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• Role of periglacial regions in mercury (Hg) cycling in the Antarctic coastal zone. • Spatial variability of Hg and MeHg concentrations in soil of ice-free areas. • Study confirms link between weathering of rocks and the Hg concentration in soil. • Presence of animals, e.g. penguins and seals, impacts the concentration of Hg in soil. • OM is a key factor affecting Hg distribution across Antarctic terrestrial ecosystems. The Antarctic plays a critical role in global mercury cycling as both a sink of Hg and, in response to rapid global warming, an emerging source of Hg through its release from thawing permafrost and recessing glaciers. At the present time, Antarctica and surrounding areas have little mercury contamination in comparison to other regions of the world. Understanding the sources and transformations of Hg in the Antarctic will be particularly important in predicting the role of a changing environment in the mercury cycle as emissions and global climate change. Study samples were collected at 12 stations, categorized into three groups based on the human or animal presence and flora. Sampling took place in December 2018 and January 2019, and soil and parent rock samples were collected and analyzed for total mercury concentration and its fractions using atomic absorption spectroscopy. Bedrock samples collected on the coast of Admiralty Bay were found to have low organic matter content, while soil samples from the west shore of the bay had a high variability of organic matter content, ranging from 3 % to 41 %. The concentration of total mercury in bedrock ranged from 2.1 ng/g to 15.0 ng/g, and in soil samples, the total mercury concentration ranged from 4.7 ng/g to 143.1 ng/g. This paper reviews current knowledge of Hg cycling in the Antarctic, including its sources, fate, and effects on the ecosystem. The implications of climate change for Hg cycling in the region are also discussed, highlighting the need for continued research to better understand the potential impacts of Hg contamination in the Antarctic. [ABSTRACT FROM AUTHOR]

• Landscape ecological vulnerability was assessed using bagging ANN-MLP and RF models. • B-MLP model was found best fit model for LEV assessment based on ROC curve, recall, precision, F1-score and accuracy. • Largest area under very high LEV was recorded in the southern part of the plains. • Rainfall, soil, vegetation and LULC were found influencing factors for LEV. • Plantation, embankments and geotextile technology are suggested to check erosion. Riverbank erosion is one of the most catastrophic hazards that renders floodplains vulnerable across the world vulnerable. It creates a significant negative impact on the environment and socio-economic life. This paper attempts to assess the landscape ecological vulnerability (LEV) to riverbank erosion in the Middle Brahmaputra floodplains of Assam, India by employing two machine learning models, namely artificial neural network-multilayer perceptron (ANN-MLP) and random forest (RF). Bagging ensembles were created for both ANN-MLP and RF (B-MLP and B-RF) to generate LEV zones. A total of eleven site-specific parameters were considered for the study. The receiver operating characteristic (ROC) based area under curve (AUC), accuracy, precision, recall and F1-score were used to validate the models and judge the models' performance. A sensitivity analysis was performed to deduce the most influential LEV parameters. The results revealed that B-MLP was the better-performing model compared to B-RF based on all five validation metrics. The largest area was found under very high vulnerability zone followed by very low, low, high and moderate vulnerability zones, based on both ensemble models. The western part of the floodplains was found to be more vulnerable than the eastern part. Moreover, the southern bank faced more vulnerability in comparison to the northern bank. The factors namely rainfall, soil type, vegetation and land /use land cover (LULC) influenced bank erosion vulnerability. This research provides evidence that the study area is under severe threat to riverbank erosion and urgently requires the implementation of effective mitigation measures. The study might benefit policymakers and local stakeholders to protect the floodplains from bank erosion and reduce vulnerability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Congeners of PCDD/Fs and DL-PCBs were examined in the sediments of Iznik lake. • PCB 118, PCB 105 and Hepta – Octa CDD/Fs are the dominant in the sediments. • Sediment close to industrial companies has the highest amount of pollutant. • Dioxin-like toxicity levels of sediments are higher than threshold of 0.85 pg TEQ/g. • Dioxin-like (PCDD/Fs and DL-PCBs) concentrations do not exceed the tolerable daily intake value. Iznik lake is the biggest lake in the Marmara region, which is the most industrialized and populated area of Türkiye. The lake is one of Türkiye's most important water supply areas and is located nearby the Iznik district of Bursa, with a population of about 45,000. It is being used for irrigation and fishery production, but not for drinking water. In this paper, the distribution, pollution source, and risk assessment of polychlorinated dibenzodioxins/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in the surface sediments of Iznik lake and streams (both flowing to and flowing from the lake) were investigated. Six surface sediments collected from the lake and four surface sediments collected from the streams were analyzed in high-resolution gas chromatography-mass spectrometry (HR/GC–MS) system in accordance with EPA 1613 and EPA 1668 methods. The concentration ranges of the ∑PCDD/Fs is 21.4 pg/g d.w. (inside the lake (IZ-6)) – 54.5 pg/g d.w. (Gülayağı stream (IZ-8)) and ∑DL-PCBs is 13.5 pg/g d.w. (inside the lake (IZ-3)) – 46.3 pg/g d.w. (Olukdere (IZ-7)) respectively, with 2.68 pg TEQ/g d.w. on average. The results showed that the high chlorinated (Hepta – Octa CDD/Fs) dioxins/furans and pentachlorinated PCBs (PCB 118 and 105) are dominant in the sediments. A detailed assessment of PCDD/F congener profiles observed in the lake sediments speculated that the wastewater discharges to the lake could be the main pollution source, while other sources such as open burning activities, runoff of pesticide residues from agricultural areas and atmospheric deposition may have some contribution also. The health risk assessment performed for polluted sediment demonstrated that, in the worst case, dioxin-like (PCDD/Fs and DL-PCBs) concentration was a total intake of 0.37 pg TEQ/kg body weight/day, no exceeds the tolerable daily intake amount, where fish consumption accounts for nearly all of the total intake. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of data record length on environmental flow calculation is presented. • Method 7Q10 is the less sensitive to environmental flow calculations. • Trend analysis should be the starting point for calculation of environmental flows. • Environmental flows have a significant impact on water resource availability. • Environmental flows are the starting point for sustainable water management. The paper presents the analysis of problems regarding the calculation of EFs using selected hydrological methods. It was conducted in 14 catchments in the Vistula and Oder River basins in Poland. The Kostrzewa, Tennant, Q 90% , and 7Q10 methods were used for the analysis. The analysis showed a significant trend in the hydrological time series. The sensitivity of different applied methods to time series length was shown. High differences were observed between environmental flow (EF) values calculated for periods defined by break points. The hydrological drought and its impact for EFs were also observed for half years in the period. Finally, different values of water deficit characteristics were presented depending on the method used for EF calculation. [ABSTRACT FROM AUTHOR]

• The early attenuation of soil strength contributes to landslides caused by changes in pore water pressure. • Corrected the safety factor curve of cohesive soil slope superficial failure. • The potential sliding surface is closely related to the spatial variation of soil properties in the 'affected layer'. Slope failure is associated with changes in pore water pressure induced by rainfall, this paper further attempt to bridge knowledge gaps that exist in understanding the relationship between mechanism of rainfall-induced regional-scale widespread shallow landslides in cohesive soils and change in pore water pressure. We designed in situ slope experiments with pre-designed vertical profiles at the toe of the slope, and used pore water pressure, conductivity, and moisture content sensors to capture the changing characteristics of soil properties during slope failure. The experiment finds that failure occurred first where internal material was continuously taken out of the slope, even before the maximum static pore water pressure is reached. However, the slope remains stable when the pore water pressure near the failure surface reached the maximum static pore water pressure that could be provided by rainfall. Instead, slope failure during subsequent rainfall periods, even if the pore pressure is then lower. Meanwhile, the soluble minerals in the soil continuously dissolve and migrate, causing the electrical conductivity before slope failure is approximately 1.38 times that after failure, on average. Here, we estimate that the changes in soil properties caused by progressive water infiltration only may have decreased test slope stability by an average of approximately 33.0%. Therefore, we suggest that the early attenuation of soil strength caused by the gradual changes in soil properties makes a significant contribution to soil failure caused by pore water pressure. This was verified in the case of the 7.25 Tianshui group-occurring landslides. Finally, by using an automatic laser particle size analyzer, scanning electron microscope, X-ray diffraction, ion chromatography, and quadruple direct shear instrument to analogize the changes in soil properties exposed to different leaching environments on loess platform, we further show that the early attenuation soil strength is caused by deteriorate in soil properties in the processes of successive years of rainfall, where the content of cemented minerals tends to decrease, fine particles tend to be lost, and pore structure tends to take the form of single macro-pores, which are more likely distributed around mineral particles >10 μm. Our results provide a new perspective on the widespread shallow landslides caused by changes in pore water pressure in a region and their associated gradual deteriorations in soil properties. [ABSTRACT FROM AUTHOR]

• We proposed a novel OBIA-GEE method for mapping gully affected areas. • 50 features from Sentinel 2 imagery and AW3D 30 DEM are used in OBIA-GEE. • OBIA-GEE considers the complex dynamic spectral characteristics of gully. • OBIA-GEE achieved good performance and robustness in mapping gully affected areas. • This research can be expanded globally since freely available dataset and platform. Gullies pose a great threat to the sustainable development of agricultural production and the ecological environment. Accurate mapping of gully affected areas plays an important role in regional environmental monitoring and management. In this paper, an object-based image analysis method based on the Google Earth Engine (OBIA-GEE) is proposed for mapping gully affected areas by using Sentinel 2 imagery and AW3D30 DEM data. The method utilizes the simple non-iterative clustering (SNIC) algorithm to segment the top-five principal component images derived from Sentinel-2 surface reflectance images. Then, the random forest (RF) algorithm is used for feature importance analysis and gully affected area mapping. Finally, the gully affected area mapping results are further optimized by establishing terrain skeleton lines. The proposed method is applied to five study areas with different landform types on the Chinese Loess Plateau, and the results show that the method achieves good performance in mapping gully affected areas, with an overall accuracy (OA) of 86.44%, an F score (F1) of 0.84, a user's accuracy (UA) of 84.97%, and a producer's accuracy (PA) of 83.90%. Compared with the OA of the results of a previous study (OA was 78.8%), the accuracy of the gully affected area mapping results herein improved by 7.64%. The RF feature importance results and findings of different feature combination cases demonstrate that textural information, time series spectral information, and topographic factors are important for mapping gully affected areas. Object-based and pixel-based classification results are compared, and the performance of the OBIA-GEE method is better than that of the pixel-based RF method. In addition, the OBIA-GEE method is highly efficient, which provides the possibility of applying the proposed method in large-scale studies. This research is beneficial to studies related to monitoring gullies and managing soil erosion. [ABSTRACT FROM AUTHOR]

• Even though check dams are full, they still control the debris flows. • The new model can quantitatively evaluate debris flow mitigation effect. • The check dams and afforestation play different roles in different stages. Check dams and afforestation are two common measures for debris-flow mitigation; however, there is a lack of methods allowing quantitative evaluation of check dam and afforestation effects on debris flow motion and deposition. Laogan Gully is an active debris-flow system with a large landslide on the right hillslope, currently representing the main source of debris flows in the catchment. Several debris flows have occurred since 1985 which led to the construction of check dams and the plantation of silver wattle (Acacia dealbata) trees between 1991 and 1993. These measures significantly reduced the volume of debris flows reaching downstream portions of the system. At the same time, large amounts of sediment were trapped on the gully bed and thereby increased the base level of the torrent, which again tended to stabilize the large landslide on the right hillslope. This paper analyzes sedimentation of debris-flow material on the gully bed and on the fan using 12 trial pits behind the check dams and 6 incised geological sections on the fan. The timing and extent of debris flow motion and deposition was reconstructed using scars and growth suppression events in the annual growth ring series of 306 Acacia trees trapped in the newly formed deposits. The gravitational potential energy of the sediment of the large landslide is calculated according to the change in the erosion base level behind the check dams. On the basis of these results, we constructed a semi-empirical vegetation coverage–landslide energy–debris flow volume model to quantitatively evaluate the effects of the check dams and afforestation on debris-flow mitigation. The model exhibited predictive capabilities for estimating the volume of debris flow generated by the reactivation of landslides. Check dams are found to play a major role in debris-flow mitigation in the early stages, whereas the Acacia trees play an increasingly important role once the check dams are filled. The partial resurgence of the landslide caused a sudden increase in the gravitational potential energy of the sediment source, which in turn affected the effectiveness of the debris-flow mitigation measures. [ABSTRACT FROM AUTHOR]

(a) Conceptual diagram showing three dominant at-a-station hydraulic geometries and bank properties in the Brahmaputra River. (b) Relation between disturbance, resistance threshold and recovery, and temporal variation of system states. The variabilities of LPI, threshold, bank erosion potential and balance between nature-to-engineered (BNE) solutions are also shown. (c) River freedom space concept and resilience-based management approach for a highly braided river system. [Display omitted] • Geomorphic stationarity concept is applied to the identify the local hydrologic nodes. • Energy expenditure gradient is better related to sand bar adjustments than conventional threshold exceedance. • The location probability concept is implemented to recognize the vulnerable reaches. • Balanced combination of nature-based and engineered solutions is required dynamic rivers like the Brahmaputra. The present paper utilizes the Google Earth Engine (GEE) cloud computing platform and hydro-morphological dataset to understand the complex process-form relationships of the highly braided Brahmaputra River, India. To identify dynamic gradients between low and high risk of geomorphic adjustment/change, an analytical approach is developed to track and quantify the spatial patterns of geomorphic adjustment. In order to address the dominant geomorphological adjustments, two processed-based novel indicators are developed- the Normalised Threshold Exceedance (NTE) considering the excess energy theory, and the Normalised Process Gradient (NPG) utilizing the gradient between hierarchical thresholds. The results show that in a highly braided river system, the sand bar adjustments prevail over other forms of morphological changes and is closely dependent on the process gradient between the hierarchical thresholds. Further, the scale of planform evolution is computed from the Location Probability Index (LPI), and the geomorphic stationarity concept is introduced for a large braided river. Finally, a multi-faceted resilience-based freedom space management approach is designed based on system state trajectory, LPI variability, proximity to thresholds, and in-channel landform configuration. [ABSTRACT FROM AUTHOR]

• Lime input significantly decreased topsoil exchangeable potassium (EK) content. • The initial EK and acidic degrees were the key factors of effect on EK decrease. • Liming enhances the excavate and uptake of subsoil EK by crop roots in Ultisol. • Soil Ca, Al, and initial EK jointly regulate the Ultisol K availability after liming. Potassium (K) is the most commonly neglected macronutrient in global change, especially in acidified areas. Lime is a typical management to eliminate soil acidification in agroecosystem soils; however, its impact on soil K dynamics remains inconsistent under different acidic environments. Here, we combine a meta-analysis based on 407 observations from 89 papers and a long-term experiment to investigate the effect and main driving factors of liming on soil K change. The meta-analysis showed that lime application significantly reduced topsoil exchangeable K (EK) content by an average of 4.8% globally. The decrease in topsoil EK content due to liming depended on various soil properties, crop types, fertilizer regimes, and experiment types. Boosted regression tree analysis showed that initial soil exchangeable K (IEK) and pH were the main factors affecting soil EK change under the lime application. The field experiment results further evidence that the decrease of soil EK after the lime application was mainly due to increased K uptake by the crop, and EK transformed to non-exchangeable K (NEK). The application of lime has a greater impact on reducing subsoil EK content at a higher IEK thresholds. Soil EK showed a significant negative relationship with exchangeable calcium (Ca) and a significant positive relationship with exchangeable aluminum (Al). Redundancy analysis revealed that K input (KI), IEK, lime, Ca, Al, pH, and exchangeable magnesium significantly affected the K in soil and crops. The partial least squares path model showed that lime application and IEK levels combined indirectly influence soil K (EK and NEK) by directly affecting soil Ca and Al, K uptake, and K balances. The findings highlight the importance of the lime effect on K management in globally adverse environmental agroecosystems and indicate the key role of initial soil EK levels and acidification degree for regulating crops to excavate the subsoil potassium when subjected to liming. [ABSTRACT FROM AUTHOR]

Abstract: Badlands are highly erodible landscapes with sparse vegetation and rapid runoff responses. Badland surfaces experience high erosion rates that may have a direct and marked influence on river channel networks and catchment scale sediment budgets. Erosion rates from badlands have been widely estimated by discrete observations of topographic change measured by erosion pins or profile meters. Recent developments in survey instrumentation provide the opportunity to build high-resolution topographic models over multiple spatial scales at sub-centimeter accuracy. In this paper we demonstrate how reliable estimates of topographic variables and temporal change can be derived for badlands by repeat Terrestrial Laser Scanning (TLS) surveys undertaken at multiple temporal (event to annual) scales. A total of seven TLS-surveys were obtained in an experimental sub-humid badland located in the Central Pyrenees. Data analyses were conducted on two temporal scales: (a) five rainfall events and (b) three long term (spaced over an annual cycle) scales. Our results show a clear erosional pattern for most of the badland at the annual scale (i.e. annual net change at around −6cmyr−1). Aspect, surface roughness and slope were significant predictors of topographic change, although the sign and magnitude of the change differed at the event scale. Net topographic change at the event scale varied from −1.8 to 1.4cm. Although these patterns could be also affected by swell-shrink processes, surface roughness was more important at controlling badland geomorphological processes at the event-scale than the annual scale. Our observations suggest that longer-term studies may underestimate the importance of surface roughness as a control on badland geomorphology. At the annual scale the effect of aspect in the sign of the topographic change was removed and slope becomes more important. Erosion proved to be dominant on slopes higher than 100%. Overall, the results indicate that coupling of appropriately-scaled spatial and temporal data is critical to understand topographic changes and their drivers on badlands. Although the approach outlined in this paper was only applied to a relatively small area, with careful survey design and application of new survey technology, it could readily be upscaled to cover entire badland systems. Such surveys would permit detailed analysis of controls of sedimentological connectivity across badlands and their influence on channel networks and catchment sediment budgets. [Copyright &y& Elsevier]

Abstract: Based on quantitative simulations on the formation and evolution of aeolian dune fields, a semi-analytical equation describing the migration of aeolian sand dunes with respect to dune height, annual wind regime, frictional wind speed, and sand grain diameter is proposed in this paper through analyzing the migration speeds of aeolian sand dunes with different heights in a dune field. The migration speeds of aeolian sand dunes on Earth predicted by the equation is consistent with field observations, and it can be applied to describe the migration of underwater sand dunes and aeolian snow dunes on Earth, as well as that of aeolian sand dunes on other planets, for example Martian sand dunes. In addition, we can also obtain the annual wind regime and the frictional wind speed in dune fields by the A–W method proposed by this paper for given dune speed and sand diameter. It provides a new way to obtain the information of wind field in desert hinterland and on other planets. [Copyright &y& Elsevier]

Geotextiles have been demonstrated to be effective in reducing erosion and subsequent slope degradation processes. However, most studies devoted to assessing the effectiveness of those elements have considered small or intermediate slope gradients (normally ≤30°), whereas real engineering works often lead to steeper slopes needing protection. In addition, although a large amount of laboratory studies exist on this topic, there are few articles reporting field experiments which consider large plots, real precipitation and prolonged study periods. This paper is the first of two in which the performance of erosion control geotextiles on steep slopes (45° and 60°) has been assessed. In this paper, the influence of geotextiles on runoff and soil loss reduction was evaluated. The second paper focuses on the effects of geotextiles on the establishment and growth of vegetation on the slope. The research was carried out on an experimental embankment built in Pamplona (Spain) following standard construction procedures in order to resemble real engineering slopes. Two biological geotextiles (jute net and coir blanket) and a synthetic polyester geogrid, installed in two positions (surface-laid and buried), were evaluated and compared with a vegetated hydroseeded control plot. After each significant rain event, runoff and soil loss amounts produced on each plot were recorded. The results showed that coir and jute geotextiles produced 2–3 times larger runoff volumes than the control plots on both the 45° and 60° slopes, whereas the synthetic geogrid did not give significantly different runoff rates from the control (at p<0.05). Geotextiles were more effective in reducing soil loss at 45° than at 60°. The most effective treatment was the surface-laid geogrid, with a median Soil Loss Reduction Effectiveness (SLRE) of 76% and 53% for the 45° and the 60° slopes, respectively. At 45° the coir blanket showed lower soil losses than the control (median SLRE of 61%), but at 60° its protection action was more irregular (median SLRE of only 8%). The jute net and the buried geogrid produced lower erosion rates (median soil loss of 3.2gm−2 and 2.1gm−2, respectively) than the control (median soil loss of 3.6gm−2) at 45°, but at 60° the erosion rates observed were similar to those of the control. In short, the surface-laid geogrid produced the lowest soil loss rates. However, when buried, the geogrid did not effectively control erosion, at least not that of the upper soil layer. Thus, its surface installation seems to be a better option. In cases where burial is preferred for aesthetic reasons (i.e. hiding the geogrid), a higher soil loss must be assumed. [ABSTRACT FROM AUTHOR]

The Mogi Guaçu River rises in Bom Repouso (Minas Gerais State — Brazil) in the Mantiqueira Ridge, and flows into the Rio Pardo river at an elevation of 483m in Pontal (São Paulo State — Brazil), after running a 530km long course. Especially along the Lower Mogi Guaçu Basin, the river morphology is extremely sinuous, characterized by intense processes of channel migration, avulsion, abandonment and reactivation of the channel, producing an extensive alluvial plain composed of a series of associated relief forms and sedimentary facies. Among these forms, point bar deposits by lateral accretion, abandoned meanders, paleo-channels and fluvial terraces are notable features. In this sense, the objective of this work was to investigate whether these features could be linked to environmental changes. To reach this goal, soil properties of a catena of the Jataí Ecological Station (Luiz Antonio — São Paulo State) were analyzed in four sectors: Slope, Terrace I, Terrace II and Alluvial Plain. The results from grain-size determination, geochemical and isotopic studies, dating, paleopalynology, coal fragments and micromorphology are presented in this paper. From these analyses, a paleo-environmental evolution divided in three stages is proposed for the area: 130,000YBP (Upper Pleistocene), when the Mogi Guaçu River base level was approximately 6m above the present one; a drier second phase 10,250years BP (Lower Holocene), when an organic horizon was formed inside of an abandoned meander (oxbow lake), and a third phase, 2096 YBP (Upper Holocene), of reactivation of a warm and humid climate that promoted the development of a two meters thick Typic Udifluvent in a sector where the Mogi Guaçu River no more floods due to the incision of its thalweg, reaching more than six-meters depth in the last 130,000years BP. Thus, this paper used a fluvial geomorphologic approach and its interplay with climate to understand how the landscape was shaped from Upper Pleistocene to Holocene, however, Neotectonics might have played a relevant role as well, not only in the Mogi Guaçu River Basin, but also in the Paraná Sedimentary Basin. [ABSTRACT FROM AUTHOR]

• Various morphometric approaches to identify highly dissected terrains. • Different complementary morphometric proxies of landscape dissection are used. • Spatial pattern of erosional 'hot spots' indicates differential uplift and subsidence. • Advantages and limitations of different approaches discussed. The paper presents an attempt to recognize areas of enhanced erosional dissection, based on a combined analysis of several geomorphometric variables and using four different approaches (rank-based, cold and hot spot analysis, k-means clustering of 'raw' data, and k-means clustering of local measures of spatial autocorrelation). The study area includes the Orlickie-Bystrzyckie Mountains Block (OBMB), which is a block-faulted range within the Sudetes Mountains, Central Europe, typified by fault-generated range fronts, remnant planation surfaces and topographic ramps due to large-scale tilting. Geology is diverse, with basement rocks and sedimentary cover, and the relevant timescale is late Cenozoic. Morphometric variables derived from a LiDAR-based DEM include contour length, standard deviation of elevation, median valley depth and standard deviation of curvature, and are considered to account for various morphometric signatures of erosional dissection. While deriving compound measures of dissection, three grid cell sizes were considered. Within the OBMB several areas were identified as erosionally dissected to a considerable degree. Their spatial pattern is complex and reflects several factors simultaneously. Differential uplift appears as the main trigger, but the erosional response varies, depending mainly on the size of runoff contributing area – itself related to the pattern of uplift, and the distance from the margins of elevated areas. Lithology (bedrock resistance to erosion) seems to play a subordinate role. We also discuss various issues related to the procedures themselves, pointing out their advantages and limitations. Procedural setups proposed in this paper are not site-specific and may be used in various topographic and geological settings. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of the paper is to describe the determination of the intensity of karst dissolution in a small ungauged catchment in the Góry Z?ote Mountains in the Sudety mountain range (SW Poland). In the study area, the marble interbed is surrounded by non-carbonate crystalline metamorphic rock. Marble corrosion is caused primarily by the influx of allogenic waters from the non-carbonate part of the catchment. Hydrochemical measurements were made over the course of eight years. The calculated denudation rate per year was 7.35m3 of marble. This translates into a rate of 203.0mmka?1 for the surface area of the investigated marble outcropping. The paper discusses both the study area's rate of denudation and the process used to calculate it. [Copyright &y& Elsevier]

Abstract: Soil and vegetation are interacting factors controlling erosion. Soil degradation processes may affect the normal tree and shrub development and inversely, vegetation can modulate the velocity and intensity of soil development or denudation. A dendrogeomorphological approach can be used to study these interactions, allowing to obtain a date and estimate mean or specific erosion rates. This is especially useful in an unrecorded badlands and gullied environments, where the scarce vegetation may be the only proxy available to quantify the different geomorphic processes which have occurred. This paper provides a fundamental review of the dendrogeomorphological methodology applied to erosion measurement in badlands. Focusing on the response of the vegetation to the geomorphic processes, this paper: (a) describes the methodology developed to estimate erosion rates with exposed roots; (b) shows new advances through case studies; and finally, (c) discusses future lines of research to reduce methodological uncertainties and for making dendrogeomorphology more widely applicable. [Copyright &y& Elsevier]

Abstract: Field scientists studying badland processes in Mediterranean and Semi-arid climates require assurances that the material in which gullies are presented is not dispersive. A dispersive context means; first, infiltration rates may be radically changing in very short periods due to swelling and deflocculation of clays; second, surface crusts could be the result of translocation of sodium into subsurface positions; third, rills may be formed or at least exacerbated by shallow subsurface erosion; fourth, large gullies with substantial up-channel headcuts, including so-called ‘bank gullies’, may have formed because subsurface pipes have collapsed; and fifth, that network connectivity and evolution may be principally internal, being effected by subsurface pipe capture network integration; and most importantly, the bulk of the sediment moving around in the landscape is not being lost from the surface. This paper presents a decision-support tool to assist the effective diagnosis of a landscape's principal genetic process suite. The soil's behaviour in response to its geochemistry in marls with high exchangeable sodium percentages (ESPs) is outlined in simple terms with minimum use of laboratory or field chemical investigations. Using examples the paper then presents a simple set of form indicators that can be used in the field to diagnose the possibility that subsurface process are dominating landscape erosion. Surface crust character, ephemeral rills, and large subsurface tunnel settings are explained and classified. In a final section, the geomorphological implications of piping in gullied landscapes are explored by reference to the literature on connectivity. [Copyright &y& Elsevier]

Abstract: The scientific subjects addressed in the research into badlands since the publication of Bryan and Yair's book (Bryan, R.B. and Yair, A. (Editors), 1982 Badland geomorphology and piping. Geo Books, Norwich, 408 pp.) are briefly analysed. With a steadily increasing number of papers per year, attention to some aspects, such as runoff generation, piping and the role of lithology and soils, varied, whereas the percentage of studies on erosion rates increased steadily over time. Vegetation was not a subject of research in early papers, as most of the papers dealing with vegetation were rather descriptive and published in local or limited-diffusion media, which contrasts with the present situation when about 40% of papers published in international journals about badlands address some aspect of vegetation. However, the growth in the attention paid to vegetation and erosion rates was not linked to any increase in papers dealing with badland reclamation. Badlands are now seen as a group of systems with some common features but diverse dynamics, depending mainly on climatic and lithological drivers. More attention should be paid in the future to investigating the evolution of these landforms over time, mostly through modelling studies, whereas emerging technologies foster detailed analyses that were not possible formerly. Although some badland areas determine on- and off-site environmental issues, others are spots of landscape diversity that merit protection rather than reclamation. [Copyright &y& Elsevier]

Abstract: This paper presents alternating periods of geo-ecological fragility and stability in a highly sensitive environmental setting: the desert-margin area of southern Peru (14.5° S). There, we have to state that fragility was dominantly triggered by climatic changes, which induced several oscillations of the desert margin. During the mid-Holocene, the study area received the Holocene maximum of precipitation, soil formation occurred and the desert retreated, as loess–paleosoil formation documents. In contrast, the Titicaca region further south-east experienced extreme drought at that time. This regional antagonism between humid and dry conditions was a result of meridional shifts in moisture transport across the Andes and occurred also during pre-Columbian times. Considering a coincidence between environmental and cultural changes, we state that success and decline of civilizations were dominated by hydrological oscillations, triggering fertility as well as a critical loss of natural resources. Fragile periods, i.e. periods of geomorphological activity, occurred contemporaneous with cultural transitions. In response to spatial changing resources cultural foci were shifted. So, the success of pre-Columbian civilizations was closely coupled to areas of geo-ecological favorability, which were directly controlled by distinct regional impacts of large-scale circulation mechanisms, including El Niño–Southern Oscillation (ENSO). This spatial view on non-uniform environmental and cultural changes has not been thoroughly considered before. Therefore, for the first time this paper offers geomorphological evidence for diachronous Andean (agri-)cultural development, which was geographically determined. [Copyright &y& Elsevier]

Abstract: Soil organic carbon (SOC) dynamics affect soil quality, agricultural productivity and atmospheric CO2 concentration. Despite the need for spatial assessments of SOC content over time, reliable estimates from traditional field survey methods are limited by data availability; where measurements are often made at discrete point locations, at a coarse sample spacing or over a limited spatial extent. Remote sensing (RS) is in a strong position to provide spatially distributed, reproducible, scale-appropriate and resource-efficient measurements of SOC content and fluxes at field, landscape and regional scales. This paper provides a critical review of optical RS techniques for such applications. The first part of the paper reviews the methods, instruments and techniques used for developing predictive models for monitoring spatial SOC content. Secondly, sources of spatio-temporal SOC variations are examined, including the lateral transfer of SOC by erosion, soil structural breakdown and land management practices, in the context of RS data and techniques. The key challenges of using RS to monitor SOC contents are discussed along with opportunities for improving SOC predictions within a spatial framework. Such opportunities include the use of ancillary data, scale-specific methods, improved development of spectral libraries and better integration of RS technologies into empirical and simulation SOC models. This paper aims to provide a transparent assessment and practical guide to RS techniques and products in order to further advance and better incorporate the use of RS methods within soil science. [Copyright &y& Elsevier]

Abstract: When overland flow concentrates rill and gully channels can be formed if a series of thresholds are exceeded. These thresholds are more or less explicitly linked to the erosion resistance of the topsoil. Moreover, flow velocity and channel width depend on total flow discharge. More recently also bed roughness in eroding channels has been attributed to the eroding effect of flow discharge while channel width was shown to be the result of the interplay between erosion resistance of the topsoil and flow discharge (see channel junction approach, Torri et al., 2006), which could be described by a modified Leopold and Maddock''s relationship. The objective of this paper is to investigate the spatial variability of channel bed roughness in rills and gullies using an approach based on these findings. Field data confirm the various aspects reported so far. Hence these were used to develop a new equation allowing one to predict bed roughness in eroding rill and gully channels. Each of the new aspects introduced into the channel width–flow discharge equation by the channel junction approach is discussed and verified with new data. The validity of this approach is tested against channel data from Mars. Finally, an equation predicting bed roughness and based on stream power is developed and compared with measured rill and gully bed roughness successfully, confirming that 1) bed roughness, if generated by concentrated flow, increases with stream power; 2) channel width, local bed slope, topsoil cohesion at saturation, and grain size are all important factors controlling channel bed roughness; and 3) these variables as well as soil characteristics, all measurable in the field after a rill or gully forming event, are sufficient to determine channel bed roughness. Therefore one may expect that bed roughness of an eroded channel (and consequently hydraulic roughness or friction) will generally increase with bed gradient, erosion resistance of the soil and grain size, following a logic which is best expressed by the final equations described in this paper. [Copyright &y& Elsevier]

The maximum depth of rainfall in any 30-minute period - I 30 - has been used as an index of erosive rainfall events for more than half a century, and is a key component of the R factor in the Universal Soil Loss Equation (USLE) and its derivatives. Other indices are in common use, including I 5 , I 10 , and I 15. However, there has been little study of the ability of I 30 to capture the erosive nature of a rainfall event in regions beyond the foundation experimental work in the USA. This paper examines several apparently neglected issues: how reliance on fixed clock-periods might diminish the efficacy of the various indices of short-interval intensity; how well a single 30-minute period is able to reflect the intensity-duration properties of long enclosing rainfall events, and hence, whether the influence of event duration should be evaluated in applications of I 30 and related indices. Results from two Australian sites with high-resolution rainfall records show that within the enclosing rainfall events, actual intensities corresponding to the I 30 value (which is an equivalent intensity or 'rainfall rate', calculated from rainfall depth in 30 min) commonly occur for both less and >30 min. Often the I 30 interval within a rainfall event excludes the most intense periods of rain, and in long events the index reflects ≪1% of the event duration. The I 30 intensity can occur for total durations of 1–3 h in the events studied, or for just a few minutes. An alternative class of indices is proposed, in which fixed clock-periods are not used, and instead, the duration of rainfall within an event that exceeds a nominated intensity is recorded as an index of intensity. This has a number of advantages, including the ability to work with events shorter than 30 min, which are frequently intense but which cannot yield an I 30 index that is strictly comparable to those of longer events. Illustrative results for this new index are presented. • Rainfall events in two high-resolution rainfall records from two Australian sites are analysed for I30. • The I30 period sometimes includes intensity peaks but frequently does not. • Determining I30 for events shorter than 30 min in a consistent way is problematic. • A new intensity index, the duration of rain at and above the I30 intensity, is explored. [ABSTRACT FROM AUTHOR]

The success of reforestation of degraded areas in semiarid environments is constrained by low soil water content and fertility. In order to overcome these limitations, several site preparation techniques previous to plantation have been developed. Organic amendments have been used to improve physical soil properties in order to increase water availability for plants. However, the role of improvement in nutrient availability produced by organic amendment could have been neglected in semiarid vegetation restoration. In this paper, we analyze the effect of two site preparation treatments on soil moisture dynamics of an experimental reforestation with Pinus halepensis Mill. in a semiarid Mediterranean ecosystem. In one treatment (S) only lineal subsoiling (60–80 cm deep) was applied, in the other (SFF) a fresh urban refuse was added at a dose of 10 kg m−1 into the subsoiled furrow. During the first 5 years the growth of pines was significantly higher in SFF. At this time, we studied soil moisture dynamics at 0–20 cm in transects (for 8 months) and in soil profiles at 5, 15, 25 and 45–55 cm depth (for 23 months). Measurements made in two adjacent off-lines unaffected by site preparation were used as covariates. We also measured soil physical properties, macronutrients (N,P,K) and total organic carbon (TOC) content. No significant differences in soil physical properties were found between the amended versus not amended treatment except for hydraulic conductivity and sand fraction content. SFF treatment showed higher hydraulic conductivity, especially in top soil layers (0–10 cm), and lower content of sand fraction. Phosphorus availability was significantly higher in soil amended with organic refuse while no effect was detected in the content of the rest of macronutrients measured. In the transects, a reduction of 30% of the mean soil water content was observed in planting lines (0.14 cm 3 cm−3) in contrast with adjacent off-lines (0.20 cm 3 cm−3); no statistically significant differences between site preparation techniques were found. Soil profiles observations revealed that soil water content was significantly higher in S than in SFF treatment. This suggests that improvement in soil moisture associated to improvement in the physical structure of the soil cannot explain differences in growth. We argue instead this is mostly attributable to improved nutrient availability and microbiological activity associated with the organic amendment. These results stress the importance of a better understanding of the role of nutrients in the restoration of water-stressed ecosystems. • Addition of organic amendment to subsoiled furrows increased growth of planted seedlings. • Soil water content was significantly higher in subsoiled than in subsoiled and amended furrows. • Difference in growth is attributable to fertilizing effects of organic amendment. • The role of nutrients in restoration of water-stressed ecosystems needs to be emphasized. [ABSTRACT FROM AUTHOR]

Farming plot reconstruction engineering is important in mitigating cultivated land fragmentation and promoting intensified production in hilly mountainous regions. As an anthropogenic disturbance, farming plot reconstruction and subsequent agricultural intensification have considerable effects on cultivated land, ecological environments, and pedogenesis. Although researchers have given considerable attention to changes in the physical and nutrient properties of soil in reconstructed farming plots, the connection between soil engineering and anthropogenic pedogenesis is often neglected. In this paper, we compared samples obtained during farming plot reconstruction engineering and agricultural intensification in terms of different soil properties. The results indicated that reconstruction changed the soil profile patterns from A–C to A–B–C, thereby significantly increasing the soil thickness, bulk density, clay content, pH, soil organic carbon, total nitrogen, C/N ratio, and cation exchange capacity. The geochemical composition notably varied in topsoil; the chemical index of alteration (CIA) and the chemical index of weathering (CIW) decreased markedly, and the Na 2 O/K 2 O ratio (Na/K) increased slightly. After a period of agricultural intensification, the physical and chemical properties of soil improved gradually with a high coefficient of variation. However, the soil exhibited Mg and Ca leaching and K and Na accumulation, and the intensity of chemical weathering was not significantly stronger with higher CIA values, higher CIW values, and lower Na/K ratios. These changes indicated that the anthropogenic disturbances from soil engineering accelerated the physical weathering and uniformity of purple soil but depressed soil chemical weathering to some extent. The anthropogenic disturbances of agricultural intensification disrupted the homogeneity of soils but did not significantly promoted the physical and chemical weathering of purple soil. This study provides guidelines for rational soil usage in reconstructed farming plots and may aid in soil classification. • Soil engineering accelerates physical weathering but destroys chemical weathering. • Agricultural intensification has positive impacts on soil quality. • Anthropogenic disturbances create a problem for soil classification. [ABSTRACT FROM AUTHOR]

Defining a suitable erosive factor for interrill erosion has been a long-going discussion that was not resolved by experimental results. In this paper, by using computational fluid simulations of individual raindrop impacts, the relevance of four erosive factors was assessed for a range of soil resistance, rainfall type and water layer depth. Computation results show that the erosivity exponent associated to the erosive factors had a very low sensitivity to soil resistance. This confirms the common practice of separating rainfall erosivity from soil erodibility. The erosivity exponent was found to be very sensitive to the rainfall type. Therefore, an universal exponent could not be found, its value depending on the rainfall type. As a result of the balance between the shear stress development and the protective effect of the water layer, the soil detachment rate was maximum for a specific water depth. This supports to better account for the water layer depth in erosion models. Overall, the computational approach shows that the choice of an erosive factor may not be of practical importance. It also encourages for new experimental designs, able to evaluate soil detachment by raindrops — and not only the amount of splashed soil. • The choice of a specific erosive factor is not of importance for practical purpose. • Soil erodibility and rainfall erosivity can continue to be considered as independent. • The type of rain is quite important when using an erosive factor. [ABSTRACT FROM AUTHOR]

Oasification is a complex oasis expansion and ecological processes caused by climate changes and human activities under available water supply in arid and semiarid regions. The process can effectively improve soil productivity, vegetation cover, and biomass production in fighting against land degradation, such as desertification and soil erosion. However, the significance of oasification has not yet reached the general cognition compared to desertification, which is regarded as one of the most severe global eco-environmental issues. This paper identifies desertification and oasification processes and their perspectives in cognition. The implication of oasification in combating desertification and controlling land degradation is emphasized by the justification between desertification and oasification processes. As opposite process of desertification, the oasification is an unable evasive process that can provide positive environmental effects in the control of desertification, ecological restoration, and land rehabilitation. According to the interaction of climatic variations and human activities, the oasification processes is classified into six main forms: natural oasis evolution process, engineering forest construction, conversion of natural landforms into farmlands, urban encroachment, constructed environments, and coupled ecosystems. These processes gradually modify the productive capacity of soils, increase vegetation cover for restoring degraded lands, and improve the living environment for human settlement and sustainability of an oasis ecosystem. Moreover, an overview of oasification research is detailed, and Northwest China as an example is used to illustrate the progress of the oasification research in recent decades. Currently, the oasification process and its mechanistic research still remain less concern in the arid and semiarid regions. A new science framework of the oasification research is proposed to effectively deal with ecological and environmental issues in the arid and semiarid regions. • Desertification and oasification and their perspectives are identified. • Implication of oasification is emphasized in comparison with desertification. • Oasification processes are classified into six main forms. • Overview of oasification research is detailed and illustrated in Northwest China. • A new science framework of the oasification research is proposed. [ABSTRACT FROM AUTHOR]

Abstract As one of the most important ecosystems, wetlands are threatened from both natural and anthropogenic activities. Mapping wetland is one of the curtail needs in order to prevent further loss. Since the beginning of the Remote Sensing revolution, different approaches using satellite images have been used for mapping and monitoring wetlands. In this paper we investigate the potential of the recently launched Sentinel satellites, both separate and in combination, for accurately mapping of different wetland classes using Support Vector Machines (SVMs) learning classifier. For investigating the influence of the Sentinel-2 red-edge bands, and the radar bands from Sentinel-1, three different datasets have been analyzed. The results showed that for more accurate mapping of different wetland classes, different datasets should be used. Thus, the red-edge bands have significant influence over the intensive vegetated wetland classes such as swamps, and the radar bands have significant influence over partially decayed vegetated wetland areas such as bogs. For future studies, in addition to the analyzed datasets, we recommend adding and investigating several vegetation indices for mapping and monitoring wetland areas. Highlights • Combination of optical and radar data for wetland monitoring • Supported Vector Machine algorithm for wetlands classification • Significant influence of the Red-edge bands over intense vegetated wetlands • Significant influence of the Radar data over decayed vegetated wetlands [ABSTRACT FROM AUTHOR]

Abstract Differential Interferometric Synthetic Aperture Radar (DInSAR) techniques have repeatedly proved to be an effective tool for built environments monitoring in areas affected by geological hazards. This paper describes how the Coherent Pixel Technique (CPT) approach has been successfully applied to assess the response of an unstable slope to the different phases of remedial works following a landslide event. The CPT technique was performed on 59 COSMO-SkyMed images obtained between May 2011 and August 2016 and centred on the Quercianella settlement (a small hamlet of Livorno municipality, Tuscany, Italy), where the reactivation of a dormant shallow slide had occurred in March 2011 and, hereafter, a geotechnical intervention, designed with the aim of mitigating the risks, has been conducted from August 2013, lasting thirteen months. The time series of CPT results show a deformation pattern with sudden accelerations (up to 21 mm in few months) corresponding to the beginning of the interventions, during which the area has been excavated to install a drainage well, followed by mild decelerations resulting from the stabilization of the area after the conclusion of the works. In particular, the integration of ground-based subsurface monitoring (inclinometers and piezometers) and DInSAR superficial data has provided consistent results for landslide characterization and helped defining the state of activity and the areal distribution of the sliding surface. Moreover, the performance of remedial works in the landslide-affected area has been observed, showing stabilization in the upper part of the hamlet and the ongoing movement in the lower part. The combined monitoring system also led the geotechnical company in charge of remedial works to design further stabilization works in order to preserve buildings and roads in the moving area. Therefore, the integration of remote sensing techniques and in situ instruments represents a timely and cost-efficient solution for intervention works monitoring, opening new perspectives on designing engineering solutions for the stabilization of unstable slopes. Highlights • DInSAR and conventional monitoring techniques were applied in Livorno, Italy. • Such integration supported the design of remedial works of the landslide. • The performances of the drainage well were observed by DInSAR and inclinometers. • The monitoring system led the company in charge to plan further stabilization works. [ABSTRACT FROM AUTHOR]

Abstract There are many controversies about the effect of forest cover on basin streamflows. The objective of this paper was to use the Soil and Water Assessment Tool (SWAT) to provide hydrological modeling of streamflows of a Brazilian Atlantic Rainforest watershed, simulating land use change scenarios with increasing and decreasing forest cover. Regarding the afforestation scenarios, the influence of the geographic location on the afforestation was also evaluated through two approaches: a) a "random" approach (RA), in which the location of reforested areas does not matter; and b) an "imposed" approach (IA), in which the geographical positions of the afforestation are precisely defined. The RA results showed little tendency of reduction in the simulated average and minimum flows with the afforestation. The IA approach showed that the geographic position of afforestation did not significantly interfere in the average flows, but interfered in the simulated minimum flows. Afforestation concentrated in areas close to streams caused a reduction in minimum flows, while its concentration in the upper parts of the basin managed to increase them. Highlights • SWAT was used to provide hydrological modeling of Atlantic Forest watershed. • Afforestation and deforestation scenarios were simulated. • Random and imposed approaches to afforestation scenarios were evaluated. • Afforestation concentrated close to streams reduced minimum flows. • Afforestation in the upper parts of the basin managed minimum flows to increase. [ABSTRACT FROM AUTHOR]

Abstract This study uses the Global Assessment of Soil Degradation (GLASOD) to map sediment sources and erosion process types within the Congo Basin as part of a scoping study to guide a basin wide sedimentation study. The GLASOD map is validated using information from literature and published sediment concentration data at the Brazzaville gauging station, which includes over 95% of the basin area. Validation is complemented by analysis of timelapse satellite images and surface water transition maps derived from Landsat images. The upper catchments are shown to be the main sources of sediment, with the largest exporter by quantity being the Upper Congo sub-basin followed by the Kasai. In terms of severity, the Kasai has the highest specific sediment production rates at 8.92 t/km2/year, followed by the Sangha and Upper Congo at 8.52 t/km2/year and 7.61 t/km2/year, respectively. The dominant erosion/degradation type is the loss of topsoil through water erosion (sheet erosion), occurring in 32% of the entire Congo Basin area, followed by loss of nutrients and organic matter through chemical degradation, 21% of area. The mapping also shows that a large proportion of the Basin (39%) consists of stable terrain under natural conditions, without any human induced erosion. The erosion levels in the Basin are generally low with the predominant mapped erosion processes occurring mostly infrequently and with low levels of severity. The GLASOD map performs satisfactorily as a tool for mapping erosion sources and process types, but fails to explain the process dynamics within the sub-basins, for example, the high sediment exportation rates published for the Sangha sub-basin despite consisting mainly of stable natural terrain (84%). Analysis of satellite images shows an increase in sediment concentration in the Congo River's waters over the years. However, this temporal increase in sediment concentration is neither reflected in the GLASOD map nor the quantitative studies reviewed for this paper, pointing to the urgent need for future research on sediment dynamics in the Basin. Questions are also raised on the roles of the Malebo Pool and Cuvette Centrale in the sediment transport processes of the Basin. The questions raised, and observations made from this study have been used to identify strategic sampling sites for further field studies. Highlights • Sheet erosion is the dominant erosion process occurring in 32% of the Basin area. • 39% of the basin consists of stable terrain under natural conditions. • Kasai sub-basin has the highest specific sediment exportation rate; 8.92 t/km2/year. • Sediment concentration in waters appears to have increased from 1984 to 2016. • Temporal increase in sediment concentrations not reflected in GLASOD or literature. [ABSTRACT FROM AUTHOR]

Abstract In the present paper we report on the only known example of a hummocky meadow in Poland. The area of the Hala Długa in the Gorce Mountains is a hotspot of complex geomorphic edge effects that have been widely studied in relation to human impacts and forest disturbances. Applying an interdisciplinary approach, we aimed to study the geomorphic activity in edge conditions between two contrasting ecosystems, a high-mountain meadow and a forest. Several methods were applied: geomorphic mapping, radiocarbon dating, soil analysis, geomorphometry, wood anatomy, and investigations of historical maps. These methods enabled us to reconstruct the history of the Hala Długa over the past ca 300 years, and to evaluate geomorphic activity and soil dynamics in this area. The treethrow pit-mound microtopography (hummocky meadow, Buckelwiese) of this area was formed under forest conditions, but due to long-term human impacts linked to sheep grazing and mowing, was preserved as a distinct topography for at least 100 years. While this topography was still clearly visible in the 1950s, when it was first reported, it is currently gradually disappearing under trees that have formed a belt around the study area. Soils of the study site were disturbed by tree uprooting, with many key features identified during the soil profile analysis: spots of coarse partly oriented sandstone fragments in pits, patches of organic matter in the metamorphic B horizon, and a large number of root remnants and pieces of charcoal in different parts of treethrow mounds and pits. We suggest a non-linear or even polygenetic soil evolution due to altered vegetation and disturbance regimes. The evaluation of wood remnants revealed that the majority of uprooted tree species were Picea abies (L.) H. Karst and Larix decidua Mill. We conclude that in the Gorce Mountains geomorphic edge effects can form hotspots of geomorphic activity driven by human impacts, natural disturbances, and the specific hydrological regime in the highest parts of the massif. Highlights • Treethrow pits and mounds persisted for at least 100 years as a high-mountain meadow. • We report on the only known hummocky meadow location in Poland. • Geomorphic edge effects occurred due to human impact and tree uprooting. • Geomorphic edge effects influenced soil properties in the highest parts of the Gorce Mts. • The hummocky meadow cannot be completely associated with Buckelwiese topography. [ABSTRACT FROM AUTHOR]

Abstract Furrow diking is a type of conservation tillage practice that is widely used throughout the world and has been proved to be effective for preventing runoff and soil loss. However, it is not easy to maintain a stable conservation effect of furrow diking in various environments. Few studies have focused on the effects of rainfall and slope on the integrity and conservation efficiency of furrow diking. Therefore, simulated rainfall experiments were conducted with four rainfall intensities (30 mm/h, 60 mm/h, 90 mm/h and 120 mm/h) and three slopes (2, 4 and 8°) to study the effects of rainfall intensity and slope on soil and runoff production of furrow diking as well as its conservation efficiency. The conservation efficiencies were obtained by comparing furrow diking with up-down slope ridges. The result indicated that as rainfall intensity and slope increased, furrow diking dams may suffer from runoff overtopping resulting in damage and ultimate collapse. During this process, runoff and soil loss increased rapidly, severe rill erosion developed on dams resulting in the loss of the ability of furrow diking to store rainwater and sediment and obvious declines of water and soil conservation efficiencies. This paper established empirical equations to estimate the conservation efficiency of furrow diking under undamaged and damaged conditions. An empirical equation was also presented to estimate the critical rainfall and slope conditions that may cause overtopping, damage or collapse of dams in order to guide the implementation of furrow diking and predict its conservation efficiency. Highlights • Geometry changes of furrow dikes and their effects on runoff and soil loss • Critical rainfall amounts and slope that damage furrow diking dams • Equations that estimate furrow dikes' water and soil conservation efficiencies [ABSTRACT FROM AUTHOR]

Abstract Inland salt lakes and saline wetlands are intricate systems in which moisture and salinity are continuously changing and especially sensitive to climate change and human pressure. Remote sensing helps to monitor the dynamic changes in the moisture and salinity of salt lakes and saline wetlands. Based on the Landsat 8 satellite data, this paper developed a multivariable linear regression model (MLRM) to predict the spatial distribution of salt on the saline playa at the Qehan Lake in Inner Mongolia, China. The developed MLRM used the remote sensing spectral indices and the Tasseled Cap Transformation wetness band (TCTW) as a variable. By using the TCTW and the surface temperature inversion data, the response of salt to surface moisture and temperature in the dry lake bed was explored. The results showed: The MLRM with brightness index (BI) and the TCTW as the auxiliary variables has the nice applicability (R adj 2 = 0.598, RMSE = 1.640). The MLRM established using the vegetation index NDVI may be more applicable to environments where vegetation and salts were doped-together. Salt distribution in the Qehan Lake may be controlled by flat lake bed and miniature piedmonts. There was a significant correlation between measured soil electrical conductivity (EC) and TCTW, but no correlation with surface temperature. The influence of surface temperature on salt may be biased towards the time scale. Highlights • A new auxiliary variable was used for surface salt inversion modeling. • The application range of vegetation indices and salinity indices was clarified. • The study shows a large variability in EC across various surface coverage type. • Soil moisture is very important in salt prediction. [ABSTRACT FROM AUTHOR]

Abstract Increasing land developments, unreasonable utilization of land, earthquakes, typhoons, and torrential rain often cause hillside disasters. Soil depth is a crucial parameter influencing the scale of shallow landslides and sustainable land use in hillside areas. This paper presents a statistical model, integrated with environmental factors, for estimating soil depth in a catchment area with complex topography. The study area selected was upstream of the Houlong River in Taiwan. The model was developed using multinomial logistic regression and environmental factors such as hill slope, hill aspect, elevation, topographical curvature, and the normalized difference vegetation index. The results were then compared with those obtained from previous models applying Ordinary Kriging, Regression Kriging, and topographical wetness index methods. A classification error matrix and the Kappa index were then employed to assess the various models. The results showed that, for the data set used for model establishment, the overall accuracy and Kappa index were 76.6% and 0.65, respectively, whereas for the data set used for verification, they were 70.5% and 0.57, respectively. By contrast, the Ordinary Kriging method yielded an overall accuracy and a Kappa index of 45.7% and 0.15, respectively; the Regression Kriging method yielded results of 46.7% and 0.16, respectively; and the topographical wetness index method yielded results of 30.5% and −0.05, respectively. The proposed model was therefore determined to be superior to the others in terms of soil depth estimation accuracy. The proposed model can predict soil depth on a regional scale and serve as a reliable tool that provides reference data for future research on land use and shallow landslides. Graphical abstract Unlabelled Image Highlights • Soil depth was modelled in a regional scale with complex topography. • Predictive performance of four statistical techniques was compared. • Multinomial logistic regression proved in soil depth estimation. • Soil depth conditioned by the topographical and geomorphological characteristics. [ABSTRACT FROM AUTHOR]

Abstract Development and protection are both vital human demands in ecologically vulnerable areas. An estimation of the land use/cover changes and their ecological responses could help to understand the regional ecosystem dynamics under various human demands and provide the scientific basis for managing and regulating ecosystems. In this paper, we analysed the spatial-temporal variations in land use/cover types and systematically quantified the relationships between these changes and environmental variables in the Three Gorges Reservoir area. Our results revealed that forestland coverage increased linearly to 53.48%, and that of construction land increased exponentially from 0.25% to 2.75% during 1990–2015. The land use/cover changes exhibited two distinct transformation phases: before and after impoundment. The mutual transformations among vegetation types were significant before 2000, while the forest, water and construction land coverages increased continuously by occupying cropland after 2000. The land use/cover changes were significantly correlated with environmental variables and were sensitive to three topographic variables namely, elevation, surface-height-fluctuation and slope. The vegetation dynamics were easily affected by the complex and rugged topography. Moreover, the responses of land use/cover changes varied among topographic variables. The two parameters estimated in the multiple linear regression, elevation and slope, were −0.164 and −0.268 for forestland change, −0.391 and 0.378 for water area change, and −0.068 and −0.061 for construction land change. Forest cover was so larger in the regions of higher elevation and steeper slope that afforestation occurred in the regions of moderate elevation and slope. Urbanization and impoundment mainly occurred in the regions of lower elevation, and the regions of steeper slope were more easily submerged, while urbanization mainly occurred in the regions of gentler slope. Therefore, the land use/cover changes due to ecological protection and economic development responded to the interactions among environmental variables and was targeted to different regions to reconcile the land use conflicts, providing a reference for ecosystem management in ecologically vulnerable areas. Highlights • Land use/cover exhibited two transformation phases before and after impoundment in the study area. • Land use/cover changes were affected by environmental variables, especially topography. • Forest restoration and urbanization occurred in different regions and periods to reconcile the land use conflicts. [ABSTRACT FROM AUTHOR]

Abstract Biochar application to soil can be considered as a means to improve soil quality, thereby optimizing irrigation management and reducing irrigation needs, especially in dryland regions. This paper is aimed at investigating the effect of biochar (BC) on a desert sandy soil (Al Foah, United Arab Emirates) in terms of bulk density, porosity, water retention, plant available water (AW max), aggregate stability (AS) and specific surface area (BET-SSA). BC was produced from forest biomass (Italy). Soil water retention was measured by the High Energy Moisture Characteristic (HEMC) and by pressure plate measurements, by using BC fractions equal to 0 (soil only), 0.014, 0.091, 0.23, 0.33 and 1 (BC only). The results indicated that BC significantly (p = 0.05) increased soil porosity and the amount of storage pores. As a consequence, water retention was enhanced and AW max from 19.3 mm/m for the sandy soil (f bc = 0), to 60.8, 102.3 and 107.6 at f bc = 0.091, 0.23, and 0.33, respectively, was raised. No significant effects of BC were detected on the soil water retention curve of the BC -amended soil at f bc = 0.014, compared to the original condition. The significant increase in the structural index (SI) at f bc , ≥0.091, indicated that BC improved soil aggregate stability. The BET-SSA was measured by nitrogen adsorption measurements and indicated that the connected porosity was significantly increased by the 0.091 BC fraction. Both AW max and SI were found to be correlated with BET-SSA. This showed an outcome that has been so far little investigated, namely that the BET-SSA played a significant role in the mechanism affecting the soil response to BC addition. The results showed that application of BC can improve soil structure and water retention and therefore optimize irrigation management by reducing irrigation needs, in the Al-Foah area and/or in similar dryland regions. Highlights • Effect of biochar on the aggregate stability of a desert sandy soil was investigated. • High Energy Moisture Characteristic technique and pressure plate experiments were used. • Specific surface area (SSA) was determined by nitrogen adsorption measurements. • Biochar improved the sand aggregate stability and the plant available water. • The BET - SSA played a significant role in detecting soil response to BC addition. [ABSTRACT FROM AUTHOR]

Abstract Chemical composition of plant litter, properties of the soil, and climatic conditions are the major factors determining rate of organic matter decomposition. Although the process of decomposition in degraded areas plays a significant role in accumulation of soil organic carbon (SOC), this issue is poorly studied. SOC content is a crucial factor determining the success of land restoration. We measured rates of decomposition of the grass Calamagrostis epigejos , the dicotyledonous N-fixer Medicago sativa , the dicotyledonous non-N-fixing Cirsium arvense and cellulose paper as a standard carrier in forest stands on a reclaimed spoil heap of the opencast lignite mine in Bełchatów (central Poland). We considered the 10 cm topsoil particle size distribution and pH as factors that can affect the rate of organic matter decomposition and soil organic carbon content. Rate of litter decomposition was slowest for the grass (mean half decay time 2.6 years), while the N-fixing litter was not decomposed faster than the dicotyledonous non-N-fixing litter (mean half decay time of both species 0.9 years). Cellulose was decomposed most quickly (mean half decay time 0.8 years). Decomposition rate was faster under the canopy of Robinia pseudoacacia (deciduous N-fixing tree species, mean half decay time 0.9 years), whereas the rate of decomposition under Pinus sylvestris (coniferous canopy) was not slower than under Betula pendula (deciduous non-N-fixing tree species, mean half decay time under both species 1.5 years). Irrespective of litter type, decomposition was faster on the northern slope (mean half decay time 0.9 years) than on the southern slope (1.6 years). The plots where decomposition was faster (under R. pseudoacacia and on the northern slope) were characterized by higher SOC content (1.95% and 1.96%, respectively) than the plots under B. pendula (1.15%), P. sylvestris (1.29%), and those located on the southern slope (0.97%). Graphical abstract Unlabelled Image Highlights • Herbaceous litter type was the most significant factor determining decomposition rate. • Grass decayed slower than dicots, while N-fixer dicots decayed as fast as non-N-fixer. • Canopy N-fixer accelerated litter decay rate and soil organic carbon accumulation. • Decomposition rate may be slowed down by water deficit e.g. on southern slopes. • Coniferous canopy trees did not slow decay rate more than non-N-fixer trees. [ABSTRACT FROM AUTHOR]

Abstract Various conservation practices have been used to control soil erosion in cropland which makes assessing the effects of soil conservation more important. Northeastern China is an important crop-producing regions, with severe soil erosion. In the study, 110 runoff plot-year observations from seven experimental stations distributed over the region were used to assess the effects of local conservation practices on soil erosion, using a simplified USLE. Under the assumption that there were no significant differences in rainfall erosivity and soil erodibility in the study area under the "no practice scenario", we described a simplified linear model based slope steepness and soil loss rate. The Jixing watershed was selected as a case study to test the model. The results indicate that the derived model can be used in the NE region of China for conservation assessment. The P factor values, related to main soil conservation practices, were derived from the observed plot-year data. The average values of P factor were around 0.01 to 0.35, which were low enough to justify their conservation effects of implementation through the assessment. Comparing to the conventional slope ridging tillage, the conservation rates of terraces, strip ridging, orchards and agro-forestry in the Jixing Watershed were 0.57, 0.6, 1.07, and 0.62 mm/ha, respectively, obtained by the assessment method in the study case. The paper neglected the seasonal variation which should be grouped to the C factor for the annual data and discussed the limitations of the assessment model for application. Highlights • A simple slope model for assessing conservation effects was proposed. • A slope equation based on the USLE was used for estimating soil loss from cropland. • Runoff plot-year data were collected for calculating the P factor values. [ABSTRACT FROM AUTHOR]

Abstract In many Mediterranean areas, citrus orchards exhibit high soil loss rates because of the expansion of drip irrigation that allows cultivation on sloping terrain and the widespread use of glyphosate. To mitigate these non-sustainable soil losses, straw mulch could be applied as an efficient solution but this has been poorly studied. Therefore, the main goal of this paper was to assess the use of straw mulch as a tool to reduce soil losses in clementine plantations, which can be considered representative of a typical Mediterranean citrus orchard. A total of 40 rainfall simulation experiments were carried out on 20 pairs of neighbouring bare and mulched plots. Each experiment involved applying 38.8 mm of rain at a constant rate over 1 h to a circular plot of 0.28 m2 circular plots. The results showed that a cover of 50% of straw (60 g m−2) was able to delay the time to ponding from 32 to 52 s and the time to runoff initiation from 57 to 129 s. Also, the mulching reduced the runoff coefficient from 65.6 to 50.5%. The effect on sediment transport was even more pronounced, as the straw mulch reduced the sediment concentration from 16.7 g l−1 to 3.6 g l−1 and the soil erosion rates from 439 g to 73 g. Our results indicated that mulching can be used as a useful management practice to control soil erosion rates due to the immediate effect on high soil detachment rate and runoff initiation reduction in conventional clementine orchards on sloping land, by slowing down runoff initiation and by reducing runoff generation and, especially, sediment losses. We indirectly concluded that straw mulch is also a sustainable solution in glyphosate-treated citrus plantations. Highlights • Citrus plantations with bare soils show high erosion rates: 15.7 Mg ha−1 h−1. • Runoff rates in citrus plantations reach as much as 67% of the simulated rainfall. • Straw mulch reduces runoff from 65.6% to 50.7% and erosion rates up to 2.6 Mg ha−1 h−1. • Sediment concentration can be reduced from 16.7 to 3.6 g l−1. • Straw mulch is an efficient solution that disconnects water and sediment flows. [ABSTRACT FROM AUTHOR]

Abstract Collapsing gully erosion, a special erosion phenomenon in the hilly granitic regions, is an important factor responsible for the deterioration of the ecological environment in southern China. The granite residual soil properties tend to vary with soil depth and their spatial variations have an important impact on the formation and development of collapsing gullies. Here, two typical granitic soil profiles in the north boundary of collapsing gully erosion in south China were selected to investigated the spatial variations of soil physicochemical, hydraulic, and mechanical properties along the profile and their influences on collapsing gully erosion. The upper two soil layers (surface soil layer and red soil layer) were significantly different from the lower two soil layers (sandy soil layer and detritus layer) in the investigated properties. The soil texture performed a large variation along the profile, which might be a positive factor for the formation of secondary vertical joints, faults, and weak structural planes. Meanwhile, the lower soil layers had a lower value of PL, LL, organic matter, and iron‑aluminum oxides, demonstrating their poor structure and vulnerability to erosion under rainfall conditions. Additionally, the upper soil layers had a higher water-holding capacity, but a lower decreasing rate in the unsaturated coefficient of permeability, leading to the overburdening of the lower soil layers under rainfall conditions. And the low soil layers had a low shear strength, which could also lead to the sliding of the gully head and sidewall, especially under saturated conditions. Collectively, the special geological structure of the granite residual soil layers plays an important role in the occurrence and development of collapsing gully erosion. The data reported in this paper may facilitate a better understanding of soil mass failure on the gully head and the collapsing gullies. Highlights • Clay, loam, and sand layers are distributed along the granite weathering profile. • The lower soil layers have a weaker structure and are more prone to erosion. • Variation in hydraulic and mechanical properties were found between soil layers. • The special geological structure played an important role in collapsing erosion. [ABSTRACT FROM AUTHOR]

Abstract In this paper the dissipative similarity of step-pool units at different spatial scales ranging from rills to streams is analyzed. This investigation benefits from the latest theoretical advances in open channel flow resistance, high-resolution topography from close-range photogrammetry applied to rill erosion and the availability of published data from literature on step-pool streams. At first, the integration of a power velocity distribution allowed to obtain a theoretically-based expression of Darcy-Weisbach friction factor, in which Γ function and δ exponent of the velocity profile are included. Then this theoretically-deduced flow resistance relationship is calibrated and tested by flow measurements carried out in rill reaches where the step-pool units occurred. In particular, the proposed Γ function is calibrated using the measurements corresponding to 88 rill reaches shaped on a plot having a slope equal to 14, 22 and 24% and the calibrated equation is also positively tested with measurements carried out in 48 rill reaches shaped on a 26% sloping plot. For the rill flow the developed analysis stated that the friction factor is characterized by estimate errors which are less than or equal to ±15% for 86% of cases and less than or equal to ±10% for 70% of cases. Using measurements of flow velocity, water depth, width and bed slope measurements carried out in 109 reaches of step-pool streams, this investigation demonstrates that the theoretical flow resistance equation can be applicable to step-pool streams carrying out a specific calibration of the Γ function. The comparison between the Darcy-Weisbach friction factor values measured in streams and step-pool rills demonstrates that in the stream features the friction factor values are, on average, higher than those related to rills with step-pool sequences. In conclusion, the comparison between rills and streams with step-pool units highlights that the same theoretical flow resistance equation can be applied even if a scale effect between the two features is detected. Highlights • Dissipative similarity of step-pool structures at different spatial scales is studied. • High-resolution topography from close-range photogrammetry is applied to rill erosion. • The power velocity distribution is integrated for obtaining the flow resistance law. • Flow resistance equation is calibrated and tested by measurements in rills with step-pool units. • Comparison between streams and rills with step-pool units is developed. [ABSTRACT FROM AUTHOR]

Abstract This paper assesses hybrid spatial models with the use of auxiliary variables based on machine learning algorithms for predicting soil Organic Matter (OM) content in Kastoria area (Greece). The machine learning methods that are used are random forests (RF) and gradient boosting (GB), also called ensemble methods, which combine multiple Classification and Regression Trees (CART). Overall, the different methods evaluated in the current study are Ordinary Kriging (OK), Regression Kriging (RK), Random Forest (RF), Random Forest Kriging (RFK), Gradient Boosting (GB) and Gradient Boosting Kriging (GBK). According to the findings of the study, machine learning methods (RF and GB) improve the prediction accuracy. The improvement ranged from 6% to 9% for RMSE, 47% to 250% for R2 and 4% to 11% for MAE. Moreover, the introduction of residuals' kriging (hybrid methods), increases the accuracy of predictions furthermore (from 1% to 34%). It is also interesting that the measured collocated soil parameters that are used as auxiliary variables have consistently more influence (increased Pearson correlation coefficient for MLR and importance for RF and GB) than the environmental parameters. The main reason could be the flat terrain and the rather homogenous study area that minimizes the effect of topography on the soils. Therefore, topography and spatial characteristics of an area should be considered in design phase, in order to choose the appropriate secondary information in soil parameters' prediction. Highlights • Auxiliary variables like DEM derivatives and other co-located soil parameters are used for predicting soil Organic Matter. • Ensample machine learning methods improve the prediction accuracy of soil organic matter • Hybrid spatial models achieved the best results. • Secondary information of soil parameters from the same locations had stronger influence than the DEM derivatives. [ABSTRACT FROM AUTHOR]

Abstract Spectroscopy has been used for rapid determination of soil physicochemical parameters and soil classification or allocation, usually at the great group level of soil genetic classification. Soil genetic classification is still the main system of classification used in China, on which the Chinese Soil Classification System is based, and includes order, suborder, great group, subgroup, genus, species, and subspecies. In this paper, we introduce a soil allocation model that uses topsoil spectral characteristics and determined the minimum level for soil allocation. The topsoil spectra of four typical soils from the Songnen Plain in Northeast China were used to extract spectral feature parameters (SFPs) with clear physical meaning for soil allocation at the great group, genus, and species levels, and principal components of reflectance and first-derivative reflectance were used for allocation to determine the optimal input. Multinomial logistic regression MLR, multi-layer perception neural network, MLPNN, and decision trees (DT) were used to build allocation models. The results show the following: 1) the first and second absorption valleys of the topsoil spectral curves are substantially different between soils at the great group and genus levels but similar at the species level; 2) the topsoil samples can be allocated with SFPs, for which genus is the minimum level within the Chinese Soil Classification System for soil allocation with topsoil hyperspectral reflectance; and 3) the DT model with SFPs as input is the most accurate at the genus level; the accuracy of allocation is 83.3% and the Kappa coefficient, an evaluation index, is 0.8. Our results suggest that soil allocations using topsoil hyperspectral reflectance can be performed accurately at genus level of classification, which can be of considerable help in research on the effects of soil minerals on soil spectral characteristics and in detailed soil mapping. Highlights • Vis-NIR data are useful for allocating soil samples at different levels. • Allocate soil samples at the genus level and species level • The minimum level for soil allocation with topsoil reflectance spectra is genus. • Use three models to allocate topsoil samples and determine the optimum model • Use three inputs to allocate topsoil samples and determine the optimum input [ABSTRACT FROM AUTHOR]

Abstract Climate warming accelerates the melting and thawing of cryosphere components. Therefore, it favours the release of contaminants stored in High-Arctic glaciers for many years. The rate of land-based glacier retreat is of particular importance for the hydrological regime of glacial rivers, but also for the chemical composition of their waters. In this study, we examined 84 surface water samples collected during a period of 42 days (melt season 2012) from the Scott River of glacial-hydrological regime (NW Wedel-Jarlsberg Land). The studies of Scott River hydro-meteorological conditions provided indication on the relation between mean air temperatures (T) and mean daily discharge (Q) (r = 0.67). Moreover, they confirmed the role of short-term meteorological events (increasing of air temperature and heavy precipitation) on the acceleration of glacier melt. In this context, the study also demonstrated incidents of the release of a more concentrated pulse of chemical compounds delivered by the Scottbreen valley glacier. The analysis covered fluctuations of physicochemical parameters, and presence of selected organic pollutants (∑phenols, formaldehyde (HCHO)). Based on the correlation matrix analysis, it was found that fluctuations of physicochemical indices (pH, specific electrolytic conductivity (SEC) and dissolved organic carbon (DOC)) were related to changes in T and Q. Principal components analysis (PCA)permitted us to distinguish two principal components (hydro-meteorological and biogeochemical conditions) responsible for 71.1% of the total hydrochemical variation. In terms of the first principal component, it was found that there was a relationship with the intensified ablation of glacier ice and with the second one, the influence of geological and biological conditions of the environment on the chemistry of the river. The combination of these factors directly shaped the hydrochemistry of the proglacial river during the melt season of 2012. The results of organic compound loads, which are presented in this paper provide unique information about the transport of contaminants such as: (DOC) (9.41–579 mgC s−1), ∑phenols (19.7–534 mg s−1), HCHO (34.0–82.3 mg s−1)) in the Scott River. It is worth noting that the differentiation of concentration and mean daily loads of DOC, between the gorge (96.0 mgC s−1) and mouth (99.6 mgC s−1) sections of the river, were related with the activity of a herring gull (Larus argentatus) colony at the river mouth. Highlights • Influence of meteorological conditions on hydrochemistry of the glacier-fed river • Releases of intense pulses of organic compounds from the melting glacier • Loads of organic compounds supplied to the Arctic Fjord by the High-Arctic river [ABSTRACT FROM AUTHOR]

Abstract The soil organic carbon (SOC) stock is severely affected by the exploitation of opencast coal mines, and the relationships of factors influencing SOC stock are complex. The influence factors of SOC stock in reclaimed lands in opencast coal mines are unclear, and the existing models can not characterize the complex relationship of SOC stock sufficiently. This paper analyzed the influence factors of SOC stock using complex network theory in the Antaibao opencast coal-mine in Shanxi province of China. An investigation of the soil, topography and vegetation in 50 reclaimed plots was performed. Soil factors, i.e., rock content (RC), total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil bulk density (BD), soil water content (SWC), SOC stock, electrical conductivity (EC), clay content, silt content, sand content and pH, vegetation factors, i.e., above-ground biomass (AGB), tree volume (TV), herb coverage (HC), canopy density (CD), and topography factors, i.e., slope, slope aspect (SA) and slope position (SP), were selected as the nodes, and the relationship among the various factors were considered as the edges to construct a complex network using Gephi. The network characteristics, including degree, betweenness and average shortest path so on, were calculated. SOC stock, SWC and BD played an important role in the complex network of SOC stock. The SOC stock was affected by three clusters: soil texture cluster, soil physicochemical property cluster, and vegetation-topography cluster. SOC stock network was not stable and was sensitive when some important nodes were disturbed. The complex network theory could be used to analyze the influence factors of SOC stock. This study provided a reference for selecting rational land reclamation measures to increase soil carbon stock. Highlights • Complex network was used to analyze SOC stock in reclaimed lands of mining area. • Influence factors of SOC stock were BD, SWC, TN, RC and clay content. • SOC stock network was divided into three clusters structure. • SOC stock network was sensitive to interference. [ABSTRACT FROM AUTHOR]

Abstract Subtropical laterites are partially found in the Argentinian province of Misiones, covering the Jurassic-Cretaceous Serra Geral flood basalts (known as Posadas Formation in Argentina). Two hypotheses have been proposed to explain the origin of these laterites. The autochthonous theory attributes the origin of these deposits to the chemical weathering of the underlying tholeiitic basalts. However, during the last decade, an allochthonous "tropical loess" model was proposed. Several mineralogical/geochemical characteristics of a lateritic profile (~2 m thick, 26°9′58″S–54°35′3″W) are analyzed in this paper in order to constrain the nature of weathering processes in this region and the provenance of the lateritic layer. The basaltic bedrock at the sampling site exhibits intergranular texture and is mainly composed of clinopyroxene, plagioclase and opaque minerals (likely titanomagnetite and ilmenite). Altered glass and apatite were also identified in lower proportions. The X-ray diffraction of the clay-size fraction shows prevailing kaolinite and hematite in the most altered samples, complemented by amorphous Fe-Al (hydr)oxides. Serra Geral basalts-normalized spidergrams and mass balance calculations confirmed almost complete losses of all major oxides (i.e., ~50 g of material was removed by weathering from each 100 g of the original basalt) and depletions of some trace elements (e.g., Sc, V, Sr, Cr, Ni, Rb and U) in the uppermost and intermediate layers of the lateritic profile, reflecting the weathering of feldspars, clinopyroxenes, volcanic glass and apatite. In contrast, some elements are enriched in the topmost and intermediate layers, due to intrinsic immobility during weathering (e.g., Zr, Hf, Ta, Th) or adsorption onto clays (e.g., Cs). Rare earth elements (REEs) are depleted in the top layers and enriched in the middle section of the profile. The preferential leaching of REEs from the uppermost levels during weathering and its accumulation in the middle section can be caused by a pH increase in this level, the decomposition of organic matter and the consequent precipitation of REEs which exhibit an affinity to form aqueous organic complexes, or the presence of Fe and Mn (hydr)oxides in the intermediate level. Weathering intensity was appraised by means of different alteration indices, which showed the extreme leaching endured by the basaltic bedrock. The index of lateritization (IOL), which ranges between 35 and 55, and the accompanying SAF ternary plot (SiO 2 -Al 2 O 3 -Fe 2 O 3), indicate an increasing weathering trend towards the profiles' top, reflecting the modest loss of SiO 2 (relative to Al 2 O 3 and Fe 2 O 3) during kaolinitization. The geochemical approach used to constrain the origin of the lateritic mantle that partially covers Misiones province, clearly relates the analyzed laterites to the underlying tholeiitic basalts, supporting the autochthonous origin theory. Highlights • A geochemical mass balance in a subtropical basalt-derived profile was calculated. • Weathering removes >50% of rock volume with almost total losses of alkalis • REEs are enriched in the intermediate level. • The chemical weathering stage of kaolinitization was recognized in the profile. • Laterites derive from the underlying basalt, supporting an autochthonous origin. [ABSTRACT FROM AUTHOR]

Abstract Geohazards often cause a lot of damage to human life and property. Among the geohazard mitigation measures, ecological restoration engineering is an ecomonic and widely-used one, but the effectiveness varies with the alternatives' settings and the local stand conditions, and there is a lack of effective means to assess it. The objective of this paper is to evaluate the effectiveness of vegetation restoration alternatives on mitigating geohazards in Bailong River Basin (BRB), where the soil erosion and debris flow are very severe. Given the significance of surface hydrological process in the formation of geohazards, the surface runoff depth (SRD) simulated by the Soil and Water Assessment Tool (SWAT) was chosen to evaluate the effectiveness of the mitigation alternatives. We designed four groups of ecological restoration scenarios, among which the first three groups returned the cropland with slope above 0, 15 and 25°, respectively, to one type of vegetation from evergreen forest, deciduous forest, mingled forest, shrub and grassland. The fourth group returned two slope levels of cropland to combination of two from the above five vegetation types. At the basin level, it was shown that all the alternatives could reduce the SRD. The evergreen forest alternative performs better than other vegetation types, and converting cropland above 15° is more efficient than converting cropland above 0 and 25°. The combination of evergreen and shrub in group 4 reduces SRD the most. At the subbasin level, the spatial heterogeneity of restoration alternatives effectiveness was shown. The reduction rate of SRD at the subbasin level reveals that the restoration measures would perform well in the northeastern basin and the eastern area of midstream. The reduction of SRD per unit returned cropland area reveals that the efficiency of reducing more SRD with less returned cropland is higher in the northeastern basin. Further, a map of most efficient group 4 scenarios at the subbasin level is obtained. Our work is expected to provide information regarding the establishment or improvement of ecological restoration policy in mitigating geohazards. Graphical abstract Unlabelled Image Highlights • Four groups of ecological restoration alternatives were simulated. • Surface runoff depth was selected as the indicator. • Evergreen forest and its combination with shrub perform good. • The spatial heterogeneity of restoration alternatives effect was shown. [ABSTRACT FROM AUTHOR]

Abstract The characteristics of ions in irrigation water can be significantly different in response to the changes in the salinity gradient. The chemical and biological processes of soils which were irrigated with this kind of water would therefore, be remarkably influenced. Based on the field sampling data and utilizing the Structural Equation Model (SEM), this paper aims to investigate the ionic characteristics of irrigation water and evaluate their direct and indirect impacts on soil salt ions, nutrients and microbial metabolic activities. The present results demonstrated that the ionic components of irrigation water had a direct influence on the soil salt ions. In particular, the Na+ concentrations in irrigation water were not only seen to significantly increase the soil Na+ concentrations but also change the other soil ions' concentrations. The contents of soil total nitrogen (TN), available phosphorus (P ava) and available potassium (K ava) appeared to change slightly with the increase of water salinity and meanwhile, no significant impact was found from any of the ions present in the irrigation water. Although high concentrations of Na+, Cl−, SO 4 2−, Mg2+ and Ca2+ in irrigation water significantly drove the reduction of the soil organic carbon (OC), the direct influences were actually relatively small in this respect, and it was the increase of soil salt ions that dominantly led this reduction. Irrigation water with high salinity contents could significantly restrain the soil microbial metabolic activities. In addition, high concentrations of SO 4 2−, Mg2+, Cl−, Ca2+ and Na+ in irrigation water (accounting for about 11% of the total effects), increased concentrations of soil salt ions (i.e., 74%) and reduced contents of soil OC (i.e., 15%) all contributed to this restraint, which together were seen to affect the microbial processes under saline water irrigation. The present results revealed that the ionic effects of irrigation water on soil processes would be more complex than we currently understood, which should attract increasing concerns in the future. Graphical abstract Unlabelled Image Highlights • The relationships between soil chemical and microbial characteristics under saline water irrigation were concerned. • The direct effects of irrigation water ions on soil salt ions were stronger than on nutrients and microbial activities. • Irrigation water ions had significantly indirect effects than direct ones on soil OC. • High water salinity, increased soil salt ions and reduced OC all resulted in the microbial activities' reduction. [ABSTRACT FROM AUTHOR]

Abstract The paper focuses on the generation of floods as a principal soil threat and on soil erosion as an additional soil threat on arable lands of hillslope areas. As the most important component of floods causing the degradation of soils on arable lands, surface runoff is analysed in this study. The protective effect of crop management on the generation of surface runoff and sediment transport on arable lands is estimated on a plot and slope scale. The site of the case study, which is located in the Myjava river basin in western Slovakia, is a hilly agricultural field with an area of 29 ha; it is characterised by arable soil, extreme erosion processes, and muddy floods. Field rainfall simulation experiments were combined with physically-based modelling for studying the formation of surface runoff under various soil covers. The field experiments consisted of simulating runoff generation from artificial rainfalls using the Eijkelkamp rainfall simulator on experimental plots with a focus on estimating the volume of surface runoff, the mass of sediments transported by the surface runoff, and the time to runoff. The volumes of the surface runoff and the values of the time to runoff have been applied in the parameterisation of the SMODERP physically-based hydrological model. The hydrological modelling of the surface runoff on the selected slope profile quantified the protective effect of various soil covers on reducing surface runoff. The outcome of the modelling was the maximum allowed lengths of the slope that represent the crucial values for flood and erosion control. When exceeding these critical values, protective measures, e.g., vegetation strips, should be proposed. Highlights • Protective effect of soil cover on surface runoff on an arable land was studied. • Results of field rainfall simulations were limited; small plot and temporal scale. • 1D - hydrological model was parametrised on the basis of plot measurements. • Winter crop has a high effect on reduction of surface runoff on a hilly arable land. • Higher reduction of surface runoff was evident in the case of lower design rainfall. [ABSTRACT FROM AUTHOR]