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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Abstract Rockfall hazards occur widely in regions with steep terrain such as Kinta Valley, Malaysia. Rockfalls threaten urban areas and the transportation corridors that pass through such areas. This paper proposes a comprehensive rockfall hazard assessment strategy based on high-resolution laser scanning data (LiDAR), both airborne and terrestrial. It provides (1) rockfall source identification by developing a hybrid model based on a bagging neural network (BBNN), which is compared with various machine learning algorithms and ensemble models (bagging, boosting, voting) and a Gaussian mixture model; (2) 3D modelling of rockfall kinematic processes (trajectory distribution, frequency, velocity, kinetic energy, bounce height, impact location); and (3) hazard zonation based on spatial modelling in combination with an analytical hierarchy process (AHP) in a geographic information system (GIS). In addition, mitigation measures are suggested based on the modelling results. The proposed methodology was validated in three study areas to test the applicability and generalisability of the methods. The results show that the proposed hybrid model can accurately identify rockfall source areas at the regional scale. It achieved a 97% training accuracy and 5-fold cross-validation area under curve (AUC) value of 0.96. The mechanical parameters of the developed 3D model were calibrated with an accuracy of 97%, 93% and 95% for Gunung Lang, Gua Tambun and Gunung Rapat areas, respectively. In addition, the proposed spatial model effectively delineates areas at risk of rockfalls. This method provides a comprehensive understanding of rockfall hazards that can assist authorities to develop proper management and protection of urban areas and transportation corridors. Graphical abstract Unlabelled Image Highlights • Airborne and terrestrial laser data were employed to derive high-resolution DTM. • Gaussian Mixture Model (GMM) was used to calculate slope angle thresholds. • Different machine learning algorithms were applied and tested. • A hybrid model was proposed to identify the source of rockfall. • 3D rockfall modelling was performed to derive rockfall trajectories. [ABSTRACT FROM AUTHOR]

Abstract The present paper describes the design of a comprehensive rainfall simulator which is particularly meant for the assessment of soil erosion at plot scale by considering various soil grain types, soil slope angles, and surface exposures under different rainfall conditions. The entire setup is divided into four major parts: (a) water supply system with single spray nozzle, (b) supporting metal frame, (c) hydraulic jack attached container table for slope adjustment, and (d) temperature simulator. It covers an area of 3 m2, out of which 0.5 m2 is the target area or experimental plot and the simulated raindrops fall from a height of 2.3 m. Four types of full-jet spray nozzles are used to simulate rainfall intensities of 65, 93, 112, and 148 mm/h. The experimental plot can attain a maximum slope angle of 40° using a hydraulic jack unit. A temperature simulator is designed to replicate the natural conditions in the laboratory. Physical and numerical simulations are carried out to measure the characteristics of simulated rainfall and compare with those of natural rainfall conditions. The Christiansen coefficient (Cu) of the designed rainfall simulator varies from 81 % to 88 %. The rain droplet size ranges from roughly 1 mm to 5 mm and their corresponding terminal velocities range from 4.76 m/s to 10.64 m/s, striking velocities are found between 5.56 m/s and 9.63 m/s, and kinetic energies ranging from 0.0081 mJ to 3.0342 mJ. The total kinetic energy of the raindrops striking the soil surface in the entire plot area of 0.5 m2 depends on the rainfall intensity and varies from about 6 J to 12 J. The designed setup is capable of simulating rainfall inside the laboratory with properties very close to those of natural rainfall. We adopt the Taguchi fractional factorial design of experiments to investigate the effects of different factors on soil erosion. Furthermore, statistical analysis of the experimental data is carried out by using signal-to-noise (S / N) ratio and the optimum condition for maximum soil erosion is predicted. The main objectives of this study are to design a comprehensive rainfall simulator setup, evaluate the properties of the simulated rainfall, provide a theoretical model and assess the several factors affecting soil erosion using reduced number of experiments in the laboratory. Highlights • A rainfall simulator is designed for soil erosion experiments in the laboratory. • Four full cone spray nozzles were used to simulate different rainfall intensities. • A temperature simulator is used to replicate natural conditions. • Theoretical explanations and simulations of rainfall properties are carried out. • Taguchi optimization is used to determine optimum condition for maximum soil erosion. [ABSTRACT FROM AUTHOR]

Abstract Soil organic carbon (OC) plays a vital role on physico-chemical and biological properties of soils and on climate change regulation. The use of pedo-transfer functions from easily available soil properties for estimating soil OC could be fast and cheap when considering field and laboratory work implications especially in Sub Saharan Africa including Tanzania. This paper attempts to develop a model for estimating soil OC contents under maize croplands ecosystem using pedo-transfer functions from soil texture. A total of 100 epipedon data entries were randomly collected from the previous soil sampling works that were conducted under maize croplands in coastal plains of Tanzania. Eighty percent of the collected data were used for training the model by using multiple regression analysis while the remained 20% were used to validate the model. The results indicated that, clay and silt had significant (p < 0.001) positive correlation with soil OC while sand contents in soils had negative (p < 0.001) correlation with soil OC. All together clay, sand and silt were revealed powerful predictors (p < 0.001, R2 = 0.82) of OC content in soils. On validation, the soil OC predicted agreed by 81.2% with the soil OC determined by laboratory test. These results imply that pedo-transfer functions for predicting soil OC based on soil texture is not only fast and cheap but also is an effective option for estimating OC content in soils. Highlights • Soil organic carbon contents differed significantly between the studied soils types. • Strong correlation exist between sand, silt and clay with soils OC contents. • Soil texture predicted significantly the contents of soil OC in the studied soils. [ABSTRACT FROM AUTHOR]

Abstract The soil organic carbon (SOC) and total nitrogen (TN) of topsoil could be greatly affected by the conversion of grassland to cropland (CGC) due to vegetation harvesting and soil erosion. However, few studies have evaluated the effects of these changes in the subsoil and distinguished its main controls at the regional scale. This paper investigated the total changes in the SOC stock (SOC S) and TN stock (TN S) of soils from 0 to 30 cm and 0–100 cm in depth over the past three decades in the Songnen Plain, China, a typical Mollisol region. The CGC resulted in a moderate loss of topsoil C and N but an increase in subsoil C and N, and the soil mapping results showed that approximately 7.47 × 1011 kg C and 1.51 × 1011 kg N were accumulated during the past three decades. Prediction uncertainty was assessed by 100 model runs with random jackknife partitions, and high uncertainty was found in the areas with rapidly changing SOC S and TN S levels. Our findings indicated that subsoil should be considered in the estimation of the SOC S and TN S at the regional scale. The SOC S and TN S of the CGC areas were anticipated to increase after long-term cultivation. In view of ongoing cropland expansion, up-to-date land use and soil type data are vital for selecting monitoring sites and understanding long-term soil evolution at the regional scale. Highlights • Conversion of grassland to cropland led to a moderate loss of topsoil C and N, but an increase in C and N in subsoil. • Subsoil should be considered for the estimation of SOC and TN stocks at the regional scale. • The SOC and TN stocks of recent cultivated soils were anticipated to increase after a long term cultivation. [ABSTRACT FROM AUTHOR]

Abstract Rill erosion is considered one of the most important processes affecting soil because of the large amount of soil loss. The rill network acts as sediment source and is able to transport both rill flow-detached particles and those delivered from the interrill areas. Small flow depth in a rill and steep slope values of its bed affect significantly flow hydraulics. When rill flow velocity is measured using a dye-tracing method, the mean velocity is calculated by multiplying the measured surface velocity of the leading edge of the tracer plume by a correction factor. The main uncertainty of the dye-tracing technique stands in the relationship between mean and surface flow velocity. In this paper, this relationship was firstly tested using the measured data pairs available from literature and then the influence of the adopted relationship on the estimate of the Darcy Weisbach friction factor was examined. The developed analysis showed that the applied estimate criteria of the correction factor do not affect the estimate performances of the theoretical flow resistance equation. Finally a new flow resistance equation for rill flows which can be directly calibrated by surface velocity measurements was deduced. The proposed procedure for estimating the friction factor was calibrated by rill data available from literature and was positively tested by the rill velocity measurements carried out in this investigation. Highlights • Rill flow velocity is measured using a dye-tracing method. • Three criteria for estimating the correction factor of the edge velocity are compared. • The influence of the edge velocity correction factor on flow resistance is evaluated. • Rill flow resistance equation calibrated by surface velocity measurements is deduced. [ABSTRACT FROM AUTHOR]

Abstract In this paper a recently theoretically deduced rill flow resistance equation, based on a power-velocity profile, was tested experimentally on plots of varying slopes and soil texture in which mobile bed rills are incised. Measurements of flow velocity, water depth, cross section area, wetted perimeter and bed slope conducted in rill reaches incised on experimental plots, having different slope values (9, 14, 22, 24 and 26%) and soil texture (clay fraction ranging from 42 to 73%), and literature data were used to calibrate the flow resistance equation. In particular, the relationship between the velocity profile parameter Γ, the channel slope, the flow Froude number and texture fractions was firstly calibrated using 147 rill reach data. Then this relationship was tested using 126 measurements carried out with soils having different texture (percentage of clay ranging from 9.6 to 73%) and slopes (6.9%–26%). The measurements allowed to establish that a) the Darcy-Weisbach friction factor can be accurately estimated using the proposed theoretical approach, and b) the data were supportive of the soil texture influence on rill velocity and flow resistance. Highlights • The effect of soil texture on rill flow resistance is experimentally investigated. • The relationship between rill flow resistance and velocity profile is investigated. • The flow resistance law is theoretically deduced by dimensional analysis. • The equation of the velocity profile parameter is calibrated by 147 rill data. • The equation of the velocity profile parameter is tested by 126 rill data. [ABSTRACT FROM AUTHOR]

Abstract In this paper we present new data on weathering and soil formation processes affecting alkaline pillow basalts on the summit of Mt. Cerviero (Calabria, southern Italy). We investigated two representative soil profiles using an integrated approach, including pedological, petrographic, mineralogical and geochemical investigations. We distinguished the main features inherited from the hydrothermal alteration of the pillow basalts in a submarine environment from the chemical weathering processes under meteoric conditions. Irregular geochemical patterns and chemical index of alteration values across the soil profiles indicate a lithological discontinuity between the bedrock and the upper soil horizons, as a response to soil rejuvenation, in turn controlled by erosive processes and an allochthonous pyroclastic input. The soil profiles display poor horizonation and an incipient to intermediate degree of weathering, in line with the clay mineralogy (chlorite or hydroxy-interlayered vermiculite, illite, kaolinite and varying mixed-layers). The degeneration microtextures of clay and iron-manganese coatings in one soil profile suggest their relict genesis, with an emplacement under warm-humid conditions during the last interglacial. A Late Pleistocene to Holocene age of soil development is supported by the trachytic composition of volcanic micropumices, correlated to explosive eruptions from the Campania Province or the Aeolian Islands, in both soil profiles. Geochemical indices obtained from selective extractions of pedogenetic Al, Fe and Si pools point to poor andic properties with humus-Al-complexes prevailing over short-range order minerals. Nonetheless, the latter are consistent with the presence of volcanic glass, an optically isotropic pedogenic matrix and the Andosol-like field features of the soil profiles, even if they developed in a non-volcanic area. This should lead to a partial reassessment of the volcanic versus non-volcanic origin of certain Andosols worldwide and claims a good field work as a basis for choosing the best-suited laboratory methods to fill the gap between ordinary lab and field results. Highlights • Inherited hydrothermal alteration of the basalt bedrock • Chemical weathering and illuvial features affect patina and the soils. • Rejuvenation of the pedogenetic front due to erosion processes and pyroclastic input • The rhyolitic composition of volcanic glass testifies to a late Quaternary soil age. • The soils exhibit andic-like field features despite being located in a non-volcanic area. [ABSTRACT FROM AUTHOR]

Abstract The need to estimate event soil loss better than the USLE and the RUSLE has led to the development of WEPP and the USLE-M, a modification of the USLE that estimates event soil loss for bare fallow runoff and soil loss plots in the USLE database better than the USLE/RUSLE when runoff is known or predicted well. Although the erosivity indices in the USLE-M and the USLE/RUSLE focus on raindrop driven erosion, the calibration of the erodibility index on plots where rilling occurs enables the USLE-M and the USLE/RUSLE to be applied on areas where sheet and rill erosion occur. This paper presents results from the application of both WEPP and the USLE-M to modelling event soil loss from 6 runoff and soil plots at the Ansai Research Station of Soil and Water Conservation, Chinese Academy of Sciences (36°56′N, 109°16′E) produced from steep slopes (8.7%–53.2%) where rills frequently developed under natural rainfall during 1985–1992. WEPP was calibrated to minimize the mean squared error (MSE) between measured runoff and predicted runoff for the events where WEPP predicted runoff and soil loss to occur. The number of events where WEPP predicted runoff and soil loss to occur varied from 25% to 41% of events that actually produced soil loss. In the comparison with WEPP, the USLE-M erodibility factor was calibrated by dividing the total observed soil loss where WEPP predicted runoff and soil loss to occur by the total of the USLE-M erosivity factor for the same set of events. Consequently, the total amount of soil lost estimated for these events by both models were the same. This enabled the ability of the models to predict event soil loses to be examined using the Nash-Sutcliffe model efficiency index. In every case, the efficiency index values for the USLE-M were higher than for WEPP irrespective of whether the values of USLE-M erosivity index were determined using observed or WEPP predicted runoff. As a model of rainfall erosion, focusing on a process based approach has not resulted in WEPP performing as well as or better than the USLE-M on the steep bare fallow plots of loessal soil at the Ansai Research Station in China. Highlights • WEPP and USLE-M models were applied to slopes up to 53%. • WEPP predicted runoff on <45% of events where runoff occurred. • USLE-M was consistently more effective in estimating event soil loss than WEPP. [ABSTRACT FROM AUTHOR]

Abstract The use of Munsell colour charts is the classical way of determining colour information in soil science. The procedure is well-known and consists of visually comparing soil samples with colour chips contained in the charts. This visual approach has several drawbacks and although the chart-based procedure is routinely used, it is not easy to find systematic studies on the accuracy of this methodology. In this paper, we seek to gain insight into the strengths and weaknesses of using soil colour charts as a colour measurement device. The tool used to conduct our study is a modification to the attribute agreement analysis (AAA) method which consists of finding matches between colour standards and colour designations obtained by several appraisers. In the experiment, standards were obtained using a trichromatic colorimeter coupled to a computer program that implements the k nearest neighbour (k-NN) classification algorithm. In order to do the experiment, 276 soil samples were observed twice by four trained appraisers (2208 data records). The naïve count of matches across all the records in the dataset gave <5% of agreement for all three colour components Hue, Value and Chroma. The modified AAA criterion implemented in the study gave a clear increase in all indicators with values ranging from 82.2% to 100% in the agreement within appraisers, 39.5% in the agreement between appraisers, and 42.8% in the agreement of appraisers vs. standards. Results also show that users of the Munsell charts tend to mostly report correct Hues but higher Values and Chromas than true soil colours. Highlights • What is the uncertainty of colour measurements using Munsell charts? • A novel approach based on attribute agreement analysis and k-NN algorithm is presented. • An experienced user can communicate colour consistently with soil charts. • Laboratory studies benefit from automated pipelines, electronic instrumentation and specific software. [ABSTRACT FROM AUTHOR]

In this paper, we examine the effect of vegetation on soil erosion, runoff generation and sediment transport on saline rangeland hillslopes. Rainfall simulations were conducted at a fixed 114 mm/h intensity on 6 m × 2 m erosion plots with varying degrees of vegetation. Plots were grouped into three categories (L, M and H) based on their canopy cover (L: <5%, M: 5–19%, H: >19%) and selected to limit variations in slope across canopy cover groups. Runoff and sediment samples were combined with three dimensional (3D) reconstruction data used to monitor soil surface microtopographic changes. Runoff initiation was significantly delayed on the L plots but cumulative runoff after 20 min of rainfall simulation indicated a positive effect of vegetation on infiltration processes. Cumulative sediment after 20 min of rainfall was similar across vegetation cover categories. The 3D data suggest that vegetation reduced net sediment delivery from the plots by primarily increasing opportunities for deposition while marginally affecting gross soil erosion. Plots with H vegetation cover experienced lower 3D-estimated erosion volumes but average erosion depth on L plots was lower than that on plots with M and H vegetation covers. Lower runoff volumes on M and H plots may have been compensated by greater runoff erosivity on these plots as runoff was concentrated in a narrower inter-patch space compared to L plots. This study highlights the need for an increased integration between traditional runoff measurement techniques and 3D reconstruction methods. [ABSTRACT FROM AUTHOR]

Soils in botanical gardens play a crucial role as they condition the growth and vegetation of huge diversity of plant species on relatively small areas. Creating favourable habitats for the planted vegetation's development frequently leads to the formation of soils with thick surface horizons with a very well developed structure, rich in organic matter and nutrients, described as hortisols. Despite significant human influence, the environments of botanical gardens are often considered to be seminatural enclaves in urban areas. The main objectives of the presented paper were to explain soil cover differentiation noted across the Botanical Garden of Jagiellonian University in Kraków and determine the share of natural and anthropogenic features in the studied soils. Moreover, the usefulness of the WRB system in the evaluation of the rate of anthropogenic transformation in soils was tested. All the investigated soils showed significant evidences of anthropogenic transformations. Both digging and overbuilding with allochthonous material rich in artefacts caused disturbances in soil morphology. On the other hand, formerly intensive liming and fertilizing with organic materials has resulted in the homogenization of soil chemical properties in the studied botanical garden. No significant relationships between the spatial differentiation of soil properties and diversity of planted vegetation or time span from the area's inclusion to the botanical garden were detected. The results of the bonitation of specific soil properties not considered by the classification system (e.g. thickness of soil profile overheap) were compatible with the WRB 2015 systematic position. This confirmed good definition of actual WRB criteria for soils disturbed by human activity and undergoing natural development. [ABSTRACT FROM AUTHOR]

The carbon cycle is being altered as a result of human-induced changes in the Earth's system. Therefore, ecosystems such as wetlands, authentic CO 2 sinks, are becoming especially important. Little information exits on the soil organic carbon (SOC) stock for the middle east-countries man-made wetlands making wadis permanent with the outflow of wastewater treatment plants. This paper presents the vertical distribution of SOC content, soil bulk density (SBD) and SOC density in soil of vegetated and bare sites in Wadi Al-Thulaima, one of the artificial wetlands in central Saudi Arabia. The mean distribution of SBD in the vegetated and bare sites increased significantly with depth. Inversely, the SOC content declined significantly with depth, from 17.1 g C kg −1 at 0–3 cm depth to 3.3 g C kg −1 at 15–18 cm depth in vegetated sites and from 4.7 g C kg −1 at 0–3 cm depth to 0.7 g C kg −1 at the 15–18 cm depth in bared sites. Vegetation significantly affected the SOC pool, the total mean SOC pool of the vegetated sites (2.0 kg C m −2 ) was higher than that of the bare sites (0.5 kg C m −2 ). Therefore, arid regions could contribute to carbon sequestration with appropriate management, which would result in the enhancement of soil quality. [ABSTRACT FROM AUTHOR]

This paper portrays the application of Fuzzy Cognitive Maps (FCMs) to elicit expert views on current condition and future scenario of coastal susceptibility to erosion in Bangladesh. The geomorphological characteristic of the coastal area is highly dynamic where land erosion and accretion with different rates are constant phenomena. This research focuses on three coastal zones: western, central and eastern that comprise the entire coastal area of the country. Using ‘Mental Modeler’ software this study quantified experts' judgements on the issue and developed FCMs by way of arranging workshops. At the basis, this study identified 33 factors of susceptibility to erosion for current baseline conditions. Considering future projections of hydro-climatic phenomena, this study accentuated potential factors of susceptibility to erosion for future scenario under three time-slices: near-future (2020), future (2050) and far-future (2080). The results generated from FCMs show that some factors such as sedimentation, soft and unconsolidated soils, shelf bathymetry, funnel shape of the Bay of Bengal, wave action, river discharge, monsoon wind, cyclone and storm surges, excessive monsoon rain, high tidal energy, variations of tidal range and sea level rise are highly influential that yielded higher centrality scores for both current and future susceptibility of the area to erosion. The experts' interpretations demonstrate that the future susceptibility to erosion might be higher in the central zone compared to the western and eastern zones of the coastal area. This is the first time that FCM based approach was applied to evaluate expert views on coastal susceptibility to erosion for the country. This study suggests coastal managers, planners and policymakers to consider the current and future factors of susceptibility of coastal lands for taking specific measures options. This study is also significant from socio-economic and demographic contexts of any densely populated coastal area like Bangladesh. [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]

Abstract: Conservation prioritization is an important consideration for planning of natural resources management, allowing decison makers to implement management strategies that are more sustainable in the long-term. However, only a current erosion status or a relative index cannot exactly identify priority area for conservation. The objective of this paper is to identify conservation priorities by a specific multicriteria evaluation method. Trends in erosion risk indicate regions of increasing erosion risk and are also chosen as one of the evaluation criteria to identify the priorities based on the instability of soil erosion in the Yongding river basin. In this paper, vegetation cover, land-use, and slope gradient are used to assess erosion risk and trends in erosion risk are obtained by comparing the results of erosion risk between 2000 and 2006. Using this information, the priority conservation areas are graded into six levels. The two highest priority levels cover the regions with severe erosion or a substantial recent increase in erosion risk (4722.56km2, or 11.82% of the study area), and are recommended as erosion control regions with appropriate conservation strategies. The middle two levels cover the regions with stable erosion status or slight change, needing only minor measures. The method presented is fast and straightforward, showing good potential for successful application in other areas. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the relations between rainfall, runoff and suspended sediment transport in the Isábena basin during a quasi-average hydrological year. The Isábena is a mesoscale river basin that drains a mountainous area comprising patches of highly erodible materials (badlands). The paper includes an analysis of the different hydrological and sedimentary responses of the catchment to a similar rainfall. Thirty-four floods were studied, with a very variable response observed. Runoff coefficients ranged from 0.32% to 33%. The sedimentary response was also highly variable, with maximum suspended sediment concentrations (SSC) oscillating between <0.1 and 90gl−1 and flood sediment loads varying from 27 to 54,000t per hydrological event. Most sediment load was concentrated in spring when competent floods occur frequently. Pearson correlation matrix and backward stepwise multiple regression indicate that the hydrological response of the catchment is strongly correlated with total precipitation, event duration, and rainfall of the previous days. Very low correlation was observed with rainfall intensity. The relation between rainfall and sediment transport followed the same trend. Sediment variables (e.g., total load and SSC) were significantly correlated with variables such as total rainfall and rainfall over the previous days, although the significance level was lower in comparison with the runoff related variables. There was again no correlation between sediment variables and rainfall intensity. On-going research in the area suggests that, apart from rainfall, factors such as sediment availability in the badlands and accumulation of sediment in the channels influences the river''s sedimentary response. The non-linear hydrosedimentary response is reflected in the wide range of runoff coefficients and sediment loads that have been observed in response to similar amounts of precipitation. [Copyright &y& Elsevier]

Abstract: Microtopography and roughness are highly dynamic properties of the soil surface and important factors governing surface runoff and erosion processes. While various remote sensing technologies were successfully applied for topography measurements at different spatial scales, there is a lack of field studies that collected systematically microtopography data over long observation periods. In this paper an approach to measure and quantify surface roughness in the field based on laser scanning technologies is presented. Between June 2004 and November 2005 97 in-situ measurements were conducted in a test site with two different sandy substrates in vegetation-free conditions. Two-dimensional high-resolution (1 mm) datasets where generated for eight micro erosion plots of 0.25 to 2.9 m2 in size. Dynamics and pattern formation were quantified for surface roughness and surface height changes. Roughness patterns at different scales were analyzed by local roughness indices using sliding windows of 3 to 55 mm in size. Results show strong spatial and temporal dynamics in surface roughness as well as substrate-specific variations. Temporal roughness variations could be detected and were linked to precipitation patterns. The methods presented in this paper are considered suitable to generate high-resolution datasets on spatiotemporal and multi-scale microtopography patterns and to advance the understanding of surface processes at small scales in natural environments. [Copyright &y& Elsevier]

Abstract: Sedimentological connectivity within drainage systems may be controlled spatially by ‘pockets’ of intact valley fill, alluvial fans impinging laterally on mainstem rivers, floodouts impinging longitudinally on valley floors, and downstream resistant rock bands and their effect on valley width. Where local conditions favor prolonged inundation of the uppermost ~0.5 m of the sediment surface, these environments of deposition host wetlands that provide several ecosystem services to society. In this paper, we examine the long-term (millennia), large-scale mediation of connectivity by geological and geomorphological controls, highlighting the relationship between drainage disconnectivity and wetland origin, and appraise ongoing rehabilitation efforts in light of the long-term natural dynamic. The paper uses a wetland system in the KwaZulu-Natal Drakensberg Foothills, eastern South Africa, as a case study, focusing particular attention on part of the system in which cut-and-fill processes are evident, and proceeds, using observations from this and other similar wetland systems in the region, to discuss successive breaks in connectivity with increasing spatial scale and time. Implications for valley morphology are discussed, and channel incision is shown to play an important role in long-term valley and wetland morphodynamics in certain geomorphological settings, creating a diversity of geomorphological features and hydrological regimes. Thus, rehabilitation practitioners should focus on interventions that improve or stabilize desired functional outcomes, rather than on restoring or maintaining what is perceived to be ‘the natural dynamic’ in which erosion is absent. [Copyright &y& Elsevier]

Abstract: Southeastern Tanzania serves as a typical example of soil degradation and soil organic carbon (SOC) losses on the African continent. Although sequestration of SOC through aforestation or reforestation proved favorable, these measures are restricted by the ability to produce rapid, cost-effective and precise sampling schemes. The aim of this study is to contribute to a better knowledge of the spatial distribution of soil C in tropical natural and plantation forest. This paper presents sampling strategies for estimating mean SOC values as well as for SOC mapping, based on different methods for SOC determination and on different precision levels. To do so we conducted a carbon variability study in five common forest types of Southeastern Tanzania (coastal dry forest, Miombo woodland, teak plantation, pine plantation and cashew plantation) using conventional statistical methods, as well as geostatistics. In the 5 forest types of this study, SOC stocks in the upper 5 cm ranges between 5 (in the cashew plantation) and 13 (in the coastal forest) t ha−1. The optimal sampling distance for measuring mean SOC stocks varies between 36 m (in the patchy miombo woodland) and 422 m (in the homogenized cashew plantation). Sample sizes fluctuate between 6 and 72 (1 t ha−1 precision) for respectively cashew plantation and coastal forest. A rectangular grid with a sample interval of 25 m can be used for SOC mapping with a point kriging estimation error of 3.0 t ha−1 in the coastal forest, 2.6 t ha−1 in miombo woodland, 2.2 t ha−1 in the teak plantation and 1.1 t ha−1 in the cashew plantation. Since the pine plantation has no spatial structure; samples can be arranged randomly and its best soil map has an average C content attributed over the whole field. Refining the sampling strategy with a new spatial variability study in other forest types can be based on a regular grid with sampling distances of half the range identified in this study. This paper proves that the optimal sampling scheme varies strongly as a result of the different spatial behavior of SOC in forests and depends on the required precision and research question. Only when the right strategy is followed, high standards of precision can be met without economic loss or risk of statistical misinterpretation. [Copyright &y& Elsevier]

Abstract: The international symposium ‘HighLand2006’, held in Mekelle (Ethiopia), from 21 to 25 September 2006, was the second time that Ethiopia could host a major international scientific event on geomorphological processes. HighLand2006 created a forum for those conducting research on the impacts of environmental change on geomorphic processes and land degradation in East African highlands as well as in similar regions around the globe. Discussions of results and exchange of experiences during indoor sessions as well as excursions have resulted in this distinctive set of scientific papers. The two main questions addressed in this special issue, through case studies in tropical mountain areas on all continents are: [1.] How have environmental changes impacted the type and intensity of geomorphic processes in tropical mountains since late Pleistocene times? The answer to this question is strongly linked to our knowledge on changes in climate, vegetation cover, human activities, hydrology, hillslope and fluvial processes for such environments. [2.] Which factors control the intensity of land degradation, its on-site and off-site impacts in tropical mountains? This question addresses the role of natural and anthropogenic factors in the degradation of the vegetation cover and in controlling the intensity of hydrological processes, soil erosion, landsliding, reservoir sedimentation and flooding. In parallel with this special Catena issue, a number of selected papers on land degradation and its mitigation in tropical highlands are presented in a special issue of Soil & Tillage Research. [Copyright &y& Elsevier]

Abstract: Rapid economic development has spurred land use change in China since the Chinese government initiated its economic reform in 1978. Although many papers have analyzed the characteristics of land use change, especially cropland conversion to non-agricultural use affected by economic development in the developed regions of China, relatively less attention has been paid to studying the characteristics of land use change affected by both economic development and environmental changes in its undeveloped regions. This paper analyzes the land use change and its driving forces in Dulan County, Qinghai Province on the Tibetan Plateau during 1990–2000. The land use change was studied based on the landscape metrics change and transition matrix of land use types, while its driving forces were analyzed according to climatic changes and socioeconomic development. The study indicates that the increase of land use benefits was given great attention; however, the protection of arid environment did not attracted much attention. The study suggests that the land use should be based on the sustainable protection of arid environment on the Tibetan Plateau. [Copyright &y& Elsevier]

Abstract: This paper reports on the development of a British database of 14C dated Holocene fluvial units over the last 15 years. Since its inception in 1989, the database has undergone substantial expansion, refinement and improvement together with considerable methodological development, so that today it serves as a powerful research tool for investigating the spatial and temporal dynamics of Holocene river development and flooding in Great Britain. The improved analytical method is here applied to the currently existing database by examining datasets of 14C dated fluvial units from river basins that lie within and beyond the limits of Late Devensian glaciation. This analysis indicates how the contrasted conditions in these two types of river environment have, to an extent, led to divergent records of flooding in response to Holocene climate and land-use change. However, even in the contrasting sedimentary records of upland glaciated, and lowland unglaciated river basins, six corresponding episodes of increased flood frequency are identified at c. 5730, c. 3540, c. 2730, c. 2280, c. 660 and c. 570 cal. BP. These represent widespread common responses from British river systems to large-scale changes in climate. The method of database construction and analysis outlined and demonstrated in this paper could be readily adopted in other parts of the world to improve our understanding of Holocene river behaviour at the continental- and global-scale. [Copyright &y& Elsevier]

Abstract: Despite general agreement that global climate change is taking place there is less consensus about the consequences and impacts that may arise. The possibility of greater climatic variability, with changes in the incidence of particular types of events, requires multidisciplinary research so that associated impacts can be considered when devising environmental management strategies. Past hydrological events investigated using palaeoenvironmental techniques, over time periods longer than the period of continuous records, are a possible source of information to complement monitored records. Six international research groups (GLOCOPH Commission of INQUA, Water Sustainability Commission of IGU, LUCIFS in IGBP–PAGES, Geomorphic Challenges for the 21st Century Commission of IGU, International Commission on Continental Erosion of IAHS, and Fluvial Archives Group [FLAG] associated with INQUA and IGU) have each contributed results from their specific time and spatial scales in integrated research collaboration. Relevant research conclusions have been combined and a research project undertaken which is the subject of four later papers. A provisional protocol for use of past hydrological events in order to understand global change is proposed and adapted in the final paper, to take account of other papers included and contributions to the discussions. [Copyright &y& Elsevier]

Abstract: This paper reviews recent changes in river management. These changes are characterised by a move from the notion of rivers as stable equilibrium forms to one of dynamic responsive ecosystems. Coupled to these changes are a series of scientific questions that provide the context for reviewing the role that palaeohydrology might have in supporting contemporary and future river management. Palaeohydrology is shown to be capable of providing important and relevant information to river managers. Furthermore a series of emerging frameworks for incorporating geomorphology in river management exist wherein palaeohydrological data and analysis can be directly interfaced with the river management process. The paper therefore concludes that within specific limits, palaeohydrology is in much stronger position to support and communicate with the river management agencies than has previously been the case. [Copyright &y& Elsevier]

Abstract: This paper investigates the influence of rainfall intensity and initial soil water content on changes in the near-surface soil hydraulic conductivity. While numerous papers have examined surface sealing, this paper outlines two important innovations: the design and application of time-domain reflectometry probes with the ability to measure and record soil water content at very short time and length scales; the design and application of stainless steel tensiometers to measure soil water potential at the same, very short, time and length scales. These permit the Richards Equation to be applied and the near-surface hydraulic conductivity computed. An exponential curve was fitted to the temporal changes in hydraulic conductivity, as both a function of water potential or soil water content, with a high degree of fit. As rainfall intensity increased, the degree of scatter about the best-fit line increased, probably due to the ability of high intensity rainfall to disrupt the near-surface soil structure. While utilising deterministic models, such as the Richards Equation, may be appropriate at the column scale there are practical difficulties due to the very small length scale variability in each of the input variables. The experimental results detailed here indicate that even with data at very short time and length scales it is still not possible to utilize the Richards Equation, or at least, it may be difficult to transfer the laboratory results to the field due to the effect of the specific laboratory experimental conditions on the results. [Copyright &y& Elsevier]

Abstract: The Unit Hydrograph (UH) technique is widely used for runoff estimation, especially for determining peak discharges. In this paper, a geomorphologically based UH has been applied. Its most remarkable characteristic is that it includes the watershed structure in its formulation. This is defined from the drainage network, each subwatershed being considered as a linear reservoir. In this method, the fact of considering this reservoir sequence according to the drainage network leads to the formulation of the model only depending on a single parameter. The Geomorphological Unit Hydrograph of Reservoirs (GUHR), proposed in this paper, is compared with Nash''s Instantaneous Unit Hydrograph (Nash''s IUH), by applying the two methods to the Aixola watershed. This 4.7-km2 watershed is located in Gipuzkoa (Northern Spain). It is characteristic of the headwaters watersheds of the area. Most of them are forested and have steep slopes. Annual rainfall is over 1500 mm and many intense rainfall events are observed, among which 18 were selected for this study. Both UH techniques were applied to the rainstorms. The resulting hydrographs were plotted against registered data and the best fits were determined. According to these results, the GUHR model behaved similarly to Nash''s IUH. However, the GUHR method seemed able to reproduce a wider range of rainstorms than Nash''s IUH. While analyzing the UHs calculated, seasonal behavior was observed in runoff generation, and different average UHs were proposed for two different periods. This variability was also observed in values adopted by the GUHR model parameter, providing some information about the watershed time response. The dynamic character of the only uncertain parameter, and the model formulation, in which the watershed morphology is reflected, together with the model''s simplicity, leads us to consider GUHR as being a promising UH model. [Copyright &y& Elsevier]

Abstract: Reasons for erosion measurements are: (1) to determine the environmental impact of erosion and conservation practices, (2) scientific erosion research; (3) development and evaluation of erosion control technology; (4) development of erosion prediction technology and (5) allocation of conservation resources and development of conservation regulations, policies and programs. A handicap for the control of the insidious erosion process is the difficulty of determining its magnitude. Four causes are often mentioned in the literature: the large temporal and spatial variation of erosion, the paucity of accurate erosion measurements, the problem of extrapolating data from small plots to higher scales and the conversion of erosion into production and monetary units (impact). It is an illusion to think that the role of measurements can be taken over by the application of erosion prediction technology. Measurements are needed to develop, calibrate and validate that technology. Measurement techniques differ in accuracy, equipment and personnel cost. The most accurate (and often most expensive) techniques do not always serve the measurement purpose. This paper gives a critical overview of current measurements techniques for erosion at different spatial and temporal scales. Examples are presented of techniques for direct measurements as well as for indirect measurements, i.e. measurements of soil properties that serve as input for models. The paper is concluded with a critical evaluation. [Copyright &y& Elsevier]