PREFACE
Natural catastrophes, such as earthquakes, hurricanes, flash floods, volcanic eruptions, and landslides, have always constituted a major problem in many developing and developed countries. In recent years, the growth of population and the diffusion of settlements over hazardous areas have sharpened the impact of natural disasters worldwide. The United Nations in declaring the decade 1990-2000 as the International Decade
for Natural Disasters Reduction (IDNDR) has provided a unique opportunity for institutions and individuals to critically evaluate current methods for predicting natural catastrophes and mitigating their impact; and to investigate the potential of new technological advancements for improving hazard evaluation and risk reduction.
for Natural Disasters Reduction (IDNDR) has provided a unique opportunity for institutions and individuals to critically evaluate current methods for predicting natural catastrophes and mitigating their impact; and to investigate the potential of new technological advancements for improving hazard evaluation and risk reduction.
Among these new technologies, Geographical Information Systems (GIS) may play an important role in order to: -a) efficiently and cost-effectively collect, store, analyze and display large sets of geographically referenced data; -b) facilitate attempts to develop new and more reliable models which better reflect the real world, i.e., incorporate the physical processes and factors leading to the occurrence in space and time of the catastrophic eve!lts.
Although the first relevant achievements in the domain of geographical data electronic processing date back to the early 1970s, at present there is no general agreement on the procedures and requirements associated with this set of techniques. In recent years, many conferences, symposia and workshops on GIS technology and applications have been held world-wide.·
This interdisciplinary cross-fertilization of knowledge and ideas has led to a better awareness of the tools and techniques available and in a better exploitation of their potential, particularly in the domain of resource inventories. However, from an examination of the literature; it appears that GIS are too frequently employed more as tool for displaying data in afashionable way than as a new technique for thoroughly analyze relevant information.
This interdisciplinary cross-fertilization of knowledge and ideas has led to a better awareness of the tools and techniques available and in a better exploitation of their potential, particularly in the domain of resource inventories. However, from an examination of the literature; it appears that GIS are too frequently employed more as tool for displaying data in afashionable way than as a new technique for thoroughly analyze relevant information.
Most natural catastrophic events are intrinsically complex phenomena caused by a large sets of factors, many of which are ill-known or unmappable. In spite of these constraints, several sound, hazard investigations have recently been carried ol:lt; some of them may constitute a reliable starting point for future projects aimed at evaluating hazard and risk within nation-wide projects.
Their prediction in space and time remains, however, a very difficult task, requiring the acquisition of many spatial data, long historical records and sophisticated models of the physical processes involved. GIS may well have great potential in such a type of investigation, but at present various obstacles hamper a wider and more effective use of this technology, namely:
Their prediction in space and time remains, however, a very difficult task, requiring the acquisition of many spatial data, long historical records and sophisticated models of the physical processes involved. GIS may well have great potential in such a type of investigation, but at present various obstacles hamper a wider and more effective use of this technology, namely:
• the acquisition of relevant data is difficult and costly; • data capture and digitization constitute an overhead cost, sometime unaffordable; • modelling and simulation within a GIS environment are still experimental; and • many experts working in the field of natural catastrophes are unable to exploit the full potential of GIS because of misunderstanding or lack of expertise or equipment.This unhealthy state, which appears primarily dependent on the fact that geographical data processing is still a pioneering field, requires significant developments both in technology and methodology.
Awareness of GIS potentials and current drawbacks, and the belief that hazard and risk prediction and mitigation need a multidisciplinary approach and international cooperation, led to the organization of an International Workshop on "Geographical Information Systems in Assessing Natural Hazards", which was held in Perugia in September 1993. Under the sponsorship of the IDNDR Secretariat, the Workshop was jointly organised by the National Group for Prevention of Hydrogeological Hazards of the Italian National Research Council and the Water Resources Research Documentation Center of the Perugia University for Foreigners.
This book brings together over one third of the papers presented at the Workshop. Since they were not commissioned, there are some gaps in the coverage of both the types of natural hazards addressed, and the many issues related to the topic. Hence, among the great number of physical processes leading to disasters, only landslides, floods, volcanic eruptions and earthquakes are discussed by one or more contributors to this book.
Although man-induced, groundwater pollution was also examined for its relevance in many industrialized societies. Case studies from the research environment are more abundant than those from operational practice. GIS applications exceed review papers on the present and future developments of the technology. In spite of these limitations, the 16 contributions contained in this book highlight the present state-of-the-art of GIS technology in the domain of hazard prediction and mapping.
Although man-induced, groundwater pollution was also examined for its relevance in many industrialized societies. Case studies from the research environment are more abundant than those from operational practice. GIS applications exceed review papers on the present and future developments of the technology. In spite of these limitations, the 16 contributions contained in this book highlight the present state-of-the-art of GIS technology in the domain of hazard prediction and mapping.
The first chapter (Alexander) deals with the devastating impact of natural catastrophes upon the social and economic structure of both developing countries and modem industrialized societies. The second chapter (Coppock) discusses limitations of GIS for hazard mitigation and reviews some of the current initiatives aimed at implementing this technology in operational systems.
In the third chapter (Detti and Pasqui), spatial data structures are reviewed and conversion algorithms discussed in the context of drainage divide networks derived from digital terrain models (DTMs). The subsequent 13 papers on case studies are loosely ordered in a progression ranging from hazard" assessment carried out in a academic/research environment to operational activities for hazard monitoring and regulatory mapping by governmental institutions.
Although all these papers deal with GIS-supported investigations or applications, the extent to which this technology is exploited greatly varies from simple data graphical display to complex spatial modelling.
In particular, Terlien, van Asch and van Westen attempt to integrate hydrological site measurements and GIS-derived (raster) data layers to develop deterministic modes of landslide hazard. Hegg and Kienholz examine computergenerated paths of gravity-driven slope processes comparing trajectories from"triangulated irregular networks" (TIN) and "vector-tree" models. Mark and Ellen present two approaches to delineate debris-flow hazard; the first uses logistic regression to predict sites of debris-flow initiation; the second applies a simulation model to detect the most probable flow paths.
In the third chapter (Detti and Pasqui), spatial data structures are reviewed and conversion algorithms discussed in the context of drainage divide networks derived from digital terrain models (DTMs). The subsequent 13 papers on case studies are loosely ordered in a progression ranging from hazard" assessment carried out in a academic/research environment to operational activities for hazard monitoring and regulatory mapping by governmental institutions.
Although all these papers deal with GIS-supported investigations or applications, the extent to which this technology is exploited greatly varies from simple data graphical display to complex spatial modelling.
In particular, Terlien, van Asch and van Westen attempt to integrate hydrological site measurements and GIS-derived (raster) data layers to develop deterministic modes of landslide hazard. Hegg and Kienholz examine computergenerated paths of gravity-driven slope processes comparing trajectories from"triangulated irregular networks" (TIN) and "vector-tree" models. Mark and Ellen present two approaches to delineate debris-flow hazard; the first uses logistic regression to predict sites of debris-flow initiation; the second applies a simulation model to detect the most probable flow paths.
By using multivariate regression analysis on "uniquecondition" terrain-units, Chung, Fabbri and van Westen describe in detail a procedure for assessing and mapping the occurrence of rapid debris avalanches. Carrara, Cardinali, Guzzetti, and Reichenbach critically review the most commonly used statistical methods for landslide hazard prediction that are based on the partition of the ground surface into either slope-units or unique-condition units; they also discuss present pitfalls of GIS in assessing natural catastrophes.
Consuegra, Joerin and Vitalini present a new procedure to delineate flood hazard through a two dimensional hydraulic model, based on detailed TIN data, and other information raster layers. The use of multisensor monitoring devices for detecting extreme rainfall events is addressed by Lanza and Siccardi who also outline flood warning procedures supported by GIS. Gitis briefly addresses seismic hazard assessment supported by GIS tools. Kauahikaua, Margriter and Moore, from the Hawaiian Volcano Observatory, discuss GIS-aided probability models of lava flow occurrence in time and space. Cavallin, Cerutti and Floris shortly describe a GIS-based assessment of factors leading to groundwater pollution in a highly industrialised region.
The different issues related to land-use planning in landslide-prone areas are examined by Hansen, Brimicombe, Franks, Kirk and Fung, who also review the activity of the Hong Kong's Geotechnical Engineering Office aimed at assessing, monitoring and mitigating natural disasters through the use of various GIS-driven techniques. Brabb provides a review of the 20-year activity carried out by the U.S. Geological Survey for predicting and mitigating landslide, seismic and other geological hazards. in the San Mateo County; a wide set of traditional and computer-generated maps is described, and fruitful lines of research for the future are discussed.
The GIS-supported, operational system for the acquisition, computation and distribution of snow water equivalent data is briefly outlined by Carroll, from the U.S. National Weather Service.
Consuegra, Joerin and Vitalini present a new procedure to delineate flood hazard through a two dimensional hydraulic model, based on detailed TIN data, and other information raster layers. The use of multisensor monitoring devices for detecting extreme rainfall events is addressed by Lanza and Siccardi who also outline flood warning procedures supported by GIS. Gitis briefly addresses seismic hazard assessment supported by GIS tools. Kauahikaua, Margriter and Moore, from the Hawaiian Volcano Observatory, discuss GIS-aided probability models of lava flow occurrence in time and space. Cavallin, Cerutti and Floris shortly describe a GIS-based assessment of factors leading to groundwater pollution in a highly industrialised region.
The different issues related to land-use planning in landslide-prone areas are examined by Hansen, Brimicombe, Franks, Kirk and Fung, who also review the activity of the Hong Kong's Geotechnical Engineering Office aimed at assessing, monitoring and mitigating natural disasters through the use of various GIS-driven techniques. Brabb provides a review of the 20-year activity carried out by the U.S. Geological Survey for predicting and mitigating landslide, seismic and other geological hazards. in the San Mateo County; a wide set of traditional and computer-generated maps is described, and fruitful lines of research for the future are discussed.
The GIS-supported, operational system for the acquisition, computation and distribution of snow water equivalent data is briefly outlined by Carroll, from the U.S. National Weather Service.
We hope the above contributions will help both in outlining the actual effectiveness of GIS for coping with natural disasters, and in setting forth a strategy for future projects aimed at assessing and mitigating hazards over wide regions. We thank Earl Brabb and Andy Hansen for many suggestions and help in organizing the Workshop from which this book was derived; the numerous anonymous referees for careful and, sometimes, severe comments on individual chapters; Mauro Cardinali, Paola Reichenbach and Emanuela Turri for assistance; the contributors for being patient during the long gestation period of this book.
Alberto Carrara, Bologna Fausto Guzzetti, Perugia December, 1994
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