Iuliana Armaş

Multi-criteria vulnerability analysis to earthquake hazard of Bucharest, Romania

The expansive infrastructure, along with the high population density, makes cities highly vulnerable to the severe impacts of natural hazards. In the context of an explosive increase in value of the damage caused by natural disasters, the need for evaluating and visualizing the vulnerability of urban areas becomes a necessity in helping practitioners and stakeholders in their decision-making processes. The paper presented is a piece of exploratory research. The overall aim is to develop a spatial vulnerability approach to address earthquake risk, using a semi-quantitative model. The model uses the analytical framework of a spatial GIS-based multi-criteria analysis. For this approach, we have chosen Bucharest, the capital city of Romania, based on its high vulnerability to earthquakes due to a rapid urban growth and the advanced state of decay of the buildings (most of the building stock were built between 1940 and 1977). The spatial result reveals a circular pattern, pinpointing as hot spots the Bucharest historic centre (located on a meadow and river terrace, and with aged building stock) and peripheral areas (isolated from the emergency centers and defined by precarious social and economic conditions). In a sustainable development perspective, the example of Bucharest shows how spatial patterns shape the “vulnerability profile” of the city, based on which decision makers could develop proper prediction and mitigation strategies and enhance the resilience of cities against the risks resulting from the earthquake hazard.

Weights of evidence method for landslide susceptibility mapping. Prahova Subcarpathians, Romania

The goal of this paper is to assess the landslide susceptibility of a hilly area in the Subcarpathian sector of the Prahova Valley, using the weight of evidence statistical method. This method aims to reduce the multitude of landslide-related conditions to a pattern of a few discrete predictive variables. The method is based on the decision of which state is more likely to occur grounded on the presence or absence of a predictive variable and the occurrence of an event (e.g., landslide) within a pixel. Based on the chi-square test and the Pearson correlation applied on the data, the selected conditionally independent variables in this study were as follows: slope gradient, slope aspect, and land use. Weights calculated individually for the three themes were added to produce a probability estimate of the area. The predictive power of the map was tested on the basis of a split sample of landslides that were not used in the modeling process. The fact that a great percent of the declivitous surfaces are susceptible to landslides shows the dominant manner of the evolution of the Subcarpathian slopes, the acceleration or deceleration of the process being influenced by the land use.

Flood risk perception along the Lower Danube river, Romania

Risk can be seen as both objective, quantifiable, and subjective, constructed at an individual level. This paper focuses on the latter and aims to explore flood perceptions in relation to socio-demographic variables and various economic measures. The data were drawn from four villages on the banks of the Danube using quantitative questionnaires, villages data sheet and in-depth semi-structured interviews. This mixed method approach allowed for ecologically sound findings. Inequality of income and capital are linked with variations of some risk perception dimensions such as disaster temporal proximity, perceived resilience, and also with a reluctance to think about the future and the dangers it might pose. Past floods are associated with most dimensions tested, including income, inequality, and whether the next flood appears to be imminent. Lower-income households expect some form of assistance not from the community, the church, or local authorities, but from the government. This highlights erosion of social values, or inter-household monetisation, as the other major issue, alongside inequality, faced by rural populations living on the banks of one of Europe’s greatest rivers.

Landslide susceptibility deterministic approach using geographic information systems: application to Breaza town, Romania

AbstractThe study is a deterministic-based approach on landslide susceptibility. The purpose of the paper is to create quantitative susceptibility maps by joining the one-dimension infinite slope stability model with a raster-based GIS (ILWIS) and taking into account the spatial distribution of input parameters. A landslide-prone area, with relative homogeneous geology and geomorphology, located in the Subcarpathian sector of the Prahova River, Romania, was selected for the study. There are frequent problems caused by active landslides in the studied area, especially in years with heavy precipitation, often causing destruction of houses and roads situated on the slopes (1992, 1997, and 2005). Detailed surveys covering a 7-year period provided the necessary input data on slope parameters, hydrological components, and the geotechnical background. Two simulations were used: one on dry soil conditions and one on fully saturated soil conditions. A third test was based on the level of the groundwater table mapped in summer 2008. Detailed analyses were particularly focused on landslides to compare predicted results with actual results using field measurements. The model is very suitable for use in raster GIS because it can calculate slope instability on a pixel basis, each raster cell being considered individually. The drawback of the model is the highly detailed data of input parameters. Despite this disadvantage, in conclusion, the usefulness of slope stability models on a large-scale basis was emphasized under infinitely high failure plain conditions and lithological homogeneity.

Insights into the possible seismic damage of residential buildings in Bucharest, Romania, at neighborhood resolution

Seismic loss estimation analysis for large cities is a very demanding yet necessary task; the modelling of such complex systems requires first of all insightful input data at good resolution, referring to local effects, buildings and socio-economic aspects. Also, the implementation of less empirical estimation methods is needed. Until recently, these requirements could not be fulfilled for Bucharest, the capital city in the European Union which is most at risk due to earthquakes. Based on 2011 and 2002 census data, standardized according to the framework of the Near-real time System for Estimating the Seismic Damage in Romania (SeisDaRo) through a unique approach, and on relevant hazard scenarios, we estimate for the first time the building damage at census tract scale. The methodology applied relies on 48 vulnerability curves for buildings, on the Improved Displacement Coefficient Analytical Method included in the SELENA software for computing damage probabilities and on deterministic seismic hazard scenarios, including the maximum possible earthquake. By using overlay analysis with satellite imagery and a new methodology integrated in GIS we show how results can be enhanced, reflecting more localized characteristics. Best practices for seismic risk mapping are also expressed. The results are promising and contribute to mitigation efforts in Bucharest.

Diagnosis of landslide risk for individual buildings: insights from Prahova Subcarpathians, Romania

Abstract The aim of this study is to quantify the landslide risk for individual buildings using spatial data in a GIS environment. A landslide-prone area from Prahova Rivers’ Subcarpathian Valley was chosen because of its associated landslide hazards and its impact upon human settlements and activities. The bivariate landslide susceptibility index (LSI) was applied to calculate the spatial probability of landslides occurrence. The Landslide Susceptibility Index map was produced by numerically adding the weighted thematic maps for slope gradient and aspect, water table, soil texture, lithology, built environment and land use. Validation curves were obtained using the random-split strategy for two combinations of variables: (a) all seven variables and (b) three variables which showed highest individual success rates with respect to landslides occurrences (slope gradient, water table and land use). The principal pre-disposing factors were found to be slope steepness and groundwater table. Vulnerability was established as the degree of loss to individual buildings resulting from a potential damaging landslide with a given return period in an area. Risk was calculated by multiplying the spatial probability of landslides by the vulnerability for each building and summing up the losses for the selected return period.

The health state of the Romanian population during the transition period

The paper attempts to make an assessment of the health state of the Romanian population during the transition period; the evolution of the health indicators, analyzed in the European context, shows the precarious health state of the Romanian population, in comparison both to Western countries and to the countries which are crossing a transition phase themselves. The values of the health indicators by region also show inequalities of health, the north-western and south-eastern areas of the country having to face serious problems.The reduction of living standard, the low quality health services, together with other factors associated with lifestyle seem to be responsible for the deterioration of the health state of the Romanian population. The introduction of adequate health and social policies in the following period could bring about an improvement of the situation.

Forest Landscape History Using Diachronic Cartography and GIS. Case Study: Subcarpathian Prahova Valley, Romania

The focus of this study is to assess the evolution of forest cover, as forest is an important indicator to describe the perceived naturalness of landscapes and has undergone radical changes in the last hundred years in Europe. The Subcarpathic sector of Prahova River was chosen as study area, because it has always been densely populated and its landscape has transformed by long-term man-made impact on the environment. Forest landscape spatial changes are highlighted in a temporal context based on large-scale historical maps and aerial images in a GIS environment. Different metrics are applied to quantify spatial changes of forest distribution and the pattern of changes over a 223 years period. The most important deforestations were recorded between 1790 and 1856 being correlated with the massive deforestation of Tara Romaneasca (the Southern Princedom of Romania), reported after the Treaty of Adrianople (1829) that liberalized trade and made wood an export product. An increase in forest cover took place between 1900 and 1980. Between 1980 and 1997, after the communist regime change (1989) and in the transition period, forest cover declined with the largest annual intensity, among causes are the restitution of forests to individual owners (followed by deforestation), legislative void, etc. Between 1997 and 2005, a slight tendency for reforestation was recorded. Comparison between 1790 and 2013 forest cover shows that almost 58 % of the landscape forest was destroyed, changing its use. Based on the index of naturalness, Prahova River Subcarpathic Valley has been included in the category of land insufficiently covered by forests for the entire period of analysis.

Vulnerability to Earthquake Hazard: Bucharest Case Study, Romania

Recent seismic events show that urban areas are increasingly vulnerable to seismic damage, which leads to unprecedented levels of risk. Cities are complex systems and as such their analysis requires a good understanding of the interactions between space and the socioeconomic variables characteristic of the inhabitants of urban space. There is a clear need to develop and test detailed models that describe the behavior of these interactions under seismic impact. This article develops an overall vulnerability index to seismic hazard based on a spatial approach applied to Bucharest, Romania, the most earthquake-prone capital in the European Union. The methodology relies on: (1) spatial post-processed socioeconomic data from the 2011 Romanian census through multicriteria analysis; and (2) analytical methods (the Improved Displacement Coefficient Method and custom-defined vulnerability functions) for estimating damage patterns, incorporated in a GIS environment. We computed vulnerability indices for the 128 census tracts of the city. Model sensitivity assessment tested the robustness of spatially identified patterns of building vulnerability in the face of uncertainty in model inputs. The results show that useful seismic vulnerability indices can be obtained through interdisciplinary approaches that enhance less detailed datasets, which leads lead to better targeted mitigation efforts.

Spatial Multi-Criteria Risk Assessment of Earthquakes from Bucharest, Romania

The current paper is a piece of exploratory research, having as its purpose the evaluation of seismic risk spatial patterns for Bucharest, the capital of Romania. In this paper, risk (expressed in terms of risk indices) is calculated as a combination of hazard and vulnerability information, based on the semi-quantitative technique of multi-criteria spatial analysis. The scale of analysis was considered at the level of the census units (2002). The hazard component consists of the probability of occurrence of two scenarios: (1) an occurred earthquake that is a typical hazard case for the Vrancea region (event of 30 August 1986, Mw = 7.1) and (2) a computed seismic hazard for the largest magnitude earthquake expected to be generated in Vrancea (Mw = 7.7). In both cases, the seismic hazard is expressed in terms of peak ground acceleration (PGA) values. The total vulnerability index is obtained using four groups of indicators: natural environment, physical, social and economical indicators. The overall vulnerability to seismic hazard is assessed by comparing total vulnerability with the compound capacity factor. The resulting risk indices are relative, expressed by numerical values, ranging between 0 and 1, that do not have a direct meaning of expected losses. The spatial pattern of risk shows a significant increase in the case of the maximum expected event as compared with the 1986 earthquake case, particularly in the central part of the city. As a general conclusion, only the strongest earthquakes are really dangerous for Bucharest.