Search

• An approach is proposed to assess extreme rainfall-triggered landslides. • 3D unsaturated flow is coupled with the infinite slope method. • Extreme precipitation events are investigated using soil depth models. • 1-year spin up for moisture conditions has little impact on the safety factor. • Simple soil depth models are viable options for landslide susceptibility studies. The susceptibility to shallow landslides is affected by several factors. Rainfall intensity, soil thickness distribution, and antecedent moisture conditions are components that influence the spatio-temporal prediction of landslides at the watershed scale. Yet, the combined impact of these factors on the susceptibility to landslides has been overlooked. The purpose of this paper is to investigate landslides triggered by extreme precipitation in the Tijuca Massif, Rio de Janeiro, southeastern Brazil. Our approach couples a 3D variably saturated flow solver with the infinite slope stability method to calculate the statistical distributions of the safety factor and the pore pressure at the soil–bedrock interface. Numerical simulations were performed for 6 scenarios considering 1-year spin-up time for soil moisture and different spatially distributed soil depths. The results show that during extreme precipitation events, soil depth and initial moisture conditions may not have much influence on the safety factor, as the intensity and duration of rainfall will be the triggering agents. Comparison of simulated unstable zones and field data from mapped landslide scars further supported this conclusion. We conclude that simple soil depth models are feasible options for regional studies of landslide susceptibility. Our findings are relevant to understanding shallow landslides induced by extreme rainfall in Rio de Janeiro and other regions with similar geological and climate settings. [ABSTRACT FROM AUTHOR]

• Soil water repellency (SWR) is considered a part of ecosystem dynamics. • Plant species significantly differ in SWR-inducing ability. • SWR severity and persistence depend on the features of plant cover. • Plants-SWR-environment linkage is discussed and research directions are proposed. Soil water repellency (SWR) is a widespread natural phenomenon that results from a complex interplay between the hydrosphere, lithosphere, biosphere, atmosphere, and anthroposphere. The plant cover largely contributes to the development of SWR as a source of hydrophobic compounds that can be found in surface and near-surface soils. Studies suggest that certain vegetation types, and even different plant species, are frequently associated with the occurrence of severe SWR. This review summarizes the current state of knowledge regarding the linkage of SWR and plant cover. By keywords-based searching of academic databases, 179 research papers were selected and analyzed. The literature review provides: i) overall research output regarding locations, climate conditions, soil and plant cover features, ii) main issues addressed in studies on SWR-plant cover research, iii) inventory of 248 plant species associated with the development of SWR, iv) identification of the plant species/types most frequently cited to induce severe SWR, v) discussion on the plant traits relevant to the development of SWR, ecological and environmental aspects of SWR-plant cover relationship, vi) suggestions for further research on the linkage of plant cover, SWR, runoff generation, and soil moisture storage through holistic approaches. [ABSTRACT FROM AUTHOR]

• Water erosion on the Qinghai-Tibet Plateau decreased from south to north. • Water erosion decreased from 1982 to 2015 but slightly increased since 2007. • Climate variability enhanced erosion and human activity reduced it from 1982 to 2015. Climate variability and human activities cause changes in precipitation and underlying surface conditions, which are the main driving forces of changes in water erosion, especially in the Qinghai-Tibet Plateau (QTP). In this paper, the water erosion on the QTP from 1982 to 2015 was quantified by the Revised Universal Soil Loss Equation (RUSLE), and the response of water erosion changes to climate variability and human activities was investigated. The results indicated that the distribution of water erosion gradually decreased from south to north during 1982–2015. Areas of severe erosion were mainly distributed along the Yarlung Tsangpo River and in the western Hengduan Mountains. The years of the abrupt change in water erosion were 1989 and 2006. Compared to 1982–1989, the amount of water erosion was mitigated in both 1990–2006 and 2007–2015, with a 19.5% and 6.2% decrease, respectively. The contribution of human activities to the decrease in water erosion was 25.4% and 16.7% for each of these periods, respectively, and the contribution of climate variability to the increase in water erosion was 5.9% and 10.5%. However, water erosion increased by 16.5% from 2007 to 2015 compared to 1990–2006. The contribution of climate variability was 4.9% and the contribution of human activities 8.4%. The increase in water erosion due to human activities may be attributed to the construction of the Qinghai-Tibet Railway and associated human activities. It is therefore important to draw attention to the influence of human activities on the QTP on erosion, to prevent potential future risks. This study is the first attempt to research the relative contributions of variation in climate and human activities to changes in water erosion on the QTP. It would be beneficial for carrying out ecological environmental protection work on the QTP. [ABSTRACT FROM AUTHOR]

A large number of studies have focused on water erosion in the southern Alps because of its intensity and the high erodability affecting numerous outcrops in this region.The aim of this paper is to determine the relations between natural and human factors on the one hand, geomorphologic behaviour of hillslopes and fluvio-torrential dynamics at two time scales (geological and historical) on the other hand. This paper specially focuses on the recent weakening of torrential activity and its linkage with reforestation and rural desertion on the watersheds. Another objective is to compare these results with a rich mainly French scientific production on this theme.Experimental data on:–current erosion measurements and the analysis of its processes on the one hand,–and geomorphologic background of river beds and slopes,are compared and analysed using archives and the present knowledge on historical climate.It has been shown that the overexploitation of watersheds leads to an increase in soil loss, in the number and intensity of floods in alpine valleys, as well as to an enhancement of sediment transport. However, climatic changes during the Holocene and during the past millennium have resulted in changes in morphological behaviour of the hillslopes upstream and of river beds downstream.Moreover, a strong sedimentary deficit can be observed over the last three or four decades in all the Alpine massifs. The consequences of this sediment deficit are firstly an entrenchment of river beds, which threatens bridges and embankments. This recent trend is probably due to the excessive extraction of material in gravel pits and the sedimentation in the numerous dams built between 1920 and 1980 in the entire alpine range. However, the entrenchment appeared recently on non-exploited rivers; therefore, the deficit is also due to the success of the natural and artificial reforestation and torrent correction since the end of 19th century. [Copyright &y& Elsevier]

[Display omitted] • Hoeffding Tree is a promising landslide susceptibility model based on ROC and AUC. • Bayes Network and Logistic Model Tree were applied for comparison. • Correlation analysis of conditioning factors was completed by Frequency Ratio. • Landslide susceptibility maps of Muchuan County and the county town were produced. Landslides, one of the most common hazards around the world, have brought about severe damage to life and property of human. To prevent and mitigate landslides, various models have been introduced to assess landslide susceptibility. In this paper, Hoeffding Tree (HT), a prevailing data stream mining algorithm, was employed to predict landslide susceptibility in Muchuan County, China for the first time. Meanwhile, Logistic Model Tree (LMT) and Bayes Network (BN) were applied to produce landslide susceptibility maps for comparison. The model performances were evaluated by Receiver Operating Characteristic (ROC) curves and areas under the curves (AUC). To obtain landslide inventory map, 279 landslides data was collected, and training and validation datasets were randomly divided with a proportion of 70% to 30%. Furthermore, twelve conditioning factors (altitude, slope angle, profile curvature, plan curvature, slope aspect, distance to roads, distance to rivers, TWI, NDVI, soil, land use and lithology) were selected to construct landslide susceptibility models. Moreover, correlations between conditioning factors and landslides were analyzed using Frequency Ratio (FR). The results showed landslides are prone to occur in areas where human activities concentrate, and all three models exhibited satisfying performances. Concretely, for training dataset, LMT model showed the highest AUC (0.854), followed by HT (0.726) and BN (0.709). However, for validation dataset, LMT and BN models generated similar AUC values (0.761 and 0.764 respectively), and the highest AUC value belonged to HT (0.802). The distributions of landslide susceptibility zones revealed that the interior of county town is mainly seated in low and very low susceptibility zones, whereas regions close to the border suffer high and very high landslide risk. The results acquired in this paper are significant to landslide prevention and urban planning in Muchuan, China. Additionally, this study proved that HT model is a promising classifier for landslide susceptibility modeling. [ABSTRACT FROM AUTHOR]

• The flood flow course in lowland areas may be influenced by valley geology. • The floodplain relief testifies influence of the valley geology on fluvial processes. • The sub-alluvial bedrock protrusions favour the creation of ice jams. • In the light of climate changes the bedrock impact on river behaviour will increase. In this paper, we analyse the significance of alluvial substrates in shaping the morphodynamics of the bottom of a lowland river valley. The research focus was a 20-km reach of the Bug River valley, an example of a large river in the Polish Lowlands. There are no anthropogenic elements in the valley that can disturb the course of natural river processes. The Bug River channel has not been engineered in the section analysed. Eighty-one geological drillings performed in the channel allowed identification of 11 zones of sub-alluvial bedrock protrusions built up from erosion-resistant deposits. The determination of the valley bottom surface morphology was based on high-resolution multispectral satellite images in natural and near-infrared colours. Geological and geomorphological mapping of the valley bottom surface were also carried out. The obtained results showed that the key factors controlling the morphodynamics of this floodplain are protrusions of sub-alluvial bedrock. Under medium- and low-flow conditions, these are hidden under a layer of channel deposits. However, during high flows, the surface of the protrusions is exposed, affecting the pattern of flood flows and forcing them to enter the floodplain in certain, recurrent zones. The result of such phenomenon is the creation of characteristic sets of accumulative and erosive landforms. Thirteen types of such forms have been identified. The presence of sub-alluvial bedrock protrusions in this river channel has promoted formation and persistence of ice jams (confirmed by analysis of hydrograms from 1969 to 2018). The case presented in this paper shows that the certain arrangement of landforms indicate morphodynamic specificity of valley bottom whose alluvial substratum exerts an influence on flood flows. Since protrusions of alluvial substrate is associated with glacial genesis of the area cut by the Bug River, the described phenomenon may also occur in other postglacial areas. [ABSTRACT FROM AUTHOR]

In this paper a new flow resistance equation for open channel flow, based on the integration of a power velocity profile, was tested for gravel bed channels. First this flow resistance equation, theoretically deduced by dimensional analysis and incomplete self-similarity condition, was reported. Then a relationship between the Γ function of the velocity profile, the channel slope and the Froude number was calibrated by the available laboratory measurements of flow velocity, water depth and bed slope carried out in 416 flume experimental runs with a gravel bed. Then the relationship for estimating Γ function and the theoretical resistance equation was tested by 83 independent flume measurements. The analysis also showed that the proposed flow resistance equation allows an estimate of the Darcy-Weisbach friction factor which is more reliable and accurate than that obtained by a semi-logarithmic flow resistance law or a variable-power resistance equation, calibrated with the same gravel bed measurements. For testing the applicability of the proposed Γ function (Eq. (17)), whose coefficients were estimated by flume measurements, available fields measurements were used. The analysis demonstrated that a scale factor (equal to 0.7611) is necessary to convert Γ values obtained by flume measurements into those corresponding to gravel bed rivers. The similitude between flow resistance in a gravel bed flume and in a gravel bed river is governed by the Γ function and a scale factor, equal to 1.6, is required to upscale the Darcy-Weisbach friction factor values obtained by flume measurements to the river case. In conclusion, the analysis showed that the Darcy-Weisbach friction factor for gravel bed channels can be accurately estimated by the proposed theoretical approach based on a power-velocity profile. [ABSTRACT FROM AUTHOR]

This paper demonstrates the applicability and usefulness of colourimetry as a fast and simple tool to assess the quality of limestones for cement and lime industry raw materials, a field where colourimetric measurements have not yet been applied. The results of the colourimetric analysis in a large sample set from the Mokrá Quarry in the Moravian Karst (NE from Brno, Czech Republic) and comparisons with the results obtained by other methods are presented here. The studied samples belong to two lithologically different series of strata: the Macocha Formation and the Líšeň Formation. Limestones of these formations differ in structure, the contents of their non-carbonate components and, therefore, in colour as well. The samples were prepared in four ways for the purposes of colourimetric measurements: i) unpolished bulk samples (fracture planes were measured), ii) polished sections, iii) powder in a plastic bag, and iv) uncovered powder. Each of these four ways led to different results, which were expressed using the CIE L*a*b* colour space. The L* (specific lightness) value gives an approximate estimate as to the amount of non-carbonate components. The specific lightness value can be used for assigning a sample to a lithostratigraphic member and, in many cases, possibly also to a correlation among members. [ABSTRACT FROM AUTHOR]

This paper describes β-fabric features and their distribution in the calcretes, and emphasizes the role of soil organisms in the formation of the calcrete profiles. Quaternary calcretes are common in the Mersin and Adana provinces occurring as powdery, nodular, tubular, fracture-infill and various forms of crusts. The stable isotope values indicate calcrete development under semi-arid climatic conditions and a pedogenic origin. Biogenic or β-fabric constituents are abundant in the hard laminated crust. These are the rhizoliths, alveolar septal structures, needle-fiber calcites, calcified filaments, spherical calcite bodies, microcodium and vadose (calcrete) pisoliths. Rhizoliths have mainly formed by the petrification of roots, and often contain cellular cortex structures. The alveolar septal structure comprises root-voids separated by a micritic wall or a bundle of tangentially oriented calcite needles. Needle-fiber calcite is common in the hard laminated crust as monocrystalline rods and polycrystalline needles. Monocrystalline rods are smooth and small (< 1 μm in length), whereas polycrystalline needles consist of a chain of calcite rhombs stacked as parallel c-axes. The elongated crystals generally form interwoven masses. The calcified filaments are straight to slightly curved tubular microstructures with a central hollow. Microcodiums are rosette-like aggregates composed of slightly curved radial-fibrous calcite crystals extending from a central cavity. Vadose pisoliths consist of irregularly coated microbial laminae around a nucleus, and often show a downward elongation indicating an in-situ formation. All these biogenic features indicate a pedogenic origin for calcretes. Their abundance in the hard laminated crust points to calcification in a biologically active zone and maturation in calcrete formation with a thin soil cover. [ABSTRACT FROM AUTHOR]

The size of the drops determines soil erosion and runoff rates, and then the fate of ecosystems. Various raindrop measurement techniques and tools have been developed to determine natural and simulated raindrop size distributions and mean drop size. There is a need to improve the procedure to determine the raindrop properties, and this is why we develop a new technique to analyze drop size distribution and fall velocity. For this purpose a rainfall simulator with two oscillating Veejet 80100 nozzles in laboratory condition, and high speed imaging technique and edge detection approach in image processing was applied to identify and measure drop size and calculate drop velocity. The results showed that the rainfall simulator was able to create drops with diameter in the range from 0.2 to 9.9 mm. Fall velocity ranged from 0.8 to 9.2 m/s for different diameter classes in the height of 0.5 m above the ground. The results indicate that the low-cost technique developed in this paper had high ability to automatically and rapidly identify raindrops characteristics with high accuracy. This technique can help to calibrate other rainfall simulators, but also to characterize natural rainfall events in different regions, which is a worldwide need due to the lack of information, and the importance of the raindrop characteristic to characterize and model the soil erosion processes. [ABSTRACT FROM AUTHOR]

In the Cabo Basin, NE Brazil, conglomerates have given rise to soils with attributes that are rarely observed in humid tropical climates and remain relatively unknown within the scientific community. These soils have high levels of Al in the exchangeable phase, diminishing their agricultural and environmental potential in an underdeveloped region of great socioeconomic importance. This paper presents the mineralogy and genesis of soils derived from conglomerates on a slope in the Cabo Basin, with the aim of meeting the demand for studies on Al–rich soils. Three soils were classified, morphologically described and sampled for the accomplishment of chemical, physical and mineralogical analyses, including the main exchangeable cations content, mineralogy of the sand, silt and clay fraction, differentiation of the Fe and Al forms, mineral micromorphology and chemical composition of mineral species. In addition, chemical and physical attributes were used in multivariate analyses. The soil mineralogy is associated with the weathering evolution of three mineralogical zones identified in the Cr horizons. Pathways of alteration followed by feldspars and micas resulted in kaolinite, smectite and hydroxy–Al interlayered smectite formation (argilification). The susceptibility of the conglomerate to weathering, constant releases of Al from the structure of aluminous minerals, low contents of exchangeable bases and consequent low pH values (<5.3) were associated with high levels of exchangeable Al. At the highest position on the slope, a C/Cr transitional horizon provided evidence of the pedogenesis advance on the Cr horizon. Pedogenetic processes then resulted in morphological, physical and mineralogical differentiation between the A and Bt horizons. In addition, a cluster analysis showed similarities between attributes of the Bt and Cr horizons due to their genetic relationships. [ABSTRACT FROM AUTHOR]

This paper associates the tectonic conditions of five rivers (integrated drainage networks) in northwestern Greece, for the purpose of formulating the conceptual model of its tectonic and geomorphological evolution. The applied methodology consisted in the synthesis of elements from the fields of Tectonics and Geomorphology, using suitable software and GIS-techniques, and the correlation of fault and drainage network trends by the use of rose diagrams to reveal the structures and tectonic events affecting the different orders of the branches and its evolution. The relation between morphology, tectonics and the development of the drainage network enabled comparison across different areas, the grouping of rivers and the identification of areas influenced by the same geodynamic regime. In northwestern Greece, two main groups of rivers were distinguished, flowing across areas featuring different tectonic conditions, while a transitional zone between them was defined. The stages of the area's tectonic and geomorphological evolution were identified with highlighting the definitive impact of tectonic structures on the configuration of the river routes, e.g. the Petousi-Souli Fault which forms a natural boundary in the centre of the study area and new elements were added. In view of the aforementioned, northwestern Greece is an independent transitional area in the geodynamic regime of the entire eastern Mediterranean. Notably, the methodology applied to these rivers may also be used in other areas, thus constituting a standard tool for investigating the geodynamic regime and evolution. [ABSTRACT FROM AUTHOR]

Soil surface sealing is a major cause of decreased infiltration rates and increased surface runoff and erosion during a rainstorm. The objective of this paper is to quantify the effect of surface sealing on infiltration for 3 layered soils with different textures for the upper layer and investigate the capability of BEST procedure to catch the formation of the seal and related consequences on water infiltration. Rainfall experiments were carried out to induce the formation of the seal. Meanwhile, Beerkan infiltration runs were carried out pouring water at different distances from the soil surface (BEST-H versus BEST-L runs, with a High and Low water pouring heights, respectively) for the same type of layered soils. Then, we determined saturated soil hydraulic conductivity, K s , values from rainfall simulation and Beerkan infiltration experiments. Rainfall simulations carried out on soil layers having different depths allowed to demonstrate that infiltration processes were mainly driven by the seal and that K s estimates were representative of the seal. Mean K s values, estimated for the late-phase, ranged from 13.9 to 26.2 mm h −1 . Soil sealing induced an increase in soil bulk density by 38.7 to 42.1%, depending on the type of soil. Rainfall-deduced K s data were used as target values and compared with those estimated by the Beerkan runs. BEST-H runs proved more appropriate than BEST-L runs, those last triggering no seal formation. The predictive potential of the three BEST algorithms (BEST-slope, BEST-intercept and BEST-steady) to yield a proper K s estimate for the seal was also investigated. BEST-slope yielded negative K s values in 87% of the cases for BEST-H runs. Positive values were obtained in 100% of the cases with BEST-steady and BEST-intercept. However, poorer fits were obtained with the latter algorithm. The comparison of K s estimates with rainfall-deduced estimates allowed to identify BEST-steady algorithm with BEST-H run as the best combination. The method proposed in this study could be used to easily measure the seal's saturated hydraulic conductivity of an initially undisturbed bare soil directly impacted by water with minimal experimental efforts, using small volumes of water and easily transportable equipment. [ABSTRACT FROM AUTHOR]

Explaining scale effects for runoff and erosion improves our understanding and simulation ability of hydrological and erosion processes. In this paper, plot scale effects on event runoff per unit area ( Q e ), sediment concentration ( C e ) and soil loss per unit area ( SL e ) were checked at El Teularet-Sierra de Enguera experimental site in Eastern Spain. The measurements were carried out for 31 events occurring in the years 2005 and 2007 in bare ploughed plots ranging from 1 to 48 m 2 . The analysis established the scaling relationship by dimensional analysis and self-similarity theory, and tested this relationship at different temporal scales ranging from event to annual scale. The dimensional analysis and the incomplete self-similarity condition allowed us to establish a power scaling relationship which was found to also be usable for the moments of k (1, 2, 3, 4) order. The power scaling relationship was theoretically deduced applying a boundary condition which is based on the hypothesis that sediment delivery processes do not occur at the selected plot scale. The simple scaling invariance condition was always verified (i.e. for each temporal horizon) for runoff and soil loss while the same hypothesis was not perfectly acceptable for sediment concentration. The analysis of the scaling relationships at event temporal scale showed that the spatial scale effects were less frequent for the composite variable (soil loss = sediment concentration × runoff) than the constituting variables. For 48% of the events, a statistically significant scale effect was detected for all tested variables. With reference to the statistically significant relationships, both runoff and soil loss always decreased and sediment concentration always increased in the passage from the reference area (1 m 2 ) to the largest one (48 m 2 ). The analysis at aggregated temporal scales suggested that annual scale effects for soil loss per unit area should be temporally more stable than those for both runoff and sediment concentration. Finally, at mean event scale the three investigated variables have a similar behaviour in terms of simple scaling invariance. [ABSTRACT FROM AUTHOR]

This paper aimed to identify indicators of soil degradation in volcanic soils developed in the ecotone between the Andean Forests and the Patagonian steppe. The study area is located in the Percy River Basin, Argentine, on alluvial fans with volcanic soils. Sampling was conducted in two adjacent hillslopes where native forest was replaced by a rangeland with grass-shrub vegetation and a 32-years old Pinus radiata plantation. Sectioned and bulk soil samples were collected along three transects in each land cover up to 40 cm depth. Two forest patches of Maytenus boaria were selected as controls. Physical, chemical and magnetic properties were analyzed. Native forest soils were rich in silt fraction, organic matter and non-crystalline minerals, and presented the lowest values of magnetic susceptibility. Rangeland and plantation soils differed from forest soils in these properties. Soil changes were mainly associated to changes in mineralogy resulting from soil desiccation and to the selective removal of fine particles by erosion, together with differences in the effects of recent volcanic events on the soils. Changes in soils associated with land use affected key properties related to pedogenetic processes. Magnetic susceptibility, organic matter content, texture, and pH NaF were key for understanding soil degradation processes in this dynamic environment. [ABSTRACT FROM AUTHOR]

Soil pollution is one of the main environmental concerns at a global scale, and different measures have been proposed for its prevention and remediation. In this paper we evaluate two measures – amendment addition and tree planting – applied to remediate soils contaminated by trace elements (TE). The Guadiamar study site (SW Spain) is a well-known example of a large-scale cleaning and remediation program intended to rehabilitate about 3000 ha of soils affected by a mine-spill in 1998. Firstly, we present the results of a long-term experiment in which two types of amendments – sugar beet lime (SL) and biosolid compost (BC) – were added to the spill-affected soil. Three different treatments were established: SL, BC, and NA (non-amended control). The experiment has been running since 2002 and new soil samples were taken in 2016. In general, the amendments increased soil pH and total organic carbon, and reduced TE availability. The available TE concentrations (CaCl 2 extraction) decreased drastically with time in all cases, but the evolution differed among treatments. The treatment effectiveness was evaluated by measuring plant biomass, TE concentrations in plant shoots, and soil-plant transfer. Secondly, we present results detailing the effects of seven tree species (three - Populus alba , Celtis australis , and Fraxinus angustifolia - were deciduous and four - Quercus ilex , Olea europaea , Ceratonia siliqua , and Pinus pinea - evergreen) on remediated soils. In 2014 (about 15 years after planting) we measured TE concentrations in leaves and roots and related them with TE concentrations (total and available) in soil. There were significant differences among the studied tree species in the uptake and accumulation of TE in leaves and roots. Soil pH differed among tree species and with respect to adjacent non-planted sites. There was a negative exponential relationship between soil pH and availability of Cd, Cu, and Zn. The bioconcentration factor (BCF, root:soil) and the translocation factor (TF, leaf:root) were calculated to evaluate the potential of each tree species to stabilize TE in soil. Finally, we propose the phytoremediation of TE-contaminated soils as a three-stage process, including addition of soil amendments, planting of trees, and monitoring of TE dynamics. [ABSTRACT FROM AUTHOR]

The exposure of tree or shrub roots represents a clear indicator of soil loss in the surrounding area. Previous studies have used this type of botanical evidence to estimate soil erosion rates, preferring roots at some distance from the tree stem because the inflection point (or root collar) undergoes a vertical displacement caused by basal growth. The aim of this paper is to develop a method that combines the inflection point of holm oaks and high-resolution digital images obtained by means of a terrestrial laser scanner to estimate soil erosion rates in Mediterranean dehesas. To correct for vertical displacement, the basal growth of each tree was determined in the field, differentiating the part of the roots that had been exposed by erosion from that generated by wood growth. Two datasets obtained through different approaches were used for validating the basal growth measured in the field survey: (i) a growth study analysing stems and cores of holm oaks and (ii) field measurements of basal growth of holm oaks located in an area without soil erosion. The results obtained by each method offered similar mean values (12.7 and 8.4 cm, respectively) as compared to the values estimated in the field survey (10.2 cm). Afterwards, soil erosion rates were corrected, reducing the values on average by 40%, with a mean loss of 26.7 t ha ‐1  y −1 . No relationship was found between tree age and basal growth. On the other hand, soil erosion rates showed a slightly negative trend with relation to tree age, indicating an upward tendency of soil losses from the year 1640 to 2014. Finally, it was possible to define three periods with varying erosion rates: 10.4 t ha −1  y −1 (1640–1830), 19.2 t ha −1  y −1 (1831–1888) and 27.2 t ha −1  y −1 (1889–2014). [ABSTRACT FROM AUTHOR]

Rainfall Simulators are widely used in studies on soil erosion. Most of the rainfall simulators use water with tap or ambiance temperature. However, previous studies showed that soil erosion may increase or decrease by up to three times while raindrops temperature varied from 2 °C to 20 °C. Therefore, it is of great importance to use a temperature control system in rainfall simulators. This paper describes the design of a temperature control system suitable for a rotating disk rainfall simulator at the Soil and Geomorphology Laboratory in Bar-Ilan University. The rain temperature is continually monitored by thermocouples, located very close to the disk. IR remote sensing results showed that the real temperature of the drops hitting on the ground surface differed from that measured with thermocouples by maximum 1° for the coldest simulated rain (2 °C), and −3° for the hottest one (35 °C), hence the continually monitoring temperature error is negligible. [ABSTRACT FROM AUTHOR]

Landslides are natural phenomena that can cause great loss of life and damage to property. A landslide susceptibility map is a useful tool to help with land management in landslide-prone areas. A support vector machine (SVM) is a machine learning algorithm that uses a small number of samples for prediction and has been widely used in recent years. This paper presents a review of landslide susceptibility mapping using SVM. It presents the basic concept of SVM and its application in landslide susceptibility assessment and mapping. Then it compares the SVM method with four other methods (analytic hierarchy process, logistic regression, artificial neural networks and random forests) used in landslide susceptibility mapping. The application of SVM in landslide susceptibility assessment and mapping is discussed and suggestions for future research are presented. Compared with some of the methods commonly used in landslide susceptibility assessment and mapping, SVM has its strengths and weaknesses owing to its unique theoretical basis. The combination of SVM and other techniques may yield better performance in landslide susceptibility assessment and mapping. A high-quality informative database is essential and classification of landslide types prior to landslide susceptibility assessment is important to help improve model performance. [ABSTRACT FROM AUTHOR]

Sampling strategies and methods used for estimating load can lead to large uncertainties in suspended sediment transport quantification, especially in rivers with a high variability in streamflow. The aim of this paper is to evaluate suspended sediment load, using a number of direct estimation techniques, in order to find a suitable method for temporary river systems, and to assess the uncertainty associated with load estimation, due to the specific method applied. One year of continuous measurement of flow, and discrete sampling ( n  = 216) of suspended sediment concentrations, taken from 2010 to 2011 in the Celone River (SE, Italy), were used to estimate annual load. Averaging, ratio, and regression estimator methods were applied to the entire dataset, and to subsets of data, to calculate load. The results show a wide range of values, from 220 to 1123 t km −2  yr −1 , with respect to the applied suspended sediment load estimation techniques. Averaging methods resulted biased. Sediment rating curves underestimated load, while, if the back-transformation bias correction was used, load was overestimated. The ratio methods generally overestimate load. Increased precision and accuracy was achieved through applying data stratification, based on flow regime and seasonality. After applying three different flow regime stratifications, the annual load ranged from 240 to 606 t km −2  yr −1 and, using seasonal stratification, from 258 to 974 t km −2  yr −1 . It seems that ratio estimator methods, and the regression equations applied to the stratification on a flow regime basis, are more suitable for estimating load in temporary, flashy streams. [ABSTRACT FROM AUTHOR]

Epikarst – the shallow, surficial part of a karstic massif – has a significant influence on the spatio-temporal variability of recharge and the hydrodynamic functioning of many karst aquifers. In the Mediterranean morphoclimatic zone, the average thickness of a well-developed epikarst is around ten metres, but the spatial patterns of its degree of development are very heterogeneous due to the complex interaction of a number of different factors such as lithology, fracturing, weathering, soil and vegetation. In addition, direct field observation is difficult because good outcropping conditions are restricted to particular locations, some areas are not accessible and the size of the study area is often too large for exhaustive field surveys. Satellite-based remote sensing, however, provides a complete coverage of an entire area with spectral resolutions that detect variability in features that can define image textures related to the development of the epikarst. This paper describes a quantitative methodology for epikarst mapping using satellite images and field data. The proposed method comprises an unsupervised classification to define the spectral signature of each of three epikarst development categories in a high-resolution satellite image followed by a supervised classification of the terrain into one of the three categories on a low spatial resolution scale. The training areas in the field are assigned to the three categories by a panel of experts using the Delphi method. Geophysical data are used for validation to overcome any bias that may be introduced by the panel. The proposed methodology has been applied to the Sierra de las Nieves karstic aquifer (Málaga, southern Spain). The outcome is a map of estimated epikarst development that is an approximation to reality and which can be improved as more experimental data become available. [ABSTRACT FROM AUTHOR]

Environmental fluctuations during the Holocene caused important landscape changes in the Central Ebro Basin, which is a very sensitive region due to its semiarid climate, lithology, and continuous human presence. Severe erosion processes hinder palaeoenvironmental and archaeological record preservation. Infills of ephemeral stream valleys in semiarid environments are some of the best contexts for geoarchaeological studies. In this paper, we analyse the geomorphological processes, pedological features, and charcoal and pollen content and composition of the sedimentary sequence of La Poza Valley catchment area, with the support of additional information from La Bajada Valley. 14 C dates for 13 charcoal fragments provide the necessary chronological control. We describe 5 sedimentary units and a polycyclic sequence of six soils that covers most of the Holocene, beginning ca. 9.5 ky cal BP. Buried soils help to identify stability periods in the sedimentary sequence, while incision stages are detected through erosive contacts and terraced organisation of the sedimentary units. Charcoal and pollen content and composition, as well as the soil development, reveal an open forest of junipers and pines for the Early Holocene in the lower part of the sequence (mainly in Unit 1), very different from the current deforested landscape, also represented in the sequence (Unit 4). Thus, La Poza record shows the environment was favourable for hunter-gatherers from the Late Mesolithic and for the first Neolithic farmers. From then on, progressive degradation due to a combination of climate changes and increasing human pressure led to the current deforested landscape. [ABSTRACT FROM AUTHOR]

The aim of this paper is to comprehensively evaluate the abiotic factors that influence changes in the annual growth rates of selected species of tundra plants ( Saxifraga oppositifolia L. and Salix polaris Wahlenb.). The study was conducted in the area of the Fuglebergsletta coastal plain, in the vicinity of the Polish Polar Station (Wedel Jarlsberg Land, SW Spitsbergen). Relationships between the studied phenomenon and basic environmental factors and climate indicators were evaluated. The spatial variation of land surface temperatures (LST) was determined, as were the effects of the physical and chemical properties of soils and the spring melting of snow cover on growth rates. It has been argued that the spatial and seasonal variability of annual growth is determined by the rate at which snow cover disappears and by soil moisture, which determines plants' access to water. Soil moisture depends on soil particle size distribution and weather; it is regulated by the supply of snowmelt water and rainfall as well as by the depth of the top layer of permafrost (thaw depth), which determines the level of groundwater during the growing season. The spatial characteristics of the process of the disappearance of seasonal snow cover are co-determined by the morphology of the substrate and the physical properties of the soil. An important but destructive role is played by thawing episodes, which are increasingly frequent in the winter season, ‘rain-on-snow’ events, and glaze ice. The values of correlation coefficients indicate a positive role for precipitation and negative influence of temperature. The higher the temperature (along with low precipitation), the lesser the extent of plant growth. The observed trend towards warming in polar areas does not inevitably lead to an increase in biomass production. An increase in temperature during the growing season does not necessarily promote plant growth, but rather indicates drought stress caused by the lowering of groundwater levels related to the increase in thaw depth. [ABSTRACT FROM AUTHOR]

Within Santa Margarita Ecological Reserve (SMER), southern California, an ~ 108 Ma diorite-gabbro pluton has weathered spheroidally resulting in the formation of concentric rindlets, i.e., a rindlet zone, around an unaltered ellipsoidal core of the parent rock. To our knowledge little is known about how spheroidal weathering is produced in Mediterranean climates like that characteristic of portions of the Peninsular Ranges. Hence, we undertook a detailed study aimed at determining the textural and chemical changes associated with the spheroidal weathering of the diorite-gabbro pluton. The parental spheroidally weathered corestone is characterized by a hypidomorphic-granular texture, and consists primarily of plagioclase, amphibole, and biotite, along with minor amounts of pyroxene and quartz. Within the corestone, sericite, and uncommonly, calcite and chlorite, replace plagioclase. The latter mineral also infrequently replaces portions of amphibole and biotite. Such alteration products are derived from sub-solidus deuteric alteration of the pluton. XRD clay mineral analysis of the 13 rindlets indicates the presence of mostly kaolinite and vermiculite, and a far lesser volume of green smectite. Thin section study of rindlet samples suggests that vermiculite is derived from the weathering of biotite, the most extensively altered mineral in the rindlet zone. Such alteration is paralleled by statistically significant losses of K mass across the rindlet zone. In addition, statistically significant losses of Ca and Na mass across the rindlet zone, likely reflect conversion of sericite to kaolinite. In contrast, the absence of statistically significant losses of Mg, Fe, and Mn over most of the rindlet zone, implies that fluids were mostly oxidizing, and that any Mg leached from amphibole was likely fixed within smectite, while leached Fe and Mn precipitated out as oxides or oxyhydroxides. Though calcite was present in the corestone, its absence in the rindlets indicates that fluids were sufficiently acidic to dissolve and remove it. Previous studies have shown that spheroidal weathering occurs when volume expansion produced by a positive ΔV of reaction builds up internal elastic strain energy in the rock. For example, this type of reaction occurs when iron oxidizes within biotite resulting in an expansion of d(001) from 10 Å to 10.5 Å, or when biotite is transformed into vermiculite leading to an expansion of d(001) from 10 Å to 14 Å. Data presented here suggest that the conversion of biotite to vermiculite, and the resulting positive ΔV produced the spheroidal fracturing of the corestone at SMER. Hence, these and other data discussed in this paper suggest that the weathering of biotite is the primary driving force in the formation of spheroidally weathered corestone in the Mediterranean climate of the Peninsular Ranges. [ABSTRACT FROM AUTHOR]

Contamination of urban lake sediments by heavy metals is a major threat to environmental safety and human health due to its high toxicity and persistence. This paper aims to examine the feasibility of using visible and near-infrared reflectance spectroscopy (VNIRS) to rapidly quantify heavy metals (i.e., As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) in urban lake sediments. Lake sediment samples ( n = 103) were collected from the East Lake in Wuhan, China. Partial least squares regression (PLSR) calibration models were developed for the heavy metals estimation. Genetic algorithm (GA) and competitive adaptive reweighted sampling (CARS) were compared to test whether spectral feature selection could improve heavy metals predications or not. Correlation analysis was carried out to gain better understanding of the predictive mechanism for the assessment of the heavy metals in sediments using VNIRS. PLSR calibration models showed that Cd, Hg, Ni and Pb had acceptable model prediction (with r 2 CV values range from 0.32 to 0.40), while model results for As, Cr, Cu and Zn were unsatisfactory (with r 2 CV values of 0.01–0.06). These different accuracies were likely caused by the different relationships between heavy metals and spectrally-active constitutes (e.g., total organic carbon, TOC). When compared with full-spectrum PLSR models, GA-PLSR and CARS-PLSR models slightly increased the accuracies by remove uninformative spectral variables. Given these undesired practices, this study demonstrated that VNIRS should not be recommended for heavy metals estimation in urban lake sediment. The inherent correlations between heavy metals and spectrally-active constitutes (e.g., TOC) rather than modeling method (e.g., feature selection algorithms) were critical for the limited heavy metals estimation using VNIRS. [ABSTRACT FROM AUTHOR]

The present paper aims to investigate the geological and environmental parameters controlling the redness of sand at the megabarchans located nearby Khnifiss lagoon (SW of Morocco). Mineralogical investigation either by laboratory or remotely sensed data showed the abundance of a mixed composition of Quartz, Carbonates and mafic minerals with a dominance of Hematite Quartz coated grains. Also, grain size analysis revealed the heterogeneity of the megabarchans sand and the dominance of fine and well to very well sorted sand with a mean grains size of (0.2 mm). Mineralogical species were adequately distributed according to their size and density. We noted the dominance of iron bearing minerals including: Magnetite, Hematite, Ilmenite, Ulvospinel, and Pyroxenes, in the very fine fraction (< 63 μm). Yet, the coarser fractions (> 63) μm knew a dominance of Hematite coated Quartz, Carbonates and Feldspars. These both fractions are carried by wind with almost the same threshold motion, which meant that the size could compensate the density. That explains their deposition in the same environment. The megabarchans migrated over the past 325 years with a rate of 2 m/year. Thus, grains may undergo many turnover cycles until they can be reactivated by wind. Climatic parameters such as precipitations with 164 mm/year, the frequent stormy events that bring a flash flooding, in addition to the high humidity and important fog and dew provide a source of moisture that make the megabarchans a moistened environment encouraging the iron oxidation. Thus, the abundance of a source of iron and a source of moisture, in addition to the stability of the megabarchans, and their water holding capacity remained the effective factors that led to the megabarchans redness. [ABSTRACT FROM AUTHOR]

In this paper the storage potential of soils within a heterogeneous structured hummocky young moraine region for organic carbon is discussed with respect to climate change and erosion. Erosion is discussed to be either a global terrestrial CO 2 sink or a source. In hummocky young moraine regions of North East Germany water and tillage erosion are steadily changing factors since the beginning of arable landuse in ancient times. For such topographically complex landscapes the knowledge on soil organic carbon (SOC) dynamics and the limits of carbon storage are still limited. Our objective is to combine data collected during former soil erosion studies with recent findings on (i) soil property and (ii) estimated “optimal” SOC data to predict the SOC storage related to tillage and crop rotation, among others. Classified catenae were analysed for texture, SOC, CO 3 -C, nutrient contents, and depth of weathering. Optimal SOC contents were estimated on the fine sized particle content. Arable soil at convex slope positions of steep catenae show 4 time smaller SOC stocks as compared to respective forest soils and to arable soils at concave position. Our findings suggest changes in SOC stocks to be almost exclusively related to decomposable carbon pools. Comparison of estimated optimal with measured SOC contents in soils at such positions indicated that such soils could potentially store a surplus of 0.6 to 0.8 g kg − 1 . SOC protection at convex positions is limited by soil texture, and frequent truncation of the respective soil profiles. Whereas truncation followed by downhill transfer may bury SOC at sedimentation/concave positions resulting in long-term SOC storage as far as decomposition is prevented by site conditions. [ABSTRACT FROM AUTHOR]

Torrential floods are hazardous hydrological phenomena that produce significant economic damage worldwide. Flood reconstruction is still problematic in ungauged mountainous areas due to the lack of systematic data, so indirect techniques are required. This paper presents an integrated palaeoflood study of a Pyrenean stream that combines fluvio-torrential geomorphology, dendrogeomorphology, palaeoflood discharge estimation and flow hydraulics. The use of a total station and airborne LiDAR data allows detailed topography for geomorphological mapping and running a one-dimensional hydraulic model. Based on the height of scars on several damaged trees, we obtained palaeodischarges of 316 m 3 s − 1 and 314 m 3 s − 1 for the 2008 and 2010 floods. The hydraulic parameters were related to the geomorphic position of trees, showing a positive relation between most energetic geomorphic elements and both flow depth and velocity values. The most affected trees are located in intermediate energy geomorphic positions. Analysing variation in scar height and flow stage differences, we suggest that most reliable trees for peak discharge estimation correspond to those in areas related with fluvio-torrential processes of intermediate energy. This multidisciplinary palaeohydrological study relates flood hydrodynamics with the damage to trees and their geomorphological characteristics, focusing on the hydraulic parameters of the peak flow (depth, velocity and unit stream power), which has never been performed before. The proposed approach shows strong potential for palaeoflood analysis in ungauged mountain catchments with scarce non-systematic data. [ABSTRACT FROM AUTHOR]

The unfavourable environmental conditions to Chernozem development in Central Europe has led to questions regarding their origin and age, and conditions necessary for Chernozem persistence in Central Europe under a humid climate. This paper deals with Chernozem transformation during the Holocene period in SW Poland in relation to land morphology. The study was based on a catenary approach, with additional remarks on parent material homogeneity and soil classification. Based on textural and geochemical indices, the homogeneity of aeolian material (loess) was proven in the main part of the catena, which confirmed that the differentiation of “dry” and “wet” chernozemic soil across the catena did not result from the variability of parent material. No differences in morphological or physicochemical characteristics of mollic horizons were identified between the well-drained and wet sections of the catena. The strong redoximorphic features (manifested as stagnic or gleyic properties) in the lowermost part of catena are, therefore, secondary features, i.e. developed after the mollic horizon development, presumably in late Holocene period. Chernozems with chernic horizon, weakly developed subsurface argic horizon and free of redoximorphic features prevail in the central, well-drained and not eroded section of the catena. It has been hypothesized that the loess soils in the uppermost, more inclined part of the catena have been truncated by erosion during the first agricultural period, then afforested and transformed into Luvisols, probably due to temporary abandonment of those sites less favourable for farming. The soils in the transitional zone received the colluvial addition of humus material from the eroded hill summit; however, the colour of the humus layer has a chroma too high for a chernic horizon that surprisingly shifted these soils to the Kastanozems group. This study showed that the direction of transformation of native Chernozems in the Holocene period was strongly related to their position in the landscape, which affected the erosion/accumulation intensity and water drainage conditions (soil moisture regime). As a final result of these transformations, a relief-related zonality of soils has developed with Stagnic/Gleyic Chernozems – Luvic Chernozems – colluvial “Kastanozems” – Haplic Luvisols, in the lower (moist), middle (well-drained), and upper colluvial/eroded sections of the undulating loess plain, respectively. [ABSTRACT FROM AUTHOR]

Badlands in Central Istria share a very frequent characteristic with other worldwide badland sites, the rapid erosion rate. Rock wall retreat measurement on such a relief is associated with all types of problems because a certain effort has to be put into the measurement equipment design. Spear vegetation and a few previous studies encouraged the testing of different photogrammetric technologies and data acquisition methods for the determination of the denudation rate in Istrian badlands. The main aim of this paper is the establishment of the most suitable methodological combination for the determination of the badland denudation rate, which is the gully rock wall retreat rate. The photogrammetric approach was tested by measuring and comparing the amount of denudation on the test site, which was established on a gully sidewall. The photogrammetric measurement was used twice within one year. The analysis of the photogrammetric technologies and data acquisition methods focused on the field and laboratory equipment and the accuracy and difference models obtained from the test site measurements. The analysis shows that the combination of digital photogrammetry and fully automatic matching data acquisition provides the most suitable measurement technique of the rock wall retreat in Central Istria badlands and other similar badlands. [ABSTRACT FROM AUTHOR]

Over recent decades, andic soils have been increasingly found in non-volcanic mountain ecosystems (NVME) in many parts of the world. In Italy, this type of soil has proved to be greatly affected by aeolian deposits and to be widely distributed geographically. However, there are still many open questions, especially regarding the genesis of these soils. This paper focuses on five representative pedons taken from NVME. Soil forming processes and relationships between soil and underlying bedrock were investigated by using an integrated approach including geochemical, magnetic, mineralogical, micromorphological and particle size distribution (PSD) analysis. The 5 pedons showed andic character and similar morphology and micromorphology (e.g. silt illuviation, pedorelicts), as well as large differences in terms of soil reaction and clay mineralogy. The analysis of the vertical distribution of C, Al and Fe extracted in pyrophosphate along with related geochemical indices (e.g. C p /Al p ) enabled us to indicate andosolization as the main process of soil formation and to exclude podzolization. With respect to the soil-bedrock relationship, 2 soils showed great similarity to the underlying bedrock along with a clear aeolian particle size distribution footprint, whereas, in the remaining 3 soils, there was a clear soil-bedrock discontinuity and an evident volcanic fingerprint. Some of the soil-bedrock differences related to the geographical settings and latitude. [ABSTRACT FROM AUTHOR]

In this paper, we report the findings from an experimental study on a parabolic cross-sectional sand bed channel with uniform fine sand under no seepage and downward seepage conditions. Through experiments, we observed that an alluvial channel, which remained at threshold condition of sediment movement during the no seepage experiment, started transporting sediments with the application of seepage in the downward direction. Shields stress of the threshold channel increased significantly from its critical value after the application of downward seepage, which led to the deformation of the cross-sectional shape and consequent development of the bedforms. The role of turbulence in the development of bedforms has also been analyzed. Measures of turbulent statistics show that the time-mean velocities and Reynolds stresses were increased significantly with the application of downward seepage. Under the action of seepage conditions, increase in the flux of streamwise turbulent kinetic energy in the streamwise direction was observed in the region close to the channel boundary. Also, quadrant analysis exhibited an increase in the contributions from all the bursting events and the thickness of the sweep-dominated zone in near-bed region after the application of downward seepage. A bedform tracking tool has been used to evaluate the variability in the geometry of bedforms. We have classified these developing bedforms as current ripples and linguoid ripples according to their evolution with time under the downward seepage condition. It has been further observed that the variation in Shields stress and corresponding bedform geometry reached an equilibrium state in the presence of downward seepage when the experiments were run over a longer period of time (24–31 h). [ABSTRACT FROM AUTHOR]

This paper addresses the timing of accelerated soil erosion and landscape degradation in central Mexico. It shows data on erosion sequences in the Valley of Teotihuacan, an area where agricultural dates back to at least since 1100 BCE, and an ideal setting to test ideas on the effect of preconquest versus post-conquest anthropogenic impacts on the environment. The methods include stratigraphy, detailed description of soil profiles and soil micromorphology, along with analysis of pottery sherds and radiocarbon dating. A chronology of events for two catenas, focusing on periods of landscape stability and change, establish the sequence of erosion events from pre-Hispanic to modern times. Six erosion phases are recognized over the last 2000 years in Teotihuacan. Although results suggest that the most intense erosion occurred after Spanish conquest, in the 16th century, several erosion phases took place during pre-Hispanic times and also in the postcolonial period, including the 20th century. Probable causes for these impacts are related to settlement dynamics, population variability, and land use changes. Thus, it provides new information for the discussion on the timing and causes of erosion, sedimentation and landscape modification in the central Mexican Highlands during the late Holocene. [ABSTRACT FROM AUTHOR]

Geomorphic processes driven by water are particularly active in mountain environments, especially under the current climate conditions. Erosion and dissolution processes shape meaningful landforms, in different kinds of deposits and rocks, and in some cases they are classified as geomorphosites. Such landforms, especially earth pyramids and rock pillars, are usually characterized by a high scientific value (e.g., representativeness, ecologic support role) and by additional values (e.g., cultural and aesthetic value) contributing to the local geoheritage. Mountain geomorphosites are growing in importance within scientific community and their morphological evolution can affect the global value of the site itself (e.g., integrity). In this paper, after a first review on the terminology used for classifying landforms modelled by water runoff and on their meaning within the mountain environment, the results of a detailed research performed at two sample sites, included in the Swiss National Inventory of Geosites, are presented. The two study sites are representative respectively of: i) water runoff on glacial deposits shaping earth pyramids (Pyramides d'Euseigne); ii) water dissolution on gypsum rocks, modelling articulate karst landscapes (Pyramides de gypse du Col de la Croix). For each site, landforms evolution was investigated and denudation rates were estimated by means of different methods: iconographic material analysis, quantitative geomorphology and dendrogeomorphology on exposed roots. Despite the long-term, average rates obtained by means of roots exposure for both water runoff on glacial deposits (e.g., 5.8 mm/y) and dissolution on gypsum rocks (5.6 mm/y) are comparable. Moreover, a strict relation between the activity degree of processes, the integrity of the site and the assignment of geomorphosites to a specific category (i.e., active, passive or evolving passive) emerged from the results. [ABSTRACT FROM AUTHOR]

This paper reports from a survey of the occurrence of large avalanches in Żleb Żandarmerii. This couloir is known to be one of the most hazardous avalanche paths in the Tatra Mountains and has one of the longest histories of avalanche observation. This survey looked at the runout distance, return period, dynamics and geoecological implications of avalanches in the context of current climate change. The study took advantage of the longest record of meteorological data available in the Tatra Mountains, as well as archival avalanche observations, topographical maps, orthophotomaps and a high-resolution digital terrain model. Avalanche data were obtained using geomorphological and dendrogeomorphic methods and through modelling with the RAMMS numerical avalanche dynamics simulation software. The largest avalanches reach the foot of its counter slope. Their length, release volume, flow velocity and pressure can exceed respectively 1000 m, 80 000 m 3 , 45 m/s and 600 kPa. The results of our study suggest that current climate warming has been accompanied by thinning and shortening of the duration of snow cover, as well as by an upward expansion of the timberline (including in the large-avalanche runout zones) of up to 80 m since the mid-1920s. No distinct temporal trend was identified in the large avalanche return period since 1909, but their mass and intensity have declined. Forests and timberline expansion were found to have no influence on the extent of the avalanches in our study, while ground relief could determine both their downward extent and lateral expansion. [ABSTRACT FROM AUTHOR]

• The challenges current approaches facing is discussed. • Using urban functional types to reflect the effect of human activities on urban heavy metal accumulation. • Combing the advantages of receptor models and GeoDetector to select key environmental covariates and tracing pollution sources. • Extending the transferability of the models is urgent to promote the application of the models. Heavy metal pollution in urban soil is one of the global environmental problems, and monitoring its spatial distribution can provide basic data for assessing and managing the ecological and environmental problems. Due to the strong human activities in the urban space and the high heterogeneity and fragmentation of the landscape, it is of great significance to explore how to characterize the diversity in human activities within the city and to establish a paradigm for mapping spatial distribution of heavy metal in urban soils. This paper reviewed the theory of soil-landscape model, the data sources for extracting environmental variables, and the geo-statistical methods for establishing regression models. Furthermore, receptor models for tracing heavy metals were discussed. We suggested that using multi-source heterogeneous geographic data (geological data, soil type data, meteorological data, terrain data, time series Landsat images) to extract environmental covariates. In particular, integrating social perception data (point of interest, Tencent user data) and remote sensing image data to extract the urban functional district types that reflect differences in human activities. GeoDetector is recommended to select key environmental covariates that spatially coupling with urban soil heavy metals, and combined with receptor models to trace the sources of heavy metals. Machine learning algorithm is a good choice to construct the estimation models by cooperating with key environmental variables, and to verify the general transferability of the models by using the local weighted and 'spiking' modeling strategies. The newly introduced methods and ideas may be expected to provide technical methods for the monitoring of heavy metal pollution in urban soils, and to further expand the application of digital soil mapping theories and methods in urban soil mapping. [ABSTRACT FROM AUTHOR]

• Electrical resistivity tomography used for the first time to investigate FGT mounds. • Fungus-growing termites increase drastically soil electrical resistivity. • Micromorphology and X-ray μ-CT emphasize the role of microstructure in resistivity. • Particle size distributions influence the range of electrical resistivity values. • The study presents a method of determining mound structure that is non-destructive. Fungus-growing termites (FGT) are important agents in subtropical and semiarid ecosystems for the biological and geological modifications they bring through the construction of their mounds. In order to survive and thrive, the mounds are designed to host the Termitomyces fungus in pre-set conditions of humidity and temperature. The interior structure of FGT mounds has only been scarcely studied in the scientific literature, making knowledge about mound morphology and development incomplete. In this study, a relic FGT mound in northern Botswana was analyzed using a combination of electrical resistivity tomography (ERT), particle size distribution (PSD), X-ray computed microtomography (X-ray micro-CT), and soil micromorphology methods. Specifically, we set out to investigate (i) whether changes in the measured soil resistivities reflect expected changes between the various functional compartments of the mound; (ii) what changes in soil texture and structure are associated with the resistivity variations; and (iii) whether this information can be used to better understand the mound compartments and their development. Our results suggest that ERT may eventually provide an attractive and efficient method to investigate the interior structure of FGT mounds that is non-destructive. The use of ERT does not require to remove the epigeal of the mound. The modifications brought by FGT to the texture and structure of the soil, respective to the function of each mound compartment, can increase resistivity of up to three orders of magnitude. Further, the work presented in this paper helps to (i) identify processes involved in the sediment transfer between the mound and its surroundings, (ii) increases the understanding of mound morphology, and (iii) show that fungus-growing termitaria affect durably savanna landscape. Finally, this study demonstrates that ERT is a pertinent non-destructive method to investigate mound structure. [ABSTRACT FROM AUTHOR]

• Hydrogeomorphic processes drive wetland-catchment connectivity dynamics. • Climatic and anthropogenic features influence landscape connectivity patterns. • The upper catchment region is well-connected and contributes to high runoff and erosion. • Identifying hotspots of catchment connectivity change can inform management. Wetlands in semiarid regions are important systems that provide numerous ecosystem services in otherwise dry environments. Their functioning depends on the connected transfer of materials from source to sink which is determined by the degree of landscape connectivity. A combination of catchment characteristics, climatic variables and human activities are important factors driving landscape connectivity; however, wetland management rarely considers all these factors when conserving these systems. In this paper, we evaluate the landscape connectivity of the Mara River catchment in East Africa to understand the hydrogeomorphic processes driving material transfer to the floodplain wetlands. This semiarid catchment hosts the UNESCO World Heritage Serengeti-Mara ecosystem providing a unique opportunity to assess the influence of protected areas on wetland-catchment connectivity patterns. We use the index of connectivity and Emerging Hot Spot analysis to assess the hillslope-channel connectivity and identify specific subcatchments which have contributed positively to the wetland's connectivity over time. The catchment-scale analysis highlights significant spatiotemporal variability in connectivity patterns and associated sediment dynamics. The results reflect that the Upper catchment is highly connected owing to the steep slopes and high rainfall and is likely responsible for the greatest sediment inputs into the fluvial network. Under greater future climatic and anthropogenic pressures, this region is expected to contribute increased sediment inputs into the river which will likely affect the geomorphic response of the downstream floodplain wetlands and may need to be prioritised for management. The protected areas are generally poorly connected due to intact vegetation and their local sediment contribution to the fluvial network is comparatively lower. Consideration of their placement in the catchment is important for managing these ecologically significant areas. Understanding the patterns and variability of hillslope-channel connectivity and the broader-scale landscape connections can help to identify and prioritise existing and emerging hotspots of change in large, semiarid catchments. [ABSTRACT FROM AUTHOR]

• A new methodology is developed to quantify stakeholder opinions on land-use change. • Increased self-sufficiency in agriculture and forestry is likely to deteriorate water quality. • More focus on sustainability in agriculture and forestry is needed to improve water quality. • Stakeholder consultations are valuable to balance bioeconomy and water management. Future development of bioeconomy is expected to change land use in the Nordic countries in agriculture and forestry. The changes are likely to affect water quality due to changes in nutrient run-off. To explore possible future land-use changes and their environmental impact, stakeholders and experts from four Nordic countries (Denmark, Finland, Norway and Sweden) were consulted. The methodological framework for the consultation was to identify a set of relevant land-use attributes for agriculture and forestry, e.g. tillage conservation effort, fertiliser use, animal husbandry, biogas production from manure, forestry management options, and implementation of mitigation measures, including protection of sensitive areas. The stakeholders and experts provided their opinions on how these attributes might change in terms of their environmental impacts on water quality given five Nordic bioeconomic scenarios (sustainability, business as usual, self-sufficiency, cities first and maximizing economic growth). A compilation methodology was developed to allow comparing and merging the stakeholder and expert opinions for each attribute and scenario. The compiled opinions for agriculture and forestry suggest that the business-as-usual scenario may slightly decrease the current environmental impact for most attributes due to new technologies, but that the sustainability scenario would be the only option to achieve a clear environmental improvement. In contrast, for the self-sufficiency scenario, as well as the maximum growth scenario, a deterioration of the environment and water quality was expected for most of the attributes. The results from the stakeholder consultations are used as inputs to models for estimating the impact of the land-use attributes and scenarios on nutrient run-off from catchments in the Nordic countries (as reported in other papers in this special issue). Furthermore, these results will facilitate policy level discussions concerning how to facilitate the shift to bioeconomy with increasing biomass exploitation without deteriorating water quality and ecological status in Nordic rivers and lakes. [ABSTRACT FROM AUTHOR]

• Five contrasting scenarios describe a developing Nordic bio-economy towards 2050. • The scenarios led to substantial differences in land use cover and intensity. • This in turn affected hydrology and nutrient load in half of the catchments. • Patterns of final ecosystem service delivery were strongly affected. • The summed total economic value was similar among the two most disparate scenarios. • The sustainability scenario optimised water quality and biodiversity without welfare loss. This paper synthesizes a five-year project (BIOWATER) that assessed the effects of a developing bioeconomy on Nordic freshwaters. We used a catchment perspective and combined several approaches: comparative analyses of long-term data sets from well-monitored catchments (agricultural, with forestry, and near pristine) across Fennoscandia, catchment biogeochemical modelling and ecosystem services assessment for integration. Various mitigation measures were also studied. Benchmark Shared Socio-economic Pathways were downscaled and articulated in dialogue with national stakeholder representatives leading to five Nordic Bioeconomy Pathways (NBPs) describing plausible but different trajectories of societal development towards 2050.These were then used for catchment modelling and ecosystem service assessment. Key findings from the work synthesized here are: (a) The monitoring results from 69 catchments demonstrate that agricultural lands exported an order of magnitude more nutrients than natural catchments (medians 44 vs 4 kg P km−2 y-1 and 1450 vs 139 kg N km−2 y-1) whilst forests were intermediate (7 kg P km−2 y-1 and 200 kg N km−2 y-1). (b) Our contrasting scenarios led to substantial differences in land use patterns, which affected river flow as well as nutrient loads in two of the four modelled catchments (Danish Odense Å and Norwegian Skuterud), but not in two others (Swedish catchment C6 and Finnish Simojoki). (c) Strongly contrasting scenarios (NBP1 maximizing resource circularity versus NBP5 maximizing short-term profit) were found to lead to similar monetary estimates of total societal benefits, though for different underlying reasons – a pattern similar across the six studied Nordic catchments. (d) The ecological status of small to medium sized rivers in agricultural landscapes benefitted greatly from an increase in riparian forest cover from 10 % to 60 %. Riparian buffer strips, constructed wetlands, rewetting of ditched peatlands, and similar nature-based solutions optimize natural biogeochemical processes and thus can help in mitigating negative impacts of intensified biomass removal on water quality. [ABSTRACT FROM AUTHOR]

• Sparse representation is employed to improve the sediment fingerprinting technique. • The SRSF method is advantageous in feature extraction and selection. • Virtual sample mixtures and empirical results tested the reliability of the SRSF. • SRSF is used to quantify contributions of sediment provenances in the Yangtze Delta. Quantitative research on the sediment source to sink process is critical to revealing the evolution of the Earth's surface. The fingerprinting technique is useful for sediment source detection, and machine learning methods are being used with this technique. However, paleo-provenance research with limited measured data from sediment cores is not adequate for big data analysis which demands a large amount of data. Hence, determining how to assess authentic source contributions by using fingerprinting techniques based on very limited measurement data is a key scientific task. Sparse representation (SR), a machine learning method with advantages in feature extraction that treats the source as a linear combination of multiple tracers, has the potential to provide satisfactory answers. In this paper, a sparse representation-based sediment fingerprinting (SRSF) method is introduced. Based on size-specific magnetic and geochemical characterizations, we applied this method to quantize the provenance of three sediment cores from the Yangtze River Delta (YRD), where Yellow River sediment has contributed to delta formation over the past 400–600 years. Our results showed that the sediments of the Yellow River contributed 19.3 ± 5.8 % of the clay and fine silt (<16 μm) and 23.5 ± 9.2 % of the medium silt (16–32 μm) in the delta, which was consistent with previously published results. This study improves the current fingerprinting technique in the feature extraction and selection stage by leveraging SR and provides reference data for the development of the modern YZD delta. The SRSF method has many potential applications, especially in paleo-provenance detection with highly limited measurement data, which could help expand our understanding of paleo-Earth surface evolution. [ABSTRACT FROM AUTHOR]

• Physical and chemical weathering characteristics among different scales are compared. • Supergene and hypogene alteration are separated by means of chemical and mineralogical properties. • Comparison of weathering features at different scales enhanced the understanding of weathering. • Aridity-humidity climate changes during Permo-Carboniferous were assessed. Intracratonic sedimentary basins develop on first-order nonconformities. Although the evolution of such basins has been the focus of many studies, the formation of the basement surfaces has rarely been considered. In this paper, we investigated the physical and chemical paleoweathering of different basement rocks at the post-Variscan nonconformity in Central Europe. We used a comprehensive approach by accounting for different scales and integrating physical and chemical weathering. Physical weathering was qualitatively classified at the macro/mesoscale and quantitatively classified at the microscale using thin sections and through measuring fracture areas by image analysis. Chemical weathering was quantified by distinguishing the mineralogical and geochemical characteristics measured by X-ray diffractometry (XRD), X-ray fluorescence (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). Compared to previous studies, common physical and chemical weathering indices were normalized to the rock types to improve the weathering intensity comparison. Clay transformation and carbonate/dolomite precipitation in the paleoweathering sections indicate a temperature interval of 100 to 300 °C for the circulating fluids during burial. The maximum chemical weathering intensity was found at the top surface of the basaltic andesite with a CIA N (normalized chemical index of alteration) value of 83, whereas the IPW N (normalized index of physical weathering) was less than 0.1. The gabbroic diorite and granite had a CIA N value of 78, whereas the physical weathering intensity was approximately 0.6. The lowest chemical weathering intensity was observed at the top of the granodiorite and tonalite at 71, and both rock types showed the highest physical weathering intensity of approximately 4. Because of the normalization procedure, the differences in the ratio of chemical versus physical weathering can be directly linked to aridity-humidity changes in the lower Permian paleoclimate. The concept and results of this work can be used for future studies on continental paleoclimate as well as for reservoir modeling. [ABSTRACT FROM AUTHOR]

• Land use and land cover classes homogenize within-class differences in vegetation density, type and other characteristics that influence surface erosion. • When these classes are used to estimate current and projected future RUSLE C-factor for native vegetation, this introduces significant error. • Remote sensing methods can be used to assess intra-class variation in C-factor, improving the soil loss estimate. • A strong, predictive relationship exists between remotely-sensed C-factor values and climate. • Current and projected changes in climate can be used to directly estimate C-factor, improving the estimate of current and future soil loss rates. This new method provides a low-cost, efficient and reliable estimate of future C. Understanding how reservoir sedimentation rates may evolve due to climate change is essential for projecting future changes in reservoir water storage capacity. The Revised Universal Soil Loss Equation (RUSLE) is commonly used to assess regional soil loss rates because of its suitability for working with the coarse temporal and spatial scale of climate model outputs. Application of the RUSLE for projecting future erosion rates is constrained by the relatively limited number of classes used in projected changes of native vegetation: this typically reduces a wide range of variation in RUSLE cover (C) factors to a single value per class, and these classes may be insensitive to changes in species composition and canopy density with time and space. This paper develops a low-cost, efficient, and objective approach to projecting future C values directly based on widely available Landsat data, downscaled climate model data, and a limited number of terrain variables. Observed C is estimated from Landsat-derived Normalized Difference Vegetation Index (NDVI) and Modified Soil-Adjusted Vegetation Index (MSAVI) values using standard methods. A linear relationship is established between the observed C values and average annual antecedent temperature, average annual antecedent precipitation, latitude, and percent sand (adjusted R2 = 0.75604, 0.7543, and RMSE = 0.09448, 0.07043, respectively). A proof of principal study demonstrates that, unlike when land cover classes are used to estimates C, a RUSLE model driven by the regression-based C provides a correct order-of-magnitude estimate of observed long-term erosion and sediment yield rates (e.g., an estimate of 2.9–3.2 t ha−1 y-1 is obtained where observed rates range from 1.2 to 3.9 t ha−1 y-1 for the same time period, and up to 8 t ha−1 y-1 historically, while standard formulations of RUSLE yield 16.1 and 0.3 t ha−1 y-1). Using climate model data to estimate both precipitation intensity (R factor) and C in the RUSLE model results in basin wide projected end 21st century soil erosion rates for relative concentration pathway 8.5 of 5.5–7.5 t ha−1 y-1, consistent with expectations for accelerated soil loss in the study area as climate change reduces soil moisture while increasing precipitation intensity. The same model driven by land cover class estimates of C produces soil loss rates an order of magnitude smaller (0.3–0.4 t ha−1 y-1), consistent with a much more heavily vegetated landscape than could be supported under the increasingly arid projected climate. [ABSTRACT FROM AUTHOR]

[Display omitted] • New image processing algorithm to analyse fine sediment deposits on gravel bars. • Method based on a high-pass filter and K-means clustering. • Calibration using close-range pictures proceesed with Basegrain algorithm. • Validation using Wolman pebble count method. • Method more robust to varying image quality than existing method. In this paper, we present a new image processing algorithm to analyse fine sediment deposits on gravel bars. The method is based on pictures taken from the river bank with an average resolution of a few centimetres per pixel. The proposed image processing algorithm consists of two steps. In the first step, the raw image is orthorectified with a 5 cm pixel size. In second step, we used an original combination of two well-known image techniques to classify pixel. First, a high-pass filter is applied in the Fourier domain to correct grey-value potential bias, i.e. to merge wet and dry deposits. Then, an unsupervised classification process based on K -means clustering is conducted to partition image pixels into K classes. The area of fine sediment deposits is calculated by summing the area of each class multiplied by weighting parameters (surface area percentage of fine deposits for each class). The value of K and the weighting parameters are calibrated using local close range photos of the bar surface representing the spatial variation of surface fine sediment distribution. The algorithm is then validated with field measurement using the finest class (d < 4 mm) of Wolman pebble count method. The impact of image resolution is investigated: the algorithm was found suitable for pixel size between 1 and 10 cm. The robustness of the present algorithm to images taken at different times and with different illuminations is studied by comparing it to two methods from the literature. The new method yields the most robust results with an average standard deviation lower than 5%. It yields larger surface of fine sediment since it includes all possible patches around coarse particles. Such results imply that the algorithm can be applied on a long image series to help us understand the temporal dynamics of fine sediment deposits on the bar surface. [ABSTRACT FROM AUTHOR]

• Recent geochronological findings are not engaged, leading to a different conclusion. • Alluviation during ca. 26–11 ka is not supported by radiocarbon dates. • Interpretation of some sediments and processes should be reconsidered. In a study where one of the objectives was to assess the impact of climate change on evolution of an alluvial fan, the authors determined some geochronological data that enabled them to discuss paleoenvironmental conditions of the Czarny Dunajec River system. They conclude that the gravelly material stored in the fan was deposited probably between c. 27 and 14 ka BP, MIS 2, and link this period of deposition with the glacier development in the Tatra Mountains. The geochronological data presented in their paper, however, does not support largely this statement, also the discussion does not take into account the newest findings in the region, which disprove the presumed connection between alluvium deposition and glacial stages. Additionally, some data on river terraces and alluvial sediments requires clarification, i.e. number of terraces and their heights, straths and the composition of terrace deposits, and the processes from which sediments and the fan originate. [ABSTRACT FROM AUTHOR]

• Both models have applicability in prediction of group-occurring shallow landslides. • Combining Scoops3D and TRIGRS shows more effective landslide prediction result. • TRIGRS has the problem of over-prediction in the simulation of unstable area. • Fitting curve of rainfall threshold supports landslide warning in basin lacking data. The stability evaluation of rainfall-induced landslides using a physical determination model supports disaster prevention, but it is mostly applied to the area with few landslides, and there is a lack of quantitative study on rainfall and landslide stability. This paper combined the Scoops3D model with the TRIGRS model (3D) to predict the shallow landslide spatiotemporal distribution and compared the simulation results with those of the TRIGRS model alone (1D), aiming to obtain more accurate assessment results. At the same time, the relationship between landslide stability and accumulative rainfall was quantitatively fitted to improve the real-time landslide prediction system. We applied the 1D and 3D models to the July 21, 2013 group-occurring landslide event (976 shallow landslides) in the Niangniangba basin, China. The required geotechnical parameters of both models were acquired by field and laboratory tests. We calculated the pressure head over time using the TRIGRS model based on practical rainfall data and predicted the shallow landslide stability using the Scoops3D model according to the resulting piezometric surface. We compared the landslide stability spatial distributions of the two models under initial and saturated conditions with the landslide catalogue. The success rate of landslides predicted by 3D model is 4.20% higher than 1D model. A composite index to quantitatively evaluate both models' performances indicates over-prediction by the 1D model in the stable region, while the 3D model more effectively predicts shallow landslides with a smaller unstable region. The relationship between instability proportion and accumulative rainfall in the 1D and 3D model can be represented by y = 24.57 x 0.18 and y = 11.59 x 0.33 , respectively. The 3D model shows more conservative result, and the rainfall threshold analysis proposed in this paper can provide reference for the time of most landslides in the case of insufficient data, which is an important indicator for disaster early warning and prediction. [ABSTRACT FROM AUTHOR]

• Sediment connectivity concepts, approaches, indices, and methods have been addressed. • The advantages and limitations of the approaches and methods have been depicted. • Structural and functional connectivities have a hard and soft nature, respectively. • Static characteristics are considered rather than dynamic aspects of connectivity. • Simultaneous assessment of connectivities will be a vital consideration for future. In recent years the concept of connectivity has emerged in sediment management to describe transfer of sediment from different sections of landscapes at various spatial and temporal scales. The sediment connectivity concept has two distinct components: structural and functional. Structural and functional sediment connectivities have a hard and soft nature, respectively, in which the former relates to physical characteristics and the latter to soil erosion and sediment transport processes. Although there has been an increase in sediment connectivity studies over the last decade, disagreement and confusion seems to remain about conceptual and especially methodological approaches, related indices, methods of quantifying sediment connectivity at a range of spatial and temporal scales, and the current situation in sediment connectivity research. A review of the relevant literature is needed to address these issues and provide a holistic overview of different aspects of sediment connectivity which would enlighten the directions of future research. In this review, 117 papers have been classified into five different categories, namely (i) developing conceptual frameworks; (ii) depicting spatial and temporal distribution of sediment source and sink areas; (iii) developing sediment connectivity indices; (iv) using and developing models; or (v) investigating sediment delivery likelihood through a network analysis approach. The reviewed contributions within each category were 8%, 23%, 55%, 10% and 4% papers respectively. The results indicated that more studies at both global and local scales are necessary to achieve a comprehensive conceptualization of sediment yield and related processes using sediment connectivity. Most studies have concentrated on static characteristics rather than dynamic aspects of connectivity, leading to mainly structural-based methods and indices, resulting in less attention being paid to functional connectivity. Process-based sediment connectivity studies, by focusing on spatio-temporal variations of sediment transport throughout a watershed, will therefore be a crucial aspect in future studies. [ABSTRACT FROM AUTHOR]

• A bibliometric analysis of Chinese Loess Plateau (CLP) studies was explored. • CLP research outputs increased exponentially during 1991–2018. • Keyword analysis indicated climate-related topics were the most popular study areas. • Research interests shifted from agriculture to ecology. • Government policies influence the choice of research hotspots. To understand the research trends and areas of focus on the Chinese Loess Plateau (CLP), a bibliometric study based on the Science Citation Index-Expanded (SCI-E) was performed. This study presented a comprehensive overview of the field based on the annual outputs, research areas, temporal trends in keywords, marked journals, institutions, and authors. In the SCI-E database, only 17 outputs occurred before 1991. Thus, we chose the study period between 1991 and 2018. The results revealed that the annual number of publications increased, with an especially rapid increase after 2006. Geology, environmental sciences and ecology, agriculture, water resources, and physical geography were the most popular Web of Science research areas. A keyword analysis indicated that "climate" was the most popular study area. After 2006, the research areas changed to "impact", "dynamics", and "land use change" topics in mechanisms and regulation. Since 2011, coupled effects among the environmental factors have been incorporated in research on the CLP. The areas of focus range from classical geology to agriculture research, ecological construction research, and research on the efficient use of resources. Catena and Palaeogeography Palaeoclimatology Palaeoecology were the most popular journals for researchers to publish their research results, and these two journals also had greater influence in the field with larger numbers of citations than other journals. The institution with the greatest research output and most citations was the Chinese Academy of Sciences. An Z. S., Fu B. J., Liu T. S., Ding Z. L., Shao M. A., and Lu H. Y. were the most competitive authors based on their large numbers of papers and citations. This paper presents an attempt to better understand the progress in research on the CLP. [ABSTRACT FROM AUTHOR]