Juraj Hreško, Bartłomiej Wyżga, Joanna Zawiejska
The increasing trend of economic losses caused by flash floods, wind storms, erosion processes and slope failures is causing concern about possible increase in the frequency of these phenomena among a wide community of scientists, implementers of landscape development plans and decision makers at levels from national to local. The chapter focuses on two areas: spatial identification and modelling of natural hazards and the assessment of their impact on the landscape, including people and their activities.
The increasing economic losses caused by natural hazards require verification whether the increase results from increased frequency/magnitude of the phenomena (e.g. Ruiz-Villanueva et al, in press) or simply from more intense management of the affected areas. In this context, we can say that very few scientists from Carpathian countries apply models of natural hazards and risks, which requires a change in the approach of their application at regional and local level. We assume that the most effective measures must be based on an integrated approach to evaluation of natural hazards, with emphasis on current land use planning and human activities in the area.
The occurrence of natural hazards in the Carpathians is understood in new contexts of changing climatic conditions and processes of land use changes with varying trends of urbanization, deforestation, abandonment of agricultural land together with vegetation succession on mountainous pastures and meadows. Climate change significantly influences the potential of difficult-to-predict slope-gravitational and water-gravitational processes which are often accelerated by socio-economic factors. A substantial part of the extreme precipitation events is associated with localized areas within the Carpathians affected by debris flows, landslides and avalanches. The focus should shift to research and projects aimed at modelling of the occurrence and effects of natural hazards using methods of remote sensing and GIS tools. An important step of the section should be an overview and summary of previous works focused on research and modeling of natural hazards in the Carpathians and adjacent areas. The database would serve as a basis for solving partial and complex topics devoted to natural hazards and risks.
Floods and surface runoff
The threat of flooding and extreme manifestations of surface runoff is closely linked with rainfall and snowmelt activity. The frequency of these events requires a detailed mapping of occurrence and manifestations in a landscape. Impacts of changes in land use and landscape structure on flood hazard and risk should be examined. One example can be flood hazard resulting from increased recruitment of wood debris following a 20th-century expansion of riparian forest in Carpathian valleys (Kundzewicz et al., 2014). In recent years, several hazard models were created for Carpathian basins including the Danube river basin (DANUBE FLOODRISK).
Research and modelling of avalanches is carried out in the Western Carpathians (Slovakia) and the Southern Carpathians (Romania). Avalanches are a focal point of interest at university departments in Slovakia, the Czech Republic, Romania and Switzerland. The validated RAMMS and other models in the GIS environment enable a relatively precise identification and prediction of avalanche occurrence, transport and accumulation of snow masses with their potential spatial risk. Evidence and modelling of maps of avalanche areas is a main source of information about the spatial distribution of avalanches in the Carpathians.
Landslides and debris flows
Over the last ten years we saw an increase in the frequency of slope deformations and debris flows in mountainous, as well as in hilly areas of the Carpathians. Their occurrence and effects closely correspond with the intensity and amount of rainfall, especially in the flysch areas of the Outer Carpathians, in the neovulcanite area, but also in the areas of central-Carpathian Paleogene and in valleys between mountains and uplands underlain by Neogene sediments. Research and monitoring of landslides resulted in the models of landslide potential and hazard and in digital databases of landslides or distribution of potential landslide areas. Debris and debris-earth flows are activated by extreme rainfall with the intensity exceeding 60 mm/24h. Their spatial occurrence is connected to the rejuvenated valleys and troughs in mountains with great relief energy, usually above the tree line. Below that debris flows are induced by human activity, especially by slavage logging following catastrophic events of spruce bark beetle infestation.
Soil erosion and gully erosion in the Carpathians and their foreland represent a significant morphodynamic phenomena closely related to land use and socio-economic activities. Data from existing research were used to create several map models of potential soil erosion, especially in the agricultural landscape.
Over the last 10 years severe wind storms occurred hitting mountainous and highland areas in the Western Carpathians and lowland areas in their foreland. The most significant wind effects were manifested on the south side of the Tatra Mts. by a complete destruction of forest resources (widespread windbreaks and uprooted trees). The existing map database of effects of wind storms and historical evidence of their manifestations represent an initial base for systematic research of potential hazard and risk of wind storms.
We recommend starting international projects and formation of scientific teams to solve problems of natural hazards in the context of historical development of landscape of mountain and foothill areas with the focus on the changing climatic conditions. The result of the work in this subject should be a better coordination of the natural hazards research in the Carpathians and the establishment of cooperation between the departments. We consider it necessary to activate research and design teams and projects aimed at individual natural hazards, and to elaborate an overview of existing research of natural hazards in the area of the Carpathians and adjacent areas. The research should focus more on the historical landscape changes and their relationship to the occurrence of natural hazards. We also indicate a need of directing the research on natural hazards towards analysis of hydrological regime and changing climate conditions in the area of the Carpathians.
Kundzewicz Z.W., Stoffel M., Kaczka R.J., Wyżga B., Niedźwiedź T., Pińskwar I., Ruiz-Villanueva V., Łupikasza E., Czajka B., Ballesteros-Canovas J.A., Małarzewski Ł., Choryński A., Janecka K., Mikuś P. 2014. Floods at the northern foothills of the Tatra Mountains – A Polish-Swiss research project. Acta Geophysica 62 : 620–641.
Ruiz-Villanueva V., Stoffel M., Wyżga B., Kundzewicz Z.W., Czajka B., Niedźwiedź T., in press. Decadal variability of floods in the northern foreland of the Tatra Mountains. Regional Environmental Change, DOI 10.1007/s10113-014-0694-9
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