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Soil erosion poses a significant problem in the Mediterranean region, posing serious threats to the environment and natural resources. The objective of this study is to identify and evaluate the risks associated with gully erosion in the Medjerda watershed in the northeastern part of Algeria. To accomplish this goal, two models were utilized: the fuzzy analytic hierarchy process (F-AHP) and the frequency ratio (FR). Twelve factors that contribute to soil erosion were considered in the study: slope, elevation, distance to streams, land use and land cover, drainage density (DD), topographic wetness index (TWI), rainfall, soil groups, lineament density, soil power index (SPI), sediment transport index (STI), and plan curvature. The results indicate that sediment transport index (STI), rainfall, and slope are the most influential factors in predicting erosion in the Medjerda Basin. To validate the models used, the area under the receiver operating characteristics curve (AUC) was employed. The AUC values obtained for the FR and F-AHP models were 75.5 and 73.7%, respectively, indicating their excellent accuracy in identifying the erosion susceptibility area. The accuracy ratings of both models demonstrate their outstanding predictive capabilities. Thus, the results of soil erosion susceptibility maps with a better success rate and forecast could be beneficial and effective for implementing various policy measures to safeguard soil. They could be useful for managing gully erosion risks in different parts of the river basin. [ABSTRACT FROM AUTHOR]

Soil erosion monitoring is essential for the ecological evaluation and dynamic monitoring of land resources via remote sensing technology. In this paper, we provide new insights into the existing problems and development directions of traditional models, which are supported by new technologies. An important role is played by remote sensing information acquisition technology in the qualitative and quantitative evaluation of soil erosion, and the data and technical support provided are systematically reviewed. We provide a detailed overview of the research progress associated with empirical statistical models and physically driven process models of soil erosion, and the limitations of their application are also summarized. The preliminary integration of remote sensing data sources with high spatial and temporal resolution and new technologies for soil erosion monitoring enables the high-precision quantitative estimation of sediment transport trajectories, the watershed river network density, and the terrain slope, enhancing the accuracy of erosion factor identification, such as spectral feature recognition from erosion information, gully erosion feature extraction, and vegetation coverage estimation. However, the current erosion models, driven by algorithms and models, are not comprehensive enough, particularly in terms of the spatial feature extraction of erosion information, and there are limitations in the applicability and accurate estimation of such models. [ABSTRACT FROM AUTHOR]

The aim of this research was to analyze the impact of implemented erosion control works (ECW) on soil erosion intensity in the watershed of the Ćelije reservoir (Rasina River) in the period between 1968 and 2022. The Erosion Potential Method was used to calculate the annual gross erosion (W), sediment transport (G), and erosion coefficient (Z) in the study area. As a result of the performed ECW there was a general decreasing trend in the intensity of soil erosion processes in the last 54 years. The specific annual gross erosion was 1189.12 m3/km−2/year−1 in 1968, while in 2022 it was 554.20 m3/km−2/year−1. The specific sediment transport was 540.18 m3/km−2/year−1 in 1968 and 253.55 m3/km−2/year−1 in 2022. Due to the changes in the intensity of erosion processes, the specific annual gross erosion decreased by 634.92 m3/km−2/year−1 and the specific sediment transport decreased by 286.63 m3/km−2/year−1. The erosion coefficient was reduced from Z = 0.62 to Z = 0.35. A dependence between the slope of siltation and the natural bed slope was defined. The results show a significant correlation between erosion intensity and performed ECW, providing a basis for future watershed management and defining a strategy for soil erosion control in the Ćelije reservoir watershed. [ABSTRACT FROM AUTHOR]

To investigate the influence of bedrock fragmentation by intensive tillage on the hydrological characteristics and soil erosion processes on slopes, two experimental treatments (soil–bedrock mixtures, WB, and pure soil, CK) in steel tanks were subjected to simulated rainfall under five rainfall patterns (constant, increasing, decreasing, decreasing–increasing, and increasing–decreasing) with the same total rainfall of 90 mm. For each rainfall event, runoff and sediment concentration were sampled at regular intervals. The flow velocity (v), effective/critical shear stress (τ/τc), Darcy–Weisbach resistance coefficient (f), unit stream power (p), and soil erodibility factor (Kr) were calculated to analyze the differences in hydrodynamic characteristics between the WB and CK. Our experimental findings show that significant differences in runoff volume and sediment yield were observed among different rainfall patterns and stages. Bedrock fragmenting significantly promoted runoff and sediment production under different rainfall patterns, with runoff volume and sediment yield increasing by averages of 59.29% and 71.62%, respectively. An increasing trend in average contribution rate of bedrock to runoff volume and sediment yield was observed across three distinct intensities: 6.37% and 4.61% for 30 mm h−1, 12.53% and 7.53% for 90 mm h−1, as well as 14.79% and 36.98% for 150 mm h−1, respectively. The v and p values under various rainfall patterns exhibited an increasing trend from the upper to the bottom slope positions, whereas the f and τ values showed an opposite trend, regardless of the WB and CK. Compared with the CK, the v, f, and p values for the WB increased by 23.34% to 48.94%, 1.59% to 53.16%, and 3.86% to 27.86%, respectively, whereas the τ value decreased by 1.52% to 22.19% for varying-intensity rainfall patterns. Among the variable rainfall patterns, the WB significantly increased sediment yield and also had a promoting effect on runoff generation. However, the WB displayed better erosion resistance compared to the CK under constant rainfall patterns. Therefore, varied-intensity patterns had a profound impact on bedrock-induced runoff and sediment transport processes. [ABSTRACT FROM AUTHOR]

Soil erosion is a severe threat for ecosystems and anthropogenic infrastructure. Glaciers are retreating rapidly due to global warming and the receding ice leaves unvegetated depositions of sediment, which are prone to mobilisation during precipitation events. Vegetation is known to serve as erosion protection, but how above- and belowground plant traits, vegetation cover and plant diversity on community level are jointly affecting erosion is unclear. Additionally, soil microbial communities may have effects on slope stability by promoting plant growth and function. We measured sediment transport on 30 plots of 2 × 3 m size on proglacial slopes of the Gepatschferner glacier (Kaunertal, Austria) over three years in a natural pristine high alpine environment. Vegetation cover, species abundances and relevant above- and belowground traits were measured for each occurring plant species on community level. Path model analysis revealed that dense and species-rich plant cover characterized by specific plant growth strategies and trait diversity was best suited to decrease erosion. Vegetation properties were also closely linked to the composition of soil microbial communities characterised by next generation amplicon sequencing, which may facilitate soil formation and further enhance the plants' soil stabilising potential. Our study illustrates that erosion control may benefit from a high vegetation cover, which is facilitated by diverse plant communities with complementary morphological traits. These vegetation properties also affect soil microbiota, but their impact on slope protection in combination with the vegetation remains to be elucidated. Our findings may inform nature-based solutions against erosion such as revegetation of alpine slopes using specific seed mixtures. [ABSTRACT FROM AUTHOR]

Soil erosion and sediment transport have significant consequences, including decreased agricultural production, water quality degradation, and modification to stream channels. Understanding these processes and their interactions with contributing factors is crucial for assessing the environmental impacts of erosion. The primary objective of this review is to identify a suitable soil erosion and sediment transport model for catchment-scale application. The study considers various model selection processes, including model capability and the spatial and temporal domains for assessing spatiotemporal distributions. The review acknowledges the limitations, uncertainties, and unrealistic assumptions associated with soil erosion and sediment transport models. Models are usually developed with a particular objective, which demands an assessment of capabilities, spatial, and temporal applicability, and catchment-scale applicability. Distributed models are often preferred for catchment-scale applications, as they can adequately account for spatial variations in erosion potential and sediment yield, aiding in the evaluation of erosion-contributing elements and planning erosion control measures. Based on the findings of this study, the authors encourage utilizing models (such as Soil and Water Assessment Tool (SWAT) or Automated Geospatial Watershed Assessment Tool (AGWA)) that can forecast net erosion as a function of sediment output for catchment erosion and sediment yield modeling. This review helps researchers and practitioners involved in erosion and sediment modeling by guiding the selection of an appropriate model type based on specific modeling purposes and basin scale. By choosing appropriate models, the accuracy and effectiveness of sediment yield estimation and erosion control measures can be improved. [ABSTRACT FROM AUTHOR]

Model-based soil erosion studies have increased in number, given the availability of geodata and the recent technological advances. However, their accuracy remains rather questionable since the scarcity of field records hinders the validation of simulated values. In this context, this study aims to present a method for measuring sediment deposition at a typical Mediterranean catchment (870 ha) in Greece through high spatial resolution field measurements acquired by an Unmanned Aerial Vehicle (UAV) survey. Three-dimensional modeling is considered to be an emerging technique for surface change detection. The UAV-derived point cloud comparison, applying the Structure-from-Motion (SfM) technique at the Platana sediment retention dam test site, quantified annual topsoil change in cm-scale accuracy (0.02–0.03 m), delivering mean sediment yield of 1620 m3 ± 180 m3 or 6.05 t ha−1yr−1 and 3500 m3 ± 194 m3 or 13 t ha−1yr−1 for the 2020–2021 and 2021–2022 estimation. Moreover, the widely applied PESERA and RUSLE models estimated the 2020–2021 mean sediment yield at 1.12 t ha−1yr−1 and 3.51 t ha−1yr−1, respectively, while an increase was evident during the 2021–2022 simulation (2.49 t ha−1yr−1 and 3.56 t ha−1yr−1, respectively). Both applications appear to underestimate the net soil loss rate, with RUSLE being closer to the measured results. The difference is mostly attributed to the model's limitation to simulate gully erosion or to a C-factor misinterpretation. To the authors' better knowledge, this study is among the few UAV applications employed to acquire high-accuracy soil loss measurements. The results proved extremely useful in our attempt to measure sediment yield at the cm scale through UAV-SfM and decipher the regional soil erosion and sediment transport pattern, also offering a direct assessment of the retention dams' life expectancy. [ABSTRACT FROM AUTHOR]

Environmental loss is primarily caused by soil, water, and nutrient loss, and runoff is associated with nutrient transport and sediment loss. Most existing studies have focused on one influencing factor, namely slope gradient or rainfall intensity, for slope erosion and nutrient loss, but the joint effects of the two factors have rarely been researched. In this context, the impact of slope gradients (0°, 5°, 10°, and 15°) and rainfall intensities (30, 40, 50, 60, 70, and 80 mm/h) on soil erosion and nutrient loss on the sloping fields of Miyun Reservoir were explored using the indoor artificial rainfall simulation testing system. Based on the results of the study, the variation of runoff coefficient with slope gradient was not noticeable for rainfall intensities <40 mm/h; however, for rainfall intensities >40 mm/h, the increased range of runoff coefficient doubled, and the increase was the fastest under 0° among the four slope gradients. The slope surface runoff depth and runoff rate showed positive correlations with the rainfall intensity (r = 0.875, p < 0.01) and a negative correlation with the slope gradient. In addition, the cumulative sediment yield was positively related to the slope gradient and rainfall intensity (r > 0.464, p < 0.05). Moreover, the slope surface runoff-associated and sediment-associated loss rates of total nitrogen (TN) rose as the rainfall intensity or slope gradient increased, and significant linear positive correlations were found between the runoff-associated TN loss rate (NLr) and the runoff intensity and between the sediment-associated NLr and the erosion intensity. In addition, there were positive linear correlations between slope runoff-associated or sediment-associated TN loss volumes and rainfall intensity, surface runoff, and sediment loss volumes, which were highly remarkable. The slope gradient had a significant positive correlation with the slope surface runoff-associated TN loss at 0.05 (r = 0.452) and a significant positive correlation with the sediment-associated TN loss at the level of 0.01 (r = 0.591). The rainfall intensity exhibited extremely positive correlations with the slope surface runoff-associated and sediment-associated TN loss at 0.01 (r = 0.717 and 0.629) Slope gradients have less effect on nitrogen loss on sloped fields than rainfall intensity, mainly because rainfall intensity affects runoff depth. Based on the findings of this study, Miyun Reservoir may be able to improve nitrogen loss prevention and control. [ABSTRACT FROM AUTHOR]

The authors also described methods and procedures for quantify soil erosion processes (sediment sampling and water level reading in the storage tanks for total erosion measurements; profilometer, and structure from motion technique for rill erosion measurements). Merlo et al. [[11]], in turn, evaluated the relationship between soil properties (microbial biomass carbon, basal soil respiration, and metabolic quotient) and erosion in areas managed with different cropping system practices under no-tillage in the Brazilian Cerrado. Soil erosion is a process in which soil particles are first detached from the soil surface and then transported by erosive agents such as rainfall, overland flow and channelized flows in rills, ephemeral gullies and gullies [[1], [3]]. 10.3390/w15132378 15 Todisco F., Vergni L., Ortenzi S., Di Matteo L. Soil Loss Estimation Coupling a Modified USLE Model with a Runoff Correction Factor Based on Rainfall and Satellite Soil Moisture Data. [Extracted from the article]

The detachment-transport coupling equation by Foster and Meyer is a classical equation that describes the relationship between detachment and transport. The equation quantifies the relationship between sediment loads and soil detachment rates, deepens the understanding of soil erosion and provides a reliable basis for the establishment of an erosion model. However, the applicability of this equation to slopes with gradients greater than 47% is limited. In this work, the detachment-transport coupling relationship is investigated using the colluvium material of Benggang. A nonerodible rill flume 4 m long and 0.12 m wide was adopted. The slope gradient ranged from 27% to 70%, the unit flow discharge ranged from 0.56 × 10-3 to 3.33 × 10-3 m2 s-1, and the sediment transport capacity (Tc) was measured under each slope and discharge combination. The sediment was inputted into the flume according to the predetermined sediment addition rate (from 0% to 100% of Tc), and the detachment rate (Dr) under each combination of the slope and discharge was measured. Dr linearly decreased with increasing sediment loads, which is consistent with the detachment-transport coupling equation by Foster and Meyer. The linear equations can predict the detachment capacity (Dc) and Tc well (Nash-Sutcliffe efficiency coefficient (NSE) = 0.98 for Dc, and NSE = 0.99 for Tc). The detachment-transport coupling equation can adequately predict the Dr (NSE = 0.89). However, its applicability to slopes of <47% (NSE: 0.92-0.96) was greater than that to slopes of =47% (NSE: 0.81-0.89), and the predicted Dr under Tc levels of 20% and 40% were higher than the measured values, while the predicted value under a Tc level of 80% was lower than the measured value. In summary, the detachment-transport coupling equation by Foster and Meyer can accurately reflect the negative feedback relationship between detachments and transports along steep-slope fixed beds and is suitable for colluvial deposit research. The results provide a basis for the construction of steep-slope colluvial deposit erosion models. In the future, the study of the hydrodynamic characteristics of sediment transport processes should be strengthened to clarify the detachment-transport effect of flows through hydrodynamics. [ABSTRACT FROM AUTHOR]

Soil erosion varies in space and time. As the contributing surface area increases, heterogeneity effects are amplified, inducing scale effects. In the present study, soil erosion processes as affected by the observation scale and the soil surface conditions are assessed. An experimental field scale setup of 18 plots (1–150 m2) with different soil surface conditions (bare and degraded, cultivated) and slopes (0.75–4.2%) are used to monitor soil losses between 2010 to 2018 under natural rainfall. The results showed that soil loss rates range between 2.5 and 19.5 t.ha−1 under cultivated plots and increase to 12–45 t.ha−1 on bare and degraded soils, which outlines the control of soil surface conditions on soil erosion. At a larger scale (38 km2), soil losses are estimated at 2.2–4.5 t.ha−1, highlighting the major contribution of scale. The scale effect is likely caused by the redistribution of sediments in the drainage network. These findings outline the nature and contribution of the emerging and dominant soil erosion processes at larger scales. At the plot scale, however, diffuse erosion remains dominant, since surface runoff is laminar and sediment transport capacity is limited, resulting in lower soil erosion rates. [ABSTRACT FROM AUTHOR]

Sediment transport is a complex, multi-dimensional process. With the advancement in computing power and sophistication of computer applications over recent decades, it has become possible to conduct detailed analysis and simulations of soil erosion and sediment transport. The primary objective of this study was to examine and predict the potential influence of human activities on sediment transport. This was achieved by analyzing sediment transport in the Saskatchewan River beneath the E.B. Campbell Dam and in the Saskatchewan River Delta. The Hydrologic Engineering Center's-River Analysis System (HEC-RAS) was deployed to ascertain the sediment transport capacity and estimate erosion, sedimentation, and riverbed changes. Cross-sectional data, flow data, and sediment data were used in conjunction with HEC-RAS. The simulation results reveal that sediment transport below the E.B. Campbell Dam is limited, leading to notable sediment erosion. The selected study area has witnessed significant erosion during high-flow periods, particularly in the event of floods. Between 2012 and 2019, the riverbed elevation at the selected survey site decreased by approximately 0.45 m. The study findings corroborate that the Saskatchewan River and its delta have been impacted by human activities. Potential erosion and deposition below the E.B. Campbell Dam have been simulated for the selected site. The aim is to provide decision-makers or related stakeholders with insight into how dam operations can be adjusted to decrease erosion while sustaining hydrological, ecological, and environmental outcomes from human activities. • The Saskatchewan River and its delta have been influenced by human activities, climate changes, and their combined effects. • The sediment transport model via HEC-RAS evaluates the potential influences on riverbed erosion in the Saskatchewan River. • Riverbed erosion intensifies downstream of the E.B. Campbell dam. [ABSTRACT FROM AUTHOR]

Soil erosion rates after wildfire are strongly controlled by intrinsic properties such as topography, weather, climate, soil, and vegetation. These landscape and hydroclimatic properties are important in determining post-fire erosion rates; however, their influence on post-fire erosion and their interaction with the intensity of a wildfire remains uncertain. A key limitation in resolving this uncertainty is the lack of conceptual models and frameworks for organising data related to the geomorphic sensitivity of landscapes to wildfire. Our aim is to develop a framework for consolidating understanding of post-fire erosion in the context of hydroclimatic conditions which contribute to system states, for example soil and vegetation properties, and wildfire regime. The framework is developed around a simple conceptual model where the change in erosion due to wildfire is a product of change in runoff generation and sediment supply, which is strongly related to landscape net primary productivity (NPP). We hypothesised that geomorphic sensitivity to wildfire should vary as a unimodal humped relationship across a gradient of NPP, peaking at an intermediate level. To develop this framework and to test the hypothesis, we first review intrinsic soil and vegetation properties related to the supply and transport of sediment from burned and unburned hillslopes. Net primary productivity is systematically related to these intrinsic properties because it integrates many processes involved in soil and vegetation development. Empirical data indicate a trend in the change in surface runoff generation with NPP after wildfire, peaking at an NPP of approximately 15 Mg C ha−1 y−1. A simple model of fuel availability and soil heating are correlated with a similar "humped" trend in sediment supply. These results are consistent with our conceptual model, which indicates that sediment supply and runoff contribute towards a distinct peak in wildfire effects on erosion at an intermediate level of NPP. We propose that landscapes of intermediate NPP typically have the highest quantity of fuel available to burn, which cause large changes to the soil surface properties. Landscapes at intermediate NPP also tend to produce intrinsic soil and vegetation properties that promote erosion after wildfire. The interplay between these short and long-term landscape characteristics is strongest at intermediate levels of NPP. Our proposed biogeographic model of geomorphic sensitivity to wildfire was supported by erosion data from burned hillslope and zero-order catchments studies from a range fire-prone landscapes in Australia and North America. Our proposed conceptual model will help identify areas most vulnerable to post-fire erosion changes. [ABSTRACT FROM AUTHOR]

The main purpose of this article is to give a general idea of the scientific activity that was carried out starting from the 2000s on the basis of the data collected in the plots installed at the Sparacia experimental station for soil erosion measurement in Sicily, South Italy. The paper includes a presentation of the experimental site, a description of the methods and procedures for measuring soil erosion processes both available in the literature and applied at the Sparacia station (sediment sampling and water level reading in the storage tanks for total erosion measurements; profilometer, and Structure from Motion technique for rill erosion measurements), and the main results obtained in the monitoring period in the experimental site. The latter concern the effects of plot size and steepness on soil loss, the measurement variability, the frequency analysis of soil loss, the rill erosion characterization, and the comparison between rill and interrill erosion rates. Each of these topics is addressed with multi-temporal analyses performed with increasing size of the available database, which allowed to draw robust conclusions. Soil loss did not vary appreciably with plot length in contrast with the assumption made in the USLE/RUSLE. The variability of the measurements of soil loss, runoff volume, and sediment concentration at the event scale in replicated plots decreased as the mean measured value increased. The normalized event soil loss was distributed according to a two-component distribution. A power relationship between rill volumes and lengths was established. The measurements also confirmed the morphological similarity between the channels of the rills and ephemeral gullies described by a power dimensionless relationship. Rill erodibility of the sampled clay soil varied over time, maintaining relatively low values. Finally, rill erosion was dominant relative to interrill erosion, and a more efficient sediment transport system through the rill network occurred as plot steepness increased. [ABSTRACT FROM AUTHOR]

Gully erosion seriously threatens farmland and causes soil loss. Estimating sediment transport in a gully system is important for understanding the mechanisms of gully erosion. The morphological method successfully applied in estimating bed-material transport in rivers, for some decades, has yet to be applied to gully erosion. Here, we estimate sediment transport in a gully system using the morphological method. It was applied to a laboratory simulation of a loess catchment. Nine high-resolution Digital Elevation Models (DEMs) were acquired by digital close-range photogrammetry and used to determine morphological change. Mass conservation was used to explain measured morphological change, and to infer the changes in sediment transport in space. The results showed that gully erosion is greater than deposition in the initial stages of gully development. Serious gully erosion occurs in the gully heads or upstream areas, and the erosion and deposition become balance in the downstream area. A large proportion of the total transport was actually concentrated into one main channel. Meanwhile, the active areas (high transport) of sediment transport gradually developed from the downstream to upstream with the gully development. [ABSTRACT FROM AUTHOR]

Concentrated surface run-off caused by torrential rain leads to the transport of sediments from soil erosion processes within catchment areas of critical points, which represents a basic component of flood risks. Clear identification of such critical points offers a basis for a suitable new strategy of threat mitigation, via both organizational and structural measures in catchment areas. Critical points are determined in places where generated paths of concentrated surface run-off cross given boundaries of built-up areas. The threshold values for the catchment area of a critical point were derived on the basis of hydrological calculations, field research, and the evaluation of hundreds of specific manifestations of damage in built-up areas for particular critical profiles. The characteristics were determined as follows: contributing area between 0.3 and 10 km2, average slope more than 3.5%, and percentage of arable land more than 40%. Indicator F was determined for the distribution of the territory of the Czech Republic according to the risk of flooding. Knowledge of the existence of critical points enables the implementation of preventive measures, the evaluation of flood risk associated with the transport of sediment due to erosion processes, and the improvement of management measures in respective catchment areas, even before an event occurs. The proposed procedure outputs shall be reflected in spatial planning documentation, land consolidation, and catchment area management plans. Incorporation of critical points into open-access public web-maps can help with assessing the semi-quantitative expression of risk to built-up areas arising from the threat of local flooding. [ABSTRACT FROM AUTHOR]

Water erosion poses a significant environmental threat in the Mediterranean region, with pronounced impacts observed throughout Morocco. It impairs soil quality and disrupts both sediment transport and water availability. Contributing factors range from natural (climate, topography, and geology) to anthropogenic (land use, vegetation cover, and management). This study introduces an improved Priority Actions Program/Regional Activity Centre (PAP/RAC) model, enriched with GIS and the Caesium-137 (137Cs) technique, to investigate erosion within Morocco's Raouz basin. Enhanced with additional variables including soil types, slope length, rainfall erosion potential, slope orientation, soil moisture, and land surface temperature, the model transcends the classical approach, promoting granularity and precision in predictions. In addition to the comprehensive model, the 137Cs method, which discerns long-term soil erosion and redistribution, provides a dual-faceted validation, bolstering the robustness of this project's erosion risk evaluation. This study's outcomes underscore the gravity of the erosion hazard with significant soil depletion rates ranging from 8.1 to 20 t ha−1 yr−1, demonstrating the model's alignment with empirical data, affirming its utility. The modified PAP/RAC model concurs with the 137Cs data, demonstrating its usefulness for water erosion assessment and management in similar areas. • The modified PAP/RAC model enhances erosion prediction. •Model validated with extensive 137Cs data. •GIS integration identifies erosion hotspots. •A comparative study with global erosion data. • The model adapts to diverse Mediterranean climates. [ABSTRACT FROM AUTHOR]

Soil loss by lateral flow is a critical bother in the Oued Laou basin due to the steepness of its landscape relief and the considerable deference altitudinal between the upstream and downstream area. Those predispositions highly increase soil vulnerability to the risk of erosion indeed; tones of sediment are transported each year, causing significant damages regarding structures and waterworks such as siltation. For this reason, this work focus on the merging of remote sensing techniques, GIS, and the Revised Universal Soil Loss (RUSLE) Equation to quantitatively evaluate soil erosion severity as well as highlight the most erosion-prone areas in the Oued Laou basin, Northwestern Morocco. Accordingly, the study site area was arranged into six soil erosion risk categories: very slight (25.3%), slight (12.4%), moderate (40.5 %), intense (12.2%), very intense, (5%) and severe (4.6%). Moderate to severe soil loss rates that are correlated to abrupt slopes defined most of the basin area. In addition to the spatial distribution of soil severity classes over the study area, the average annual soil erosion rate was estimated to be 31.5 t ha-1 year-1 in the Oued Laou watershed. The latter amount was compared to many previous studies that have been carried out in the surrounding basins based on RUSLE or other techniques to validate the model accuracy. [ABSTRACT FROM AUTHOR]

• The runoff, sediment load and runoff erosion power decreased significantly. • Compared with runoff, runoff erosion power-sediment relationship is better. • The power function of runoff erosion power and sediment is better than linear. • Erosion in particular geographic locations responds strongly to runoff erosion power. In recent years, the acceleration of urbanization in the Yangtze River Economic Belt (YREB) has brought about problems such as soil erosion, ecosystem degradation and decline in ecological service functions. Therefore, this paper selects the Fujiang River Basin (FRB) in Upper Yangtze River (UYR), and analyzes the relationship between runoff erosion power (REP) and sediment transport (ST) on the basis of analyzing the variation characteristics of hydrological elements. Based on SWAT model, a variety of scenarios are set up to quantitatively analyze the impact of different land use changes on runoff and ST and REP in the basin. The results indicated that: (1) The annual precipitation in FRB from 1960 to 2018 did not change significantly, while the annual runoff, annual ST and annual REP decreased significantly. Compared with runoff and runoff depth, the relationship between sediment transport modulus (STM) and REP is the best, especially the power function between them is better than the linear function. (2) The results of the evaluation indexes of the simulation results of the SWAT model based on the measured runoff and sediment data from 2008 to 2018 are pass and above, that is, the simulation results are considered reliable. (3) Under the five scenarios of conversion of sloping farmland to forest, conversion of dry land to paddy field and conversion of grassland to bushland and forest land, the runoff and ST in the basin decreased but the overall range was small. The simulation results of SWAT model show that the erosion of specific areas in the basin shows the greatest degree of weakening with the decrease of REP. [ABSTRACT FROM AUTHOR]

Soil erosion and suspended sediment transport understanding is an important issue in terms of soil and water resources management in the critical zone. In mesoscale watersheds (>10 km2) the spatial distribution of potential sediment sources within the catchment associated with rainfall dynamics is considered to be the main factor in the observed suspended sediment flux variability within and between runoff events. Given the high spatial heterogeneity that can exist for such scales of interest, distributed physically based models of soil erosion and sediment transport are powerful tools to distinguish the specific effect of structural and functional connectivity on suspended sediment flux dynamics. As the spatial discretization of a model and its parameterization can crucially influence how the structural connectivity of the catchment is represented in the model, this study analyzed the impact of modeling choices in terms of the contributing drainage area (CDA) threshold to define the river network and of Manning's roughness parameter (n) on the sediment flux variability at the outlet of two geomorphologically distinct watersheds. While the modeled liquid and solid discharges were found to be sensitive to these choices, the patterns of the modeled source contributions remained relatively similar when the CDA threshold was restricted to the range of 15 to 50 ha , with n restricted to the range 0.4–0.8 on the hillslopes and to 0.025–0.075 in the river. The comparison of the two catchments showed that the actual location of sediment sources was more important than the choices made during discretization and parameterization of the model. Among the various structural connectivity indicators used to describe the geological sources, the mean distance to the stream was the most relevant proxy for the temporal characteristics of the modeled sedigraphs. [ABSTRACT FROM AUTHOR]

Suspended sediment load in rivers is highly uncertain because sediment production and transport at catchment scale are strongly variable in space and time, and they are affected by catchment hydrology, topography, and land cover. Among the main sources of this variability are the spatially distributed nature of overland flow as an erosion driver and of surface erodibility given by soil type and vegetation cover distribution. Temporal variability mainly results from the time sequence of rainfall intensity during storms and snowmelt leading to soil saturation and overland flow. We present a new spatially distributed soil erosion and suspended sediment transport module integrated into the computationally efficient physically based hydrological model TOPKAPI-ETH, with which we investigate the effects of the two erosion drivers – precipitation and surface erodibility – on catchment sediment fluxes in a typical pre-Alpine mesoscale catchment. By conducting a series of numerical experiments, we quantify the impact of spatial variability in the two key erosion drivers on erosion–deposition patterns, sediment delivery ratio, and catchment sediment yields. Main findings are that the spatial variability in erosion drivers affects sediment yield by (i) increasing sediment production due to a spatially variable precipitation, while decreasing it due to a spatially variable surface erodibility, (ii) favouring the clustering of sediment source areas in space by surface runoff generation, and (iii) decreasing their connectivity to the river network by magnifying sediment buffers. The results highlight the importance of resolving spatial gradients controlling hydrology and sediment processes when modelling sediment dynamics at the mesoscale, in order to capture the key effects of sediment sources, buffers, and hillslope hydrological pathways in determining the sediment signal. [ABSTRACT FROM AUTHOR]

A careful analysis of rainfall-runoff events and patterns of sediment and pollution load to water bodies is crucial for the proper management of agricultural land. This study simultaneously employed the WaTEM/SEDEM long-term erosion model and the HEC-HMS episodic hydrological and erosion model to describe the runoff and sediment load evoked by extreme rainfall events in a small agricultural catchment in Czechia, using the long-term monitoring discharge and water quality episodic data. WaTEM/SEDEM helped to delineate the runoff and sediment critical source areas, subsequently incorporated into HEC-HMS. The acquired results showed that the spatial distribution of land use is a fundamental factor in the protection of watercourses from diffuse pollution sources and the transport and delivery of sediment profoundly depends on the status of crop cover on arable land near a watercourse. Integrating both models, it was shown that the tabulated Curve Number (CN) values as well as the average C-factor values had to be lowered for the majority of the modelled events to match the monitored data. A noticeable role of catchment runoff response most probably played tile drainage, which appeared to profoundly modify the episodic runoff pattern. This study showed a promising approach for the simulation of different rainfall-runoff responses of small agricultural catchments and could be applied for the delineation of areas where soil conservation measures or protective management is of high priority. The results further revealed the obvious need to revise the CN values for tile-drained catchments. [ABSTRACT FROM AUTHOR]

Gypsiferous soils in karstic landscapes are important areas in terms of biodiversity and geology. One of the geological formations occurring in gypsum regions is the doline lakes. Subsidence dolines must be preserved because of their formation and fossil heritage. Erosion is one of the most serious types of degradation among these types of lakes. The Bakkal Lake is one of the most important doline lake in central Turkey and is at risks with sediment flow. In this study, we aimed to determine how erosion poses a threat to the geological heritage in areas such as doline lakes and to simulate what measures can be taken to protect them. RUSLE/GIS/remote-sensing technologies were used to estimate the distribution and amount of sediment flowing into the lake. According to the results of the study, the amount of sediment transported to the lake was estimated to be 2.73tha−1y−1, and the total amount of sediment transported was 2876 m3y−1. The time until Bakkal Lake is filled with sediment flux was calculated to be 698 years. The simulation was developed by offering protection measures to reduce sediment flow to the lake. As a result of the simulation, it was calculated that the amount of sediment flowing into the lake decreased to 2.29 tha−1y−1 and the filling time increased to 833 years. The study showed that a doline lake, which under natural processes would not be filled for thousands of years, will soon be filled unless radical measures are not taken. This study asserts that more planners should use simulations to model sediment flow to better select appropriate conservation measures. [ABSTRACT FROM AUTHOR]

Literature review reveals that many erosion models have limitations for application to constructed landforms. The new EroCA model aims to address this gap. The model uses established erosion and sediment transport models applied to multiple particle size classes at fine spatial and temporal resolutions, covering both suspended load and bedload. Using data from an experimental plot in Northern Australia, global sensitivity analysis was used to investigate the sources of uncertainty, limitations of the model, and priorities for data collection. Further analysis explored sensitivity to model grid size. The results showed that the Manning roughness, erodibility parameters and particle size are the most important parameters. Results also showed low parameter identifiability and hence the difficulty of calibration, even when using high quality experimental data. EroCA has the capacity to be a powerful landform modelling tool at appropriate scales of application; however ideally its data needs would be considered during monitoring design. • In-depth attempt to develop and assess a high spatial resolution process-based erosion model for a mined landform. • Improved understanding of the effects of various parameters on soil erosion process and modelling. • New insight into the limitations of experimental plot data sets for supporting high resolution erosion models. [ABSTRACT FROM AUTHOR]

Water erosion on agricultural land and sediment delivery to streams are a major threat to soil productivity and surface water quality. Climate change and different national and international societal drivers now require Denmark to take action to protect soil and water resources. In this study, we adapted the spatially distributed sediment transport model WaTEM using the best data available at national scale. To calibrate and validate the model, sediment yield data from 31 catchments and 189 slope units in Denmark were compared with the model output, which was produced at a fine spatial resolution of 10 × 10 m. Residual analysis and cross-validation were used to identify potential catchment outliers and assess model robustness. We obtained a median Nash & Sutcliffe model efficiency range of 0.06–0.6 for the Danish environment. Based on the equifinality concept, an ensemble of 100, NSE-weighted model realisations for acceptable transport capacity coefficients was used to assess model uncertainty. The comparison between rill survey data and predicted values indicates that although the model captures well the spatial variability in erosion, it may underestimate the long-term average of soil erosion. Based on the modelling, 71% of the agricultural land in Denmark is mapped as stable in terms of the amount of erosion and deposited material. Overall, 6.1% of the farmland is estimated to have unsustainable erosion and 0.9% of the farmland exceeds erosion rates of 7.5 t ha−1 a−1. Sediment export into surface water in Denmark equals 92,000 t a−1, corresponding to an average sediment yield of 2.7 t km−2. The performance of WaTEM is considered satisfactory in this study. Importantly, modelled water erosion exceeds the perceived erosion risk in Denmark. Strengthened by distributed uncertainty assessment at national scale, our study provides an important national knowledge base for engaging land users and regulators in the process of targeted erosion mitigation planning that is required to comply with national and EU regulation. Future investigations concerning the deviation between predicted and observed data and specific catchment parameters for the non-behavioural catchments are required as well as studies that include the establishment of catchment sediment budgets. • High resolution national water erosion modelling for future mitigation planning • Model calibration and validation with 31 nationwide catchments and field surveys • Explicit consideration of model uncertainty [ABSTRACT FROM AUTHOR]

The agricultural land found in the Czech Republic is strongly degraded by water erosion. The main reasons for this situation are the changes in the landscape caused by large-area agricultural production in the second half of the 20th century. In the model locality Starovice – Hustopeče (223.5 ha) (South Moravia Region), we analysed the changes in the landscape structure and land use for the period 1825–2018. In 1825, the mean size of a land block was 0.4 ha. In 1968, the studied locality consisted of just one land block of a size of 223.5 ha. This period marks the beginning of massive water erosion. In 2003, the locality was proposed for land consolidation. Its goal was to reduce erosion and the risk of floods. To date, a number of protective measures have been applied in the locality. The risk of water erosion was assessed for the landscape state in 1968 and 2018 in GIS using the USLE method. The effect of the adopted measures was strongly manifested in the reduction of the erosion risk (by 44%). The transport of sediment out of the locality was assessed for 1968 and 2018 by means of the WaTEM-SEDEM model. The protective measures resulted in a decrease of sediment transport out of the locality by 111 t/year (40% reduction). The economic balance of the soil loss showed a positive impact of the applied protective measures. On the basis of the mean price of arable land in the Czech Republic and the costs of the soil relocation within the locality, the application of protective measures brought an economy of at least € 5,000 per year. This sum does not include the losses caused by a potential decrease of agricultural crop yields due to the soil degradation, reduction of ecosystem services, and other factors in the past years. The actual benefits of applying the protective measures aimed at reducing erosion and increasing water retention in the landscape are significantly higher. [ABSTRACT FROM AUTHOR]

The erosion, transport and deposition of sediments in small valley reservoirs represent a significant impact on their operations, mainly with regard to reducing the volume of their accumulation. The aim of this study is a comparison and uncertainty analysis of two modelling concepts for assessment of soil loss and sediment transport in a small agricultural catchment, with an emphasis on estimating the off-site effects of soil erosion resulted in sedimentation of a small water reservoir. The small water reservoir (polder) of Svacenicky Creek which was built in 2012, is a part of the flood protection measures in Turá Lúka and is located in the western part of Slovakia, close to the town of Myjava. The town of Myjava in recent years has been threatened by frequent floods, which have caused heavy material losses and significantly limited the quality of life of the local residents. To estimate the amount of soil loss and sediments transported from the basin, we applied two modelling concepts based on the USLE/SDR and WaTEM/SEDEM erosion models and validated the results with the actual bathymetry of the polder. The measurements were provided by a modern Autonomous Underwater Vehicle (AUV) hydrographic instrument. From the sediment data measured and the original geodetic survey of the terrain conducted at the time of the construction of the polder, we calculated changes in the storage volume of the polder during its four years of operation. The results show that in the given area, there has been a gradual clogging of the bottom of the polder caused by water erosion. We estimate that within the four years of the acceptance run, 10,494 m3 of bottom sediments on the Svacenicky Creek polder have accumulated. It therefore follows that repeated surveying of the sedimentation is very important for the management of the water reservoir. [ABSTRACT FROM AUTHOR]

Computer-based coupled soilscape-landform evolution models provide an avenue for estimating the erosion potential of a landform over geological timescales. They also provide tools to understand soil-landform relationships in the context of both field and modelled pedogenesis processes. In this study, we used the State Space Soil Production and Assessment Model (SSSPAM) and CAESAR-Lisflood landform evolution model to simulate the evolution of a natural catchment where soil erosion rates have been closely monitored over the last 20 years. Both models predict comparable erosion rates to that of field measurements and produce similar catchment scale geomorphological patterns. Rock content data measured in the field along two transects were compared with SSSPAM simulations at the same representative points. The results showed that SSSPAM produced similar rock content variation along the respective transects. The findings demonstrate 'SSSPAM's ability to predict catchment scale erosion and surface soil distribution. The insights demonstrated here provide confidence in the SSSPAM model for Soilscape predictions for natural, agricultural and post-mining landform assessment. [Display omitted] • SSSPAM and CAESAR-Lisflood models were used to simulate the evolution of a natural catchment. • Both models produced catchment erosion rates comparable with field observations. • SSSPAM reproduced surface rock content variation on 2 transects observed in the field. • SSSPAM also revealed a possible relationship between area, slope and soil grading. • This study demonstrates SSSPAM's ability to predict erosion and surface soil distribution. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum Polonorum. Formatio Circumiectus is the property of Wydawnictwo Uniwersytetu Rolniczego im. Hugona Kollataja w Krakowie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Water & Land Development is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Sediment Transport and Erosion Prediction (STEP) model is methodically described in this paper. The STEP model was implemented at a 3.47 km × 3.47 km grid resolution in the Kalisapi sub-watershed, Central Java, Indonesia. It was calibrated and validated in the period of 2003–2008 and 2010–2014 respectively. The result shows that the STEP model functions satisfactorily at monthly and annual time window in the calibration and validation periods. In both periods, the STEP model is able to produce fruitful annual sediment transport rates with R2 values of 0.71 and 0.9 in the calibration and validation period respectively. Moreover, the STEP model exhibits more equitable spatial variability than that of the widely known USLE model. Correspondingly, it can be surmised that the STEP model is capable of simulating spatial and temporal variability of sediment transport from a watershed at monthly and annual time scales. • STEP model is developed to simulate soil erosion, deposition and sediment transport processes in time and space. • STEP model has been successfully implemented, calibrated and validated in the Kalisapi sub-watershed, Indonesia. • Calibrating STEP model to fit the observation is straightforward as it only needs to modify two model parameters. • STEP model source code and input data for the study area are freely available in the Bitbucket repository service. [ABSTRACT FROM AUTHOR]

Ephemeral gully erosion, prevalent on agricultural landscapes of the Great Plains, is recognized as a large source of soil loss and a substantial contributor to the sedimentation of small ponds and large reservoirs. Multi-seasonal field studies can provide needed information on ephemeral gully development and its relationship to physical factors associated with field characteristics, rainfall patterns, runoff hydrograph, and management practices. In this study, an ephemeral gully on a no-till cultivated crop field in central Kansas, U.S., was monitored in 2013 and 2014. Data collection included continuous sub-hourly precipitation, soil moisture, soil temperature, and 15 field surveys of cross-sectional profiles in the headcut and channelized parts of the gully. Rainfall excess from a contributing catchment was calculated with theWater Erosion Prediction Project (WEPP) model for all storm events and validated on channel flow measurements. Twelve significant runoff events with hydraulic shear stresses higher than the critical value were identified to potentially cause soil erosion in three out of fourteen survey periods. Analysis of shear stress imposed by peak channel flow on soil surface, antecedent soil moisture condition, and channel shape at individual events provided the basis on which to extend the definition of the critical shear stress function by incorporating the intra-storm changes in soil moisture content. One potential form of this function was suggested and tested with collected data. Similar field studies in other agriculturally-dominated areas and laboratory experiments can develop datasets for a better understanding of the physical mechanisms associated with ephemeral gully progression. [ABSTRACT FROM AUTHOR]

A new modeling platform was developed to simulate spatially distributed sediment production and transport in agricultural landscapes. The sediment production at the grid scale was computed using the stand-alone Water Erosion Prediction Project-Hillslope Erosion code, while an advection-dispersion equation represented sediment transport. The model's performance was tested in the Water Resources and Erosion watersheds at the Oklahoma and Central Plains Agricultural Research Center, El Reno, OK, USA. Results showed that this modeling approach could capture the complex behavior of sediment under different management practices in the watersheds. The modeling framework provides mechanistic processes to simulate the fate and transport of sediment across the watershed at spatio-temporal scales that are useful in assessing the environmental impacts of management schemes. Therefore, this study is expected to help advance the current approaches to estimating soil erosion by bridging scale differences to capture the large-scale effects of small-scale soil erosion processes. • A new modeling framework was developed for estimating soil erosion. • Sediment production is evaluated in fully distributed settings. • Different sizes of sediment are considered in simulations. • The model provides mechanistic processes in simulating sediment transport. • The model is able to capture changes in land and management practices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Water & Land Development is the property of Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the greatest threats to maintaining sustainable agro-ecosystems is mitigating the episodic soil loss from farm operations, further exacerbated by meteorological extremes. The Revised Universal Soil Loss Equation (RUSLE) is a model that combines the effects of rain, soil erodibility, topography, land cover, and conservation practices for estimating the annual average soil losses. This study aims to quantify soil water erosion to continental South America (S.A.) through RUSLE using available datasets and characterizing the average sediment delivery rate (SDR) to the major S.A. basins. Soil erodibility was estimated from the Global Gridded Soil Information soil database. LS-factor's topographical parameter was derived from Digital Elevation Models using the "Shuttle Radar Topography Mission" dataset. The R-factor was estimated from a previous study developed for S.A. and the C-factor from the Global Land Cover (Copernicus Global Land Services) database. We used a modeling study for SDR that simulated the annual average sediment transport in 27 basins in S.A. RUSLE set up presented a satisfactory performance compared to other applications on a continental scale with an estimated averaged soil loss for S.A. of 3.8 t ha−1 year−1. Chile (>20.0 t ha−1 year−1) and Colombia (8.1 t ha−1 year−1) showed the highest soil loss. Regarding SDR, Suriname, French Guyana, and Guyana presented the lowest values (<1.0 t ha−1 year−1). The highest soil losses were found in the Andes Cordillera of Colombia and the Center-South Region of Chile. In the former, the combination of "high" K-factor, "very high" C-factor, and "very high" LS-factor were the leading causes. In the latter, agriculture, livestock, deforestation, and aggressive R-factor explained the high soil loss. Basins with the highest SDR were located in the North Argentina – South Atlantic basin (27.73%), Mar Chiquitita (2.66%), Amazon River basin (2.32%), Magdalena (2.14%) (in Andes Cordillera), and Orinoco (1.83%). • Water erosion is one of the most relevant impacts on sustainable food production. • South America (S.A.) shelters several biomes and landscapes on the earth planet. • Countries in S.A. are highly dependent on agricultural and livestock for their GPD. • RUSLE was set up for the first time in all S.A. to identify critical erosion areas. • Planning and management of the soils are fundamental for a cleaner production. [ABSTRACT FROM AUTHOR]

Combinations of storm surge and extreme waves may cause overtopping of coastal protection of structures, resulting in structural damage and flooding behind these structures. The high turbulence of the overtopping flow is an important factor for soil erosion and may be responsible for the destruction of levees during combined overtopping. The goal of this study was to investigate the turbulence and erosion characteristics of one levee strengthening technique, high-performance turf reinforcement mat, under combined wave overtopping and storm surge overflow. A three-dimensional hydrodynamic and sediment transport model known as ECOMSED has been calibrated and verified with overflow discharge and full-scale overtopping experimental results. The study simulated 41 storm surge overflow and combined overtopping cases with different freeboards and significant wave heights. Overtopping hydrodynamic flow, turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope under combined overtopping conditions were calculated. New equations for estimating turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of a landside slope were developed. The equivalency of erosion rate under storm surge overflow and combined wave and surge overtopping are provided. The range of the application of these equations is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Analysis of typhoon- and earthquake-triggered landsliding and fluvial response in the Tachia River, central Taiwan, documents highly episodic sediment supply over decade to century timescales. Landslide data from the Chi-Chi earthquake (1999) and subsequent typhoons (2001, 2004, and 2005) quantify the sediment supply from these events. Fluvial response was investigated by decadal-scale and century-scale longitudinal river profile data spanning 1904 to 2008 and by sediment delivery recorded in suspended sediment load and reservoir sedimentation data. Our results show that the different time periods of satellite images and aerial photographs used in previous studies make it difficult to unambiguously identify the causes of landslides previously attributed by some studies to the effects of the Chi-Chi earthquake rather than subsequent high intensity precipitation. In response to significant variability in sediment delivery from hillslopes, century-scale profile variation data indicate substantial bed surface elevation change of 2.6±6.7m, and decade-scale bed surface elevation change of 1.1±3.3m. Since 1993, the downstream reaches incised in response to bedload sediment trapping by reservoirs while headwater reaches aggraded in response to increased sediment delivery from uplands. A tremendous increase in reservoir sedimentation after 2000 likely reflects the effects of the highest decade-average daily rainfall since 1900. Suspended sediment load data indicate a post Chi-Chi earthquake increase in sediment concentration in low-flow events but do not exhibit the clear influence on sediment yields at higher flows as (e.g., typhoons) reported by others for fluvial response in the epicentral region. [Copyright &y& Elsevier]

Abstract: The tropics of northern Australia have received relatively little attention with regard to the impact of soil erosion on the many large river systems that are an important part of Australia''s water resource, especially given the high potential for erosion when long dry seasons are followed by intense wet season rain. Here we use 137Cs concentrations to determine the erosion processes supplying sediment to two major northern Australian Rivers; the Daly River (Northern Territory), and the Mitchell River (Queensland). We also present data from five sediment samples collected from a 100km reach of the Cloncurry River, a major tributary of the Flinders River (Queensland). Concentrations of 137Cs in the surface soil and subsurface (channel banks and gully) samples were used to derive ‘best fit’ probability density functions describing their distributions. These modelled distributions are then used to estimate the relative contribution of these two components to the river sediments. Our results are consistent with channel and gully erosion being the dominant source of sediment, with more than 90% of sediment transported along the main stem of these rivers originating from subsoil. We summarize the findings of similar studies on tropical Australian rivers and conclude that the primary source of sediment delivered to these systems is gully and channel bank erosion. Previously, as a result of catchment scale modelling, sheet-wash and rill erosion was considered to be the major sediment source in these rivers. Identifying the relative importance of sediment sources, as shown in this paper, will provide valuable information for land management planning in the region. This study also reinforces the importance of testing model predictions before they are used to target investment in remedial action. [Copyright &y& Elsevier]

Forest fires are common in Mediterranean environments and may become increasingly more frequent as the climate changes. Destruction of the forest cover and litter layer leads to greater overland flow and increased erosion rates. The greatest risk occurs during the first rainstorms following a major fire, so local authorities must act quickly to put erosion control methods in place in order to avoid excessive post-fire sediment loads in river channels. Deciding on which methods to use requires accurate knowledge of their impact on sediment load and an estimate of their cost efficiency. The objective of this study was to evaluate the efficiency of Log Debris Dams (LDDs) and a sedimentation basin for their effectiveness in trapping sediments. Paired sub-catchments were studied to quantify the amount of sediments trapped in stream channels by a series of LDDs and a sedimentation basin. Cost efficiency was evaluated for each of the measures as a function of the cost per unit volume of sediments trapped. In addition, grain size analyses were performed to characterise the nature of the sediments trapped. A third sediment trapping method, Log Erosion Barriers (LEBs) was evaluated more superficially than the first two and conclusions regarding this method are tentative. LDDs trapped a mean volume of 1.57m3 per unit (median=1.28m3); mean LDD height was 105.4cm (std. dev.=21.9cm), and mean height of trapped sediments was only 50.0cm (std. dev.=22.9cm), showing that the traps were only half filled. Sediment height was limited by the presence of gaps between logs or branches that allowed runoff to flow through. Comparison of the textural characteristics of slope and trapped sediments showed distinct sorting: particles greater than 20mm were not mobilised from the slopes during the study period, sediments in the medium to coarse sand size fractions were trapped preferentially by the LDDs, and sediments in the sedimentation basin were enriched by clay and silt sized (<0.050mm) particles as coarser sediments were trapped upstream by the LDDs. Cost efficiency of LDDs was estimated at about 143 €m−3 for the LDDs and 217 €m−3 for the sedimentation basin at the time of sampling. The LDDs are therefore a cost effective method of trapping sediments, but they can only be used when pine trees or straight-trunked trees are locally available. In this case, they should be combined with LEBs, which had a cost efficiency estimated at about 250 €m−3. Installation of the LEBs had not been optimised and they have the advantage of trapping sediments on the slopes where they can continue to play an ecological role, so this method can give better results with more care. Sedimentation basins can be emptied if necessary and are useful in areas where pine trees are not available and where the site can be secured. [Copyright &y& Elsevier]

In order to improve water quality and restore impaired watersheds, managers need to make decisions using data that are able to gather. Data collection can be expensive, tedious and time consuming. Not all watershed managers have sufficient budgets to undertake such exercises. In such situations using modeling approach makes sense. The Sediment Nutrient Assessment Program (SNAP) is a functionally distributed model. It uses Geographic Information System (GIS)-based methodology employing commonly used Revised Universal Soil Loss Equation (RUSLE) to estimate the amount of erosion that can occur in the study area and Flux model for estimating the sediment transport. By adopting this methodology a modeler can estimate fractions of sediment contributions from the three landforms (upland, surface tiled, riparian). An intermediate result is mapping of areas producing erosion at rates above, below and equal to tolerable rates for each soil type. The model works best on smaller watersheds (<4,000 hectare) where staff have time and resources to inventory water quality. A good understanding of the watershed is needed to validate the model outputs. The model implementation is relatively cheap, cost effective and easy. Existing data and freely available information in the public domain are used for computations. It takes a multifaceted and holistic approach by integrating current, localized research literature, field surveys, water quality data, and GIS into one tool for refining watershed management decisions. The SNAP model serves as a first stage of analyzing as to how bad the sedimentation problem is with limited resources. [ABSTRACT FROM AUTHOR]

This study presents a revised and scale-adapted Foster-Meyer-Onstad model (Foster et al., 1977) for the transport of soil erosion sediments under scarce input data, with the acronym CliFEM (Climate Forcing and Erosion Modelling). This new idea was addressed to develop a monthly time scale invariant Net Erosion model (NER), with the aim to consider the different erosion processes operating at different time scales in the Sele River Basin (South Italy), during 1973-2007 period. The sediment delivery ratio approach was applied to obtain an indirect estimate of the gross erosion too. The examined period was affected by a changeable weather regime, where extreme events may have contributed to exacerbate soil losses, although only the 19% of eroded sediment was delivered at outlet of the basin. The long-term average soil erosion was very high (73Mgha-1 per year±58Mgha-1). The estimate of monthly erosion showed catastrophic soil losses during the soil tillage season (August-October), with consequent land degradation of the hilly areas of the Sele River Basin. [ABSTRACT FROM AUTHOR]