Jaromír Demek

Thermokarst in Siberia and its influence on the development of lowland relief

“Thermokarst” as a process is the melting of ground ice and the consequent formation of depressions. Thermokarst landforms depend on the tectonic regime of a region, the ground ice content, and the degree to which the permafrost equilibrium is disturbed. Thermokarst forms are especially prominent in the lowlands of the subnival region with permafrost. The authors distinguish two modes of thermokarst development—permafrost back-wearing and down-wearing—based on their investigations in Siberia. The first mode is characteristic of a more dissected relief. In this case permafrost back-wearing takes place and the process is characterized by development of gullies, thermocirques, and parallel retreat of steep walls with ice veins, resulting in a lower lowland level. The second mode of thermokarst development is due to permafrost melting from above and is typical of a flat undissected relief, mainly that of watershed regions. characteristic forms are depressions with steep slopes and flat floors (alases). Thermokarst valleys develop through coalescence of alases. Thermokarst processes destroy the lowland relief of large areas and create characteristic forms resulting in a lower lowland level. Thus thermokarst represents a special type of lowland development in permafrost conditions.

Development of land use and main land use change processes in the period 1836–2006: case study in the Czech Republic

Two different sets of maps, on a scale of 1:110,000, show the development of land use and main land use change processes in a 500 km2 study area that occurred over the last 170 years. Analytical maps of land use were derived from old topographical military maps, as well as from base maps, using five time periods by the process of on-screen digitization. These analytical maps formed a basis for synthetic maps of land use change processes, number of changes, stably used areas and land use change trajectories. Maps of land use change processes record the spatial distribution of main processes that occurred between two adjacent time steps. The overall dynamics of land use changes are depicted in the map of land use change trajectories. The map of the number of changes shows how many times land use was changed in the given plot, while the map of stably used areas gives an idea of which land use categories did not change during the researched period.

Changes in Land-Use and the River Network of the Graben Dyjsko-Svratecký Úval (Czech Republic) in the Last 242 Years

Changes in Land-Use and the River Network of the Graben Dyjsko-Svratecký Úval (Czech Republic) in the Last 242 Years Landscape-ecological parameters characterizing the landscapes structure, its function and changes over time (dynamics and development) play an important role as the indicators of sustainable development. Rapid changes in landscape patterns actually expressed by changes in land use are characteristic features of the contemporary cultural landscape. Both geography and landscape ecology have elaborated their own methodological approaches for monitoring of changes in landscape structure. The authors used historical topographical maps from the period 1764 to 2006 to monitor and study changes in land use and in the river network of the Graben Dyjsko-svratecký úval in the eastern part of the Czech Republic. Digital processing of maps in GIS milieu enabled high-quality quantitative assessment of changes that have occurred in cultural landscapes over 242 years. The quantitative study of land use changes by the Human society provides information on the intensity of landscape dynamics and development through the ages. The historical topographic maps are very useful as a source of information for such landscape-ecological studies.

The landscape as a geosystem

Abstract The main object of study of geography is the landscape sphere that includes the surface of our planet. The landscape sphere differs from the other geospheres by displaying unusual complexity and consists of structured sets of components which exhibit discernible relationships with one another and operate as a system. The functioning of the landscape sphere is conditioned by the interrelationships of components, as well as by the transfer of mass and energy from one part of the landscape sphere to another in the form of streams of mobile elements. The author is using the name geosystem for determination of this system of planetary dimensions. The landscape sphere may be further divided into subsystems exhibiting characteristic features which facilitate their identification and delimitation.Territorial differentiation of the landscape sphere, on the basis of the law of zonality, produces horizontal, latitudinal and vertical zones called by author geoms. These geoms may be further subdivided into geosystems of smaller dimensions called geochoras. The basic geochora is the landscape. In most landscapes the key elements in these geosystems are controlled by Man and so-called cultural landscapes are developed. The cultural landscapes are parts of the landscape sphere within which natural and socioeconomic geosystems co-exist. The author further distinguishes cultured, disturbed and devastated landscapes. The study of cultural landscape is amongst the most difficult fields of investigation, but such studies are of great significance in terms of predicting future environmental developments.

Geomorphological processes and landforms in the southern part of the Polická vrchovina Highland (Czech Republic)

The paper examines relations among geomorphological processes and the landforms of the Polická vrchovina Highland in the Bohemian Massif. Geologically, the Polická vrchovina Highland is a part of the Intra-Sudetic Basin on the boundary between Bohemia and Poland. The basin structure of the Highland developed during the neotectonic period. In the outer parts of the Highland, Mesozoic rocks dip gently to the centre of the basin to form cuestas. In the central part, layers are horizontal or subhorizontal. Mesas (Hejda and Ostaš Mesa) provide evidence of the erosion of the Mesozoic deposits. The relative uplift of the Highland resulted in the incision of the Metuje River and its tributaries. Unloading of rocks and erosion initiated typical geomorphological processes such as deep- seated creep, cambering, rockfalls, landslides and pseudokarst processes. These processes produced some typical forms controlled by rock properties, jointing, relative differences in height and climatic changes in the Tertiary and Quaternary.

Geomorphology and the location of nuclear power plant sites: the Czechoslovakian experience

The need for secure sites for such sensitive installations as nuclear power plants and radioactive waste storage has brought increasing significance to the study of the geodynamic processes of the Earths crust. Among other Earth sciences, geomorphology in Czechoslovakia is also participating in the study of both planning and operating nuclear power station sites. The experience of Czech geomorphologists has shown that the geomorphological information is necessary part of the accurate prediction of events and time which can endanger the security of nuclear power plants, radioactive waste storages, pipelines and other large installations. Geomorphological mapping and morphostructural analysis are important tools for such studies.

Global warming and permafrost in Eurasia: a catastrophic scenario

Abstract Since models of global warming predict that climatic changes will be greatest in the Arctic and might already be in progress, it is prudent to attempt to understand the rapidly changing thermal regime on Eurasia cold regions. In this paper the author tries to evaluate the probable catastrophic implications of global climatic change in the cold regions of Eurasia. The impact on Man activities in permafrost regions is discussed.

QUANTITATIVE MONITORING OF SLOPE MOVEMENTS AT THE BŘIDLIČNÁ HORA MT. (HRUBÝ JESEN ÍK MTS., CZECH REPUBLIC, EU)

Monitoring of scree cover (blockfield) on a plot located on slopes of the Břidlicna hora Mt. (1358.0 m a.s.l.) in the Hrubý Jesenik Mts. In the NE part of the Czech Republic has shown various slow movements of the majority of the blocks in the period of 1972–2008. Irregular and fluctuating movements without a certain trend were observed in 28 percent of cases (rotation and tilting of blocks). By the elevation of 30% blocks moved from minus 10 to minus 50 mm, by 10 percent they moved from minus 50 to 100 mm. Extreme elevation movement values of downslope movements have been observed in 7 percent of blocks (from minus 276 to minus 436 mm). The rest (25 percent) of block was stable.

Recent Landform Evolution in the Moravian–Silesian Carpathians (Czech Republic)

Topographic changes in the Moravian-Silesian Carpathians have been due to variations of natural conditions (climatic changes, accelerated rates of exogenic geomorphic processes during the Little Ice Age), but mainly to the growing intensity of human activities (tillage, deforestation, accelerated soil erosion, urban sprawl). In this geomorphologically highly sensitive region, land-use changes exerted a great influence on the intensity and type of exogenic geomorphological processes in the last millennium. Their impact is studied on archive maps. The density of slope deformations (like deep-seated slope failures, lateral spreading, toppling, sackung, translational and rotational landslides, earthflows, debris flows, and rockfalls) in the study area is the highest in the Czech Republic. Other geomorphic processes presented in this overview are erosion by water on the surface and underground (piping), wind erosion, and a range of anthropogenic processes (urbanization, mining, industry, water management, and transport).

HODNOCENÍ RIZIK DOPADU PROJEKTŮ TĚŽBY UHLÍ NA RELIÉF MORAVSKO-SLEZSKÝCH KARPAT V ČESKÉ REPUBLICE: PŘÍPADOVÁ INŽENÝRSKO-GEOMORFOLOGICKÁ STUDIE DOBÝVACÍHO PROSTORU TROJANOVICE

The aim of the paper is prediction and estimation of risks of planned hard coal deep mining in Trojanovice mining area below sensitive young terrain of the Moravian-Silesian Carpathians and impact of mining activities on the relief. The authors carried out detailed geomorphological mapping of the area, compiled digital geomorphological map and 3-D model of geomorphological hazards. The engineering-geomorphological analysis has shown that planned underground mining activities will accelerate geodynamic processes in the area and cause substantial changes of mountain and highland relief.