A method for calculating the sediment delivery ratio during erosion in a small catchment area is proposed. A physically based model of soil erosion, transport and accumulation of sediments is used. The dependence of the erosion intensity on the amount of sediment particles transported in a given place is taken into account. If it is necessary to calculate the absolute values of erosion and accumulation, then the proposed model is well calibrated using measurement data, which allows it to be used for catchments for which there are measurement data for at least one runoff episode. If it is sufficient to know only the sediment delivery ratio, then this value is calculated by the relative values of erosion and accumulation and is practically independent of the absolute erosion rate. The main factor is the non-eroding flow velocity, the value of which is quite definitely assigned by formulas and does not require calibration. This allows calculating the sediment delivery coefficient based on a relatively small number of input characteristics of the relief, water runoff and soil and vegetation cover. The absence of the need for precise calibration makes the proposed model convenient for practical application, as well as for studying the dependencies of the sediment delivery ratio on the factors influencing it.
The long-term patterns of the erosional potential of precipitation (R-factor) in the monsoon climate of Primorsky Krai are investigated using modern time series analysis methods.
This study presents an analysis of the rainfall erosivity potential (R-factor) under a humid continental climate with hot summers (Dwa in the Köppen climate classification) using Detrended Fluctuation Analysis (DFA) and Power Spectral Density (PSD) methods. The original data, covering the period from 1960 to 2022, were pre-processed by removing trends and seasonal components, which allowed for identifying the dominant role of seasonal and random fluctuations in shaping temporal variations of the R-factor. The DFA results demonstrated a high degree of linear conformity in logarithmic scale (R2 = 0.983) with a scaling parameter α ≈ 0.534, indicating weak persistence and moderate correlations typical for processes dominated by short-term episodic precipitation events. The analysis of local DFA slopes revealed a stable region at a scale of approximately 15.8 months, reflecting the influence of annual seasonal cycles and potential interannual climate oscillations, such as the Pacific Decadal Oscillation (PDO) or the Atlantic Multidecadal Oscillation (AMO). Meanwhile, PSD analysis confirmed the absence of pronounced long-term memory and fractal structure in the spectrum, consistent with DFA findings. These results emphasize the importance of a comprehensive approach to studying rainfall erosivity potential and highlight the promising application of fractal analysis methods for identifying climatic and hydrological patterns in regions with pronounced seasonality and high rainfall variability.
The article is devoted to the description and comparison of two approaches used in the study of the planimetry of meandering channels by methods of hydromorphological analysis: the approach developed and widely used in the Soviet (Russian) school of channel process research, in which the bend is taken as the basic morphological unit of a meandering channel, and the approach in which the basic morphological unit is the meander – this approach it is more common in the works of foreign authors. It is shown that the first approach, which defines a river bend as a section of the channel between two successive inflection points of the channel centerline, allows for unambiguous identification of bends during the processing of cartographic materials. At the same time, the formulations used in the second approach, in most cases do not even allow for precise identification of the section of the channel defined as a meander. Moreover, within the second approach, there are two methods for defining a meander. One method defines a meander as a section of the channel between three successive inflection points of the channel centerline, while the other method defines it as a section between two consecutive apexes lying on one side of the axial line of the meandering belt. Given the increasing use of semi-automated and automated procedures in conducting of hydromorphological analysis, it is becoming increasingly important to accurately identify the objects being analyzed. Therefore, the concept of «bend» seems to be more certain, technologically advanced and reliable than the concept of «meander». So, when conducting morphometric analysis and searching for patterns in the plan configuration of meandering channels, it would make sense to rely primarily on the approach that uses the bend as the main morphological unit.
The question of the parameters characterizing the asymmetry of bends and meanders deserves special consideration, since most bends and meanders have obviously asymmetrical plan forms, and this fact has been noted by many researchers. In addition, the asymmetry indices of bends (meanders) are included in a number of expressions used to approximate the plan forms of the channel centerline. This paper discusses some indicators used as asymmetry indices of bends, specifies the parameters included in the formulas determining these indices, and compares them from the standpoint of the completeness of the description of the asymmetry of river bends (meanders) and the convenience of use in analyzing the planimetry of meandering channels.
The peculiarities of development and distribution of morpholithogenesis types in the river mouth area of the Tumen, Razdolnaya, and Partisan rivers of Southern Primorye were studied. Satellite images from free access (Yandex-maps, GoogleMaps, Google Earth Pro) were used in the study. Analysis and comparison of multi-temporal images (1985-2024) allowed to obtain reliable information on spatial and temporal changes in the location of relief elements, to determine the morphodynamic channel types and zoning of river mouth area. The role and share of influence of fluvial (channel), tidal and wave processes in the river mouth area morpholithogenesis are analyzed. The leading processes of modeling the overwater (coastal) and underwater (bottom) relief were wave processes and storm surges in channel-type estuaries. Channel processes became the leading processes of modeling the overwater (coastal) and underwater (bottom) relief in estuaries of the liman type. The nature of the development of erosion-accumulative processes in estuaries and near-estuary parts of the seashore indicates that an important feature of their modern formation in Southern Primorye is the great influence of directed natural processes. These include sea level rise and vertical movements of the Earth’s crust of negative sign characteristic for this part of Primorye.
