Owing to the disastrous damages due to the earthquakes in spring 2015 and the following monsoon p... more Owing to the disastrous damages due to the earthquakes in spring 2015 and the following monsoon period, numerous debris flows, land- and rockslides occurred in the Nepalese mountains. Within this study, the complex natural hazard system of the Gongar Khola (GK) catchment area consisting of large rockslides and rockfall areas in the uppermost part to slope processes such as landslides and channel processes including high water, debris- and mudflows that deliver material to the fan, respectively into the Tamakoshi River was investigated. Magnitudes of rockslides up to approx. 1.3 million m3 in the upper part as well landslide areas between 10,000 m3 and several 100,000 m3 in the lower regions were estimated. Torrential process such as debris- and mudflows endangered the Gongar Khola village as well as operations buildings and infrastructure of the 456 MW Upper Tamakoshi Hydroelectric Project (UTKHEP) that are situated in the lower GK catchment. Debris flow modeling for the lower GK ca...
Dendrogeomorphic analysis of 372 Norway spruce (Picea abies (L.) Karst.) trees of the Reiselehnri... more Dendrogeomorphic analysis of 372 Norway spruce (Picea abies (L.) Karst.) trees of the Reiselehnrinne (Tyrol, Austria) allowed reconstruction of past avalanche and debris-flow activity for the last 140 years. Determination of event years was performed by analyzing the (i) number and (ii) intensity of growth disturbances within tree-ring series and (iii) the spatial distribution of affected trees. Differentiation of debris-flow from snow avalanche events was based on (iv) the intra-annual position of scars, callus tissues or tangential rows of traumatic resin ducts and on (v) the spatial distribution of trees with simultaneous reactions in the tree-ring series. We introduced a weighting factor to substantiate the dating of past events in a comprehensive way and to compare individual events as to their intensity and total number of tree-ring responses. The accuracy of the dendrogeomorphic assessment was evaluated by comparing the reconstructed event frequency with event chronologies av...
Structural mitigation structures are an integral part of countermeasures against floods and debri... more Structural mitigation structures are an integral part of countermeasures against floods and debris flows and act as water and sediment controlling components. Within the last centuries different types were developed, originating mainly on empirical approaches. These structures have to fulfil different functions within a protection concept and to withstand high impact forces. The historical development of structural mitigation measures is summarized and an overview of designs applied nowadays in torrential catchments is mentioned. The effectiveness of function types is shown by an Austrian sample and impact forces are listed. Considerations about failure mechanisms lead to suggestions strengthening the structures.
In natural hazard research, the impact of flood events and their adverse consequences highlight t... more In natural hazard research, the impact of flood events and their adverse consequences highlight the increasing importance of studies on flood hazard and risk, not only on a global scale but in particular on a national and sub-national level. However, data on flood losses is neither comprehensive nor standardised in terms of data quality throughout Europe; and the limitations of spatial and temporal information on floods has repeatedly been claimed. The aim of this paper is to close this gap by taking the Republic of Greece as an example. Based on data collection and data mining techniques we established a comprehensive flood inventory for the period 1887-2010 by using information from multiple sources, and analysed the characteristics of flood hazards and losses in Greece. It is shown that there are considerable spatial and temporal dynamics in the events recorded, as well as in the number of fatalities, which could be mainly attributed to (1) the implementation of technical mitigat...
Summary In the framework of flood risk assessment, vulnerability is a key concept to assess the s... more Summary In the framework of flood risk assessment, vulnerability is a key concept to assess the susceptibility of elements at risk. Besides the increasing amount of studies on flash floods available, in-depth information on vulnerability in Mediterranean countries was missing so far. Moreover, current approaches in vulnerability research are driven by a divide between social scientists who tend to view vulnerability as representing a set of socio-economic factors, and natural scientists who view vulnerability in terms of the degree of loss to an element at risk. Further, vulnerability studies in response to flash flood processes are rarely answered in the literature. In order to close this gap, this paper implemented an integrated vulnerability approach focusing on residential buildings exposed to flash floods in Greece. In general, both physical and social vulnerability was comparable low, which is interpreted as a result from (a) specific building regulations in Greece as well as general design principles leading to less structural susceptibility of elements at risk exposed, and (b) relatively low economic losses leading to less social vulnerability of citizens exposed. The population show high risk awareness and coping capacity to response to natural hazards event and in the same time the impact of the events are quite low, because of the already high use of local protection measures. The low vulnerability score for East Attica can be attributed especially to the low physical vulnerability and the moderate socio-economic well-being of the area. The consequence is to focus risk management strategies mainly in the reduction of the social vulnerability. By analysing both physical and social vulnerability an attempt was made to bridge the gap between scholars from sciences and humanities, and to integrate the results of the analysis into the broader vulnerability context.
Österreichische Wasser- und Abfallwirtschaft, 2014
ABSTRACT On several debris cones and alluvial fans a tendency of wealth moving into flood prone a... more ABSTRACT On several debris cones and alluvial fans a tendency of wealth moving into flood prone areas can be observed during the last decades, which results in an increased flood risk. So far, this trend was repeatedly overseen due to the parallel implementation of flood mitigation measures leading to a decrease of flood risk. Without the implementation of appropriate maintenance strategies, however, the effectiveness of flood mitigation, such as consolidation check dams, will decline over time. As a consequence, hazard risk patterns may remain undetected if the functional performance of protection measures is not assessed over their entire life cycle. To close this gap, recent findings regarding the damage susceptibility of consolidation check dams are reviewed and related future challenges for both research and practice are identified.
Owing to the disastrous damages due to the earthquakes in spring 2015 and the following monsoon p... more Owing to the disastrous damages due to the earthquakes in spring 2015 and the following monsoon period, numerous debris flows, land- and rockslides occurred in the Nepalese mountains. Within this study, the complex natural hazard system of the Gongar Khola (GK) catchment area consisting of large rockslides and rockfall areas in the uppermost part to slope processes such as landslides and channel processes including high water, debris- and mudflows that deliver material to the fan, respectively into the Tamakoshi River was investigated. Magnitudes of rockslides up to approx. 1.3 million m3 in the upper part as well landslide areas between 10,000 m3 and several 100,000 m3 in the lower regions were estimated. Torrential process such as debris- and mudflows endangered the Gongar Khola village as well as operations buildings and infrastructure of the 456 MW Upper Tamakoshi Hydroelectric Project (UTKHEP) that are situated in the lower GK catchment. Debris flow modeling for the lower GK ca...
Dendrogeomorphic analysis of 372 Norway spruce (Picea abies (L.) Karst.) trees of the Reiselehnri... more Dendrogeomorphic analysis of 372 Norway spruce (Picea abies (L.) Karst.) trees of the Reiselehnrinne (Tyrol, Austria) allowed reconstruction of past avalanche and debris-flow activity for the last 140 years. Determination of event years was performed by analyzing the (i) number and (ii) intensity of growth disturbances within tree-ring series and (iii) the spatial distribution of affected trees. Differentiation of debris-flow from snow avalanche events was based on (iv) the intra-annual position of scars, callus tissues or tangential rows of traumatic resin ducts and on (v) the spatial distribution of trees with simultaneous reactions in the tree-ring series. We introduced a weighting factor to substantiate the dating of past events in a comprehensive way and to compare individual events as to their intensity and total number of tree-ring responses. The accuracy of the dendrogeomorphic assessment was evaluated by comparing the reconstructed event frequency with event chronologies av...
Structural mitigation structures are an integral part of countermeasures against floods and debri... more Structural mitigation structures are an integral part of countermeasures against floods and debris flows and act as water and sediment controlling components. Within the last centuries different types were developed, originating mainly on empirical approaches. These structures have to fulfil different functions within a protection concept and to withstand high impact forces. The historical development of structural mitigation measures is summarized and an overview of designs applied nowadays in torrential catchments is mentioned. The effectiveness of function types is shown by an Austrian sample and impact forces are listed. Considerations about failure mechanisms lead to suggestions strengthening the structures.
In natural hazard research, the impact of flood events and their adverse consequences highlight t... more In natural hazard research, the impact of flood events and their adverse consequences highlight the increasing importance of studies on flood hazard and risk, not only on a global scale but in particular on a national and sub-national level. However, data on flood losses is neither comprehensive nor standardised in terms of data quality throughout Europe; and the limitations of spatial and temporal information on floods has repeatedly been claimed. The aim of this paper is to close this gap by taking the Republic of Greece as an example. Based on data collection and data mining techniques we established a comprehensive flood inventory for the period 1887-2010 by using information from multiple sources, and analysed the characteristics of flood hazards and losses in Greece. It is shown that there are considerable spatial and temporal dynamics in the events recorded, as well as in the number of fatalities, which could be mainly attributed to (1) the implementation of technical mitigat...
Summary In the framework of flood risk assessment, vulnerability is a key concept to assess the s... more Summary In the framework of flood risk assessment, vulnerability is a key concept to assess the susceptibility of elements at risk. Besides the increasing amount of studies on flash floods available, in-depth information on vulnerability in Mediterranean countries was missing so far. Moreover, current approaches in vulnerability research are driven by a divide between social scientists who tend to view vulnerability as representing a set of socio-economic factors, and natural scientists who view vulnerability in terms of the degree of loss to an element at risk. Further, vulnerability studies in response to flash flood processes are rarely answered in the literature. In order to close this gap, this paper implemented an integrated vulnerability approach focusing on residential buildings exposed to flash floods in Greece. In general, both physical and social vulnerability was comparable low, which is interpreted as a result from (a) specific building regulations in Greece as well as general design principles leading to less structural susceptibility of elements at risk exposed, and (b) relatively low economic losses leading to less social vulnerability of citizens exposed. The population show high risk awareness and coping capacity to response to natural hazards event and in the same time the impact of the events are quite low, because of the already high use of local protection measures. The low vulnerability score for East Attica can be attributed especially to the low physical vulnerability and the moderate socio-economic well-being of the area. The consequence is to focus risk management strategies mainly in the reduction of the social vulnerability. By analysing both physical and social vulnerability an attempt was made to bridge the gap between scholars from sciences and humanities, and to integrate the results of the analysis into the broader vulnerability context.
Österreichische Wasser- und Abfallwirtschaft, 2014
ABSTRACT On several debris cones and alluvial fans a tendency of wealth moving into flood prone a... more ABSTRACT On several debris cones and alluvial fans a tendency of wealth moving into flood prone areas can be observed during the last decades, which results in an increased flood risk. So far, this trend was repeatedly overseen due to the parallel implementation of flood mitigation measures leading to a decrease of flood risk. Without the implementation of appropriate maintenance strategies, however, the effectiveness of flood mitigation, such as consolidation check dams, will decline over time. As a consequence, hazard risk patterns may remain undetected if the functional performance of protection measures is not assessed over their entire life cycle. To close this gap, recent findings regarding the damage susceptibility of consolidation check dams are reviewed and related future challenges for both research and practice are identified.
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Papers by Johannes Hübl