Shkolniy, Danila Igorevich

Shkolnyi D., Magritsky D., Chalov S.

Shkolnyi D.I., Chalov R.S.

The incised pebble-boulder channels of large mountain rivers (including the Yana in its mountainous area), their morphology and history of formation are well studied. However, local conditions within the intermountain depressions lead to the emergence of specific features of the channel development and its morphology — in this case, the formation of finger-shaped meander. The paper analyzes the historical and modern features of the formation of the Yana riverbed in the “Porogi” section located in the depression inside Kular range, and describes the negative impact of channel processes on navigation. Using this case study, we consider the characteristic features of the channel development of a large river under the influence of a complex of factors — the regional geological conditions (which caused active incision of the channel), discharge, and channel sediment composition. Characteristics of lateral migration and curvature development of meander controlled by bedrock and narrowing of the valley are presented. The discharge conditions under which the displacement of riffles is possible are calculated. The forecast of the further channel development and recommendations for sustainable navigation are given.

Shkolnyi D.I., Bakhareva E.I., Semakov V.A., Shkolnaya D.K., Yatsumira D.A.

The features of precipitation and its spatial distribution over the territory of the Primorsky krai during the passage of Typhoon Hinnamnor (September 4–7, 2022), as well as the characteristics of the flood caused by the typhoon, are studied based on ground observational data and the ERA5-Land reanalysis. A list of the settlements affected by the flood and an assessment of the impact of the disaster on transport infrastructure are given. The relationship between the precipitation maxima and the movement of storm cells is shown. Deformations were recorded for 30% of the length of the Primorsky krai river channels as a result of the typhoon passage. The relationship among the changes in the channels, spatial characteristics of precipitation (including their intensity) and the slope of the catchment were determined. Areas of extreme channel deformations (including mudflows) and their magnitudes on rivers of different scales are described.

Чалов С.Р., Чалова А.С., Школьный Д.И.

A quantitative assessment of channel planform changes on the 600-km channel of the Kamchatka River was carried out. Possibilities of semi-automatic GIS-interpretation of satellite images were used for retrospective analysis of such an extended section of a large river. It was estimated that 37% of the left bank length and 44% of the right bank length are eroded. The amount of material coming into the channel due to riverbanks erosion significantly exceeds the sediment runoff, which determines channel type and regime of channel changes. Processes of bank erosion vary on the scale of the longitudinal profile and different channel types. Downstream according to decrease of channel slope, a decrease of bank erosion intensity is observed. The most important factor of bank erosion on the river local section is the volume of material coming from the upstream sections. A quantitative analysis and forecast of planform changes of a river section requires a differential assessment for different morphodynamic channel types, taking into account characteristics of channel processes in the upstream river sections. The bank erosion prognostic equations obtained for the meandering channel and the floodplain-channel multiple branches of the Kamchatka River are discussed.

Чалов Р.С., Школьный Д.И.

This paper represents definitions of extreme and specific manifestations of channel processes and reviews relationships between themselves and connections with extreme or extraordinary hydrological situations. The main sign for referring channel processes as extreme is the anomaly of their manifestation, which is reflected in extremely high rates and duration of development (significantly exceeding the mean maximum values), unexpectedness of occurrence and difficulties or impossibility of forecasting. Specific channel processes occur in conditions of channel formation, which differ from typical for a river or rivers in the region and have limited distribution. Criteria provided to characterize the extremality or specificity of the manifestations of channel processes, their qualitative and quantitative assessments, as well as the analysis of hydrological, geological, geomorphological and anthropogenic factors of their origin and development are given. The spatial scale of manifestations, their frequency, negative social and economic consequences and the possibility of prevention are considered. An approach to the classification of extreme and specific channel processes and the evaluation of their risk to economic activity is proposed. Typical examples of extreme and specific manifestations of channel processes in various temporal and spatial scales and natural zones are shown.

Chalov S.R., Tsyplenkov A.S., Pietron J., Chalova A.S., Shkolnyi D.I., Jarsjö J., Maerker M.

Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012–2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9∙104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model–modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.

Alekseevskii N.I., Magritskii D.V., Koltermann P.K., Toropov P.A., Shkol’nyi D.I., Belyakova P.A.

Inundatios on the Black Sea coast of Krasnodar krai between 1945 and 2013 have been analyzed. The main genetic types of inundations on the coast have been identified. The specific features and regularities of inundation wave transformation along the rivers and over time have been studied. Seasonal and maximal runoff of Black Sea rivers has been analyzed over a long-term period. Regularities in the variations of the number of inundatios and their characteristics over the coastal area have been revealed both at the annual and long-term scales. Quantitative estimates are given to the hazard and damage to the population and economic activity due to inundations in the valleys of Black Sea rivers.

Chalov S.R., Shkol’nyi D.I., Promakhova E.V., Leman V.N., Romanchenko A.O.

An assessment is made of the contribution from different sources supplying sediments to the rivers flowing in areas of open-cast mining of placers in places of their contemporary exploitation (using the Russian Federation and Mongolia as an example). We examine the sediment yield transformation processes in conditions of open-cast gold and platinum mining in the valleys of creeks and small and medium-sized rivers where extraction of mineral resources is an exceptionally important kind of activity (the rivers of the Vyvenka basin, Kamchatka krai) or characteristic for a given territory (Tuul river downstream of the city of Ulaanbaatar, Selenge river basin, Mongolia). We summarized the assessments of the sediment yield transformation downstream of the areas of mining placer deposits along the rivers of Russia, Mongolia, USA, India, Australia, and Surinam. It is shown that stream-channel erosion in anthropogenically modified channels is responsible for up to 90% of technogenic changes in sediment yield. The most significant (by several orders of magnitude) increase in sediment yield has been recorded for small rivers. For large rivers that are characterized by low background values of sediment yield, its change is by a factor of 1.1‒1.2 in the case of single mining operations in the drainage area and reaches a factor of five for large-scale mining operations.

Kuksina L., Belyakova P., Golosov V., Zhdanova E., Ivanov M., Tsyplenkov A., Gurinov A.

Rossoni R.B., Laipelt L., de Paiva R.C., Fan F.M.

Shkolnyi D., Magritsky D., Chalov S.

Zelenin E., Gurinov A., Garipova S., Zakharov A.

Yermolaev O., Mukharamova S.

This paper describes the modelling of suspended sediment yield in a plains region in the European part of Russia (EPR) and its prediction for ungauged catchments. The studied plains area, excluding the Caucasus and Ural Mountains, covers 3.5 × 106 km2 of the total area of about 3.8 × 106 km2. Multiple regression methods, such as a generalized linear model (GLM) and a generalized additive model (GAM), are used to construct the models. The research methodology is based on a catchment approach. There are 49,516 river basins with an average area of about 75 km2 in the plain regions. The suspended sediment yield geodatabase contains data from 385 gauging stations. The linear GLM model of suspended sediment yield explains about 50% and the GAM model about 65% of the data variability (R-squared adjusted). The models include mean slope steepness, percentage of arable land, runoff per unit area, catchment area, soil rank and catchment soil erodibility as significant predictors. They also include a zonal-sectoral gradient (the sum of active temperatures and the standard deviation of air temperature, or directly by geographic coordinates). A GAM model is trained to predict suspended sediment yields for unexplored areas of the area. The paper presents the results of extrapolating suspended sediment yield values to ungauged river basins in a plains region of the EPR. For the first time for such a large area, the models built and the use of the basin approach made it possible to predict runoff values for hydrologically unexplored river basins.

Lipatov V., Mavlyanova N., Tiefenbacher J.

A disaster community's priority is to ensure the safety of populations during natural hazards. Disaster risk reduction strategies require knowledge of what is hazardous, who is vulnerable, and what is risky. As of now, engineering methods predominate in Russian disaster research, while social science rarely analyzes floods, earthquakes, wildfires, etc. Study aims to test the applicability of new methods for delineating flood hazards, characterizing social vulnerability, and determining overall societal risk in Russia. Multidisciplinary nature makes the problem complex. The research will concentrate on the ten representative counties of the Kuban River basin in a southern Russian region, where at the beginning of the XXI century catastrophic floods led to enormous fatalities and huge economic damage. Flood hazards are assessed based on the county-scale spatial distribution of records produced by a Regional Early Warning System, impact information, and flood management infrastructure. Social vulnerability is investigated using a County Comparable Social Vulnerability Profiling model that encompasses three pillars (physical, socio-economic and awareness), nine themes (age, disability, poverty, etc.), and seventeen census variables (aged 0–19 years, density, one-person household in detached housing, only nine years of school, etc.). Finally, a holistic flood risk map is compiled. The results show that the three riskiest counties require measures to reduce flood hazard and social vulnerability in all phases of disaster risk management (mitigation, preparation, emergency, and rehabilitation). Data-poor nations such as Russia can benefit from these methods, but their use is limited by insufficient flood hazard and census information.

Zang C., Sugita M., Okita A., Bi S.

Because volcanic rocks have high permeability, rainfall quickly infiltrates into the ground. Perennial rivers often do not exist in volcanic areas. However, available studies elucidating hydrologic characteristics and the mechanisms of stream formation in young volcanic areas are limited in number, extent, and coverage prohibiting a comprehensive understanding of runoff formation. By measuring river discharge for two years, we examined the characteristics of surface runoff in four adjacent headwater catchments within a young volcanic area of Mt.Fuji. The runoff coefficient R is small, rainfall thresholds for discharge are large, and the lag time Tlag and duration D of rainfall-runoff events are short. These characteristics can be explained by the groundwater flow as the dominant runoff mechanism with high hydraulic conductivity. Due to differences in topography and the depth of groundwater, some differences existed amongst the four adjacent catchments. In addition, a comparison of runoff characteristics between the young volcanic headwater catchments (VHCs) and non-volcanic headwater catchments (NVHCs) reported in other studies established that young VHCs have a smaller R, a shorter Tlag and D, and a larger runoff threshold for storm runoff than NVHCs. These differences are attributed to differences in the hydraulic conductivity of the underlying geology. These findings should help improve hydrological models and river structures for flood prevention.

Munanku T., Banda K., Nyimbili P.H., Mhlongo S.E., Masinja J.

Mine tailings have a huge footprint on the environment and can have serious consequences that are difficult to reverse during mining operations or even long after mining has ceased. Despite several studies that have been conducted on tailings dumps, effective impact assessments of their potential pollution risk have been a challenge. This challenge can, to a certain extent, be attributed to the lack of identification of a common criterion for risk classification to items of environmental concern (people, natural landscapes, and their components) including the absence in consideration of time frames. Consequently, this has made it difficult to conduct impact assessment studies of mine tailing dumps. This study assessed the potential pollution risk of the dumps using a multi-criteria decision making (MCDM) tool called an Analytical Hierarchy Process (AHP). An appropriate criterion for risk assessment was developed with the help of experienced experts and weighted using an AHP methods. This enabled the determination of the potential pollution risk to the environment from three selected Zambian-based tailings dumps (i.e., Kabwe Lead–Zinc, Mopani Copper Mine and Lumwana Mine dumps) by means of a criterion scoring technique developed. Five key indicators were adopted that included: 1) physical properties; 2) soil chemical accumulation; 3) properties of the environment around the dump; 4) climatic factors around the dump area; and 5) protective structures. Specific factors per indicator were identified using expert opinion and experiences. Results of the analysis revealed that the Kabwe Mine tailings dump had the highest pollution potential followed by the Lumwana Mine and then Mopani mine tailings dump when compared against severity of risk scale. The tool was then validated using a tailing dump at Musina Copper Mine, in South Africa, where a different approach was previously used and this tool showed comparable results. Accordingly, this decision support tool can be used by environmental management agencies during the environmental impact assessment (EIA) review processes to improve efficiency in investigating scenarios that would propagate contamination and thus improve environmental management interventions.

Kuksina L.V., Beljakova P.A., Golosov V.N., Zhdanova E.J., Ivanov M.M., Gurinov A.L.

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.

Latushkin A.A., Artamonov Y.Y., Skripaleva E.E., Fedirko A.A., Ryabokon D.D.

The results of hydrological and hydrooptical measurements carried out in the spring (April 22–May 17) and summer (July 29–August 10) 2021 in the north-eastern part of the Black Sea during cruises 116th and 117th of the R/V Professor Vodyanitsky are presented. It is shown that in spring, when there was an intensive rivers run-off, the area with a high content of total suspended matter was a strip up to 40 km wide, stretched along the coast of the Krasnodar Krai. In summer, when the river run-off was weakened, the maximum values of the total suspended matter concentration were noted in a relatively narrow coastal strip no more than 20 km wide. Maximum turbidity was noted in the surface layer in spring and in summer it descended into the layer of seasonal thermocline, halocline and pycnocline. The consistency of the horizontal distributions of the total suspended matter concentration and temperature had a significant level deeper than the seasonal thermocline – in the spring in the layer from 20 to 35 m, in the summer in the layer from 15 to 70 m, while a direct correlation was observed, i.e. at these depths, warmer waters were characterized by increased turbidity. The maximum level of consistency between the horizontal fields of the total suspended matter concentration, salinity and density in spring was observed in the upper 20–25 m layer, while the correlation was inverse, i.e. at these depths, less saline and denser waters were characterized by increased turbidity, which is explained by intensive river run-off. In summer, the nature of the correlation was preserved, and the best consistency of the horizontal fields of the total suspended matter concentration, salinity and density was observed in the surface 10-m layer and deeper than the seasonal halocline and pycnocline in the 20–40 m layer.

Burova V.N.

Sheverdyaev I., Misirov S.

The rivers of the North-Western Caucasus, despite the flood regime of runoff, until 2013 were not covered by regular observations of the water level. The network of automatic level gauges accumulated level observations every 10 minutes in 2014–2020. Spatial analysis tools were used to calculate the distribution of flood runoff velocities and the distribution of water runoff time on watersheds. Histograms of the distribution of watershed areas of level gauges by travel time were obtained and hydrographs for extreme precipitation were calculated using the example of July 6–7, 2012 in Krymsk. In the water level observation data, periods of level growth of more than 20 cm, accompanied by intense precipitation—4110 flood events at 69 level gauges, were identified. Flood cases are divided according to level growth into groups: up to 0.5 m, up to 1.0 m, up to 2.0 m and more than 2.0 m. The distribution of maximum daily precipitation according to ERA5-Land data for the watersheds of level gauges is considered. The calculated discharges and observations of the level showed that the highest discharges and high and frequent flood levels are observed on the rivers of the northern macroslope of the Caucasian watershed—rivers Abin, Shebsh and Pshish. On the southern macroslope, rivers are distinguished. Mezyb, Vulan, Pshada, Shapsho and Dzhubga, however, they are inferior to the watersheds of the northern macroslope. The scale and number of flood level rises in the northern watersheds (left tributaries of the Kuban River) increases from west to east and in accordance with the growth of the watershed area. In the southern watersheds, the trend is similar, but due to smaller watersheds in general, less noticeable. The highest value of the ratio of the maximum discharge to the total runoff is observed in the smallest watersheds, i.e. the most sudden floods are observed on them, however, due to the small catchment area, they do not form dangerous flood levels. A small number of flood events in the watersheds of the western part of the region is due to the nature of precipitation in 2012–2020 and small areas.

Mironenko A.A., Rets E.P., Frolova N.L.

The present-day dynamics of maximal water levels was evaluated, and space and time variations of level excess during unfavorable and hazardous events in North Caucasian rivers were analyzed. The study was based on data from 59 hydrological gages over period 1961–2017. The mathematical expectation of maximal water levels was found to increase everywhere from 1961–1990 to 1991–2017, and the increase in the variance was also a dominating trend in North Caucasian rivers. In the period under consideration, water levels of unfavorable and hazardous phenomena were exceeded by maximal water levels on the average in 19.3 and 10.6% cases, respectively. At some sections, this characteristic reached 93.2 and 88.6%, respectively. The marks of unfavorable and hazardous phenomena in the Kuban basin and in rivers of the Caucasian Black Sea coast was found to increase between 1961–1990 and 1991–2017. In rivers in the Terek and Kuma basins, the numbers of gages where the marks of unfavorable phenomena increased or decreased were the same; however, from 1961–1990 to 1991–2017, dominating are gages with a tendency toward a decrease in the number of cases with levels above the marks of hazardous phenomena.

Belyakova P.A., Moreido V.M., Tsyplenkov A.S., Amerbaev A.N., Grechishnikova D.A., Kurochkina L.S., Filippov V.A., Makeev M.S.

Abstract The potential of construction of machine learning models was considered as applied to water level forecasting in mountain river reaches in Krasnodar Krai based on observation data on water levels at automated hydrological complexes of the Automated System of Flood Conditions Monitoring in Krasnodar Krai. The study objects were two mountain rivers in Krasnodar Krai―the Pshish and Mzymta. These rivers flow in different natural conditions and differ in their water regimes and the character of lateral inflow in the reaches under consideration. The study focused on three widely used machine learning architectures: regression model of decision trees M5P, gradient boosting of decision trees XGBoost, and artificial neural network based on multilayer perceptron. The forecast quality was evaluated for lead time from 1 to 20 h; variations for rivers with different water regimes and the potential of the examined models as applied to operational forecasting are discussed. The optimal lead time for the Pshish river was found to be 15–18 h (with S/σΔ varying within 0.38–0.39 for XGBoost model); the simulation quality for the Mzymta river is evaluated as good; however, the necessary forecast efficiency is not attained (at the lead time of 5 h, we have S/σΔ = 0.87 for MLP model). The obtained results allow the machine learning models to be regarded as acceptable for short-term hydrological forecasting based on high-frequency water level observation data.

Zamana L.V., Vakhnina I.L.

Abstract Based on the results of the analysis of satellite images and field observations, data on the length of the gold-bearing placers disturbed by the development along a number of main tributaries of the Shilka and Argun rivers are presented, the formed technogenic relief forms are indicated. Depending on the method of development, two types of technogenic landscapes have been identified - the excavation-dump with hydromonitor mining and belt trench-dump when washing with drags. The main directions of research on the assessment of placer gold mining in the natural complexes of river valleys are proposed.

Ilyushina P.G., Shikhov A.N., Makarieva O.M.

Gold mining at ore and alluvial deposits substantially negatively impacts the natural environment, in particular, by land degradation and the contamination of watercourses with suspended solids. In this study, we consider a methodology for identifying and mapping the negative impact of gold mining enterprises on the natural environment based on a long-term series of free-available Landsat and Sentinel-2 satellite images. This study is carried out using the example of Tenkinsky, Susumansky, and Yagodninsky districts in Magadan oblast, where the largest gold deposits are located. Identifying features of active mining areas, as well as abandoned ones (on which vegetation began to recover), have been found in satellite images. Based on the expert interpretation of the images and NDVI analysis, it is found that about 2% of the study area has been affected by gold mining. The processes of vegetation recovery are identified only on 10% of the degraded lands. In the Tenkinsky district, the area of disturbed lands for the period 2001–2021 increased more than seven times, which is associated with a substantial increase in gold mining. Using the C2RCC processor (module of the SNAP software package), the content of suspended solids in the water of the most impacted rivers, the Berelekh, Ayan-Yuryakh, and Kolyma, has been estimated in comparison with natural values (typical for noncontaminated water). We have found that the main source of suspended matter in the rivers is the alluvial gold deposits located in the floodplain of the Berelekh River. At the same time, the seasonal variability of water contamination is determined by the hydrological situation. In particular, water turbidity decreases during low water periods and increases during high-flow periods.

Habel M., Nowak B., Szadek P.

Our study provides a retrospective evaluation of the perturbances of the opencast mining on the small river. Based on a standard 'before-after-control-impact' approach, we assess the impact of disturbances on aquatic ecosystems. For this purpose, we used IHA (Index of Hydrological Alteration) statistics to fully quantify the impact of open-pit mine on flow regimes of small-to-medium-size rivers. The analysis results in flow data captured in the 33 parameters of the range variability approach (RVA) and five ecological flow components (EFC). This approach helped us comprehensively evaluate the alteration in the flow regime in areas of open-pit mining on the example of the Noteć River, a typical lowland river. We conclude that the level integrated hydrologic alterations to this river under the influence of the groundwater depression cone and water from the mine dewatering are high, as assessed by the RVA and EFC methods. Specifically, this work uses the IHA framework to verify the necessity of including a specific group of indicators. Our analysis shows that for the post-impact period on the investigated river, the functioning of the river ecosystem was degraded. One of the EFC components completely disappeared at both water gauge stations. There were also profound hydrologic alterations, such as increased frequency or duration of "extreme low flows" at one station; at the second station, "high flow pulses" occurred more frequently. More than 65 % of the altered parameters in five IHA groups were modified drastically. In the river section affected by the groundwater depression cone, both the minimum and maximum flows decreased by 20 % to 55 %. In the section where water from the mine dewatering is fed in, the minimum flows changed by + 170 to + 230 %. The use of the IHA tool provides an opportunity for environmental flow restoration of water conditions in degraded post-mining areas.

Ferrer-Boix C., Scorpio V., Martín-Vide J.P., Núñez-González F., Mora D.

This research analyses multiple anthropogenic pressures in the Bernesga River, a gravel-bed river in Northwestern Iberian Peninsula. Among the causes of river incision in Bernesga River are extensive mining during the second half of the twentieth century, a ∼100 years-long history of channelization and river training starting around 1900, and to a lesser extent, land-use changes in the basin. As a result of these impacts, reach-averaged incision exceeds 8.5 m. Severe incision occurred simultaneously with a dramatic change in channel pattern: from ∼450 m-wide braided morphology around middle of the twentieth century to a narrow single-thread (∼40 m wide) channel in 2017. Quaternary alluvial deposits have been mostly depleted exposing the underlying bedrock. Unlike other rivers, bedrock outcrops have not stopped incision. Extremely narrow channels (∼12 m wide) have developed and incised at rates of ∼0.11 m/yr into bedrock materials, headcuts have formed on bedrock deposits and have rapidly retreated (at 33 m/yr) and the channel has incised forming adverse slopes under the presence of bed sills. Cause-effect relationships of cumulative impacts have been established between the recent evolutionary trajectory of the Bernesga River and multiple and simultaneous anthropogenic pressures.

Shikhov A., Ilyushina P., Makarieva O., Zemlianskova A., Mozgina M.

Gold mining generates major environmental impacts like landscape degradation, accumulation of waste rock dumps, and water contamination by suspended solids. Russia ranks third in the world in gold production, but the impact of gold mining has not been previously estimated for its vast northeastern part. This study provides a detailed overview of land-cover changes associated with gold mining in the Magadan region (northeast Russia) in the 21st century, where alluvial gold production has increased by a third in the last 20 years. A long-term series of Landsat and Sentinel-2 images obtained in July and August are used to compile two datasets of mining-impacted areas with totally removed vegetation for 2000–2002 and 2022. We calculated the NDVI difference and then discriminated mining-related vegetation losses from other bare areas, using additional data like the classification of landforms based on the digital surface model and the data on mining allotments. The total area of gold-mining sites was estimated as 41,206 ha in 2000–2002 and 72,602 ha in 2022, with an increase of 26,031 ha over the past 4–6 years. Moreover, this is a lower-boundary estimate, without taking into account man-made reservoirs and historical mines recovered by vegetation. The spatial distribution of mining sites has not changed significantly over the past two decades and has a maximum in the western part of the region. We found that the floodplains of the Berelekh and Debin Rivers (large tributaries of the Kolyma River) are most heavily impacted by gold mining with a removed vegetation canopy occupying 16.0% and 11.2% of their area. Along with the land degradation assessment, we found that 19,900 ha of historical gold-mining sites in the Berelekh River basin are recovered by vegetation, which is comparable in size to the areas impacted by mining over the past 20 years.

Tang L., Werner T.T.

AbstractMining is of major economic, environmental and societal consequence, yet knowledge and understanding of its global footprint is still limited. Here, we produce a global mining land use dataset via remote sensing analysis of high-resolution, publicly available satellite imagery. The dataset comprises 74,548 polygons, covering ~66,000 km2 of features like waste rock dumps, pits, water ponds, tailings dams, heap leach pads and processing/milling infrastructure. Our polygons finely contour the edges of mine features and do not include the space between them. This distinguishes our dataset from others that employ broader definitions of mining lands. Hence, despite our database being the largest to date by number of polygons, comparisons show relatively lower global land use. Our database is made freely available to support future studies of global mining impacts. A series of spatial analyses are also presented that highlight global mine distribution patterns and broader environmental risks.

Nolos R.C., Zamroni A., Evina K.F.

Palawan Island is home to one of Southeast Asia’s largest, oldest, and most diversified rainforests hence it was called the «Last Frontier.» However, the island province’s forest is contending with increased conversion of forest lands to plantation and household-level agriculture, intensive mineral mining, illegal logging, and other pressures on its ecosystems. Understanding these factors in relation to the prevalence of deforestation and forest degradation in Palawan is imperative. This paper analyzed these drivers of deforestation and forest degradation in Palawan using the social-ecological systems (SES) and institutional analysis development (IAD) frameworks. A literature review was conducted using a variety of web-based databases and sources and additional data were collected from official websites and reports. The identified major drivers of deforestation and forest degradation in the province include increasing population, migration from lowland to upland areas, illegal logging, mining, wide-scale kaingin and oil palm plantation, wildlife poaching, and weak policy implementation and enforcement. These identified drivers can be the target of the government of Palawan for their forest management plans. Additional findings and recommendations of this paper will also aid in the forest management planning in Palawan and other areas where similar settings exist.

Chalov S., Prokopeva K.

Lena River is one of the largest “pristine” undammed river systems in the World. In the middle and low (including delta) 1500 km course of the Lena main stem river forms complex anabranching patterns which are affected by continuous permafrost, degradation of the frozen ground and changes in vegetation (taiga and tundra). This study provides a high-resolution assessment of sediment behavior along this reach. Comprehensive hydrological field studies along the anabranching channel located in the middle, low and delta courses of the Lena River were performed from 2016 to 2022 including acoustic Doppler current profiler (ADCP) discharge measurements and sediment transport estimates by gravimetric analyses of sediment concentration data and surrogate measurements (optical by turbidity meters and acoustic by ADCP techniques). These data were used to construct regional relationships between suspended sediment concentrations (SSC, mg/L), turbidity (T, NTU) and backscatter intensity (BI, dB) values applicable for the conditions of the Lena River. Further, field data sets were used to calibrate the seasonal relationships between Landsat reflectance intensities and field surface sediment concentration data. Robust empirical models were derived between the field surface sediment concentration and surface reflectance data for various hydrological seasons. Based on the integration of in situ monitoring and remote sensing data we revealed significant discrepancies in the spatial and seasonal patterns of the suspended sediment transport between various anabranching reaches of the river system. In the middle course of the Lena River, due to inundation of vegetated banks and islands, a downward decrease in sediment concentrations is observed along the anabranching channel during peak flows. Bed and lateral scour during low water seasons effects average increase in sediment load along the anabranching channels, even though a significant (up to 30%) decline in SSC occurs within the particular reaches of the main channel. Deposition patterns are typical for the secondary channels. The anabranching channel that was influenced by the largest tributaries (Aldan and Viluy) is characterized by the sediment plumes which dominate the spatial and temporal sediment distribution. Finally, in the distributary system of the Lena delta, sediment transport is mostly increased downwards, predominantly under higher discharges and along main distributary channels due to permafrost-dominated bank degradation.

Camalan S., Cui K., Pauca V.P., Alqahtani S., Silman M., Chan R., Plemmons R.J., Dethier E.N., Fernandez L.E., Lutz D.A.

Monitoring changes within the land surface and open water bodies is critical for natural resource management, conservation, and environmental policy. While the use of satellite imagery for these purposes is common, fine-scale change detection can be a technical challenge. Difficulties arise from variable atmospheric conditions and the problem of assigning pixels to individual objects. We examined the degree to which two machine learning approaches can better characterize change detection in the context of a current conservation challenge, artisanal small-scale gold mining (ASGM). We obtained Sentinel-2 imagery and consulted with domain experts to construct an open-source labeled land-cover change dataset. The focus of this dataset is the Madre de Dios (MDD) region in Peru, a hotspot of ASGM activity. We also generated datasets of active ASGM areas in other countries (Venezuela, Indonesia, and Myanmar) for out-of-sample testing. With these labeled data, we utilized a supervised (E-ReCNN) and semi-supervised (SVM-STV) approach to study binary and multi-class change within mining ponds in the MDD region. Additionally, we tested how the inclusion of multiple channels, histogram matching, and La*b* color metrics improved the performance of the models and reduced the influence of atmospheric effects. Empirical results show that the supervised E-ReCNN method on 6-Channel histogram-matched images generated the most accurate detection of change not only in the focal region (Kappa: 0.92 (± 0.04), Jaccard: 0.88 (± 0.07), F1: 0.88 (± 0.05)) but also in the out-of-sample prediction regions (Kappa: 0.90 (± 0.03), Jaccard: 0.84 (± 0.04), and F1: 0.77 (± 0.04)). While semi-supervised methods did not perform as accurately on 6- or 10-channel imagery, histogram matching and the inclusion of La*b* metrics generated accurate results with low memory and resource costs. These results show that E-ReCNN is capable of accurately detecting specific and object-oriented environmental changes related to ASGM. E-ReCNN is scalable to areas outside the focal area and is a method of change detection that can be extended to other forms of land-use modification.

Zamana L.V., Vakhnina I.L.

Abstract Based on the results of the analysis of satellite images and field observations, data on the length of the gold-bearing placers disturbed by the development along a number of main tributaries of the Shilka and Argun rivers are presented, the formed technogenic relief forms are indicated. Depending on the method of development, two types of technogenic landscapes have been identified - the excavation-dump with hydromonitor mining and belt trench-dump when washing with drags. The main directions of research on the assessment of placer gold mining in the natural complexes of river valleys are proposed.

Chalov S., Prokopeva K., Habel M.

This study presents detailed suspended sediment budget for the four Siberian river deltas, representing contrasting conditions between Northern and Southern environments. Two of the studied rivers empty their water and sediments into the marine located in the permafrost zone in the Arctic region (Lena and Kolyma), and the other two (Selenga and Upper Angara) flow into Lake Baikal located in the steppe and forest-steppe zone of Southern Siberia. For the first time, these poorly monitored areas are analyzed in terms of the long-term and seasonal changes of spatial patterns of suspended sediment concentrations (SSC) over distributaries systems. Remote sensing reflectance is derived from continuous time series of Landsat images and calibrated with the onsite field measurements of SSC. Seasonal variability of suspended sediment changes over deltas was captured for the period from 1989 to 2020. We identify significant variability in the sedimentation processes between different deltas, which is explained by particularities of deltas networks and geomorphology and the existence of specific drivers—continuous permafrost impact in the North and abundant aquatic vegetation and wetland-dominated areas in the South. The study emphasizes that differences exist between Northern and Southern deltas regarding suspended sediments transport conditions. Mostly retention of suspended sediment is observed for Southern deltas due to sediment storage at submerged banks and marshlands located in the backwater zone of the delta during high discharges. In the Northern (arctic) deltas due to permafrost impacts (melting of the permafrost), the absence of sub-aquatic banks and river to ocean interactions of suspended sediment transport is mostly increased downwards, predominantly under higher discharges and along main distributary channels. These results shine light on the geochemical functions of the deltas and patterns of sequestering various metals bound to river sediments.

Muñoz-Sabater J., Dutra E., Agustí-Panareda A., Albergel C., Arduini G., Balsamo G., Boussetta S., Choulga M., Harrigan S., Hersbach H., Martens B., Miralles D.G., Piles M., Rodríguez-Fernández N.J., Zsoter E., et. al.

Abstract. Framed within the Copernicus Climate Change Service (C3S) of the European Commission, the European Centre for Medium-Range Weather Forecasts (ECMWF) is producing an enhanced global dataset for the land component of the fifth generation of European ReAnalysis (ERA5), hereafter referred to as ERA5-Land. Once completed, the period covered will span from 1950 to the present, with continuous updates to support land monitoring applications. ERA5-Land describes the evolution of the water and energy cycles over land in a consistent manner over the production period, which, among others, could be used to analyse trends and anomalies. This is achieved through global high-resolution numerical integrations of the ECMWF land surface model driven by the downscaled meteorological forcing from the ERA5 climate reanalysis, including an elevation correction for the thermodynamic near-surface state. ERA5-Land shares with ERA5 most of the parameterizations that guarantees the use of the state-of-the-art land surface modelling applied to numerical weather prediction (NWP) models. A main advantage of ERA5-Land compared to ERA5 and the older ERA-Interim is the horizontal resolution, which is enhanced globally to 9 km compared to 31 km (ERA5) or 80 km (ERA-Interim), whereas the temporal resolution is hourly as in ERA5. Evaluation against independent in situ observations and global model or satellite-based reference datasets shows the added value of ERA5-Land in the description of the hydrological cycle, in particular with enhanced soil moisture and lake description, and an overall better agreement of river discharge estimations with available observations. However, ERA5-Land snow depth fields present a mixed performance when compared to those of ERA5, depending on geographical location and altitude. The description of the energy cycle shows comparable results with ERA5. Nevertheless, ERA5-Land reduces the global averaged root mean square error of the skin temperature, taking as reference MODIS data, mainly due to the contribution of coastal points where spatial resolution is important. Since January 2020, the ERA5-Land period available has extended from January 1981 to the near present, with a 2- to 3-month delay with respect to real time. The segment prior to 1981 is in production, aiming for a release of the whole dataset in summer/autumn 2021. The high spatial and temporal resolution of ERA5-Land, its extended period, and the consistency of the fields produced makes it a valuable dataset to support hydrological studies, to initialize NWP and climate models, and to support diverse applications dealing with water resource, land, and environmental management. The full ERA5-Land hourly (Muñoz-Sabater, 2019a) and monthly (Muñoz-Sabater, 2019b) averaged datasets presented in this paper are available through the C3S Climate Data Store at https://doi.org/10.24381/cds.e2161bac and https://doi.org/10.24381/cds.68d2bb30, respectively.

Jones E., Wing A.A., Parfitt R.

AbstractThis study compares the spread in climatological tropical cyclone (TC) precipitation across eight different reanalysis datasets: NCEP-CFSR, ERA-20C, ERA-40, ERA5, ERA-Interim, JRA-55, MERRA-2, and NOAA-20C. TC precipitation is assigned using manual tracking via a fixed 500-km radius from each TC center. The reanalyses capture similar general spatial patterns of TC precipitation and TC precipitation fraction, defined as the fraction of annual precipitation assigned to TCs, and the spread in TC precipitation is larger than the spread in total precipitation across reanalyses. The spread in TC precipitation relative to the inter-reanalysis mean TC precipitation, or relative spread, is larger in the east Pacific than in the west Pacific. Partitioned by reanalysis intensity, the largest relative spread across reanalyses in TC precipitation is from high-intensity TCs. In comparison with satellite observations, reanalyses show lower climatological mean annual TC precipitation over most areas. A comparison of area-averaged precipitation rate in TCs composited over reanalysis intensity shows the spread across reanalyses is larger for higher intensity TCs. Testing the sensitivity of TC precipitation assignment to tracking method shows that climatological mean annual TC precipitation is systematically larger when assigned via manual tracking versus objective tracking. However, this tendency is minimized when TC precipitation is normalized by TC density. Overall, TC precipitation in reanalyses is affected by not only horizontal output resolution or any TC preprocessing, but also data assimilation and parameterization schemes. The results indicate that improvements in the representation of TCs and their precipitation in reanalyses are needed to improve overall precipitation.

Domingo J.P., Attal M., Mudd S.M., Ngwenya B.T., David C.P.

An important gap in the management of land erosion in mining-affected areas is the understanding of the entire sediment routing system and the links between sources and storage at the catchment scale. In this study, we examine sediment delivery and its seasonality in the nickel mining-affected Santa Cruz and Pamalabawan catchments in the Philippines. We monitored discharge, suspended sediment concentrations and suspended sediment loads across 13 sub-catchments with contrasting degrees of mining influence from June 2018 to July 2019. First, we show the importance of the size of the area that has been physically disturbed within our sub-catchments, with as little as 10–22% of relative disturbance area being enough to generate four-fold to eight-fold increase in the sediment yield relative to less disturbed and pristine areas. We found that sub-catchments with > 10% disturbance exhibit the highest sediment yields (15.5 ± 44.7 t km−2 d−1) compared with sub-catchments with < 10% disturbance (3.6 ± 17.7 t km−2 d−1) and undisturbed catchments (2.0 ± 5.7 t km−2 d−1). We also show that sediment flushing predominantly occurs in the most disturbed sub-catchments at the onset of the wet season. A small number of flood events transports the bulk of the sediment, with hysteresis effects being most pronounced in disturbed areas. Lastly, we show that floodplain sediment recycling exerts a key control on sediment delivery at both reach and catchment scales, with the relative contribution of floodplain sources to the sediment budget becoming dominant in the latter stages of the wet season- up to 89% of the total sediment export per storm event. This study highlights the importance of both degree of disturbance and sediment pathways in controlling sediment transport in mining-disturbed areas, and that considering the entire sediment routing system including intermediate stores is crucial to optimizing existing and future measures against siltation and potential contamination of trace metals and metalloids downstream of mining areas.

Wang P., Huang Q., Pozdniakov S.P., Liu S., Ma N., Wang T., Zhang Y., Yu J., Xie J., Fu G., Frolova N.L., Liu C.

Abstract Despite the increasing Siberian river discharge, the sensitivity of streamflow to climate forcing/permafrost thawing is poorly quantified. Based on the Budyko framework and superposition principles, we detected and attributed the changes in streamflow regimes for the three great Siberian rivers (Ob, Yenisei, and Lena) during 1936–2019. Over the past 84 years, streamflow of Ob, Yenisei and Lena has increased by ∼7.7%, 7.4% and 22.0%, respectively. Intensified precipitation induced by a warming climate is a major contributor to increased annual streamflow. However, winter streamflow appears to be particularly sensitive to temperature. Whilst rising temperature can reduce streamflow via evapotranspiration, it can enhance groundwater discharge to rivers due to permafrost thawing. Currently, every 1 °C rise in temperature likely leads to 6.1%–10.5% increase in groundwater discharge, depending on the permafrost condition. For permafrost-developed basins, the contribution to increased streamflow from thawing permafrost will continue to increase in the context of global warming.

Souza‐Filho P.W., Lobo F., Cavalcante R., Mota J.A., Nascimento W., Santos D.C., Novo E., Barbosa C.C., Siqueira J.O.

The Amazon region has suffered considerable deforestation rates related to logging, cattle ranching, and agriculture. Recently, attention has been given to deforestation due to mining activities. This paper aims to estimate the land area affected by mining activities in protected and nonprotected areas, the value of the traded mineral extraction per commodity, and the mineral commodity with the highest trade (mineral extraction per mining area). Our results show that mining activities occupied 1,110 km2 of the Amazon, where 65% and 35% of this was due to artisanal and industrial-scale mining, respectively. Gold exploitation was responsible for 58% of the total, followed by aluminum (15%), tin (13%), and iron (8%). In the region, 47% of the total mining area was located inside protected areas, where extraction was dominated by artisanal gold mining. The Amazonian states generated US$ 12.6 billion in 2017. Analysis of the values of the traded production showed that iron was responsible for 63.6%, followed by copper (16.2%), aluminum (7.6%), and gold (6.5%). The value of the traded production of gold was relatively low (US$ 810 million) in comparison to iron (US$ 8.01 billion) and copper (US$ 2.04 billion), which occupied the smallest areas. The value of the traded production per area showed that iron ore exploitation generated US$ 91.8 million/km2, while gold generated only 1.3 million/km2. We conclude that the industrial mining of iron ore presented the lowest impacts in mining areas with higher traded mineral extraction, while artisanal gold production ran contrary to environmental conservation goals.