Showing papers by "C.J. van Westen published in 2015"
TL;DR: A new expert based approach that allows physical vulnerability assessment of buildings to hydro-meteorological hazards in areas with limited information about the hazard or the exposed elements and it can be used for decision-making support in disaster response and risk management.
Abstract: As the number of reported natural disasters resulting in casualties and damages increases worldwide, assessing vulnerability of the built environment represents a fundamental step towards reducing the probability of loss. This is a challenge in areas where data are sparse, and where no vulnerability curves exist for different building types. The aim of this paper is to develop a new expert based approach that allows physical vulnerability assessment of buildings to hydro-meteorological hazards in areas with limited information about the hazard or the exposed elements. The methodology is based on three steps: firstly, a vulnerability index is calculated based on expert weighing of vulnerability indicators using Analytical Hierarchy Process analysis. Secondly, a set of vulnerability curves is selected from the literature and a generic vulnerability curve is calculated as the average of these input functions. Lastly, the vulnerability index together with the generic vulnerability curve is used to generate a specific vulnerability curve representative for the studied area. The applicability of this approach is demonstrated in Nehoiu Valley, Romania. The results show that vulnerability indices for the 60 sampled buildings vary between 0.2 and 0.6 for all hazard types, and no buildings exhibit indices lower than 0.2 for debris flows or slow moving landslides. The specific curves show generally lower values of degree of loss for similar inundation depths compared with the general vulnerability curve. The proposed methodology exploits two vulnerability models in a new, complementary manner and it can be used for decision-making support in disaster response and risk management.
78 citations
TL;DR: The main purpose of the platform is to assist the experts and stakeholders in the decision-making process for evaluation and selection of different risk management strategies through an interactive participation approach, integrating web-GIS interface with decision support tool based on a compromise programming approach.
Abstract: This paper presents the current state and development of a prototype web-GIS (Geographic Information System) decision support platform intended for application in natural hazards and risk management, mainly for floods and landslides. This web platform uses open-source geospatial software and technologies, particularly the Boundless (formerly OpenGeo) framework and its client side software development kit (SDK). The main purpose of the platform is to assist the experts and stakeholders in the decision-making process for evaluation and selection of different risk management strategies through an interactive participation approach, integrating web-GIS interface with decision support tool based on a compromise programming approach. The access rights and functionality of the platform are varied depending on the roles and responsibilities of stakeholders in managing the risk. The application of the prototype platform is demonstrated based on an example case study site: Malborghetto Valbruna municipality of North-Eastern Italy where flash floods and landslides are frequent with major events having occurred in 2003. The preliminary feedback collected from the stakeholders in the region is discussed to understand the perspectives of stakeholders on the proposed prototype platform.
23 citations
TL;DR: In this paper, the authors show that the evolving mountain environment, including the changed geographic distribution of new landslides and the continuously uplifting riverbed, creates emerging risks for existing and rebuilt houses, and highlight the often neglected dynamic process that involves changes in the natural environment and man-made constructions and their interaction.
Abstract: . Six years after the devastating Ms 8.0 Wenchuan earthquake, new landslides, debris flows, and flash floods still occur frequently in the earthquake-stricken regions. This shows that the geological hazards that occur after a major earthquake in a mountainous environment can be a long-term threat. However, post-earthquake reconstruction and relocation of local residents often neglect this evolving threat, and its interaction with existing and rebuilt houses has not been well studied. Here we show that the evolving mountain environment, including the changed geographic distribution of new landslides and the continuously uplifting riverbed, creates emerging risks for existing and rebuilt houses. We use spatial analysis of landslide debris and the location of houses from high-resolution images and field survey in the study area and find that new landslides and the houses rebuilt after the Wenchuan earthquake have a similar trend of moving to lower elevations, gentler slopes, and closer to rivers. This study confirms that the persistent downward movement of landslide debris has rapidly filled up riverbeds over the past 6 years. The elevated riverbeds make the study area extremely susceptible to flash floods, creating further risks to newly rebuilt houses that are closer to the river. We highlight the often neglected dynamic process that involves changes in the natural environment and man-made constructions and their interaction. This dynamic process requires long-term monitoring and adaptive management of mountainous regions after major earthquakes that can fully consider the sophisticated evolving risks caused by the changing environment, exposure, and vulnerability in the region.
19 citations
01 Jan 2015
TL;DR: According to dam composition material and sedimentological features, landslide dams were categorized into three types: dams mainly composed of large boulders and blocks; dams composed of unconsolidated fine debris; and dams with partly intact rock strata at the base of dams as discussed by the authors.
Abstract: The devastating 2008 Wenchuan earthquake with a magnitude of Mw 7.9 was the largest seismic event in China in more than 50 years. It triggered numerous landslides over a broad area, some of which dammed rivers, posing severe threats to downstream settlements. The coseismic landslides are classified into rock/debris avalanches, debris flows, rock/debris slides and rock falls. A number of representative examples of each type and the corresponding landslide dam features were studied. According to dam composition material and sedimentological features, landslide dams were categorized into three types: dams mainly composed of large boulders and blocks; dams composed of unconsolidated fine debris; and dams with partly intact rock strata at the base topped by large boulders and blocks or soil with rock fragments, showing two-layered or three-layered depositional structure. This classification is linked to the typology of damming landslides and considered to be a preliminary indicator of dam stability. In addition, dam stability also largely depends on valley morphometry as well as landslide runout distance and mechanism.
9 citations
01 Jan 2015
TL;DR: In this article, a quantitative risk assessment method was applied to map cumulative risk levels arising from a number of hazardous installations located in Haldia, one of the industrial towns of India.
Abstract: In this paper, we have applied a quantitative risk assessment method to map cumulative risk levels arising from a number of hazardous installations located in Haldia, one of the industrial towns of India. The methodology consists of the following steps: frequency and consequences assessment of the select reference accident scearos; estimation of grid-level population distribution using a dasymetric interpolation approach; and finally risk estimation using both individual and societal risk metric. The risk maps were prepared in using common GIS tools and functions, and their sensitivity to various factors ascertained using uncertainty analysis techniques.
2 citations
Proceedings Article•
01 Jan 2015TL;DR: Wang et al. as discussed by the authors used satellite remote sensing to map pre-seismic rural mountainous housing over large areas, and thus can accurately determine the location of coseismic landslide damaged housing spatially.
Abstract: Determining the location of coseismic landslides damaged buildings is critical to the understanding of human losses from earthquake-induced landslides during major earthquakes in mountainous regions. Because of the vast area of the earthquake affected region and the sparse locations of rural settlements, previous knowledge on buildings and human losses resulting from coseismic landslides mainly rely on rough estimations from limited field work. Application of high resolution satellite remote sensing opens a new way to map pre-seismic rural mountainous housing over large areas, and thus can accurately determine the location of coseismic landslide damaged housing spatially. In this work, we used the 2008 Wenchuan Earthquake as an example and use SPOT5 images taken before the earthquake for a seimi-automated mapping of buildings in rural areas. Then, by spatial overlay analysis with an existing coseismic landslide inventory, we mapped the location of landslide damaged buildings in this area. This semi-automatic method can be further applied to the entire Wenchuan Earthquake affected region to determine the locations of all landslides damaged buildings and finally improve the performance of earthquake loss estimation models.