scholarly journals The landslides of 5 May 1998 in Campania, Southern Italy- are they natural disasters or also man-induced phenomena?

2000 ◽  
Vol 22 ◽  
Author(s):  
Francesco Maria Guadagno
Keyword(s):  
Debris Flows ◽  
Southern Italy ◽  
Slip Surface ◽  
Slope Angle ◽  
Dominant Factor ◽  
Cut Slope ◽  
Limestone Bedrock ◽  
Rock Interface ◽  
Colluvial Soils ◽  
Severe Destruction

Following an intense and prolonged rainfall, debris flows occurred in the Sarno-Quindici region on 4 and 5 May 1998. They took place in an area where recent pyroclastic materials mantle the Mesozoic limestone bedrock. The debris flows extended up to 4 km into the surrounding lowlands and reached four towns causing severe destruction. Generally, they initiate as debris slides or debris avalanches, involving pyroclastic horizons and colluvial soils (0.5-2 m thick) on steep and vegetated slopes at the heads of gullies. These failures, whose slip surface generally coincides with the soil and rock interface, transformed very rapidly to debris flows. Whilst the rainfall was undoubtedly a dominant factor in all of the instabilities, a large number of initial failures occurred where tracks have recently been cut into the pyroclastic veneers. These tracks interrupted the morphological and hydrogeological features of the slopes. The tracks had the cut slope angle significantly higher than that of already steep natural slope. It is thought, therefore, that these conditions have been the main cause of a great number of failures, and, therefore, the origin of the catastrophic flows concentrated within an area of 70 square kilometres.

scholarly journals The Development of a 1-D Integrated Hydro-Mechanical Model Based on Flume Tests to Unravel Different Hydrological Triggering Processes of Debris Flows

Water ◽  
2018 ◽  
Vol 10 (7) ◽  
pp. 950 ◽  
Author(s):  
Theo van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Debris Flow ◽  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Slope Angle ◽  
Great Influence ◽  
Flume Experiments ◽  
Triggering Mechanisms ◽  
Bed Material ◽  
Triggering Process

Many studies which try to analyze conditions for debris flow development ignore the type of initiation. Therefore, this paper deals with the following questions: What type of hydro-mechanical triggering mechanisms for debris flows can we distinguish in upstream channels of debris flow prone gullies? Which are the main parameters controlling the type and temporal sequence of these triggering processes, and what is their influence on the meteorological thresholds for debris flow initiation? A series of laboratory experiments were carried out in a flume 8 m long and with a width of 0.3 m to detect the conditions for different types of triggering mechanisms. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. On the basis of these experiments, an integrated hydro-mechanical model was developed, which describes Hortonian and saturation overland flow, maximum sediment transport, through flow and failure of bed material. The model was calibrated and validated using process indicator values measured during the experiments in the flume. Virtual model simulations carried out in a schematic hypothetical source area of a catchment show that slope angle and hydraulic conductivity of the bed material determine the type and sequence of these triggering processes. It was also clearly demonstrated that the type of hydrological triggering process and the influencing geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves for the start of debris flows.

scholarly journals Debris-flow susceptibility assessment through cellular automata modeling: an example from 15–16 December 1999 disaster at Cervinara and San Martino Valle Caudina (Campania, southern Italy)

2003 ◽  
Vol 3 (5) ◽  
pp. 457-468 ◽  
Author(s):  
G. Iovine ◽  
S. Di Gregorio ◽  
V. Lupiano
Keyword(s):  
Cellular Automata ◽  
Debris Flow ◽  
Urban Areas ◽  
Debris Flows ◽  
Soil Cover ◽  
Southern Italy ◽  
Landslide Risk ◽  
Campania Region ◽  
Optimal Values ◽  
Debris Flow Susceptibility

Abstract. On 15–16 December 1999, heavy rainfall severely stroke Campania region (southern Italy), triggering numerous debris flows on the slopes of the San Martino Valle Caudina-Cervinara area. Soil slips originated within the weathered volcaniclastic mantle of soil cover overlying the carbonate skeleton of the massif. Debris slides turned into fast flowing mixtures of matrix and large blocks, downslope eroding the soil cover and increasing their original volume. At the base of the slopes, debris flows impacted on the urban areas, causing victims and severe destruction (Vittori et al., 2000). Starting from a recent study on landslide risk conditions in Campania, carried out by the Regional Authority (PAI –Hydrogeological setting plan, in press), an evaluation of the debris-flow susceptibility has been performed for selected areas of the above mentioned villages. According to that study, such zones would be in fact characterised by the highest risk levels within the administrative boundaries of the same villages ("HR-zones"). Our susceptibility analysis has been performed by applying SCIDDICA S3–hex – a hexagonal Cellular Automata model (von Neumann, 1966), specifically developed for simulating the spatial evolution of debris flows (Iovine et al., 2002). In order to apply the model to a given study area, detailed topographic data and a map of the erodable soil cover overlying the bedrock of the massif must be provided (as input matrices); moreover, extent and location of landslide source must also be given. Real landslides, selected among those triggered on winter 1999, have first been utilised for calibrating SCIDDICA S3–hex and for defining "optimal" values for parameters. Calibration has been carried out with a GIS tool, by quantitatively comparing simulations with actual cases: optimal values correspond to best simulations. Through geological evaluations, source locations of new phenomena have then been hypothesised within the HR-zones. Initial volume for these new cases has been estimated by considering the actual statistics of the 1999 landslides. Finally, by merging the results of simulations, a deterministic susceptibility zonation of the considered area has been obtained. In this paper, aiming at illustrating the potential for debris-flow hazard analyses of the model SCIDDICA S3–hex, a methodological example of susceptibility zonation of the Vallicelle HR-zone is presented.

scholarly journals An 1-D Integrated Hydro-Mechanical Model to Unravel Different Hydrological Triggering Processes of Debris Flows

2018 ◽  
Author(s):  
Theo W.J. van Asch ◽  
Bin Yu ◽  
Wei Hu
Keyword(s):  
Mechanical Model ◽  
Debris Flows ◽  
Overland Flow ◽  
Model Simulation ◽  
Slope Angle ◽  
Great Influence ◽  
Source Area ◽  
Material Model ◽  
Flume Experiments ◽  
Bed Material

Many studies, which try to analyze the meteorological threshold conditions for debris flows ignore the type of initiation. This paper focuses on the differences in hydrological triggering processes of debris flows in channel beds of the source areas. The different triggering processes were studied in the laboratory and by model simulation on the field scale. The laboratory experiments were carried out in a flume, 8 m long and a width of 0.3 m. An integrated hydro-mechanical model was developed, describing Hortonian and Saturation overland flow, through flow, maximum sediment transport and failure of bed material. The model was tested on the processes observed in the flume. The flume experiments show a sequence of hydrological processes triggering debris flows, namely erosion and transport by intensive overland flow and by infiltrating water causing failure of channel bed material. Model simulations carried out on a schematic hypothetical source area of a catchment show that the type and sequence of these triggering processes are determined by slope angle and the hydraulic conductivity of the bed material. It was also clearly demonstrated that the type of initiation process and the geometrical and hydro-mechanical parameters may have a great influence on rainfall intensity-duration threshold curves, indicating the start of debris flows.

Landslide susceptibility mapping using GIS and Remote Sensing: A case study of the Rangamati District, Bangladesh

2020 ◽  
Author(s):  
Afruja Begum ◽  
Md Shofiqul Islam ◽  
Md. Muyeed Hasan
Keyword(s):  
Remote Sensing ◽  
Water Pressure ◽  
Research Work ◽  
Slope Angle ◽  
Steep Slope ◽  
Landslide Susceptibility Mapping ◽  
Dominant Factor ◽  
Natural Phenomenon ◽  
Slope Aspect ◽  
Gis And Remote Sensing

Abstract The landslide is a natural phenomenon and one of the most commonplace disasters in the Rangamati Hill tract area which appeals for better forecasting and specify the landslide susceptible zonation. This research work examines the application of GIS and Remote Sensing techniques based on different parameters such as altitude, slope angle, slope aspect, rainfall, land-use land-cover (LULC), geology and stream distance by heuristic model to identify the landslide susceptible zones for the study area. Among the parameters, rainfall, steep slope, geology and LULC are the dominant factor that triggering the landslide. Clayey or silty soils of the study area during heavy and prolong rainfall behave a flow of debris due to water pressure within the soil, resulting landslides. Steep slope has greater influences for weather zones of the rock-masses for susceptible landslides. Result and field observation indicate that the population density and LULC has a vital effect on landslide within the study area. However, landslide susceptible zones were created based on the susceptibility map of the study area which shows that about 19.43% of the area are at low susceptible zone, 56.55% of the area are at medium susceptible zone, 19.19% of the area are in the high susceptible zone and 4.81% of the area is at the very high susceptible zone.

Approaches to the study of hillslope development due to mass movement

1993 ◽  
Vol 17 (1) ◽  
pp. 32-49 ◽  
Author(s):  
S.M. Brooks ◽  
K.S. Richards ◽  
M.G. Anderson
Keyword(s):  
Internal Friction ◽  
Pore Water ◽  
Water Table ◽  
Soil Cover ◽  
Slip Surface ◽  
Mass Movement ◽  
Slope Angle ◽  
Geological Time ◽  
Stability Of Slopes ◽  
Pore Water Pressures

Slope-angle histograms have traditionally provided a data base for the evaluation of changing angles over geological time. Ideas relating to hillslope development due to mass movement have considered a lowering in regolith shear resistance due to weathering, producing slope-angle decline. Decreasing values for angles of internal friction, along with increasing pore water pressures, have been suggested to explain slope-angle decline through time. These ideas have considered simple changes in undifferentiated regolith. This article considers the role of progressive pedogenesis in determining the changing stability of slopes. For this it is necessary to evaluate the changes which occur within individual horizons to produce an increasingly differentiated soil cover. Angles of internal friction alter at different rates and in different ways depending on whether the horizon is losing or gaining weathered material through translocation. Furthermore, the increasing internal differentiation of the soil cover has complex effects on its hydrological response. Instead of the two scenarios previously envisaged, one involving the water table below the slip surface and the other involving the water table at the ground surface, slope stability needs to be evaluated in the light of continually changing negative or positive pore water pressures. Each storm produces a different response, and this response alters with soil development, complicating the assessment of failure timing and depth. The study of evolving soil profiles is of fundamental significance to a range of geomorphological processes, requiring closer evaluation in the future.

Effect of antecedent-hydrological conditions on rainfall triggering of debris flows in ash-fall pyroclastic mantled slopes of Campania (southern Italy)

Landslides ◽  
2015 ◽  
Vol 13 (5) ◽  
pp. 967-983 ◽  
Author(s):  
E. Napolitano ◽  
F. Fusco ◽  
R. L. Baum ◽  
J. W. Godt ◽  
P. De Vita
Keyword(s):  
Debris Flows ◽  
Southern Italy ◽  
Hydrological Conditions ◽  
Ash Fall

scholarly journals Multiple Effects of Intense Meteorological Events in the Benevento Province, Southern Italy

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1560 ◽  
Author(s):  
Paola Revellino ◽  
Luigi Guerriero ◽  
Neri Mascellaro ◽  
Francesco Fiorillo ◽  
Gerardo Grelle ◽  
...  
Keyword(s):  
Soil Erosion ◽  
Debris Flows ◽  
Southern Italy ◽  
Statistical Characteristics ◽  
Total Rainfall ◽  
Campania Region ◽  
Rainfall Events ◽  
Pattern Distribution ◽  
The Town ◽  
Flooded Areas

In October 2015, two intense rainfall events hit the central and southern regions of Italy and triggered a combination of different and widespread effects, including floods, landslides, and soil erosion. These outcomes devastated about 68 municipalities of the Benevento province (Campania region), killed two people, and caused millions of euros worth of damage to structures, infrastructures, and agriculture. The town of Benevento was one of the sectors most affected by overflow. Extensive areas characterized by flyschoid outcrops experienced widespread occurrences of soil erosion and landslides, and destructive, high-velocity debris flows (about 50) afflicted areas that had experienced heavy rainfall of higher intensity (total rainfall of 415.6 mm). In this study, the characteristics of these rainfall events and related geomorphological processes were determined by (i) analyzing the available rainfall data to identify the spatial pattern, distribution, and statistical characteristics of the two storms and (ii) mapping the storm effects, such as flooded areas, landslide types, and soil erosion. These effects were then related to the spatial distribution of the storms and the local geological and geomorphologic settings that drove their initiation and development.

scholarly journals Description and analysis of the debris flows occurred during 2008 in the Eastern Pyrenees

2010 ◽  
Vol 10 (7) ◽  
pp. 1635-1645 ◽  
Author(s):  
M. Portilla ◽  
G. Chevalier ◽  
M. Hürlimann
Keyword(s):  
Debris Flows ◽  
Regional Scale ◽  
Slope Angle ◽  
Large Mass ◽  
Rainfall Data ◽  
Published Data ◽  
Mountainous Regions ◽  
Initiation Zone ◽  
Eastern Pyrenees ◽  
Fluid Rheology

Abstract. Rainfall-triggered landslides taking place in the Spanish Eastern Pyrenees have usually been analysed on a regional scale. Most research focussed either on terrain susceptibility or on the characteristics of the critical rainfall, neglecting a detailed analysis of individual events. In contrast to other mountainous regions, research on debris flow has only been performed marginally and associated hazard has mostly been neglected. In this study, five debris flows, which occurred in 2008, are selected; and site specific descriptions and analysis regarding geology, morphology, rainfall data and runout were performed. The results are compared with worldwide data and some conclusions on hazard assessment are presented. The five events can be divided into two in-channel debris flows and three landslide-triggered debris flows. The in-channel generated debris flows exceeded 10 000 m3, which are unusually large mass movements compared to historic events which occurred in the Eastern Pyrenees. In contrast, the other events mobilised total volumes less than 2000 m3. The geomorphologic analysis showed that the studied events emphasize similar patterns when compared to published data focussing on slope angle in the initiation zone or catchment area. Rainfall data revealed that all debris flows were triggered by high intensity-short duration rainstorms during the summer season. Unfortunately, existing rainfall thresholds in the Eastern Pyrenees consider long-lasting rainfall, usually occurring in autumn/winter. Therefore, new thresholds should be established taking into account the rainfall peak intensity in mm/h, which seems to be a much more relevant factor for summer than the event's total precipitation. The runout analysis of the 2008 debris flows confirms the trend that larger volumes generally induce higher mobility. The numerical simulation of the Riu Runer event shows that its dynamic behaviour is well represented by Voellmy fluid rheology. A maximum front velocity of 7 m/s was back-analysed for the transit section and even on the fan velocities larger than 2 m/s were obtained. This preliminary analysis of the major Eastern Pyrenean debris flows represents the first background for future studies. Additional research on other events is necessary to support the results presented herein, and to properly assess and reduce hazard related to debris flows.

scholarly journals Creating a national scale debris flow susceptibility model for Great Britain: a GIS-based heuristic approach

2019 ◽  
Author(s):  
Emma J. Bee ◽  
Claire Dashwood ◽  
Catherine Pennington ◽  
Roxana L. Ciurean ◽  
Katy Lee
Keyword(s):  
Great Britain ◽  
Debris Flow ◽  
Debris Flows ◽  
Methodological Approach ◽  
Slope Angle ◽  
Transport Infrastructure ◽  
Stream Channels ◽  
National Scale ◽  
Susceptibility Model ◽  
Debris Flow Susceptibility

Abstract. Debris flows in Great Britain have caused damage to transport infrastructure, buildings, and disruption to businesses and communities. This study describes a GIS-based heuristic model developed by the British Geological Survey (BGS) to produce a national scale spatial assessment of debris flow susceptibility for Great Britain. The model provides information on the potential for debris flow occurrence using properties and characteristics of geological materials (permeability, material availability and characteristics when weathered), slope angle and proximity to stream channels as indicators of susceptibility. Building on existing knowledge, the model takes into account the presence or absence of glacial scouring. As determined by the team of geologists and geomorphologists, the model ranks the availability of debris material and slope as the two dominant factors important for potential debris flow initiation, however it also considers other factors such as geological controls on infiltration. The resultant model shows that over 90 % of the mapped debris flows in the BGS inventory occurred in areas with the highest potential for instability and approximately 6 % were attributed to areas where the model suggested that debris flows are unlikely or not thought to occur. Model validation in the Cairngorm Mountains indicated a better performance, with 93.50 % in the former and less than 3 % in the latter category. Although the quality of the input datasets and selected methodological approach bear limitations and introduce a number of uncertainties, overall, the proposed susceptibility model performs better than previous attempts, representing a useful tool in the hands of policy-makers, developers and engineers to support regional or national scale development action plans and disaster risk reduction strategies.

An early warning system for rainfall-triggered shallow slides and debris flows. Application in Catalonia, Spain and Canton of Bern, Switzerland

2020 ◽  
Author(s):  
Rosa M Palau ◽  
Marc Berenguer ◽  
Marcel Hürlimann ◽  
Daniel Sempere-Torres ◽  
Catherine Berger ◽  
...  
Keyword(s):  
Early Warning ◽  
Debris Flows ◽  
Risk Mitigation ◽  
Regional Scale ◽  
Slope Angle ◽  
Early Warning Systems ◽  
Warning Systems ◽  
Radar Rainfall ◽  
Susceptibility Maps ◽  
Landslide Event

<p>Risk mitigation for rainfall-triggered shallow slides and debris flows at regional scale is challenging. Early warning systems are a helpful tool to depict the location and time of future landslide events so that emergency managers can act in advance. Recently, some of the regions that are recurrently affected by rainfall triggered landslides have developed operational landslide early warning systems (LEWS). However, there are still many territories where this phenomenon also represents an important hazard and lack this kind of risk mitigation strategy.</p><p>The main objective of this work is to study the feasibility to apply a regional scale LEWS, which was originally designed to work over Catalonia (Spain), to run in other regions. To do so we have set up the LEWS to Canton of Bern (Switzerland).</p><p>The LEWS combines susceptibility maps to determine landslide prone areas and in real time high-resolution radar rainfall observations and forecasts. The output is a qualitative warning level map with a resolution of 30 m.</p><p>Susceptibility maps have been derived using a simple fuzzy logic methodology that combines the terrain slope angle, and land use and land cover (LULC) information. The required input parameters have been obtained from regional, pan-European and global datasets.</p><p>Rainfall inputs have been retrieved from both regional weather radar networks, and the OPERA pan-European radar composite. A set of global rainfall intensity-duration data has been used to asses if a rainfall event has the potential of triggering a landslide event.</p><p>The LEWS has been run in the region of Catalonia and Canton of Bern for specific rainfall events that triggered important landslides. Finally, the LEWS performance in Catalonia has been assessed.</p><p>Results in Catalonia show that the LEWS performance strongly depends on the quality of both the susceptibility maps and rainfall data. However, in both regions the LEWS is generally able to issue warnings for most of the analysed landslide events.</p>

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