No 2 (2019)

Riverbank erosion: factors, mechanism, human activity
Berkovich K.M., Zlotina L.V., Turykin L.A.

The riverbank erosion produces a great risk for the urban development, structures and communications located on the banks. Bank erosion, as an integral part of the lateral river channel migrations, is a multi-factorial phenomenon. Empirical evidence suggests that the riverbank erosion depends on the size of the river, the morphology of the bends, water flow; however, a big role plays erosion resistance of the banks, due to their structure and vegetation. It varies at changeable riverbank soils wetting in accordance with the hydrological regime of the river. Human activity contributes significantly to the intensification of lateral migrations, especially the construction of reservoirs that change the hydrological regime of rivers and sediment transport. Incision, daily flow regulation, redistribution of annual runoff, reducing the sediment load are the main factors that intensify the riverbank erosion. As an example, the situated downstream of the dam sections of the Volga River and Sheksna River in the Rybinsk City were examined and all these factors were revealed there themselves clearly. Considering these factors allowed predicting the riverbank erosion and provided the basis for bank protection program.

Geomorphology RAS. 2019;(2):3-17
The expected future super-eruption of the Yellowstone super volcano (USA) is “cancelled” by the Pleistocene glaciation and by the inversion of caldera complex development
Melekestsev I.V.

The review of the reconstructions of the eruptive activity of the Yellowstone Caldera Complex (YCC) in the USA allows to suggests three groups of arguments supporting that the “volcanic super-eruption of Yellowstone” is not likely to occur in the coming hundreds or thousands of years. First is the gradual weakening of the volcanic potential of the magmatic source (which is the frontal lobe of the magmatic super-flow, and not the mantle plume) during the last 2 million yeats. Second is the impact of the repeated occurrence of ice sheets in the YCC area during the past 640 thousand years. Finally, the equivalent super-eruption, in terms of energy released and the mass of exploded material, had already occurred at about 70 thousand years ago, and since that time, the YCC has passed from the volcanic to the hydrothermal evolutionary stage.

Geomorphology RAS. 2019;(2):18-36
Ecological and Applied Geomorphology
Assessment of contemporary erosion/sedimentation rates trend within a small cultivated catchment using the radiocaesium-137 as a chronomarker (a case study from the Udmurt republic, European Russia)
Gusarov A.V., Rysin I.I., Sharifullin A.G., Golosov V.N.

This paper is devoted to revealing and estimating the contemporary soil erosion rates trend within arable lands in the south of the forest zone of European Russia, based on the study of sedimentation rates at a small dry valley bottom with almost completely cultivated catchment slopes. The dry valley catchment (0.68 km2) is located in the south part of the Udmurt Republic (the mixed forests zone) within the Izh River basin. The bomb-derived and Chernobyl-derived radiocaesium–137 was used for dating valley bottom sediments in two time intervals: 1954(1963)–1986 and 1986–2016. To analyze the causes of change in sediment redistribution rates, morphological and morphometric analyzes of the valley, the results of year-to-year observations for gully heads retreat in the catchment vicinities, hydrometeorological observations of the Russian Hydrometeorological Survey network, and also aero- and satellite images across years were used. There was a noticeable decrease in the sedimentation rates of washed-out soil material from the catchment slopes at the valley bottom over the past 60 years: from 1.8–2.5 cm/year during 1954–1986 to 0.15–0.75 cm/year for 1986–2016. Hence, the sedimentation rates have decreased by 2.5–3 times as a minimum. This trend is consistent with a decline of the average retreat rates of gully headcuts within cultivated lands in the Udmurt Republic over the past 40 years — from 1.3 m/year in 1978–1997 to 0.3 m/year in 1998–2014. We suppose that the main reason for such significant reduction of erosion rates was a increase in protective crop coefficient associated with a increase in the proportion of perennial grasses since the late 1980s. Additional contribution to the erosion reduction was owing to a decrease in surface snowmelt water runoff within the catchment area since the early 2000s, associated with the reduction in soil freezing depth and general increase in air temperature during the winter and spring months in this region of the Russian Plain.

Geomorphology RAS. 2019;(2):37-56
Scientific Research Methods
Methodology of the multiscale assessment of geomorphological safety of seacoasts, on the example of the south-eastern Baltic coast
Abdullaeva I.V., Bredikhin A.V.

The article presents a methodological approach to assessing the geomorphological safety of sea coasts based on the close interdependence between geomorphological conditions and active coastal recreational activities. One of the key stages of the proposed assessment is recreational-geomorphological zoning, which results in separation of regions, districts and local areas in relation to relief homogeneity and recreational situation. The suggested approach is based on the quantitative indicators of the environment — conditions of relief formation and the geomorphological properties of the territory. Group of criteria for the situation of relief formation includes lithological, hydrometeorological, human and social factors. Among the group of geomorphological criteria are: morphometric characteristics of the coast, the dynamics of the coast and the activity of slope processes. Resultant geomorphological safety was classified into three classes: the most suitable areas for recreation; territories subject to further refinement; and inconvenience territories that cannot be used at all. The results of the geomorphological safety assessment are designed to increase the effectiveness of recreational environmental planning. The suggested principles of geomorphological assessment can be used not only for the Baltic region, but almost for any coastal region, which may require some correction of criteria.

Geomorphology RAS. 2019;(2):57-67
The application of the scale-space theory for medium-resolution DTM in geological and geotectonic studies
Rybas O.V., Gilmanova G.Z.

The article presents a technique for identifying structural elements and details of the geological structure in digital terrain models (DTM) based on the theory of scale spaces. With its help, linear, dome-shaped and textural features are singled out from medium-resolution DTM (for example, SRTM03, GMTED2010), allowing to significantly improve the quality of studies related to tectonic and geological mapping and zoning. In general, the theory of scale — spaces is described in application to the solution of these problems and illustarted on the examples of a number of case studies.

Geomorphology RAS. 2019;(2):68-78
Short communications
Morpholithodynamics of lagoonal straits of the North-Eastern Sakhalin
Afanasev V.V.

The results of the analysis of geospatial and geological information on the structure and dynamics of the lagoon coast of the North-Eastern Sakhalin are presented. On the basis of a number of parameters of the coastal erosion-accumulation processes and migration of lagoon straits during the period 1927–2014. the morpholithodynamics system of the North-Eastern Sakhalin was considered. The volume of sediments transported during the migration of the straits, was estimated with the help of three-dimensional models, in which, parallel with time-averaged areas of erosion and accumulation, additional data were used, namely: bathymetry of the straits and adjacent water area, characteristics of the relief of the barrier forms and geological information obtained as a result of georadar survey and drilling. Georadar data, together with remote sensing data, have made it possible to create a model of sedimentation, which formed the basis for the analysis of the history of the coast formation beyond the period of observations. Currently, we can trace the situation as long as to the middle of the XIXth century.

Geomorphology RAS. 2019;(2):79-94
History of Science
Study of erosion-channel systems and its components: theory, history, and practice
Chalov R.S., Berkovich K.M., Larionov G.A., Litvin L.F.

The article is dedicated to the 50th anniversary since the N. I. Makkaveev’s Scientific Research Laboratory for soil erosion and channel processes was organized at the Moscow University. The history of scientific school, created by N. I. Makkaveev, establishment is considered, as well as the discipline on integral erosion-depositional process and its evolution to the theory of catchment erosion-fluvial systems. The analysis of the fundamental researches performed by the Laboratory is submitted, and the application tasks in the area of soil erosion, gully erosion, channel and estuarine processes are outlined. Main directions of research are formulated, the prospects for their development are evaluated.

Geomorphology RAS. 2019;(2):95-108

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