve. This method allows to define rainfall threshold corresponding to different exceedance probabilities. We observed that the threshold for remote sensing data is permanently lower than the threshold obtained with rain-gauge measurements. Finally, we found a relationship between the two thresholds. This is important because it permits the use of sensing precipitation data to obtain rainfall thresholds for the possible occurrence of landslides in those areas where rain gauge measurements are insufficient, or inexistent
Remote sensing precipitation data to determine rainfall thresholds for the possible occurance of landslides in central Italy.
No full textWe defined rainfall thresholds for possible landslide occurrence in central Italy using remote sensing precipitation data. For the purpose, we used 3-hour cumulated rainfall on a 0.25° 0.25° grid provided by NASA. We compared the thresholds with thresholds defined for the same area using rainfall measurements obtained from a network of 154 rain gauges in central Italy. For each rainfall event that has resulted in one or more landslides in the period 2002-2010, we calculated the cumulated rainfall E (mm) and the duration D (h) of the rainfall event. We compiled two data sets of empirical rainfall conditions (D, E) obtained from the rain gauge measurements
and the remote sensing precipitation data. Using this information, we defined two different ED thresholds, for rain gauge measurements and for the remote sensing estimates. To define the thresholds, we adopted a Frequentist probabilistic method that assumes that the threshold curve is a power law E = D, where E is the cumulated
rainfall (mm), D is the duration of the rainfall event (h), is a scaling constant (the intercept), and is the slope of the power law curve. We defined rainfall thresholds corresponding to an exceedance probability of 5% for the remote sensing data T5S,and for the rain gauge measurements T5R. Inspection of the two thresholds shows that
the threshold curves have a similar scaling exponent, with T5S exhibiting a lower intercept . We conclude that, in the study area, the cumulated rainfall required to initiate landslides estimated using the remote sensing precipitation data is persistently lower than the cumulated rainfall measured by the rain gauges. The result is significant. The two thresholds have a similar slope and this suggests that remote sensing precipitation data can be used to obtain rainfall thresholds for the possible occurrence of landslides. This can be useful in areas where rain gauge measurements are insufficient, or inexistent
Rainfall thresholds for the possible initiation of shallow landslides in the Italian Alps
No full textAbstract Rainfall-induced shallow landslides are frequent in the Italian Alps, where they cause severe economic damages and loss of life. The prediction of rainfall-induced slope failures is of utmost importance for civil protection purposes and relies upon the definition of physically based or empirical rainfall thresholds. Reliable empirical rainfall thresholds require a large amount of information on the geographical and temporal location of past rainfall events that caused the observed mass movements. We have compiled a catalogue listing 453 rainfall events that have triggered landslides in the Italian Alps in the 13-year period 2000-2012. For the purpose, we searched national and local newspapers, blogs, technical reports, historical databases, and scientific journals. In the catalogue, for each rainfall event that triggered one or more failures, the information includes: (i) landslide geographical position, (ii) date of the landslide occurrence, (iii) landslide type (if available from the source of information), and (iv) rainfall information. Using the available information, we calculated the cumulated amount (E) and the duration (D) of the rainfall that likely caused the documented slope failures. We exploited the catalogue to calculate new ED threshold curves and their associated uncertainties for the Italian Alps adopting a frequentist approach. To define seasonal rainfall thresholds, we also investigated the monthly distribution of the landslides. The new thresholds are compared with similar curves in the same general area. We expect the results of our study to improve the ability to forecast shallow landslides in the Italian Alps and, more generally, in the wider Alpine regio
Definition and performance of a threshold-based regional early warning model for rainfall-induced landslides
Full text linkUtilizzo di stime di precipitazione da satellite per la definizione di soglie pluviometriche per l'innesco di frane in Italia centrale.
No full textVengono definite soglie pluviometriche empiriche per l'innesco di frana di tipo cumulata-durata dell’evento pluviometrico, per un’area di studio in Italia centrale, che comprende le regioni Umbria, Marche e Abruzzo, ottenute utilizzando misure a terra da una rete pluviometrica e stime di pioggia da satellite
Influence of geological, morphological and climatic factors in the initiation of shallow landslides in North Western Italy
No full textLandslides are recurrent geomorphic processes in Italy and represent a serious economic and societal problem. Historical catalogues report thousands of landslide casualties since the 9th Century. The importance to predict landslide occurrence is particularly evident to prevent the effects of rapid mass movements. The mitigation of landslide-related risk needs the improvement of prediction skills, obtained with a better understanding of triggering mechanisms, which are peculiar of the specific geological and environmental settings. The prominent role of rainfall in mass movement activations is widely recognised in the scientific community and several authors all over the world have long attempted to define the critical values responsible for landslide initiation. In Italy, the National Department for Civil Protection (DPC) is funding a CNR-IRPI (National Research Council-Research Institute for Hydro-geological Protection) research, aiming at the definition of regional rainfall thresholds for shallow landslides for the entire national territory. In this study, we investigated the role of geological, morphological and climatic factors on the initiation of rainfall-induced slope failures in the Piedmont, the Aosta Valley and the Lombardy regions (NW Italy
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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