/ The preparation of landslide maps is an important step in any landslide hazard assessment. Land... more / The preparation of landslide maps is an important step in any landslide hazard assessment. Landslides maps are prepared around the world, but little effort is made to assess their reliability, outline their main characteristics, and pinpoint their limitations. In order to redress this imbalance, the results of a long-term research project in the Upper Tiber River basin in central Italy are used to compare reconnaissance and detailed landslide inventory maps, statistical and geomorphologically based density maps, and landslide hazard maps obtained by multivariate statistical modeling. An attempt is made to discuss advantages and limitations of the available maps, outlining possible applications for decision-makers, land developers, and environmental and civil defence agencies. The Tiber experiment has confirmed that landslides can be cost-effectively mapped by interpreting aerial photographs coupled with field surveys and that errors and uncertainties associated with the inventory can be quantified. The experiment has shown that GIS makes it easy to prepare landslide density maps and facilitates the production of statistically based landslide hazard models. The former supply an overview of the distribution of landslides that is easily comprehended but do not provide insight on the causes of instability. The latter, giving insight into the causes of instability, are diagnostically powerful, but are difficult to prepare and exploit.
... triggers, provided that the event slope failures leave discernable features captured by ... c... more ... triggers, provided that the event slope failures leave discernable features captured by ... change detection techniques applied to high-resolution (HR) and very-high-resolution (VHR) optical ... a description of the construction and validation of multivariate terrain classification models ...
The definition of landslide warning thresholds, based on the analysis of hydrological data, is p... more The definition of landslide warning thresholds, based on the analysis of hydrological data, is proposed. In the Tiber River Basin of central Italy historical information on landslides and floods, for the period 1918–1990, was available from a nationwide bibliographical and archive inventory on geohydrological catastrophes. Hydrological data were obtained from mean daily discharge records at various gauging stations within the basin. Several hundred hydrological events, broadly defined as a series of consecutive days having mean daily discharge exceeding a predefined value, were identified. Hydrological parameters obtained from the discharge records were used to rank the events according to their probability to trigger mass movements or inundations and to define regional thresholds for the occurrence of landslides and floods. The proposed approach, not lacking limitations, has conceptual and operational advantages, among which is the possibility of using historical information on geohydrological catastrophes.
Technologies such as Geographical Information Systems (GIS) have raised great expectations as pot... more Technologies such as Geographical Information Systems (GIS) have raised great expectations as potential means of coping with natural disasters, including landslides. However, several misconceptions on the potential of GIS are widespread. Prominent among these is the belief that a landslide hazard map obtained by systematic data manipulation within a GIS is assumed to be more objective than a comparable hand-made product derived from the same input data and founded on the same conceptual model. Geographical data can now be handled in a GIS environment by users who are not experts in either GIS or natural hazard process fields. The reality of the successful application of GIS within the landslide hazard domain seems to be somewhat less attractive than current optimistic expectations. In spite of recent achievements, the use of GIS in the domain of prevention and mitigation of natural catastrophes remains a pioneering activity. Diffusion of the technology is still hampered by factors such as the difficulty in acquiring appropriate raw data, the intrinsic complexity of predictive models, the lack of efficient graphical user interfaces, the high cost of digitisation, and the persistence of bottlenecks in hardware capabilities. In addition, researchers are investing more in tuning-up hazard models founded upon existing, often unreliable data than in attempting to initiate long-term projects for the acquisition of new data on the causes of catastrophic events. Governmental institutions are frequently involved in risk reduction projects whose design and implementation appear to be governed more by political issues than by technical ones. There is an unfortunate general tendency to search for data which can be collected at low cost rather than attempting to capture the information which most readily explains the causes of a disaster. If the technical, cultural, economic and political reasons for this unhealthy state cannot be adequately tackled, the International Decade for Natural Disaster Reduction will probably come to an end without achieving significant advances in the prediction and control of natural disasters.
In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex ... more In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex combination of landslides and floods, and may cause casualties and damage to urban areas and the utility network. On 1 October 2009, a high intensity rainstorm in the Messina area, Sicily, triggered more than 500 shallow landslides in an area of about 60 km2, mostly in the soils mantling the metamorphic and crystalline bedrock of the Peloritan Arc. The high intensity rainfall further resulted in massive erosion and deposition of debris along the ephemeral drainage channels, widespread inundation, and local modification of the coastline. Damage was particularly severe in the several small villages present in the area, including Giampilieri, Scaletta Zanclea, Guidomandri, Pèzzolo, Altolìa, and Itàla. Damage to the transportation network was also severe and widespread. The several rainfall-induced landslides and the inundations have resulted in 31 deaths, 6 missing persons, numerous injured persons, and more than 2500 evacuated and homeless people. In the aftermath of the event, we: (i) completed a preliminary field survey in the area most affected by landslides and inundations, documenting the ground effects of the intense rainfall, (ii) acquired satellite imagery, including very-high-resolution optical images taken by QuickBird and high-resolution radar images taken by COSMO-SkyMed, and (iii) acquired stereoscopic aerial photography, including pre-event aerial photographs taken in 1954, 1995, and 2005, and post event, very-large scale images taken by helicopter immediately after the event. In this work, we present preliminary results of the exploitation of multiple remote-sensing technologies and information for the identification, mapping and classification of the rainfall induced landslides, and of the eroded and the inundated areas. Emphasis is given to the critical analysis of the capacity and limits of the available airborne and satellite remote sensing technologies for the rapid mapping of geo-hydrological events, and the associated damage.
/ The preparation of landslide maps is an important step in any landslide hazard assessment. Land... more / The preparation of landslide maps is an important step in any landslide hazard assessment. Landslides maps are prepared around the world, but little effort is made to assess their reliability, outline their main characteristics, and pinpoint their limitations. In order to redress this imbalance, the results of a long-term research project in the Upper Tiber River basin in central Italy are used to compare reconnaissance and detailed landslide inventory maps, statistical and geomorphologically based density maps, and landslide hazard maps obtained by multivariate statistical modeling. An attempt is made to discuss advantages and limitations of the available maps, outlining possible applications for decision-makers, land developers, and environmental and civil defence agencies. The Tiber experiment has confirmed that landslides can be cost-effectively mapped by interpreting aerial photographs coupled with field surveys and that errors and uncertainties associated with the inventory can be quantified. The experiment has shown that GIS makes it easy to prepare landslide density maps and facilitates the production of statistically based landslide hazard models. The former supply an overview of the distribution of landslides that is easily comprehended but do not provide insight on the causes of instability. The latter, giving insight into the causes of instability, are diagnostically powerful, but are difficult to prepare and exploit.
... triggers, provided that the event slope failures leave discernable features captured by ... c... more ... triggers, provided that the event slope failures leave discernable features captured by ... change detection techniques applied to high-resolution (HR) and very-high-resolution (VHR) optical ... a description of the construction and validation of multivariate terrain classification models ...
The definition of landslide warning thresholds, based on the analysis of hydrological data, is p... more The definition of landslide warning thresholds, based on the analysis of hydrological data, is proposed. In the Tiber River Basin of central Italy historical information on landslides and floods, for the period 1918–1990, was available from a nationwide bibliographical and archive inventory on geohydrological catastrophes. Hydrological data were obtained from mean daily discharge records at various gauging stations within the basin. Several hundred hydrological events, broadly defined as a series of consecutive days having mean daily discharge exceeding a predefined value, were identified. Hydrological parameters obtained from the discharge records were used to rank the events according to their probability to trigger mass movements or inundations and to define regional thresholds for the occurrence of landslides and floods. The proposed approach, not lacking limitations, has conceptual and operational advantages, among which is the possibility of using historical information on geohydrological catastrophes.
Technologies such as Geographical Information Systems (GIS) have raised great expectations as pot... more Technologies such as Geographical Information Systems (GIS) have raised great expectations as potential means of coping with natural disasters, including landslides. However, several misconceptions on the potential of GIS are widespread. Prominent among these is the belief that a landslide hazard map obtained by systematic data manipulation within a GIS is assumed to be more objective than a comparable hand-made product derived from the same input data and founded on the same conceptual model. Geographical data can now be handled in a GIS environment by users who are not experts in either GIS or natural hazard process fields. The reality of the successful application of GIS within the landslide hazard domain seems to be somewhat less attractive than current optimistic expectations. In spite of recent achievements, the use of GIS in the domain of prevention and mitigation of natural catastrophes remains a pioneering activity. Diffusion of the technology is still hampered by factors such as the difficulty in acquiring appropriate raw data, the intrinsic complexity of predictive models, the lack of efficient graphical user interfaces, the high cost of digitisation, and the persistence of bottlenecks in hardware capabilities. In addition, researchers are investing more in tuning-up hazard models founded upon existing, often unreliable data than in attempting to initiate long-term projects for the acquisition of new data on the causes of catastrophic events. Governmental institutions are frequently involved in risk reduction projects whose design and implementation appear to be governed more by political issues than by technical ones. There is an unfortunate general tendency to search for data which can be collected at low cost rather than attempting to capture the information which most readily explains the causes of a disaster. If the technical, cultural, economic and political reasons for this unhealthy state cannot be adequately tackled, the International Decade for Natural Disaster Reduction will probably come to an end without achieving significant advances in the prediction and control of natural disasters.
In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex ... more In Italy, severe meteorologically induced geo-hydrological events are characterized by a complex combination of landslides and floods, and may cause casualties and damage to urban areas and the utility network. On 1 October 2009, a high intensity rainstorm in the Messina area, Sicily, triggered more than 500 shallow landslides in an area of about 60 km2, mostly in the soils mantling the metamorphic and crystalline bedrock of the Peloritan Arc. The high intensity rainfall further resulted in massive erosion and deposition of debris along the ephemeral drainage channels, widespread inundation, and local modification of the coastline. Damage was particularly severe in the several small villages present in the area, including Giampilieri, Scaletta Zanclea, Guidomandri, Pèzzolo, Altolìa, and Itàla. Damage to the transportation network was also severe and widespread. The several rainfall-induced landslides and the inundations have resulted in 31 deaths, 6 missing persons, numerous injured persons, and more than 2500 evacuated and homeless people. In the aftermath of the event, we: (i) completed a preliminary field survey in the area most affected by landslides and inundations, documenting the ground effects of the intense rainfall, (ii) acquired satellite imagery, including very-high-resolution optical images taken by QuickBird and high-resolution radar images taken by COSMO-SkyMed, and (iii) acquired stereoscopic aerial photography, including pre-event aerial photographs taken in 1954, 1995, and 2005, and post event, very-large scale images taken by helicopter immediately after the event. In this work, we present preliminary results of the exploitation of multiple remote-sensing technologies and information for the identification, mapping and classification of the rainfall induced landslides, and of the eroded and the inundated areas. Emphasis is given to the critical analysis of the capacity and limits of the available airborne and satellite remote sensing technologies for the rapid mapping of geo-hydrological events, and the associated damage.
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Papers by M. Cardinali