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In this study, we used a new approach to measure and determine the splash detachment based on theories of soil erosion, the large number of articles published on the topic and simulated rainfall experiments. It is a necessity to use and improve new methods to accurately evaluate and quantify the processes of soil erosion. In this experiment, a soil pan with three areas, which consisted of a test area, complementary border area and a splash collector for slots, was used to obtain the ability of soil to undergo splash detachment. In this study, the soil surface was uniform and composed of a smooth slope and depth of thin layer flow that was

Root anchoring in the soil provides significant resistance for trees to resist against the wind and potential soil shear failure in a slope. Soil conditions and root properties affect pullout resistance of plant roots in the soil, which govern the anchoring capacity of plants. Soil water conditions may change considerably during rainfalls and affect the anchoring capacity of plant roots. Therefore, research on the effect of soil water conditions on plant roots' pullout behavior is essential to better understand the anchoring of plants in the soil during rainfall. In-situ pullout tests on roots of Paper Mulberry are carried out at various soil water conditions. Significant findings in this research are: (1) the initial pullout stiffness decreases with root length and soil water content; (2) increase in soil water contents causes a noticeable reduction in the soil-root bond strength; (3) the soil-root bond strength decreases with root length; (4) the pullout resistance for roots tested in the field takes into account root branching and interlocking of root hairs with surrounding undisturbed soils.

Phosphoric fertiliser has enormously contributed to agriculture; however, it generates five tonnes of phosphogypsum per ton of phosphoric acid synthesised. Phosphogypsum houses heavy metals and long-lived radioactive elements that represents an environmental issue requiring remediation. This paper presents a methodology for characterising phosphogypsum deposits using geophysical, geochemical, and statistical tools. Gamma-ray probes determined the abnormal radioactive zones within the phosphogypsum deposits while electrical resistivity tomography provided the geometry and distribution of the phosphogypsum deposits. Chemical results confirmed the high presence of heavy metals in the waste determining chromium as the most concentrated metal. Radiological measures indicate that the effective ambient dose equivalent average in the study area surface is approximately 8.5 times higher than the average for Europe. While at 1.0 m depth, in the phosphogypsum layer, the ambient dose equivalent average surpasses approximately 27 times the European average. Statistical correlation analysis supports that the radiation increases due to the uranium presence. This methodology might reduce time and cost avoiding the use of expensive traditional methods, and it is exportable to any deposit. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Connectivity analysis has proved a very valuable approach in understanding runoff and sediment fluxes in catchments. Many analyses use Connectivity Indices to model the patterns, but various versions of the Index have been developed. This paper tests the effects of these variants of the Index as applied to an agricultural-terraced catchment in the semi-arid Mediterranean region where occurrence of connectivity is relatively well documented to validate the modelling. This paper compares three versions of the Connectivity Index that use vegetation/land use (C), topography (RI) and roughness (n) as the weighting factors. Two different slope algorithms are also tested. The weightings are derived from a UAV (drone) survey, with simultaneous ground field mapping. The UAV imagery is found to provide a good, high resolution basis for determining detailed topography and vegetation cover. The slope limit present in some modelling is found to be unsuitable in this landscape where steep terrace embankments that are vegetated in places, and also partially vegetated uplands, occur. Subsequent modelling removed the slope limit. The major patterns of flow produced are similar between the models and are largely related to the overall topography and major drainage lines but considerably modified by the terracing. The model outcomes differ in detail, with the C factor model, incorporating vegetation, coming nearer to the field situation. The main deficiency in all the indices is the weakness in modelling ponding and sedimentation created by the terraces, and therefore the disconnectivity in the landscape. Comparison with field data confirms the variable connectivity in rainstorms, the effects of features such as tracks, and the effect of management actions. Evidence from field mapping during the last two decades indicates that the models probably represent the maximum possible functional connectivity.

Surface roughness, i.e. local variations in elevation which indicate less and less local smoothness, is an important concept for the analysis of solid earth/planetary surfaces and of the related surface processes. Surface roughness is a general concept covering multiple aspects of the surface spatial variability structure, that can be characterized at different scales and with different metrics. Accordingly, it is not surprising the wide range of approaches and algorithms adopted for the analysis of surface roughness and the lack of an accepted standard for its evaluation. In this context, geostatistical-based roughness indexes are a valid solution, providing a good balance between flexibility of algorithms and interpretability of the results. However, despite the long record of applications and the well-known and robust theoretical framework, geostatistical-based surface roughness tools have still not gained momentum in the context of geomorphometric analysis. Many geomorphometric studies concerning with the evaluation of roughness indexes are based on popular approaches, such as the ones based on measures of dispersion of normal vectors to surface. Unfortunately, these indexes present some drawbacks in the capability to represent specific aspects of surface roughness and from the perspective of their interpretability. Accordingly, in this paper some of the key aspects and advantages of geostatistical-based approaches for roughness analysis are highlighted, including the relevance of roughness anisotropy. Then, a new approach tailored to the analysis of short-range roughness, requiring a minimum intervention by the user, is introduced discussing the advantages compared to the vector dispersion-based roughness. The new approach is implemented as open-source code both in R language using the functions of the “Terra” package as well as in Python for Esri ArcMap GIS. The methodological considerations and algorithms presented can be applied also in the broader context of image analysis.

The relevant erosive effects of extraordinary rainfall events due to climate change require establishing soil conservation strategies to prevent damages due to hydrogeological instability. The “tolerable” soil loss, i.e., the maximum soil loss compatible with sustainable soil use, represents a quantitative target to establish the effectiveness of actions to control soil erosion. In this paper, a new approach to defining the condition corresponding to a tolerable soil loss is proposed. At first, using the statistical analysis of the measured annual values of the rainfall erosivity factor, the cover and management factor CT, for which the maximum tolerable soil loss is equal to the annual soil loss of given return period T, is defined. Then, for the Sicilian region, a relationship between the CT factor obtained for T = 1000 years and the mean annual value of the rainfall erosivity factor, R, is established. For a given value C of the cover and management factor, this relationship allows for the establishment of the corresponding mean annual rainfall erosivity factor, named Rland-use. The result C ≤ CT for T = 1000 years is obtained for areas with R ≤ Rland-use, and the compliance with soil loss tolerance is then assured. Conversely, for areas characterized by R > Rland-use, the reduction of C to a value less than CT for T = 1000 years is required to obtain a tolerable soil loss condition. Finally, for the Sicilian region, the overlay between the C spatial distribution for arable lands (mainly cereals and legumes) and areas covered by vineyards, derived from the land use map, and the CT spatial distribution allowed to define areas in which tolerable soil loss conditions occur or soil conservation strategies are required.

Policy makers in Nordic countries envisage a developing bioeconomy as an important element in the transition towards a fossil-energy-free future. However, although the shape of such a bioeconomy is unclear, impacts on land use and land management are likely. To analyse the possible impact on ecosystem services value of this transition, we used five scenarios that describe possible socio-economic environments in the four Nordic countries in the year 2050. These five Nordic Bioeconomy Pathways (NBPs) have been labelled in brief as: ‘sustainability first’, ‘conventional first’, ‘self-sufficiency first’, ‘city first’ and ‘growth first’. In this paper, we adapted an existing integrating framework of ecosystem service delivery to accommodate these NBPs and estimated economic value of all services for six study catchments across the Nordic countries: Odense (DK), Simojoki (FI), Haldenvassdraget (NO), Orrevassdraget (NO), Sävjaån (SE) and Vindelälven (SE). We articulated the scenario storylines to a set of numerical attributes per NBP using input from secondary data sources and interviews with stakeholder representatives and local experts. We made land use change spatially explicit based on the catchment's physical characteristics and used links between catchment attributes and ecosystem services flow to estimate annual ecosystem services generation in biophysical and monetary units. Outcomes suggest: the value of active recreation increases more in 'sustainability first' and 'growth first' than in other scenarios; variations in total value are largest among catchments under 'city first'; the overall rank order of ecosystem services value within catchments largely remains unchanged under all NBPs. We conclude that outdoor recreation contributes a high benefit to society that is likely not adequately considered relative to provisioning services in current decision making, and that these benefits appear sensitive to how a bioeconomy will develop. Overall, the estimated summed value delivered in these catchments is highest under the 'sustainability first' and 'growth first' scenarios.

It is widely admitted that changes in land use land cover (LULC) influence the hydrology of the catchment. However, how these changes affect hydrological model prediction uncertainty is still a raising question. In this paper we addressed this question by investigating the impacts of the rapid change in LULC in the Siliana catchment in Tunisia on monthly flow and magnitude of flow extremes using the SWAT hydrological model while quantifying the contribution of LULC to the model parameter and prediction uncertainty. At a first step, the SWAT model parameter and prediction uncertainty were estimated using the GLUE method and acceptable parameter sets were identified. Subsequently, the SWAT model was fed with historical LULC as derived from Landsat 5 and 8 satellite images for the years 1990, 2000, 2013 and 2019, and run with the acceptable parameter sets. The results show that the increase in olive plantations (+380 %), urban area (+200 %), and irrigated lands (+309 %) from 1990 to 2019, has LULC decreased monthly flow, high flows magnitude but did not impact low flows in particular over the previous two decades. The findings also suggest that model prediction uncertainty can mask LULC effects, suggesting that model results can be misleading without explicit consideration of uncertainty when assessing the hydrological impacts of changes in LULC.

At a global scale, intertidal areas are being reclaimed for agriculture as well as urban expansion, imposing high human pressure on the coastal zone. The Ganges-Brahmaputra Delta (GBD) is an exponent of this development. In this delta, land reclamation accelerated in the 1960's to 1980's, when polders were constructed in areas subject to regular marine flooding. A comprehensive analysis of tidal channel evolution in the southwest GBD reveals how land reclamation leads to tidal amplification, channel shoaling, bank erosion, and interaction between channels in which one tidal river captures the storage area of a neighbouring river. We identify-two positive feedback mechanisms that govern these morphological changes. First, reclaiming intertidal areas results in immediate loss of tidal storage, which leads to amplification and faster propagation of the tides. In systems with abundant sediment supply, the blind tidal channels progressively fill in with sediment, leading to a continued loss of tidal storage and therefore further distorting the tides. Secondly, when intertidal areas of parallel (and inter-connected) river delta distributaries are asynchronously or unevenly reclaimed, one channel distributary may expand its intertidal area at the expense of the other. This is initiated by an increasing propagation speed of the tidal wave in the partially reclaimed distributary, travelling into the non-reclaimed distributary through connecting channels. These connecting channels progressively expand while the pristine channel shoals, and potentially degenerates. Both positive feedback loops are very stable and are responsible for pluvial flooding of polders, large-scale bank erosion, and poorly navigable primary waterways, including the navigation channel accessing Bangladesh's second-largest port. Interventions aiming to solve these problems have to account for the complex positive feedback mechanisms identified in this paper and be nature-based and holistic.

Groundwater abstraction is among the main anthropogenic causes of wetland desiccation worldwide, and corrective measures must be taken to avoid degradation of this valuable ecosystems. A case study is the Agua Amarga salt marsh (≈180 ha) (SE Spain). Agua Amarga includes a solar saltwork pond network in operation between 1925 and 1975, when it was abandoned, and the ponds were colonized by salt marsh vegetation. In 2008 two desalination plants were operating in the marsh vicinity, which were supplied with groundwater. To mitigate the possible negative impact on the salt marsh ecosystem due to groundwater drawdown, in 2009 a sea water irrigation program was implemented. This paper summarizes the results of a ten-year monitoring program (2010–2020) to evaluate the effects of the irrigation program on groundwater levels and quality, soil salinity and moisture, and vegetation cover. During this period, average groundwater level was 2.5 m below the surface and around 1 m deep near the irrigated ponds. Groundwater salinity was not affected outside the saltmarsh, but inside, where the saltworks caused values to rise above 300 mS/cm, it decreased more than 150 mS/cm in some 20 m deep piezometers. Between 2012 and 2020, vegetation cover increased between ≈10 and ≈25 %, with halophyte species such as Arthrocnemum macrostachyum and Sarcocornia fruticosa being the most favoured. In areas with prolonged flooding, Ruppia maritima, a plant species that lives submerged in saline water, was found. In the irrigated areas, soil electrical conductivity (1:5 soil:water extracts) decreased from ≈7-14 mS cm-1 to ≈2-6 mS cm-1. We present an example of sustainable actions in a coastal wetland, where the exploitation of water resources in semiarid areas is combined with promoting natural habitats. Financial support for this research was provided by Mancomunidad de los Canales del Taibilla (http://www.mct.es). M.N. González-Alcaraz holds a Ramón y Cajal research contract from the Spanish Ministry of Science and Innovation (RYC2020-029322-I). We much appreciate the help of M. Carmen Tercero, Héctor M. Conesa and B. Aránega, from Technical University of Cartagena, and Francisco J. Jiménez-Cárceles, from Biocyma environmental consulting, during field and laboratory work. We thank to the technicians of the SAIT-UPCT for their laboratory and analytical assessments. Finally, we want to give special recognition to Doctor Tomás Rodríguez Estrella for his contributions in the field of hydrogeology.

The collapse of collapsing walls is a key process during the Benggang development in southeast China and is closely related to the soil shear strength. Plant root reinforcement can effectively improve the soil shear strength. However, there are few studies on the effect of roots on the soil shear strength of collapsing walls. To explore the influence of roots on the soil shear strength of collapsing walls, the roots of Neyraudia reynaudiana was selected as the research object. This paper studies the tensile properties of the roots through root tensile tests and performs a direct shear test to study the influence of the roots on the soil shear strength by setting different mass moisture contents (15%∼30%) and root weight densities (0 ∼ 1.25 g 100 cm−3). Root tensile force is positively correlated with root diameter by a power function, while tensile strength is negatively correlated with diameter by a power function. Roots could increase the soil shear strength, and which was mainly reflected in cohesive force. The shear strength and cohesive force increase first then decrease with the increasing root density, while root density has no effect on the internal friction. The shear strength, cohesive force and internal friction of root-soil complex all decreased with increasing moisture content. The WWM (Wu and Waldron model) greatly overestimated the cohesion of herbaceous roots, and a new prediction model of the shear strength of root-soil composites was obtained by revising the WWM model by introducing the moisture content and root density (NSE = 0.94). In conclusion, Neyraudia reynaudiana roots could improve the soil shear strength, whereas the strengthening effect decreased under the condition of high moisture content. The results provide a basis for the selection and allocation of vegetation restoration measures in Benggang erosion in southern China.

Soda-saline loessal soils are distributed extensively in the Songnen Plain of Northeast China. Freeze-thaw effects on soil structure and mechanical properties are becoming more frequent and intense with global warming, which further affects soil erosion in cold regions. Quantifying the effects of freeze-thaw cycles (FTCs) on the erodibility of saline soils is challenging because of the abundant soluble salt content and complex soil mechanical responses. In this study, direct shear tests, disintegration tests, and scanning electron microscopy were conducted to investigate the effects of freeze-thaw action on the erodibility indicators (shear strength and disintegration velocity) of soda-saline loessal soils and their microscopic deterioration mechanisms. Four initial moisture contents (IMCs: 8%, 13%, 18%, 23%), three soluble salt contents (SSCs: 0.5%, 1.0%, 1.5%), and six FTCs (0, 1, 3, 6, 10, 15) were considered. The results showed that successive FTCs continued to degrade the erosion resistance of the soil until it stabilized after approximately 10 FTCs. After 15 FTCs, the shear strength and cohesion decreased by 8.6–19.8% and 24.1–59.2%, respectively, while the angle of internal friction was relatively unaffected. Meanwhile, the soil disintegration velocity increased by 52.3–208.8%. During the freeze-thaw process, the water-ice phase change and the crystallization of soluble salts both led to the continuous adjustment of the microstructure of soda-saline loessal soils. It was found that microcracks within the soil structural units increased significantly, cementation between the structural units weakened continuously, pore connectivity was enhanced, and pore size homogenization increased. Correlation analysis showed that IMC was the fundamental factor affecting the soil mechanical properties, whereas SSC mainly affected the soil's resistance to disintegration. The increase in IMC and SSC exacerbated the deterioration of the soil by freeze-thaw action. This paper presents a new understanding of the erosion characteristics and micromechanisms of soda-saline loessal soils in seasonally frozen regions under freeze-thaw action.

The coastline of the Pearl River Estuary (PRE) experienced significant changes due to the increasing demand for land. Previous studies have focused on coastline changes of the mainland in China; thus changes of island coastlines have not been well investigated. In this study, the coastlines of the continent and islands of the Pearl River Estuary from 1978 to 2018 were extracted and analyzed by integrating Canny edge detection and Otsu methods based on Landsat data, and the coastline was classified into six types including biological, sandy, muddy, estuarine, rocky, and artificial via visual interpretation. The coastline length, coastline change rate and change area were calculated and analyzed for the 40 years period. The precision test showed that the coastline extraction methods presented in this paper meet the accuracy standard. The coastline length of the Pearl River Estuary was found to have increased rapidly from 789 km in 1978 to 979 km in 2018. During the past four decades, a large proportion of natural coastline converted into artificial one (66% in 2018), while 577 km2 land increased in this area. The coastline of the western PRE demonstrates more rapid change rates than that of the eastern part, and more land reclamation has occurred in the western area. Between 1988 and 1997, the coastline length and area of reclamation experienced the most extensive changes. Both natural factors, including sediment transport, sea-level rise, wind, tide, as well as anthropogenic factors, such as land reclamation and dam construction, have impacted coastline variation of the Pearl River Estuary in the past four decades. In general, the western part of the study area showed more remarkable coastline change and experienced the enormous influence of land reclamation, dam construction and sediment transport, compared with the eastern part.

The paper presents records of lithofacial succession in the sediments of the Bagno Staw alkaline fen (Western Polesie Lowland, Eastern Poland), documenting the phase of rapid morphogenetic transformations during LG/H in the Lublin chalkland. Environmental conditions responsible for the morphogenesis and evolution of the site (from a shallow periglacial lake to an alkaline fen) were reconstructed. A detailed geological survey in combination with the analysis of Cladocera assemblages revealed the presence of numerous palaeodepressions under the plain covered today by the alkaline fen, which were initially small shallow lakes with a well-developed phytolittoral zone. Geochemical data and the analysis of stable O and C isotopes indicated that these lakes were supplied by ascending waters. Karstic phenomena under periglacial conditions, including subsidence at the bottom of biogenic accumulation basins, played an important role in the transformation of this site. These changes were largely determined by the chronology and dynamics of permafrost degradation.

Landslides are widespread natural phenomena that play an important role in landscape evolution and are responsible for several casualties and damages. Slope instability is linked to the combination of geological, geomorphological, and climatic factors with various triggering mechanisms; among these, seismic shaking can induce relevant changes in the landscape, leading to coseismic and post-seismic phenomena such as landslide events. The Abruzzo Region (Central Italy) is severely affected by Earthquake-Induced Landslides (EILs), linked to the geomorphological dynamics and the severe seismicity of the area. The distribution, mechanisms, and typology of landslides are strictly related to the different physiographic and geological-structural settings. This paper focuses on the realisation of an EILs susceptibility map, following a heuristic approach combined with a statistical analysis, integrated using GIS technology. This approach led to the identification of nine instability factors. These factors were analysed for the construction of thematic maps. Hence, each factor was assigned proper expert-based ranks and weights based on the critical evaluation of literature data as well as on available landslide inventories and combined in a preliminary map wherein high/low numerical values correspond to a high/low propensity of the slope to fail; furthermore, a statistical analysis of these values was performed to derive suitable susceptibility classes. Results presented herein highlight the robustness of the approach; remarkably, the applied methodology is suitable even in areas where a detailed landslide catalogue is lacking, when the same classification and weighting of available parameters is performed. The statistical analyses and the adoption of an absolute scale ranging from minimum to maximum potential values, finally, ensures the comparability of results among different study areas. Finally, this work represents a scientific and multidisciplinary tool for better defining situations that could lead to hazards (such as landslides) following an earthquake to develop sustainable territorial planning, emergency management, and loss-reduction measures.

In this paper, we studied the soils of recreational areas of Volgograd within three research areas. The survey found that in research area I the soils spatial distribution is mainly represented by the following soil group according to WRB: Urbic Technosols, Urbic Technosols (Mollic) and Gleyic Terric Phaeozem (Mollic, Prototechnic). Buried soils are represented by Gleic Cambisols (Protocalcic). In research area II, among natural soils, the largest areas are occupied by Calcaric Fluvisols (Loamic, Technic, Protovertic), Calcaric Fluvisols (Arenic, Salic), and Gleyic Calcisols (Sodic, Protocalcic, Technic, Salic). The anthropogenic-transformed soils include Urbic Technosols, and Ekranic Technosols are under buildings and road surfaces. In research area III, the natural soils spatial distribution is homogeneous and mainly represented by Gleyic Cambic Calcisols (Protocalcic), Gleyic Cambisols (Protocalcic, Prototechnic), and Calcaric Colluvic Regosols (Arenic, Prototechnic) in the bottoms of small flat-bottom valleys. In irrigation sites occur Urbic Technosols, and on hiking trails – Gleyic Cambisols (Prototechnic). Despite the presence of reclaimed horizons with a high content of phosphorus in the soils (average concentration of 82 mg kg−1), none of the profiles revealed Hortic horizon, but only some of its properties (colour, horizon thickness, zoogenic activity). The thickness of urbic-stratifying layer (Au) varies in a wide range from 10 to 135 cm, and the thickness of reclaimed horizons (A) also varies from 10 to 48 cm. The bulk density in Au horizons is 1.4 g cm−3, in the reclaimed horizons (A) – 1.39 g cm−3. The content of soil carbon in soil surface horizons varies from 0.85% to 4.58% in urbic horizons, and to 1.49% in reclaimed horizons. Chemical analysis of urbic (Au) and reclaimed (A) horizons revealed a low content of easily soluble salts (0.16%) and carbonates (1.5% and 1.7%, respectively).

Sedimentation in the Three Gorges Reservoir (TGR) affects flood control, navigation, power generation and the ecological environment. We present a comprehensive analysis of the characteristics of sedimentation in the TGR from 2003 to 2018. The data set includes field measurements (runoff and sediment) at hydrological stations and estimation for areas where measured data are not available. Based on the data set, the amount of sedimentation in the TGR was calculated with the Sediment Budget Model (SBM) and Section Topography Method (STM). Finally, the variation in sediment Trapping Efficiency (TE) in the TGR was assessed. The results indicate that sediment from smaller tributaries in the TGR region, which has been ignored in most previous studies, constituted approximately 10.8% of the total incoming sediment. The total sedimentation in the TGR was 205478 × 104 t in 2003–2018, and the contribution rates of sediment load flowing into the TGR, the water depth in front of the dam, and runoff discharge flowing into the TGR were 94.4%, 24.5% and −18.9% respectively. The average annual TE was 78.5% in 2003–2018, and it was closely related to the ratio of reservoir storage capacity to flow discharge in the flood season and to sediment concentration in the non-flood season. The results in this paper not only play an important role in the optimal operation of the TGR but also have important reference value for other large reservoirs worldwide.

For many geoscience applications, the quality of digital elevation models (DEMs) is the first and foremost requirement. DEM quality generally depends on the interpolation procedure, especially in forested areas with complex terrain. However, classical interpolation methods do not always preserve terrain features, owing to their isotropic and local estimation nature. Therefore, this paper presents a feature-preserving interpolation method, where a structure tensor is integrated into the radial basis function to ensure its anisotropy. This method alleviates the influence of points located on different surface patches. The performance of the proposed method was compared with those of classical interpolation methods, including the inverse distance weighting (IDW), ordinary kriging (OK), topo to raster (ANUDEM), and natural neighbour (NN) methods. The performance of these methods was tested on benchmark data provided by the International Society for Photogrammetry and Remote Sensing (ISPRS) Commission, and on one private dataset. Both datasets were collected via the airborne light detection and ranging (LiDAR) technique. The results from both datasets demonstrate that from a quantitative perspective, the proposed method produces more accurate DEMs than the classical interpolation methods. Specifically, in terms of root mean square error (RMSE), the proposed method is at least 15.8% and 7.6% more accurate when applied to the ISPRS and private data, respectively. Moreover, the proposed method produces more visually appealing surfaces with a good trade-off between terrain feature retention and noise removal.

Global warming has significantly affected the terrestrial C and N cycling processes. Whereas, it is unclear how global warming impacts the C and N concentrations in the above- and belowground ecosystems. We performed a meta-analysis with the results presented in 136 papers and 1886 observations. The data reveals that global warming increased C concentrations in leaf, shoot, and microbial biomass and N concentrations in the shoot. The C:N ratios of microbial biomass also increased under conditions of warming. However, the soil C concentration and soil C:N ratios decreased. Furthermore, these responses are more evident with longer warming duration and elevated warming magnitudes. The warming effects on C and N concentrations and C:N ratios never changed with warming methods, ecosystem types, or background climates. Also, in response to warming, soil moisture was negatively correlated with leaf C concentration as well as C:N ratio in microbial biomass. Soil pH response to warming was in a negative correlation with those of soil C concentration, soil C:N ratio, and microbial biomass C concentration. Our analysis has identified some key ecosystem processes that can be potentially implemented into the ecosystem models for predicting how warming affects future terrestrial C and N dynamics.

Studies of the provenance of aeolian dunes are crucial for providing knowledge of landscape evolution and developing management strategies to control aeolian desertification. The lakeshore dune is a typical aeolian landform that is widely distributed around the world. However, there has been little work on the provenance and formation mechanism of lakeshore dunes. By comparing the elemental and grain-size compositions of lakeshore dunes and potential sources around Co Nag Lake, this paper combines sediment fingerprinting analysis and end-member modeling. The results identify the provenance of aeolian sands on the eastern bank of Co Nag Lake and draw the following conclusions. (1) The combined use of fingerprinting analysis and grain-size analysis can yield a comprehensive and reliable provenance assessment. (2) The lakeshore dunes on the eastern bank of the lake are primarily derived from lacustrine deposits and fluvial deposits on the eastern bank. The coupling of fluvial and aeolian systems promotes the development of eastern sandy land. (3) Sand-control projects in the Co Nag Lake region should be carried out according to the sources of aeolian sands. It is necessary to strengthen efforts to control lacustrine deposits and sands in gullies.

Various forms of microtopography are widely distributed and exist in the loess area of northern Shaanxi. Microtopography is also an important consideration for near-natural vegetation restoration models. The soil quality under the different microtopography types affects which near-natural vegetation configuration and restoration mode should be applied. Therefore, this paper took the microtopography of the Hegou watershed, which was restored by the natural exclosure method, and that of the Chaigou watershed, which was restored by artificial afforestation, in the loess region of northern Shaanxi as the research objects. A comprehensive evaluation of the soil quality in the study area was carried out by assessing 22 soil indicators and performing sensitivity analysis and principal component analysis. The results showed the following: (1) Soil available phosphorus, total nitrogen, organic matter, sucrase activity, urease activity, maximum water-holding capacity, field capacity, capillary water-holding capacity, noncapillary porosity, natural water content, available nitrogen, available potassium, cation exchange capacity, total phosphorus, total potassium, alkaline phosphatase and catalase constituted a sensitive-indicator data set for soil quality evaluation in the study area. (2) There was a significant linear fit between the sensitive-indicator data set and the all-indicator data set (y = 1.032x − 0.027, R2 = 0.96 (P platform (0.565) > shallow gully (0.529) > gully (0.515) > undisturbed slope (0.422) > scarp (0.351). The microtopography types under artificial afforestation were ranked by soil quality as follows: gully (0.731) > platform (0.66) > undisturbed slope (0.431) > shallow gully (0.411) > scarp (0.395) > collapse (0.221).

Knowledge of pedodiversity is essential for the protection and management of soil resources. The analysis of regional pedodiversity is typically based on analysis units of different sizes. However, the effect of analysis unit size on regional pedodiversity studies remains unclear. In this paper, the effects of analysis unit size on the studies of spatial distribution characteristics of pedodiversity and its major driving factor in China were studied based on two levels of geomorphological regions. A combined method encompassing the moving window, soil richness, and Shannon index was used to analyze the spatial distribution pattern of pedodiversity in China. A geographical detector was used to determine a major driving factor of pedodiversity in each geomorphological region. The spatial distribution pattern of pedodiversity based on two levels of geomorphological regions both showed that pedodiversity was highest in southern China, followed by northern China, and lowest in the Qinghai-Tibet Plateau, which indicated that analysis unit sizes had little effect on the study on spatial distribution pattern of pedodiversity. The major driving factor analysis of pedodiversity based on first-order geomorphological regions showed that the major driving factor in China, except for the Qinghai-Tibet Plateau, was parent material. However, the results based on second-order geomorphological regions showed that the major driving factors of pedodiversity, except for the Qinghai-Tibet Plateau, were parent material and topography in hilly regions, topography in mountainous regions, and parent material in regions occupied by alluvial landforms, aeolian landforms, or karst landforms. The driving factor analysis of pedodiversity based on the two levels of geomorphological regions suggested that the effect of the analysis unit sizes on the major driving factor study was significant. The results of this study are an important supplement for pedodiversity studies.

Lakes and wetlands in populated areas have become very vulnerable to pollution and habitat degradation, seriously threatening regional ecological security and socio-economic development. Exploring long-term environmental changes in these systems is essential to reveal the interactions of human activities and catchments, and further to provide valuable reference for current restoration. In this paper, we present paleolimnological data from a short sedimentary core from Liangzi Lake, a typical wetland nature reserve in the middle and lower Yangtze River Basin, China. Multiple sedimentary proxies (principally pollen but also geochemistry and grain size data) combined with historical records were used to establish environmental changes of Liangzi Lake, in both terrestrial and lacustrine aspects, over the last 150 years. Despite the influence of hydrological processes to some extent, our results indicate that the anthropogenic effects (negative and positive) are well recorded by the sedimentary records. The landscape changes of the wider Liangzi Lake wetland can be placed into four stages: less disturbed background (before the 1950s), hydrological regulation (1950s–1960s), intensive reclamation (1970s–1990s), and wetland restoration (starting in the late 1990s). Agriculture and hydrological control were the most important factors in transforming the wetland landscapes, as well as the aquatic ecosystem. The changes in the lake itself could be divided into three main stages: low nutrient levels and unstable hydrologic condition with dominant emergent plants (before the 1960s), rising nutrient levels and a stable water environment with increasing submerged plants (1960s–1990s), and high nutrient and pollution levels with the subsequent adjustment and restoration (after the late 1990s). Our study provides a comprehensive history of environmental changes of a typical inland lake and its surrounding wetland, and may contribute to future wetland conservation in similar regions, as well as pollen-based environmental reconstruction studies.

As a physical property of soil, magnetic susceptibility (MS) has been widely used to delineate soil drainage conditions over the past two decades, where all MS values were derived from laboratory measurements. In this paper, the ability of an electromagnetic induction (EMI) instrument, Geonics EM38, in in-field measurements of apparent magnetic susceptibility (MSa or κa) of topsoil was tested on six selected soil profiles having different drainage conditions. The MSa data, measured in both vertical and horizontal coil configurations of EM38, were then inverted using an iterative 1-D inversion procedure to calculate real volume MS of soil layers up to 1 m depth. Moreover, volume and mass-specific MS of the soil profiles were directly measured in laboratory by employing Bartington MS2C and MS2B sensors applied on core and dried soil samples, respectively, collected at the soil profiles. Comparing the results revealed that volume MS profiles derived from inversion of MSa data were positively correlated with MS profiles measured in laboratory, especially at topsoil. It was also found that MS values in poorly drained soil profile were lower than those of a well-drained profile. So, considering that EMI methods are fast, precise and cost-efficient, they would be preferred over conventional methods for delineating soil drainage conditions if using soil MS assessment is considered as soil drainage criteria.

Wildfires can have strong negative effects on soil and water resources, especially in headwater areas. The spatially explicit OpenLISEM model was applied to a burned catchment in southern Portugal to quantify the individual and combined impacts of wildfire and rainfall on hydrological and erosion processes. The companion paper has calibrated and assessed model performance in this area before and after a fire. In this study, the model was applied with design storms of six different return periods (0.2, 0.5, 1, 2, 5, and 10 years) to simulate and evaluate pre- and post-wildfire hydrological and erosion responses at the catchment scale. Our results show that rainfall amount and intensity played a more important role than fire occurrence in the catchment discharge and sediment yields. Fire occurrence was found to be an important factor for peak discharge, indicating that high post-fire hydro-sedimentary responses are frequently related to extreme rainfall events. The results also suggest a partial shift from runoff to splash erosion after fire, especially for higher return periods. This can be explained by increased splash erosion in burned upstream areas saturating the sediment transport capacity of surface runoff, limiting runoff erosion in downstream areas. Therefore, the pre-fire erosion risk in the croplands of this catchment was partly shifted to a post-fire erosion risk in upper slope forest and natural areas, especially for storms with lower return periods, although erosion risks in croplands were important both before and after fires. These findings have significant implications to identify areas for post-wildfire stabilization and rehabilitation, which is particularly important given the predicted increase in the occurrence of fires and extreme rainfall events with climate change.

Numerous artificial slopes emerged in the watersheds of the Chinese Loess Plateau (LP) after the Gully Land Consolidation project (GLCP) that cut slopes to create farmland in the gully, which had incurred instabilities over time and could potentially resulted in soil erosion and geological hazard. This paper explored the characteristics and prevention mechanisms of artificial slope instability after the GLCP with field investigation in a typical watershed and the Back Propagation Neural Network (BPNN) method. The results showed that: (1) 439 instabilities induced by infiltration and erosion were found in 79 artificial slopes. (2) The difference of soil moisture and failure mode resulted in the instability degree of shady slope and lower slope were significantly higher than that of sunny slope and upper slope. (3) Among the surface condition factors, slope instability volume was significantly influenced by gradient, soil compactness, height and soil shear strength. Platform instability volume had great connection with soil compactness and its shear strength. (4) A “Drain-Improve-Green-Reinforce (DIGR)” system was proposed as the prevention mechanism for artificial slope instability, which included drainage system, soil improvement, vegetation protection, and reinforcement engineering. Taken together, this research provides the scientific reference for a better understanding and prevention of artificial slope instability, which would contribute to ensuring GLCP effectiveness and ecological security in the LP.

Reclamation of highly degraded mine lands to a sustainable environmental quality has become a major policy concern in many countries with a long mining tradition. This paper reports the soil quality status of a historical mine site fifteen years after its reclamation, using indicators of chemical reactivity, soil fertility and health, and discusses the progress and effectiveness of the implemented measures by a comparative analysis between pre- and post-reclamation conditions. Twenty composite surface samples (0–20 cm depth) were obtained for physical and chemical characterization from the open pit mine and waste disposal area, using a stratified random sampling approach. Additionally seven sites were selected to collect topsoil samples for microbiological testing. Results showed that soil quality changed noticeably over the study period (2003–2018), with overall improvements in key properties, such as structural stability, cation exchange capacity, degree of base saturation, soil organic carbon, and available phosphorus. Prior to reclamation, the mine soil was unable to support vegetation due to hyperacidity coupled with elevated levels of toxic metals and nutrient deficiencies. The combined use of sugar beet lime and composted biosolids as a low-cost, locally available, soil amendment was effective in neutralizing both active and exchangeable acidity, and reducing the mobility, plant uptake and human bioaccessibility of trace elements. The amendment addition also enhanced soil fertility, carbon storage, nutrient availability and microbial biomass (bacteria and fungi). Revegetation with Pinus pinea and Nerium oleander has proven to be a successful strategy to create a vegetative cover aesthetically pleasant and environmentally compatible with the surrounding undisturbed landscape, although further efforts should be made to monitor over time the phytotoxic and bioaccessible levels of residual metals, notably Cd, Cu and Zn. The insights gained from this land reclamation experience provide success criteria for assisting natural attenuation in other abandoned mining sites worldwide.

Cropland conversion is a significant theme of the influence of human activities on ecological systems and global food security. Conventionally, cropland conversion in China has been deemed to match the dynamic balance of cropland resources well and to ensure food security for the whole country. However, local studies have presented some conflicting signs that call for an integrated analysis from a national viewpoint. In this paper, by considering the significance of slope in cropland-related natural and socioeconomic issues, we explore the slope features of China’s cropland conversion during 2000–2015 and endeavor to identify some potential risks hidden in the process. High-resolution remotely sensed images, digital elevation model and spatial analytical methods are adopted to conduct the analysis. The results show that, the features of cropland conversion in diverse slope division areas are all distinct. Some risks indicated by these conversion features can be identified as follows: (1) unsuitable reclamation of cropland in flat areas causes ecological damage, (2) the invasion of sparsely populated construction land on cropland in steep areas has a dramatic impact on the local area, (3) excessive greening in Northwest and Northeast China, and insufficient greening in Southwest China are not healthy for regional sustainability, (4) cropland’s upslope reclamation and downslope loss pose potential risks for food security. In the context of dynamic balance management and other related national policies, cropland conversion in China is not as optimistic as former surveys have indicated, and promoted measures should be elaborately adjusted based on local conditions.

The use of techniques to calibrate soil prediction models based on legacy maps is restricted to areas where conventional survey and soil mapping were performed. It is necessary to seek alternatives to calibrate soil predictive models without a legacy soil map. The problem is the difficulty to delineate polygons of soil classes based on soil sampling points. This paper presents a novel digital soil mapping strategy using only georeferenced points of soil profiles to delineate detailed polygons of soil classes by the Geographic Object-Based Image Analysis (GEOBIA) approach and Artificial Neural Networks (ANN) models. The main objective was to evaluate the integration of the GEOBIA approach at different segmentation levels with ANN’s models and sampling points to produce a digital soil map of the Vale dos Vinhedos region, in Rio Grande do Sul, Brazil. From a Digital Terrain Model, 10 predictive variables were extracted. From the RapidEye remote sensing image the following spectral variables were extracted: Normalized Difference Vegetation Index and Normalized Difference Water Index. A new set of variables was produced using principal component analysis after standardization of the original variables. The multiresolution segmentation algorithm was used to create image objects at different segmentation levels. Four segmentation levels were tested with scale parameter (SP) 1, 2, 5 and 10; and the Cheesboard segmentation (CS) was used to transform the original pixels into polygons. Information on types of soil was obtained from 163 georeferenced soil profiles. Five ANN’s structures were implemented: four for the segmented data (SP01, SP02, SP05 and SP10) and one for the per-pixel approach (CS); 16 repetitions of each ANN were performed. With the best models for each segmentation level, extrapolations of soil classes were performed for the entire study area and validated with a detailed legacy soil map. The per-pixel approach model obtained the worst result. The best result in the extrapolation of soil types found was with the object-based approach (SP1). In our understanding, the scientific community can profit from the proposed methodology particularly when it only has georeferenced points of soil classes and not a legacy map, i.e., immediately after a field survey without the need for photointerpretation for delineation of the soil mapping units. The use of GEOBIA for digital mapping of soil classes seems to be a promising approach for future research.

Gully erosion is a major soil degradation problem in many parts of the world. Assessment of this process and its contributing factors are becoming increasingly important, especially in terms of climate change. Rainfall runoff is known to initiate and exacerbate gully erosion processes. In this paper, research over the past two decades focussing on the influence of rainfall on gully erosion is explored. A common notion is that gully erosion increases with higher rainfall intensities. However, there is some debate on the role of rainfall on gully development, with some studies suggesting large influences of extreme rainfall, while others show limited impacts. Although the rainfall factor started receiving more attention in gully erosion studies in recent decades, there is still a need to determine the influence of rainfall on gully erosion at different temporal scales. Single- and multiple events over varying temporal scales, including periodicity of extreme rainfall events, ENSO periods, and aspects such as antecedent moisture, are highlighted as areas that should be expanded in research. The interplay between gullies, rainfall, and vegetation and the risk of climate change has potential to affect these events is also underscored. The use of new advancements in technologies for gully erosion research, namely the applications of outdoor rainfall simulators, unmanned aerial vehicles and photogrammetric/digital surface modelling, has become increasingly prevalent. The advent of these technologies offers considerable potential to assess the influence of rainfall events on gully development, especially in data poor countries.

Previous studies demonstrated that for open channel flows the power velocity profile can be integrated to obtain the flow resistance law. In this paper the relationship between Γ coefficient of the power velocity distribution, the channel slope and Froude number (Eq. (9) ) is firstly presented. Then the measurements carried out in a laboratory flume covered by hemispheric elements for two different hydraulic conditions (partially inundated and inundated) are used to calibrate this relationship. These elements are placed with a square arrangement and have a concentration range 4–64%. For the two investigated hydraulic conditions, this analysis demonstrates that the relationship to estimate the coefficient of the velocity profile is characterized by the same exponent of slope and Froude number while a different scale factor a has to be used. The effect of roughness element concentration Ch on flow resistance is also studied by the calibration of Eq. (9) for each experimental series characterized by a single value of Ch. For the partially inundated condition and values of the roughness element concentration less than 25%, the coefficient a increases with Ch while for Ch values ranging from 25 to 64% a decreases with concentration. For the submerged condition, the coefficient a increases with Ch and results almost constant for concentration values greater than 49%. The variability of the coefficient a with Ch is the effect of the variability of the reference plane for the water depth measurement with the concentration. Finally, the obtained relationships to estimate Γ function and the theoretical flow resistance law are verified by 205 measurements carried out in gravel bed rivers. In conclusion, the developed analysis demonstrates that an accurate estimate of the friction factor can be obtained for the investigated gravel surfaces by the proposed flow resistance equation and the obtained relationship to estimate Γ function.