Vol 155, No 2 (2023)
- Year: 2023
- Articles: 7
- URL: https://journals.eco-vector.com/0869-6071/issue/view/11239
- DOI: https://doi.org/10.31857/S0869-60711552
Full Issue
Articles
Stochastic Parameters of Flash Floods Formation in the North of the Black Sea Coast
Abstract
Abstract—
Flash floods are one of the most dangerous hydrometeorological events all over the World. In the current paper stochastic parameters of flash floods formation are studied on the basis of data on flash floods in 1990–2021 in the small river basins of the Caucasus and Crimea Black Sea Coast. The main factor of flash floods formation is heavy rain, but in some cases its occurrence could depend on critical combination of various factors. Flash floods are usually formed in summer-autumn period in the studied region with the maximum of observed events in August. They are characterised by very rapid water level rise of about 1.2–1.3 m/h. Sediment yield during one flash flood could be compared with mean annual values. Statistical analysis of precipitation long ranges demonstrates probability of more often flash floods occurrence in the region in comparison with observed events.
3-24
Calculation of Seasonal Erosion on the Oka River Riverbanks Using Geodetic Modeling
Abstract
Abstract
—Directed erosion of riverbanks stands out among the dangerous geomorphological processes on large lowland rivers. In the middle reaches of the Oka river, horizontal channel deformations make a significant contribution to regional lithodynamics and the reduction in the area of floodplain lands. We carried out field geological and geomorphological studies in the valley of this large tributary of the Volga, which revealed the complex facies architecture of the floodplain. The forecast for riverbank erosion near the city of Ryazan has recently declined due to the unstable water regime of the Oka river. For a detailed assessment of the consequences of destabilization of the coastal slopes, their surface was surveyed using a total station and aerial photography from a UAV. Regular observations of erosion by the seasons of the hydrological year allowed us to obtain actual data on the redistribution of soils along the height of the slope. We have found that erosion in summer low water is three times weaker than during high water. The predominance of collapses of the uppermost (0.0–2.0 m from the day surface) part of the erosion fronts was also revealed. The article also discusses possible reasons for the mobilization of the geological filling of the river bank, arising from local differences in the Pleistocene-Holocene evolution of the morpholithic system of the Oka river floodplain and the fixation of geological information in it.
25-43
Morphology and History of the Upper Kama and Kolva Valleys in the Late Glacial and Holocene
Abstract
Abstract
—The article deals with the evolution of the river network of the northern Kama region, a region that has experienced the influence of a late quaternary glacier. This glacier was located to the north, in the basins of the upper Vychegda and Pechora, but the influence of its meltwater was reflected in the restructuring of the river network of the lowland Kama-Vychegda interfluve. In order to find out the extent of this influence in the conditions of postglacial warming, the article compares the floodplain-channel complexes of the Upper Kama and Kolva formed in the Holocene. In the upper Kama in the late Quaternary, there was a flow of water from Vychegda along the rivers North and South Keltma; there were no additional water flows to the Kolva River, located 30 km to the east. It turned out that the parameters of the floodplain-channel complexes of both rivers are identical. Consequently, the flow of the Vychegda waters into the Kama was carried out not in the late Quaternary-Holocene time, but earlier, and it was no longer reflected on the channels and floodplains of the Kama and Kolva. At the same time, on the Kama – Vychegda interfluve there are traces of other watercourses that have now disappeared, formed during the melting of the glacier. The origin and time of the formation of these “blind” watercourses have yet to be determined.
44-56
Socio-Ecological Aspects in Geoecological Assessment of Nonmetal Construction Materials Mining in the Oka Riverbed
Abstract
Abstract
—The evaluation of socio-ecological risks of the mining of sand-gravel mixture (SGM) from the riverbed is an important applied aspect of geo-ecological analysis. The article provides an overview of international scientific publications on this issue. The authors bring to light the most discussed, hence, the most relevant socio-ecological problems related to the extraction of SGM: a growing demand and shortage of these materials, deteriorating living conditions in areas adjacent to mining sites, deteriorating road conditions, water supply problems, increasing limitations to recreational land use, labor market distortions, rising crime, etc. The authors demonstrate that optimal management decision-making requires both an investigation of sand-gravel mining conditions and standards, and a socio-ecological assessment of the area, including the population’s environmental awareness regarding this problem; and illustrate this notion with the results of a study (semi-structured interviews in the form of a case study, combined with a quantitative pilot study) on population’s environmental concerns that has been conducted in several cities on the Oka River in the Moscow Region. The study suggests that the population’s awareness regarding the environmental issues of non-metal mineral resources extraction could be described as ranging from moderate to insufficient. The most active part of the population has an understanding of how SGM extraction affects the riverbed. However, the population’s overall appreciation of the importance of water resources for the existence of the region is rather low. The environmental concern levels could be described as moderately wary: there is subjective preoccupation with the issue of deterioration of the ecological state of the river, but there also is an understanding of the economic importance of SGM mining. Based on the conducted study, the authors provide specific recommendations as to how it could be increase the environmental awareness regarding the topic at hand. In addition, the authors stress the environmental importance of observing the regulations regarding the SGM, explain the benefits of informational support of the population and organization of educational events, and suggest conducting regular monitoring of the socio-ecological state of the region. The proposed method for identifying the levels of environmental concern of the population is believed to allow for a reduction of potential social tensions within the region.
57-72
River Sediment Runoff in the Aldan River Basin and Mining Activities
Abstract
Abstract
—The article contains the results of a study of the features and causes of a sharp decrease of water turbidity and the suspended sediment discharges of rivers (1.5–5 times) in the Aldan River basin, which has been recorded since the second half of the 1980s and 1990s. The possible factors of this decrease are considered in detail. These are the runoff and temperature of water, economic activities, and the method of measurements at the gauging stations. It was found that water runoff, in general, increased in the average range of 5–30%. The maximum water discharges on the different stations had a multidirectional trends. The water temperature, as an important factor of thermal erosion, has increased. That is, hydrological factors could not have caused such a reduction in sediment runoff. Since the 1990s, the reliability of stationary data has decreased Main reason lies in the mining industry, its degradation in the 1990s, a new revival in the XXI century, but already under the pressure of strict environmental restrictions. Using numerous open sources, the author has built a map of exploited mineral deposits, identified the main stages of their development and the parameters of mining operation. All this information allowed us to substantiate the conclusion about the similarity of long-term fluctuations in river sediment runoff and the dynamics of mining, the stages of discovery and development of deposits, changes in the structure and localization, the implementation of measures to reduce the negative impact of mining on rivers. It was also found that the data of the stations from the very beginning of their collection did not reflect the natural regime of sediment discharges and water turbidity.
73-87
Transformation of River Channels in the Process of their Self-Development and Influence of Natural and Anthropogenic Changes in the Factors of Channel Processes
Abstract
Abstract
—In article analyze the main ways of river channels transformation, their morphodynamic type, its complication or transition from one structural level of channel processes to a higher one, in the course of self-development of channel forms. On meandering rivers meanders in the process of development turn into large meanders with rectilinear “inserts” between adjacent forms, into loop-like meanders, which are a combination of the original in the near-top part and segmental ones on their wings. Other way – into chest meanders when the river approaches the bedrock bank (forced bend), elongation of the lower wing along it and the formation of an adapted bend when the channel deviates towards the floodplain. On rectilinear “inserts” between adjacent large bends and on their upper wings, single branches are formed. In the near-apex parts of steep bends with a violation of the condition of flow around the banks (r < 2.5br), islands form in local channel extensions due to erosion of the convex bank or due to the rejection of part of the bend spur. For branched channels, under certain conditions, transformation in the process of self-development of single and conjugated branches into unilateral or alternating and intra-valley restructuring of the channel network due to erosion of floodplain isthmuses between branches and floodplain channels is characteristic. These reshaping, leading to the morphodynamic transformation of the channels, are superimposed by natural and anthropogenic changes in water content and sediment runoff and technogenic impacts on the channels, during which the channels are fixed and stabilized in an optimal position for the economic development of rivers. Accounting for the self-development of river channels is necessary in the operation of rivers and the use of water resources, in paleoconditional and paleohydrological analysis, and also in the development of forecasts for channel reformations.
88-108
Small and Medium-Sized Lakes: Characteristics of their Functioning at Present and Methodological Issues of their Recreational Potential Assessment (on the Example of Lakes on the Territory of the Republic of Bashkortostan)
Abstract
Abstract
—The article reveals the main characteristics of the functioning of small and medium-sized lakes at present under the influence of a set of natural and anthropogenic factors, as well as methodological provisions for assessing their recreational potential. It is shown that the most significant negative changes in them occur especially in those regions which are characterised by high scales of influence of economic activity confined on their catchments. The main factors influencing the level of eutrophication of lakes and, consequently, their use for recreation purposes include such factors as the removal of dissolved and undissolved substances from catchments into water bodies themselves, siltation, changes in morphometric characteristics and reduction in the intensity of external water exchange. In order to justify the optimal parameters of recreational loads on the studied water bodies, the analysis of currently used methodological approaches was carried out, their advantages and disadvantages were revealed, which allowed to justify new approaches to the assessment of recreational potential of water bodies.
109-120