In this study, correlation reception of thermal acoustic radiation by a pair of sensors was carried out. The experiment used receivers with different bandwidths, varied the size of the heated sources and the distance from the sources to the receivers, and also shifted the sources in the transverse direction perpendicular to the acoustic axis of the system. For each case, applying the relations used in radio astronomy, the correlation functions of thermal acoustic radiation were calculated. It is shown that the experimentally obtained and calculated cross-correlation functions are close, taking into account the measurement error.

Monitoring the internal temperature of active elements (AE) of high-power lasers is necessary for their safe operation. The article describes a method and device for monitoring the internal temperature of the AE of lasers. The measurements utilize pulsed ultrasonic (US) probing and the temperature dependence of the sound speed in the AE material. A change in the sound speed leads to a change in the phase of the ultrasonic signal passing through the object, which is recorded by the described device. The results of monitoring the AE temperature using ultrasonic probing during operation of an laser device are presented.

An array consisting of three sensors was used for correlation measurements of thermal acoustic radiation. For the first time, all cross-correlation functions were obtained for each pair of sensors. The measurements were carried out at two positions of the source (a heated narrow Teflon cylinder), the distance between which was equal to half the spatial period of the cross-correlation function of adjacent sensors. The measured correlation functions were in antiphase, which corresponds to the calculated correlation functions of thermal acoustic radiation. To pass from correlation functions to temperature distribution, spatial cross-correlation functions for adjacent and the outermost sensors in the array are summed. The correlation methodology makes it possible to significantly increase the spatial resolution of the method.

This study presents results of the first detailed absolute chronology of the Early Khvalynian transgression of the Caspian Sea based on optically stimulated luminescence (OSL) dating. Study was carried out for special facies of the Khvalyninan deposits–Chocolate Clays, widely distributed in the Northern Caspian Lowland. In the studied reference sections of the Lower Volga region (Srednyaya Akhtuba, Raygorod, Leninsk), Chocolate Clays are of considerable thickness, three subfacies are distinguished in their structure: a unit of interbedded sands and loams; unit of unified dense clays; and a unit of characteristic clays with thin interlayers of silt, forming a characteristic fine-platy structure. The first unit reflects the conditions of the initial penetration of the Khvalynian waters into the studied area, the second unit reflects conditions of a deep-sea bay, while the third unit reflects the time of regression, with a significant influence of alluvial processes on sedimentation. OSL chronology was obtained for both quartz and feldspar grains using modern measuring protocols. Our dating results clearly indicate that formation of the Lower Khvalynian marine deposits in the northern part of the Lower Volga region took place between 27 and 14 ka. New data on the age of the Khvalynian deposits are further confirmed by dating of the overlying Kastanozem soils (9.6–0.7 ka) and the underlying loess-paleosol series (37–19 ka). High-resolution luminescence dating for the first time distinguished four stages in the development of the Khvalynian transgression in the Lower Volga region: the initial penetration of waters to a level of ~5 m (27 ka); stage of stabilization and gradual level rise from ~5 to ~7 m (27–20 ka); the stage of active sea level rise and movement of the coastline northward (16–15 ka); and the final regressive phase with a drop in sea level (15–14 ka).

Unraveling sources of sediment supply, their temporal and spatial variability is of key importance to determine origin of deposits and to explore the formation mechanism of Selenga Delta landscape units. From an environmental point of view this solution would help to identify the particle-bound pollution sources. We used geochemical fingerprinting (the FingerPro R package), which is a modern quantitative implementation of the method of sedimentary provenance analysis. The main aim was to recognize the main patterns of sediment and associated particle-bound pollutants transport and deposition within the delta. At the old floodplain from 55% to 90% of sediments were delivered from the eroded floodplain and terrace banks upstream and only about 10-15% originates from the remote basin sources. Sedimentary environment in the Khlystov Zaton reveals a greater variety than on the floodplains. 40% of sediments from the upper 5 cm-layer originated from the flood, taking place in 2013, and 30% were the product of floodplain and terraces banks erosion. Nevertheless, analysis of the fine-grained component of suspended sediment sets the material from eroded floodplain banks as the dominant source of accumulation within the delta. This means that the self-absorption is the leading process in the Selenga delta at the moment. Heavy metals and metalloids accumulates in the lower reaches of the Selenga on the floodplain surface, deltaic lakes and oxbows during high floods. Runoff decrease during floods can lead to the release of pollutants into the Lake Baikal.

An improved pulsed correlation gas flowmeter with clamp-on sensors for measuring gas flows in pipes has been created and studied. Such devices operate by measuring vortex motion velocity in a turbulent flow. The problems of isolating a weak useful signal that has passed through a gas against a background of interference from signals propagating along the pipe wall are discussed. A schematic of a correlation flowmeter with pulsed probing and the possibility of automatic search for a useful signal against a noise background is proposed. The operation of the flowmeter is demonstrated against the background of pipe wall vibrations and liquid droplets in the flow.

Over the last two decades, unmanned aerial vehicles (UAVs) have become widely used in geomorphological investigations at local spatial scales for different purposes. Here we present several examples of the UAV survey application for evaluation of soil redistribution volumes on cultivated hillslopes over a timescale of single to several runoff events. Several cultivated fields with prominent soil erosion and deposition features have been discovered during reconnaissance car trips through several regions of Central European Russia carried out in April-May 2021. The observed features included rill and ephemeral gully networks as well as several types of deposition features such as sheets and fans located within the field, along the field lower boundary and on the adjacent dry valley bottom. Detailed airborne surveys of the detected erosion and deposition zones were carried out using the DJI Phantom 4 Pro quadcopter-type drone with ground control points surveyed by Leica GS 1200 differential GNSS system. Simultaneous control hand measurements of volume of representative sets of erosion and deposition features were carried out within the same areas. Photogrammetric processing of the UAV survey data using the Agisoft Metashape software package allowed producing DEMs and orthorectified images of the surveyed areas with spatial resolution within ±2 cm. Following that, manual and semi-automatic detection of erosion and deposition features were employed and their available parameters (length, width, depth, areas of selected cross-sections, approximate volume for rills and ephemeral gullies; perimeter, area and shape for deposition features) have been measured in the Global Mapper software package. To obtain deposition volumes, the above parameters were combined with hand measurements of the deposited layer thickness. Zones of predominant sediment entrainment, transit, within-slope redeposition, export from the field and deposition in adjacent dry valleys were determined and local sediment budget parameters estimated. Comparison of the results obtained with the spring 2021 meteorological records allowed us to make conclusions on the relative contribution of snowmelt and rainfall-generated runoff into the observed soil and sediment redistribution. The study is supported by the Russian Science Foundation (Project No. 19-77-10061).

Retisols are the most spread soil in the boreal forests of the Russian Plain. Their features are usually linked to the Holocene pedogenesis. However, Retisols formed in the bipartite sediments of Moscow age (sandy cover layer on top of the glacial till) could have experienced pedogenic and cryogenic impact much earlier, starting from the last Interglacial. The subdivision of relic and modern features is still incomplete. In our work, OSL datings together with micromorphological studies indicate that the cover layer was formed by local rewashing of the glacial till during the deglaciation of the Moscow glacier. GPR investigation shows the mantle bedding of the cover layer and proves the stability of uplands and slopes since deposition, which confirms their exposure to long time pedogenesis. Detailed morphology, micromorphology, microtomography, clay mineralogy and AMS dating confirm the presence of polygenetic modern and relic features in the profile of Retisols. Within the cover layer, pedogenesis resulted in a set of embedded soil profiles that have been formed in balance with the modern environment. In the glacial till pedogenesis is mostly exhibited on the ped faces as a set of multi-layered clay and clay-humus coatings. Based on AMS dating of the inner layer of the clay infilling, it was argued that clay illuviation had started during the last interglacial (MIS5e) and continued through the Holocene. The studied soils should be considered as surface paleosols (polygenetic soils) with the palimpsest type of soil memory, reflecting environmental evolution during the last interglacial-glacial cycle and the Holocene.

Watershed landscapes of the Central Russian Plain, which were subjected to the Late Pleistocene permafrost, bear witness to widespread cryogenic structuring. It is reflected both in semi-regular spots, blocks and polygons in soil and vegetation cover on arable fields and as vertically oriented wedge casts in surficial deposits. This study aimed to identify relict periglacial features in both the landscape and sedimentary sequence of the Borisoglebsk Upland to determine if there is a correspondence of these cast networks to the distribution of landforms and regular patterns of soil and vegetation cover. Combined interpretation of aerial and satellite multi-temporal imagery and detailed investigation of vertical cross-sections in gradually expanding geotechnical trenches including apparent magnetic susceptibility measurements allowed us to reveal and spatially correlate three generations of wedge casts, each buried by well-pronounced sedimentary units, and a specific bulbous type of cast. The type of cryogenesis, erosion and slope mass-movements changed from the Late Pleniglacial to Late Glacial, representing a good proxy in the watershed sedimentary cover for palaeoenvironmental reconstructions. However, regular polygonal patterns caused by these casts are almost erased in the modern topography whereas shallow dry gullies mostly inherit pre-Holocene wider linear depressions with no clear relationship to the buried cryogenic polygons.

We present a detailed luminescence chronology of the loess-palaeosol sequences in the Lower Volga region of Russia at the Leninsk site - an important palaeogeographic archive describing the climate and environmental conditions of regressive stages of the Caspian Sea. The chronology of these sediments has received very little attention compared to the under- and overlying marine deposits. The degree of bleaching was addressed by making use of the differential resetting rates of quartz and feldspar. Our results show that the quartz OSL and feldspar pIRIR(50)(,)(290) signals were sufficiently bleached before deposition and uncertainties in bleaching have a negligible impact on the reliability of the luminescence ages. The combined quartz OSL and K-feldspar pIRIR(50)(,)(290) chronology constrains the main stages of the Northern Caspian Lowland evolution during the Late Quaternary. During early MIS 5 (130-120 ka), the northern part of the Lower Volga was covered by a shallow brackish water estuary of the warm Late Khazarian Caspian Sea transgression. After similar to 122 ka, the Volga incised the Northern Caspian Lowland surface following sea-level decrease and the start of subaerial conditions at Leninsk. Loess accumulation rate increased towards the end of MIS 5 and two palaeosols of presumably MIS 5c and MIS 5a age formed, exhibiting features evidencing a dry, cold climate, influenced by long seasonal flooding by the Volga River. Cryogenesis affecting the MIS 5a soil is a regional phenomenon and is dated to between similar to 70 and 90 ka. The overlying thick Atelian loess unit formed during the cold periods of MIS 4 and MIS 3. Clear erosional features at the top of the Atelian loess are constrained by luminescence to similar to 35 to similar to 24 ka, allowing reconstruction of erosion of 150-200 cm of loess.

A method for measuring a gas flow rate is proposed based on ultrasonic sounding of the turbulent flow in a pipe with subsequent cross-correlation processing of signals passed through the flow in two pipe sections. It has been shown that information on the velocity of vortices is obtained from the pipe center due to focusing of ultrasound by a pipe wall. The velocities of vortices were measured using an ultrasonic flow meter and simultaneously by two mutually spaced heat–loss anemometers. Based on the correlation measurements of the time delay it has been shown that the velocity of vortices is less than the maximum flow velocity in the center measured using the Pitot–Prandtl tube. The possibility of measuring the volumetric gas flow rate using the data on the speed of vortices has been demonstrated.

Controlling deep temperature in parts of the human body is necessary for hyperthermia and thermal ablation used in oncology. UHF heating of single hands of patients was chosen as the model for this procedure. For the control, a plastisol cylinder was heated in the same manner: a substance with acoustic and thermophysical properties close to those of soft tissues of the human body. Passive acoustic thermometry was used to measure the deep temperature of the hand, and infrared thermometry was used to measure the surface temperature. After 5 min of UHF heating, the deep temperature of the hand increased by an average of 0.7 ± 0.6°C, and the surface temperature, by 0.8 ± 0.6°C. The same methods, as well as independent measurements, were used to determine the plastisol temperature. After the same procedure, the deep temperature of the plastisol increased by 4.3 ± 0.4°C; the surface temperature, by 3.2 ± 0.2°C; the temperature measured with a thermometer at the center of the object, by 3.3 ± 0.5°C. The smaller heating of the hand compared to the model object is related to effect of blood flow, which should be adequately taken into account in further studies. The noninvasive methods indicated in the study can be used to control temperature in oncology during hyperthermia and thermal ablation under the effect of a high-frequency electromagnetic field.

Recent detailed investigations of landforms, soils and surface deposits of the Borisoglebsk Upland northeastern slope within the Nero Lake basin (Central European Russia, Yaroslavl Region) allowed deciphering co-evolution of the major landscape components of the case study area since the Late Pleistocene. The Late Pleistocene to Holocene transition in the gully network was represented by relatively short but high-magnitude (up to 12 m) incision phase followed by significant infill till 6.5 ka. Absence of the well-developed early Holocene paleosols in the studied sections and cores suggests dominantly negative sediment budget. There is so far limited evidence of sedimentation over the first half of the Holocene. Discontinuous deposition with certain interruptions (but without distinct buried soil formation) occurred only within closed depressions and on gully fans. The second part of the Holocene prior to the widespread human settlement left more substantial traces in soil and sediment record. Despite the common perception of the pristine boreal forest landscapes to be geomorphologically stable due to erosion-protective role of woodland vegetation, several phases of dramatically increased soil and gully erosion rates have been identified. It is identified in soil bodies and sediments, both at locations dominated by denudation (evidences of multiple topsoil truncation in Atlantic and Subatlantic) and at zones of alternating incision and infill of small linear erosion features. Such extremes were most likely associated with combination of several triggers including natural forest fires and high-magnitude rainfall or snowmelt runoff events. There are several 14C dated layers of pyrogenic charcoal indicating pre-anthropogenic wildfire-induced incision and infill cycles during the middle and late Holocene.The last phases of increased hillslope and fluvial activity within the study area can be related to increased human interference, starting from about 1600-900 years ago. The onset of cut-and-burn cultivation is independently established from available archeological evidences, dating of cut and burnt tree logs remnants, organic material buried by agrogenic colluvium and gully fans. Latest period of intensive gully growth can most likely be attributed to the XIXth Century land tenure reform, when most of the study area gullies experienced significant linear growth, bottom incisions and appearance of several new gully branches. The most recent trend of soil and gully erosion has been evaluated by 137Cs sediment tracing, soil empirical modeling and comparison of historical and modern maps, airborne photos and satellite images. Rates of soil redistribution on slopes decreased significantly over the last several decades due to combination of natural and anthropogenic impacts: 1) decreased spring snowmelt runoff caused mainly by generally lowered thickness of seasonally frozen topsoil layer; 2) arable land abandonment or shift from row crops and cereals to perennial grass-dominated crop rotations in the post-Soviet period. In addition, local short-term (from several years to within-year) cycles of relatively low-magnitude (not exceeding ±1 m range) incision and infill in gullies are often triggered by biogenic activities, namely beaver dam constructions and breaches and local log jams.The study is supported by the Russian Science Foundation (Project No. 19-77-10061) and Russian Foundation for Basic Research (Project No. 19-29-05238).

The 100-km long upper reach of the Volga River between the Selizharovo and Zubtsov towns is oriented opposite the Late Valdai ice sheet which covered the Volga River sources, i.e. the area of the Verkhnevolzhskiye Lakes, during the Last Glacial Maximum (LGM), about twenty thousand years ago. Due to the Glacial Isostatic Adjustment (GIA), crustal subsidence occurred in the progalcial area and further from the ice sheet a compensational rise was formed towards which the Volga River valley was directed. The study is aimed at the investigation of the influence of GIA-induced changes in gradients during MIS 2 and the Holocene on the evolution of the Volga River valley. At the key site near the Bolshaya Kosha village (Selizharovo district, the Tver Oblast) it was found that prior the LGM the alluvial aggradation in the valley was most probably associated with the decrease of valley gradient because of the GIA-induced formation of a crustal proglacial flexure. However, the total depth of subsidence was not enough to completely stop the Volga River flow and promote the formation of a proglacial lake. During the LGM the highest (third) and widest river terrace was formed by both river and glacial melt waters. After the LGM the river incision resulted in the formation of a terrace staircase. The incision was caused by the increase of valley gradient due to the glacio-isostatic uplift of the proglacial area in the process of deglaciation. The incision was over in the Mid-Holocene (about 6 kyr BP). The total depth of incision was 15 m and the average incision rate was about 1 mm/year.

For the landscape and climatic conditions of the Eastern European Plain fluvial processes are considered to be the leading geomorphic force during the Holocene. Different hierarchical levels of fluvial landforms from individual hillslopes through gully network to river systems are characterized by various degrees of resilience and relaxation times in response to external impacts of different duration, magnitude and frequency. These characteristics of fluvial systems largely depend on their spatial scale, effective discharges and morphodynamics. Particularly important is understanding of hydrological and geomorphic connectivity at various scales, rates and patterns of hydrological and sedimentary signals propagation and variable sources-pathways-sinks structure of geomorphic cascades under changing climate and land use conditions. It is generally accepted that landscapes of the European plains have experienced alternating periods of relative stability and significant shifts in climate, soil and geomorphological development over the Holocene. A number of studies has been devoted to the Holocene soil and gully erosion processes in Russia and other European countries. Available sources of information on the past erosion and deposition cycles in small catchments include truncated soils, completely or partially infilled gullies, colluvial deposits and lake or reservoir sediments. The highest temporal resolution may be derived from lacustrine sediments. Such geoarchives are characterized by continuous records and often store signals of landscape changes, surface dynamics and vegetation variability (including land use patterns for the historical period) in decadal to seasonal resolution. However, because of the problem of variable fluvial connectivity and associated limited sediment delivery in cascade fluvial systems, quantification of small catchment sediment budget can be a very difficult task requiring thorough consideration of colluvial deposits storages and remobilization. This study presents the new results of multidisciplinary reconstruction of interaction of geomorphic and soil-forming processes, landscape changes and stabilization phases during the Holocene for the Puzbol gully catchment (about 7.95 km2) draining the Borisoglebsk Upland northeastern slope towards the Nero Lake (Yaroslavl Region, central European Russia). The study is based on complex geomorphic, lithostratigraphic and soil surveys by means of detailed field description, photo-fixation, sampling and laboratory analysis of materials from >40 natural or artificial exposures, cores and soil sections. Observed absence of the early Holocene deposits can be explained by generally negative sediment budget of the catchment. It was more likely caused by high-magnitude low-frequency runoff events associated with climatic extremes rather than by dominance of continuous moderate erosion. A series of the middle Holocene 14C dates obtained by analyzing total organic carbon from humic layers of buried soils, lake gyttja and peats provides strong evidence of the synchronous phase of landscape stabilization in both upper and lower parts of the Puzhbol catchment accompanied by active infilling of smaller tributary gullies along its banks at middle part. The upper part of the Puzhbol Gully fan sediment shows clear evidence of synchronous accumulation of agrogenic colluvium and gully alluvium since XIIth Century on top of the Nero Lake terrace deposits. The study is supported by the Russian Science Foundation (Project No. 19-77-10061).

Despite the abundance of charcoal material entrapped in soils, they remain relatively less studied pyrogenic archives in comparison to the sedimentary paleofire records (e.g., lacustrine and peat deposits), and that is especially the case in most of Russia’s territory. We report here on the deep soil archives of the Holocene forest fires from the Pinega District of the Arkhangelsk region (64.747° N, 43.387° E). Series of buried soil profiles separated by charcoal layers and clusters were revealed in specific geomorphological traps represented by the active and paleokarst subsidence sinkholes on sulfate rocks overlaid by glacial and fluvial deposits. We combine the study of soil morphology and stratigraphy with a set of radiocarbon data on charcoal and soil organic matter, as well as the anthracomass analysis, to extract a set of paleoenvironmental data. A total of 45 radiocarbon dates were obtained for the macrocharcoal material and the soil organic matter. The maximum temporal “depth” of archives estimated from the radiocarbon dating of macrocharcoal reached 10,260 ± 35 cal yr BP. Soil formation with Podzols established at the inter-pyrogenic stages repeatedly reproduced within the period of ten thousand years, while the dominant tree species was Pinus sp. According to the macrocharcoal data, the intervals between fires have shortened in the last thousand years. Dendrochronological estimates suggest the occurrence of fires in almost every decade of the 20th and early 21st centuries. This is the first study of the millennia-scale soil record of forest fires in this particular region of Russia.

During the Holocene, interfluvial landscapes of European plains have experienced alternating periods of relative stability and significant shifts in climate, soil and geomorphological development. Assumed to be an arena of major transformation their evolutionary model is not entirely resolved yet. Based on lithostratigraphic, geomorphologic and soil survey, new results on the Holocene dynamics of fluvial and related processes including landscape stabilization phases for one of the gully catchments draining the Borisoglebsk Upland northeastern slope towards the Nero Lake are presented. Common absence of the early Holocene deposits can be explained by generally negative sediment budget of the catchment. Nevertheless, continuous erosion was not likely whether rare climatic extremes probably were the case. A series of middle Holocene dates obtained by analyzing total organic carbon from organicaccumulative layers of buried soils, lake gyttja and peats highlights strong evidence of the synchronous phase of landscape stabilization in both upper and lower parts of the Puzhbol catchment accompanied by active infilling of small erosion cuts in its middle part. The upper part of the Puzhbol Gully fan sediment shows clear evidence of synchronous accumulation of agrogenic colluvium and gully alluvium since XIIth Century on top of the lake terrace deposits.

Gullies are traditionally considered as one of the most active landforms in agricultural areas. In many places gully erosion leads to massive loss of fertile soil, decline of areas available for cultivation and a number of other land use complications. In addition, gullies in many cases act as the most effective runoff and sediment routing pathways, promoting better connectivity and increasing sediment delivery from cultivated hillslopes into fluvial network. Hence, gully network development may also cause significant detrimental off-site effects, including small river degradation, reservoir siltation, particle-bound pollutants concentration, etc. On the other hand, this process is often not progressive and unidirectional, but rather includes cycles of incision and head retreat alternating with infill periods. Understanding this dynamics and knowing its control factors may help to predict the future process trends for different climate and land use change scenarios, save fragile soil and water resources and design sustainable agricultural activity in changing environment. We analyzed five different small river basins in Central European Russia to investigate the cycles of gully growth and infill. The main approach was to acquire gully network structure from topographic maps or by manual visual interpretation of satellite images. A set of topographic maps was used to map the spatial structure of gullies over the case study areas for several time intervals from mid XIX century to the end of XX century. In addition, recent satellite images were used to investigate the up-to-date (2018-2019) gully network structure and distinguish its possible latest changes related to climate or land use changes. It is common to consider agriculture as the main factor of gully erosion activation in this area. We found that land use changes over the last 150 years lead not only to erosion rates shifts, but to incision and infill cycles. Besides, morphometric parameters of individual gullies, spatial patterns of gully network and gully density within different catchments strongly depend on local topography. Particularly important controls are topographic ranges, long profile and planform shapes of catchment slopes. Recent studies also showed that planform structure of upper parts of gully network (especially small tributary gullies of larger gully systems), as well as smooth slope depressions and periodically formed ephemeral gullies on cultivated hillslopes are in many cases strongly related to relic cryogenic features (RCF) of the Late Pleistocene cold stages. Evidence of partly infilled gullies incised into the RCFs such as ice or ice-ground wedge pseudomorphs are widely observed both on satellite and airborne images and in natural (undercut gully or small valley banks) or anthropogenic (quarries) exposures. Interaction of climatic impact, intrinsic gully headcut retreat threshold and recent land use changes determine modern gully network conditions. The main presently observed tendency is stabilization or gradual infill of most of the small- and medium-sized gullies by sediments transported by sheet wash, rill and ephemeral gully erosion from arable fields. At the same time, small discontinuous bottom gullies are developed in larger gully systems. This study is supported by the Russian Foundation for Basic Research (Project No. 18-05-01118a).

The paper presents an integrated approach for the apportionment of water and sediment sources and pathways in ungauged territories. The approach comprises various elements such as a large-scale semi-distributed hydrological and erosion model (using the SWAT tool), a statistical assessment of regular discharge data, the discrimination of runoff sources using end-member mixing analysis (EMMA), the apportionment of sediment sources using fingerprinting technique and sediment concentration and water discharge hysteresis rating curves analyses. The approach has been applied to Western Dvina River Basin (WDRB). The results discussed in the paper indicate main features of the water and sediment regime. The components of the presented framework provide a guide for detailed water and sediment studies making it an inexpensive way to develop a roadmap to understand important hydrological processes at a watershed scale.

Medium magnitude debris flow phenomena are widespread in the Kola Peninsula Mountains. Most frequently observed types are snowmelt period slushflows and rainfall-induced debris flows. Similar sets of hazardous events are reported for mountainous areas of Scandinavia, Japan, and Northern America.