Geografie 1973, 78, 81-96

Regional Division of the Relief of the Czech Socialist Republic

Břetislav Balatka1, Tadeáš Czudek1, Jaromír Demek1, Jaroslav Sládek

1Geografický ústav ČSAV, Mendlovo nám. 1, Brno, Czechia

During 1964 to 1970 the geomorphological division of the Czech Socialist Republic was compiled in the Institute ol Geography of the Czechoslovak Academy of Sciences. Its aim was a landscape classification and delimitation of geomorphological units of various taxonomic range. A geomorphological unit is an exactly defined territory of a certain taxonomical range in the system of regional-geomorphological division. The present division of the relief of the Czech Socialist Republic is based on the study of morphography, morphostructure and genesis of the relief. Under the term morphostructure the authors understand the structural-geological fundaments, involving both the rocks and the affects of older tectonics, and on which the relief type develops as a result of neotectonic and exogenic geomorphological processes. The term relief type designates a more or less homogeneous complex of landforms in a certain altitude with equal morphometrical features and genesis related to the same morphostructure, to the same complexes of geomorphological agents and the same history of development of the given area. In the division mentioned a dasymetric map illustrating the relief amplitude derived from maps on 1:25,000 was used as one of auxiliary criteria for the geomorphological division of the relief of the Czech Socialist Republic and its subsequent morphographical characteristic. Based on O. Kudrnovska's research (1948, 1965) a square of 16 km2 has been taken as an area of comparison for the evalution of the relief amplitude. The resulting values R16 were plotted in a 1 km2 square grid on a scale of 1:200,000 (dasymetric map). This map has then allowed to characterize the geomorphological units on the territory of the Czech Socialist Republic according to relief amplitude as follows: 0-30 m plains, 30-75 m gently undulated hilly lands, 75-150 m dissected hilly lands, 150-200 m gently undulated highlands, 200-300 m dissected highlands, 300-450 m gently undulated mountains, 450-600 m dissected mountains. In classing the geomorphological units the prevailing relief amplitude Rt occurring in the said territory on as much as 80 % of its area or characteristic of the territory was an important criterion. The basic unit in the regional relief division submitted is the geomorphological region. This is an area in a certain regional position usually associating lower geomorphological units of the same morphostructure and/or relief genesis and development and differing distinctly from the adjacent area. It is characterized by a complex of features of various importance in the different relief types. The main features are morphography and morphometry, morphostructure, relief genesis and development. The morphographic criteria are decisive in the delimitation of geomorphological region with a mountain relief, the other criteria coming into play above all in the case of strikingly structurally and tectonically conditioned geomorphological units (e. g. Bohemian Plateau, Tertiary basins, neovolcanic relief). The geomorphological regions usually involve several various relief types connected by a uniform morphostructure and/or orography. The geomorphological regions are grouped into geomorphological subsystems defined predominantly on the basis of the same morphostructure and similar orographical conditions. The subsystems are joined into geomorphological systems corresponding predominantly to basic morphostructural areas in the Czech Socialist Republic. Several geomorphological systems form then geomorphological provinces corresponding to structural-tectonic areas of higher order. The geomorphological regions are divided into sub-regions characterized by similar features as regions but displaying a greater orographic and genetic homogeneity of the relief. Towards lower units the homogeneity of the relief increases and the weight of orographical, morphostructural and genetic features augments as well. On the territory of the Czech Socialist Republic were distinguished: 4 geomorphological provinces (Bohemian Highlands, Central European Lowland, Western Carpathians and Pannonian Province), 10 geomorphological systems (Šumava Mts. System, Bohemian-Moravian System, Ore Mts. System, Sudeten System, Berounka System, Bohemian Plateau, Middle Polish Lowlands, Outer Carpathian Depressions, Outer Western Carpathians and Inner Carpathian Depressions), 27 subsystems, 93 geomorphological regions and 234 sub-regions. For the purpose of typological relief classification even units of lower level were delimited (geomorphological districts). Every geomorphological unit has its more or less distinct borders. The borders of geomorphological units are differently distinct in dependence on their orographical expressiveness. Most outsanding are the borders in places of the contact of orographically distinct geomorphological units, such as mountains and depressions. Valleys come into play as borders mainly in the case of geomorphological units of lower range (geomorphological sub-regions and districts). Water gaps and valleys form usually no geomorphological borders. An important feature of any geomorphological unit is its area extent. If the geomorphological unit does not reach a certain area given by the conditions in the whole Czech Socialist Republic it can be classified not even as a sub-region though it differs distinctly orographically and morphostructurally from its surroundings. A serious problem in the regional division of the relief of the Czech Socialist Republic was the terminology of geomorphological units. Their terminology should correspond to the geomorphological relief type (e. g. mountains, highlands, hilly lands, basins, etc.) with regard to deep-rooted names though they sometimes do not exactly comport with the character of the relief. The names of geomorphological units were given official approval at the 2nd meeting of the Terminological Commission within, the frame of the Czech Board of Geodesy and Cartography, Praha, on 24th November 1971.