74 research outputs found
Risk-based damage potential and loss estimation of extreme flooding scenarios in the Austrian Federal Province of Tyrol
Within the last decades serious flooding events occurred in many parts of Europe and especially in 2005 the Austrian Federal Province of Tyrol was serious affected. These events in general and particularly the 2005 event have sensitised decision makers and the public. Beside discussions pertaining to protection goals and lessons learnt, the issue concerning potential consequences of extreme and severe flooding events has been raised. Additionally to the general interest of the public, decision makers of the insurance industry, public authorities, and responsible politicians are especially confronted with the question of possible consequences of extreme events. Answers thereof are necessary for the implementation of preventive appropriate risk management strategies. Thereby, property and liability losses reflect a large proportion of the direct tangible losses. These are of great interest for the insurance sector and can be understood as main indicators to interpret the severity of potential events. The natural scientific-technical risk analysis concept provides a predefined and structured framework to analyse the quantities of affected elements at risk, their corresponding damage potentials, and the potential losses. Generally, this risk concept framework follows the process steps hazard analysis, exposition analysis, and consequence analysis. Additionally to the conventional hazard analysis, the potential amount of endangered elements and their corresponding damage potentials were analysed and, thereupon, concrete losses were estimated. These took the specific vulnerability of the various individual elements at risk into consideration. The present flood risk analysis estimates firstly the general exposures of the risk indicators in the study area and secondly analyses the specific exposures and consequences of five extreme event scenarios. In order to precisely identify, localize, and characterize the relevant risk indicators of buildings, dwellings and inventory, vehicles, and individuals, a detailed geodatabase of the existing stock of elements and values was established on a single object level. Therefore, the localized and functional differentiated stock of elements was assessed monetarily on the basis of derived representative mean insurance values. Thus, well known difference factors between the analysis of the stock of elements and values on local and on regional scale could be reduced considerably. The spatial join of the results of the hazard analysis with the stock of elements and values enables the identification and quantification of the elements at risk and their corresponding damage potential. Thereupon, Extreme Scenario Losses (ESL) were analysed under consideration of different vulnerability approaches which describe the individual element's specific susceptibility. This results in scenario-specific ranges of ESL rather than in single values. The exposure analysis of the general endangerment in Tyrol identifies (i) 105 330 individuals, (ii) 20 272 buildings and 50 157 dwellings with a corresponding damage potential of approx. EUR 20 bn. and (iii) 62 494 vehicles with a corresponding damage potential of EUR 1 bn. Depending on the individual extreme event scenarios, the ESL solely to buildings and inventory vary between EUR 0.9–1.3 bn. for the scenario with the least ESL and EUR 2.2–2.5 bn. for the most serious scenarios. The correlation of the private property losses to buildings and inventory with further direct tangible loss categories on the basis of investigation after the event in 2005, results in potential direct tangible ESL of up to EUR 7.6 bn. Apart from the specific study results a general finding shows that beside the further development of modelling capabilities and scenario concepts, the key to considerably decrease uncertainties of integral flood risk analyses is the development and implementation of more precise methods. These are to determine the stock of elements and values and to evaluate the vulnerability or susceptibility of affected structures to certain flood characteristics more differentiated
Snow accumulation of a high alpine catchment derived from LiDAR measurements
The spatial distribution of snow accumulation substantially affects the
seasonal course of water storage and runoff generation in high mountain
catchments. Whereas the areal extent of snow cover can be recorded by
satellite data, spatial distribution of snow depth and hence snow water
equivalent (SWE) is difficult to measure on catchment scale. In this study we
present the application of airborne LiDAR (Light Detecting And Ranging) data
to extract snow depths and accumulation distribution in an alpine catchment.
<br><br>
Airborne LiDAR measurements were performed in a glacierized catchment in the
Ă–tztal Alps at the beginning and the end of three accumulation seasons. The
resulting digital elevation models (DEMs) were used to calculate surface
elevation changes throughout the winter season. These surface elevation
changes were primarily referred to as snow depths and are discussed
concerning measured precipitation and the spatial characteristics of the
accumulation distribution in glacierized and unglacierized areas. To
determine the redistribution of catchment precipitation, snow depths were
converted into SWE using a simple regression model. Snow accumulation
gradients and snow redistribution were evaluated for 100 m elevation bands.
<br><br>
Mean surface elevation changes of the whole catchment ranges from 1.97 m to
2.65 m within the analyzed accumulation seasons. By analyzing the
distribution of the snow depths, elevation dependent patterns were obtained
as a function of the topography in terms of aspect and slope. The high
resolution DEMs show clearly the higher variation of snow depths in rough
unglacierized areas compared to snow depths on smooth glacier surfaces. Mean
snow depths in glacierized areas are higher than in unglacierized areas.
Maximum mean snow depths of 100 m elevation bands are found between 2900 m
and 3000 m a.s.l. in unglacierized areas and between 2800 m and
2900 m a.s.l. in glacierized areas, respectively. Calculated accumulation
gradients range from 8% to 13% per 100 m elevation band in the
observed catchment. Elevation distribution of accumulation calculated by
applying these seasonal gradients in comparison to elevation distribution of
SWE obtained from airborne laser scanning (ALS) data show the total
redistribution of snow from higher to lower elevation bands.
<br><br>
Revealing both, information about the spatial distribution of snow depths and
hence the volume of the snow pack, ALS data are an important source for
extensive snow accumulation measurements in high alpine catchments. These
information about the spatial characteristics of snow distribution are
crucial for calibrating hydrological models in order to realistically compute
temporal runoff generation by snow melt
The calamity of eruptions, or an eruption of benefits? Mt. Bromo human–volcano system a case study of an open-risk perception
In this paper we investigate the question not of how, but why people actively
choose to live with continued exposure to considerable hazard. A field
survey of the human–volcano interaction at Bromo Volcano was based on
semi-structured interviews and focus group discussions. The recorded
interviews were transcribed and analysed according to recurrent themes in
the answers. Findings from field investigation were then confronted with
previous existing concepts of human exposure to natural hazards. The result
shows that the interaction between humans and the volcanic environment at Bromo
volcano is multifaceted and complex. The Tengger people choose – rather
than being forced – to live with volcanic hazards. They are not only
exposed to its negative consequence, but also enjoy benefits and
opportunities of physical, spiritual and socio-cultural nature that arise
within the human–volcanic system. Following this perspective, the concept of
risk itself must be revisited and expanded from a one-sided focus on
hazardous processes to a more holistic view of risk that includes the
various positive aspects that pertain to the entire system. The development
of a generic human–volcanic system model could provide the basis for the
development of an open-risk concept
Avalanche related damage potential - changes of persons and mobile values since the mid-twentieth century, case study GaltĂĽr
When determining risk related to natural hazard processes, many studies neglect the investigations of the damage potential or are limited to the assessment of immobile values like buildings. However, persons as well as mobile values form an essential part of the damage potential. Knowledge of the maximum number of exposed persons in an endangered area is of great importance for elaborating evacuation plans and immediate measures in case of catastrophes. In addition, motor vehicles can also be highly damaged, as was shown by the analysis of avalanche events. With the removal of mobile values in time as a preventive measure this kind of damage can be minimised. <P style='line-height: 20px;'> This study presents a method for recording the maximum number of exposed persons and monetarily assessing motor vehicles in the municipality of Galtür (Tyrol, Austria). Moreover, general developments of the damage potential due to significant socio-economic changes since the mid-twentieth century are pointed out in the study area. The present situation of the maximum number of persons and mobile values in the official avalanche hazard zones of the municipality is described in detail. Information on the number of persons is derived of census data, tourism and employment statistics. During the winter months, a significant increase overlaid by strong short-term fluctuation in the number of persons can be noted. These changes result from a higher demand of tourism related manpower as well as from varying occupancy rates. The number of motor vehicles in endangered areas is closely associated to the number of exposed persons. The potential number of motor vehicles is investigated by means of mapping, statistics on the stock of motor vehicles and the density distribution. Diurnal and seasonal fluctuations of the investigated damage potential are pointed out. The recording of the number of persons and mobile values in endangered areas is vital for any disaster management
Geodetic reanalysis of annual glaciological mass balances (2001-2011) of Hintereisferner, Austria
This study presents a reanalysis of the glaciologically obtained annual glacier mass balances at Hintereisferner, Ă–tztal Alps, Austria, for the period 2001-2011. The reanalysis is accomplished through a comparison with geodetically derived mass changes, using annual high-resolution airborne laser scanning (ALS). The grid-based adjustments for the method-inherent differences are discussed along with associated uncertainties and discrepancies of the two methods of mass balance measurements. A statistical comparison of the two datasets shows no significant difference for seven annual, as well as the cumulative, mass changes over the 10-year record. Yet, the statistical view hides significant differences in the mass balance years 2002/03 (glaciological minus geodetic records=+0.92mw.e.), 2005/06 (+0.60mw.e.), and 2006/07 (-0.45mw.e.). We conclude that exceptional meteorological conditions can render the usual glaciological observational network inadequate. Furthermore, we consider that ALS data reliably reproduce the annual mass balance and can be seen as validation or calibration tools for the glaciological method.(VLID)3146447Version of recor
Primary succession and its driving variables – a sphere-spanning approach applied in proglacial areas in the upper Martell Valley (Eastern Italian Alps)
Climate change and the associated glacier retreat lead to
considerable enlargement and alterations of the proglacial systems. The
colonisation of plants in this ecosystem was found to be highly dependent on
terrain age, initial site conditions and geomorphic disturbances. Although
the explanatory variables are generally well understood, there is little
knowledge on their collinearities and resulting influence on proglacial
primary succession. To develop a sphere-spanning understanding of vegetation
development, a more interdisciplinary approach was adopted. In the
proglacial areas of FĂĽrkeleferner, Zufallferner and Langenferner (Martell
Valley, Eastern Italian Alps), in total 65 plots of 5×2 m were
installed to perform the vegetation analysis on vegetation cover, species
number and species composition. For each of those, 39 potential explanatory
variables were collected, selected through an extensive literature review.
To analyse and further avoid multicollinearities, 33 of the explanatory
variables were clustered via principal component analysis (PCA) to five
components. Subsequently, generalised additive models (GAMs) were used to
analyse the potential explanatory factors of primary succession. The results
showed that primary succession patterns were highly related to the first
component (elevation and time), the second component (solar radiation),
the third component (soil chemistry), the fifth component
(soil physics) and landforms. In summary, the analysis of all explanatory
variables together provides an overview of the most important influencing
variables and their interactions; thus it provides a basis for the debate on future
vegetation development in a changing climate.</p
- …