Wyniki wyszukiwania - Biblioteka Nauki

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Landslides on river banks in the western part of Podhale (Central Carpathians, Poland)

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Kukulak J. , Augustowski K.

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tom Vol. 60, No. 3

561--571

EN

The authors studied landslides in alluvial sediments on undercut steep banks of the rivers flowing in the western part of the Podhale region. The landslides are of rotational type. Landsliding processes are complex and they differ from those on solid rock slopes because of the heterogeneous lithology of the alluvial sediments in the banks (muds, sandy gravels, clays) and because of uneven degree of their consolidation. Their course depends on the mode rate of water infiltration into the sediments. Multiannual observations of changing landslide surfaces and measurements of scarp surface with erosion pins indicate that each type of sediment behaves in a different way during the sliding. The layers of mud in the highest parts of the banks were sliding down in blocks and soon became fragmented, soaked and washed away. Sandy gravels were sliding as whole layers or separate fragments. The more compact the alluvium, the more compact was the resulting colluvium. The thick layers of massive claystones underlying the alluvial sediments at the bank bases were mobilized by landsliding only to the depth to which they became plastic. The claystones appeared the most resistant to landsliding among the bank materials. The surfaces of rupture were shallow and uneven where poorly consolidated layers of alluvium lied horizontally (landslides at Chochołów and Ludźmierz). In areas where alluvial sediments were more consolidated and inclined, and the layers of clay alternated with sands and gravels, the surface of rupture occurred deeper and was smooth (Stare Bystre landslide). Landslides in undercut river banks are an important source of debris in fluvial channels.

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Strategy of protection against hazardous channel and hydrological processes in rivers of developed territories and territories with focal development

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Zavadsky A. S. , Surkov V. V. , Golovlev P. P. , Ruleva S. N. , Krylenko I. V. , Krylenko I. N. , Goryachko M. D. , Samokhin M. A.

Geography and Tourism

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2018

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tom Vol. 6, No. 1

33--40

EN

In 2012-2015, the Makkaveev Research Laboratory of Soil Erosion and Fluvial Processes of MSU, Department of Geography, carried out a research, including analysis of hydrological and channel regimes of the Tom river in the Kuznetsk basin (Kuzbass) and the Katun river up to Uimonsky (the Altai), intra-mountain drainage basins, the survey of floodplains and eroded banks, and modelling of floods occurring in floodplains. As a result, a concept has been developed to improve protection measures against hazardous hydrological and channel processes. More than 200 engineering and organisational events were suggested as part of the concept. Given the dense network of river banks and the high potential damage caused by floods in Kuzbass, the continuous protection of cities, large residential and commercial areas, as well as sections of roads and railways subject to erosion is a priority in the flood control concept. In the case of the Katun river basin, characterized by local development, low population density, and relatively small damage caused by floods, the emphasis is put on organisational measures: prevention, evacuation of people and property, insurance and compensation. Selective engineering structures should, as a matter of priority, reduce the dangerous erosion of river banks and ensure a high level of protection of the territory against floods.

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River channel deformations under different phases of hydrological regime and various energy floods

63%

Chernov A. V. , Korableva O. V. , Zavadsky A. S.

Geography and Tourism

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2017

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tom Vol. 5, No. 2

67--74

EN

The paper presents the results of the regular bank erosion monitoring on three rivers of the Eastern European (Russian) Plain: the Kerzhenets River (left tributary of the Volga River), the Sherna River (left tributary of the Klyazma River) and the Tarusa River (left tributary of the Oka River). The first two rivers are characterised by wide floodplains and meandering channels, the third one is distinguished by an incised straight channel and a narrow floodplain. Results of the bank erosion monitoring carried out twice a year – after a spring snowmelt flood and a summer low-water period - over the last 5-15 years allowed the authors to arrive at the following conclusions: 1. Bank erosion and channel lateral migration were observed only during the flood events. No channel deformations were observed during the low-water periods on the rivers of the humid temperate climate zone. 2. Bank erosion and channel lateral migration were observed only during the years with the highest flood magnitude, regardless of the stream bed sediment grain size composition. In the years with moderate flood events, bank erosion occurred, but its rates were inconsiderable and comparable to the measurement accuracy limit. During dry years, no channel deformations were observed. 3. As a consequence of the meander development and its sinuosity changes, zones of the maximum concave bank retreat change their locations along the meander. First, the maximum erosion rate zone occupies most of the concave bank length, then moves towards the lower limb and concentrates at the meander apex when reaching the maximum sinuosity. 4. Formation of cutoffs in a high-sinuosity meander is mainly associated with intrinsic mechanisms of the meander self-development and to a lesser extent with a flood magnitude. In this case, the main factor of the cutoff process is a very fast increase in the channel longitudinal profile gradient, rather than flood discharge.