Abstract: Abstract. In this paper, a simplified methodological approach is used to assess damage indices related to landslide phenomena that occurred in Calabria (Italy) between November 2008 and January 2009. This approach, which was designed for and applied to single landslides, uses the Support Analysis Framework (SAF), a procedure containing the elements that can be damaged by a landslide grouped in categories. In this paper, we test wide-ranging use of the SAF on a number of landslides, assessing landslide damage on a municipal scale to get a final estimate of the amount of damage caused by all of the landslides that occurred in a selected municipality.
Data regarding the damage caused by landslides were gathered from the press. Daily newspapers were systematically collected and elaborated to assess direct, indirect and intangible damage caused during the abovementioned period by a rainfall-triggered landsliding event. In the paper, regional- and provincial-scale results are described, and the methodological approach is briefly described.
The application of the proposed methodological approach to the 2009 landsliding event shows that the results can be used to summarise landslide damage from a complex event in order to better plan an intervention strategy at a regional, provincial or municipal scale.
The availability of newspaper data during the event and the speed of the proposed approach allow for rapid location of the damaged sectors during the event, which will continuously upgrade the regional damage framework. This can all be done almost in "real time".
For regional agencies, this framework can be a starting point to both manage the emergency and to acquire and interpret data giving a more detailed damage distribution so that a response can be organised. Moreover, based on the damage assessment, a characterisation of the landsliding event can also be carried out and used to describe the damage scenario occurring after each type of event.
Abstract: Landslide Periods (LPs) are defined as periods, shorter than a hydrological year, during which one or more landslide damage events occur in one or more sectors of a study area. In this work, we present a methodological approach, based on the comparative analysis of historical series of landslide damage and daily rainfall data, aiming to characterise the main types of LPs affecting selected areas. Cumulative rainfall preceding landslide activation is assessed
for short (1, 2, 3, and 5 days), medium (7, 10, and 30 days) and long (60, 90, and 180 days) durations, and their Return Periods (RPs) are assessed and ranked into three classes (Class 1: RP=5−10 years; Class 2: RP=11−15; Class 3: RP>15 years). To assess landslide damage, the Simplified Damage Index (SDI) is introduced. This represents classified landslide losses and is obtained by multiplying the value of the damaged element and the percentage of damage affecting it. The comparison of the RP of rainfall and the SDI allows us to indentify the different types of LPs that affected the study area in the past and that could affect it again in the future. The results of this activity can be used for practical purposes to define scenarios and strategies for risk management, to suggest priorities in policy towards disaster mitigation and preparedness and to predispose defensive measures and civil protection plans ranked according to the types of LPs that must be managed. We present an application, performed for a 39-year series of rainfall/landslide damage data and concerning a study area located in NE Calabria (Italy); in this case study, we identify four main types of LPs, which are ranked according to damage
severity.
Abstract: A period of bad weather conditions due to prolonged intense rainfall and strong winds can trigger landslides, floods, secondary floods (accumulation of rain on surfaces with low permeability), and sea storms, causing damage to humans and infrastructure. As a whole, these periods of bad weather and triggered phenomena can be defined as damaging hydrogeological events (DHEs). We define a methodological approach based on seven simple indexes to analyze such events. The indexes describe the return period (T) and trend of rainfall, the extent of hit areas, and the level of damages; they can be considered attributes of georeferenced features and analyzed with GIS techniques. We tested our method in an Italian region frequently hit by DHEs. In a period of 10 years, 747 damaging phenomena (landslides, 43%; floods, 38%) and 94 DHEs have been classified. The road network and housing areas are the most frequently damaged elements, threatened by all types of damaging phenomena. T classes are almost in accordance with the level of damage. These results can be used to outline warning levels for civil protection purposes, to forecast the areas most likely to be hit and the potential ensuing damage, to disseminate information concerning vulnerable areas, and to increase people's awareness of risk.
Abstract: A period of bad weather conditions due to prolonged intense rainfall and strong winds can trigger landslides, floods, secondary floods (accumulation of rain on surfaces with low permeability), and sea storms, causing damage to humans and infrastructure. As a whole, these periods of bad weather and triggered phenomena can be defined as damaging hydrogeological events (DHEs). We define a methodological approach based on seven simple indexes to analyze such events. The indexes describe the return period (T) and trend of rainfall, the extent of hit areas, and the level of damages; they can be considered attributes of georeferenced features and analyzed with GIS techniques. We tested our method in an Italian region frequently hit by DHEs. In a period of 10 years, 747 damaging phenomena (landslides, 43%; floods, 38%) and 94 DHEs have been classified. The road network and xD;housing areas are the most frequently damaged elements, threatened by all types of damaging phenomena. T classes are almost in accordance with the level of damage. These xD;results can be used to outline warning levels for civil protection purposes, to forecast the areas most likely to be hit and the potential ensuing damage, to disseminate xD;information concerning vulnerable areas, and to increase people’s awareness of risk.
Abstract: The Support Analysis Framework (SAF) is a tool that converts descriptions of landslide effects into numerical indices expressing direct, indirect and intangible damage. Sections assessing direct damage are made up of ‘elements’ characterised by relative values and the ‘levels of loss’ that they can suffer. By typing an x value into the cell representing an element and a level of loss, formulas multiply the value of the element by the level of loss, obtaining a value used in the damage indices assessing. Indirect damage deals with: (a) emergency response and (b) efforts to restore pre-landslide conditions. The level of loss depends on the number of people affected (a) or the cost of actions (b). For intangible damage, the level of loss depends on the number of people affected. We assess the damage indices for a landslide occurred in Calabria (Italy) in 2005, using both the SAF and the SAFL, a customised version that takes into account the local socio-economic framework by including only elements present in the analysed municipality. We assess the damage indices for three scenarios with different initial conditions and compare them to the 2005 event; the results would have been useful to mitigate damage. The SAF can be used by nonspecialists, and it allows the ranking of damage caused by different landslides, thus supporting local authorities in prioritising countermeasures and civil protection offices to speed up responses to refund requests. The sorting of dormant phenomena according to their possible damage helps with defensive measures, emergency plans and insurance purposes.
Abstract: The analysis of data describing damage caused bymass movements in Calabria (Italy) allowed the organisation of the Support Analysis Framework (SAF), a spreadsheet that converts damage descriptions into numerical indices expressing direct, indirect, and intangible damage. The SAF assesses damage indices of past mass movements and the potential outcomes of dormant phenomena re-activations. It is based on the effects on damaged elements and is independent of both physical and geometric phenomenon characteristics. SAF sections that assess direct damage encompass several lines, each describing an element characterised by a value fixed on a relative arbitrary scale. The levels of loss are classified as: L4: complete; L3: high; L2: medium; or L1: low. For a generic line l, the SAF multiplies the value of a damaged element by its level of loss, obtaining dl , the contribution of the line to the damage.
Indirect damage is appraised by two sections accounting for: (a) actions aiming to overcome emergency situations and (b) actions aiming to restore pre-movement conditions. The level of loss depends on the number of people involved (a) or the cost of actions (b). For intangible damage, the level of loss depends on the number of people involved. We examined three phenomena, assessing damage using the SAF and SAFL, customised versions of SAF based on the elements actually present in the analysed municipalities that consider the values of elements in the community framework. We show that in less populated, inland, and affluent municipalities, the impact of mass movements is greater than in coastal areas. The SAF can be useful to sort groups of phenomena according to their probable future damage, supplying results significant either for insurance companies or for local authorities involved in both disaster management and planning of defensive measures.
Abstract: Damaging Hydro-geologic Events (DHEs), de- fined as landslides and floods caused by heavy or prolonged rainfall, represent an important source of economic damages. We propose an approach to classify DHEs, considering 1) meteorological antecedent conditions, 2) the season during which the event occurs, 3) the return period of maximum daily rainfall triggering the event, 4) geographic sectors hit, 5) types of triggered damaging phenomena; and 6) induced damage. We applied this approach to a case study of time series of DHEs that occurred over 85 years in Calabria (southern Italy). We analysed 13 DHEs that, between 1921 and 2005, triggered landslides, floods and secondary floods, causing severe damage and tens of causalities all over the Calabria region. During the analysed events, 64% of Calabria’s municipalities suffered many types of damage. The most relevant rain phenomena and the largest damages were caused by the persistent effects of perturbations on Calabria, which were preceded by the appearance of low-pressure fields in two different areas located westwards. We sorted the events into three types based on geographic damage distribution and types of triggered phenomena and induced damage. The first two types are characterised by similar severity levels, while the third shows the highest severity, in terms of both damage and victims. Independent of the type of event, the S-SE and E sectors of the region are the most frequently affected by DHEs. As regards human life, floods are the most dangerous type of phenomenon, causing the highest number of fatalities. Our analysis indicates a decreasing frequency of DHEs during the study period, and an absence of the most severe type for more than 50 years. The number of victims is also decreasing over time.
Abstract: Damaging Hydrogeological Events are defined as periods during which phenomena, such as landslides, floods and secondary floods, cause damage to people and the environment. A Damaging Hydrogeological Event which heavily damaged Calabria (Southern Italy) between December 1972, and January 1973, has been used to test a procedure to be utilised in the zonation of a province according to damage susceptibility during DHEs. In particular, we analyzed the province of Catanzaro (2391 km2), an administrative district composed of 80 municipalities, with about 370 000 inhabitants. Damage, defined in relation to the reimbursement requests sent to the Department of Public Works, has been quantified using a procedure based on a Local Damage Index. The latter, representing classified losses, has been obtained by multiplying the value of the damaged element and the percentage of damage affecting it.
Rainfall has been described by the Maximum Return Period of cumulative rainfall, for both short (1, 3, 5, 7, 10 consecutive days) and long duration (30, 60, 90, 180 consecutive days), recorded during the event. Damage index and population density, presumed to represent the location of vulnerable elements, have been referred to Thiessen polygons associated to rain gauges working at the time of the event. The procedure allowed us to carry out a preliminary classification of the polygons composing the province according to their susceptibility to damage during DHEs. In high susceptibility polygons, severe damage occurs during rainfall characterised by low return periods; in medium susceptibility polygons maximum return period rainfall and induced damage
show equal levels of exceptionality; in low susceptibility polygons, high return period rainfall induces a low level of damage. The east and west sectors of the province show the highest susceptibility, while polygons of the N-NE sector show the lowest susceptibility levels, on account of both the low population
density and high average rainfall characterizing these mountainous areas. The future analysis of further DHEs, using the tested procedure, can strengthen the obtained zonation. Afterwards, the results can prove useful in establishing civil defence plans, emergency management, and prioritizing hazard mitigation measures.
Abstract: A study of the effects of human modification of a coastal plain mainly involving land reclamation and flood protection is proposed. The approach involves historical, geomorphological and hydrological data as a whole, taking into account the equilibrium of rivers, plains and coastal areas. The test area, a telling example of profound economic and social transformation of a coastal plain, is the Piana di Sibari (Calabria, southern Italy), subject to major human modifi- cations over the last 150 years. The study area, at most 300ma.s.l., is 450 km2 wide and comprises 24 hydrographic basins. The approach is based on the creation and analysis of four databases: 1) a historical series of geo-coded flood damage (DAMAGES database), concerning damaging floods which occurred over the past few centuries in the study area; 2) a geocoded series of protection works for land reclamation, protection from floods and improvement of soil stability in steep areas (WORKS database), gathered from the archives of the agencies that carried out the works, organized in a GISformat; 3) a historical series of maximum flood discharges and extreme rainy events (HYMAX database) aimed at defining the trends of occurrence and the intensity of flooding; 4) a coastal line position and migration over time (COASTAL database), created using mainly literature data based on discontinuous data such as historical maps and images. The work describes the complex succession of floods, protection and reclamation works, human transformation of the plain and major land use changes over the last two centuries in the test area. The new characteristics of the plain and its modifications, including major engineering works, land-use transformation and urbanisation, are illustrated. The damaging floods of the last 200 years, the modifications of runoff and flooding due to works built over the basins, hydrological data and the records concerning coastal modifications were Correspondence to: O. Petrucci (o.petrucci@irpi.cnr.it) used to create specific databases and a GIS in which these data can be analyzed by typology, location and extension. The proposed approach highlights the high degree of correlation between drainage basin management, mainly in terms of increasing protection from natural hazards, and anthropogenic development in a broad coastal plain.
Abstract: Landslides, floods and secondary floods (hereinafter called phenomena) triggered by rainfall and causing extensive damage are reviewed in this paper. Damaging Hydrogeological Events (DHEs) are defined as the occurrence of one or more simultaneous aforementioned phenomena. A method for the characterisation of DHEs based upon xD;historic data is proposed. The method is aimed at assessing DHE-related hazard in terms of recurrence, severity, damage, and extent of the affected area. Using GIS, the DHEs historical and climatic data collection, the geomorphological and hydrogeological characterisation of the hit areas, the characterisation of induced damage, the evaluation of triggering rainfall return period and critical duration of each DHE were carried out. The approach was applied to a test site in Southern Italy (Calabria) for validation purposes. A database was set up including data from 24 events which have occurred during an 80-year period. The spatial distribution of phenomena was analysed together with the return period of cumulative rainfall. The trend of the occurred phenomena was also compared with the climatic trend. Four main types of Damaging Hydrogeological Events were identified in the study area.
Abstract: This paper describes a methodological example of a data-integration procedure to improve the knowledge of landslide hazard related to a seismic area in the southern Apennine (Italy). Attention is focused on remote sensing data. The analysis is validated using detailed topographical, geophysical, geotechnical and hydrogeological data as ground truth. The investigated phenomenon, which started at the end of 1993, is an earthflow. The presented methodology recommends the combined use of DEM, multi-temporal panchromatic visible aerial photographs and thermal infrared images. The integration between these data and multidisciplinary monitoring data proved useful. The main hydrogeological pattern, the geological and geomorphological framework and the areas of latent instability can be clearly determined. Insight can be gained through the synoptic slope view in the relative short time needed to cany out the analysis. The proposed approach can be regarded as a useful contribution to the evaluation of landslide hazard, particularly during emergency periods. 0 2001 Elsevier Science Ltd. All rights reserved the 1980 earthquake. Interdisciplinary investigations and monitoring ‘were carried out between 1994 and 1996, within an EC funded research project (EC, 1996) and partially continued by Authors. This area has been chosen as a case study owing both to the landslide dimensions, which are large enough to allow remote sensing, and the wealth of available data. The selection of the most suitable kind of data - mainly remotely sensed - and the proposal of the most appropriate processing is aimed at improving landslide knowledge. The availability of field data ensures the validation of the proposed work. The combined analysis of DEM, panchromatic visible aerial photographs and thermal infrared images has been carried out aiming to perform a study approach able to provide a multi-temporal and multi-spectral analysis of slope instability phenomena. This framework has then been merged to data coming from multidisciplinary monitoring of study area in order to both verify the results of image analysis and test the proposed methodology
