Articles
In recent years, interest in applied geomorphological studies aimed at the human-environment interaction decreased. This is largely due to the lack of appreciation of geomorphological knowledge. To overcome this, it is necessary to change the status of applied geomorphological research and create a new line of basic geomorphological studies – anthropogenic geomorphology – and to define its subject and logical structure. These questions are proposed to geomorphologists for discussion.
The modern plain and mountain river valleys had the maximum depth at the beginning of Quaternary. Buried alluvium in the valleys occurs at different depth and is in different states of preservation due to Quaternary intra-valley alterations. But placer mineral content is richest in the most ancient alluvium. That is why the quaternary valley history and the state of preservation of buried alluvium play an important role in the heavy mineral placers prospecting.
Complex investigation of the peculiarities of landscape formation and sedimentation is an important component of regional paleogeographical reconstructions. The geomorphological and lithological maps compiled by the authors demonstrate the regularities of spatial differentiation and trends of age changeability of morpholitosystems. These trends served as the basis for mapping the paleogeographical zones of the East-European Plain with the history of regions’ development taking into account. The separation of the territory into paleogeographical zones, provinces, regions was fulfilled with the following estimation of landforms stability. Paleogeographical approach based on the purposive zoning gives the possibility of complex assessment of natural environment stability and regions of ecological risk. Paleogeographical expertise improves reliability of forecast for the morpholithosystems development in extreme situations.
Ecological and Applied Geomorphology
It is shown that the coastline near the canyon Novyi is characterized by a rapid recession (about 7 m/y). Simultaneously the coast prominence at Cape Konstantinovskiy is truncated (4 m/y), and the eroded material is mainly transported into adjacent canyons. At the east ledges of the canyons Novyi and Konstantinivskiy the wave refraction leads to the energy concentration and the increase of longshore drift capacity. Because of intensive incision the drift of deposits will after some time run out. In order to save the beaches a pebble material should be placed into eroded coast sections (90 and 50 m3m-1y-1, respectively).
Changeable regime of semi-mountain rivers i.e. alternation of calm flow during low water and turbulent flood strongly complicates the forecasting of river bed deformations which characterized by intensive dynamics. Hazardous channel deformations near the bridge under construction over river East Handyga and near the rebuilding bridge over river Abakan are described. Errors in the forecasting channel deformations had been made earlier due to the use of the old standard methods which do not take into account the horizontal deformations of the channel.
Short communications
The loess-soil series structure of Melekino test site was studied in detail in the coastal outcrop and the drill profile. It is possible to reveal specific features of watershed morphodynamics in the Northern Azov region since the Muchkap time (MIS 13, ~ 470-500 kyr). The position of paleosols and textural features of deposits indicate leading role of loess accumulation in the development of watersheds relief before the Valdai glacial epoch. Intensity of denudation was a relatively low at the time. Stage of unique denudation intensity was diagnosed for the Valdai glacial epoch (as follows from indirect data, to its end - MIS 2, ~ 29-12 kyr). The denudation resulted in the development of linear erosion and slope processes even on gentle slopes (2-4 degrees). Analysis of paleosol deformations revealed the specific of watersheds relief evolution during the transitions from interglacial to glacial epochs. We determined that early stages of glacial epochs were characterized by sharp intensification of processes of arid and cryo-arid types. These processes led to the formation of specific micro-knobby surface.
On the outer continental shelf of a northwest part of the Black Sea the detailed researches of bottom relief were fulfilled on two ranges. Bathymetric and geomorphological maps, schemes and survey profiles of a bottom surface were compiled. Shelf edge, submarine valleys and deltas of the Dnieper, Dniester, and other rivers, steps of the terraces formed during the sea regressions (80-100 and 130-140 m below sea level), rills and ridges are the most prominent forms. In the N-Q stage bottom relief formation was governed in the first place by neotectonic movements, and also by accumulation, abrasion, and erosion.
It is shown that accumulation of sediments and formation of the coastal banks on the Angara reservoirs occur in the areas of predominant abrasion shores. Abrasion produces more than 2 Mt/y of loose sediments, 40% to 90% of which participates in formation of coastal banks occupying only 1% of the reservoirs’ area. Granulometric composition, mineralogical and geochemical characteristics of the coastal banks sediments correlate with the abrasion shores rock composition.
The main methodical approaches of riverbed processes forecasting under increase/decrease of water content due to climate changes and human impact are analyzed. The authors estimate the workability of hydrologic-morphologic dependences. The relations of radii and wavelengths of meanders with water discharges are most elaborated, while such common correlations for braded channels are practically absent. The possibilities of the QI-diagrams use for the evaluation of the riverbed transformation due to changes of the factors affecting channel processes are shown. The main difficulties in further forecasting are formulated, in particular the lack of more or less reliable scenario of water content changes; the important aims are the validation of the most reasonable scenario, its application for channel processes forecasting for certain rivers, further estimation of hazardous consequences of channel processes.
The existing definitions of the terms “sor” and “sor depression” were analyzed. A variety of formulations arises from the lack of the knowledge about genesis of these arid landforms. Multiplicity of their origin leads to the diversity of their morphometric, geochemical, and soil characteristics. The analysis of literature and data obtained during field researches allowed author to suggest general definition of the term “sor”: closed depression of various genesis with an ephemeral piece of water, characterized by intensive salinization and formation of solonchaks with strongly pronounced saline horizon.
ISSN 2949-1797 (Online)