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• A novel model integrating hillslope and in-stream sediment processes is developed. • We quantified the effects of soil-water conservation (SWC) on the Loess Plateau. • SWC contributes to 54.4% and 91.9% of the decline in discharge and sediment load. • Sediment reduction effect of hillslope SWC is more lasting compared to that of check dams. Soil erosion and sediment transport processes, which are intimately connected with hydrological processes, strongly affect land surface morphology and earth system dynamics. Over the past 60 years, intensive Soil-Water Conservation (SWC) measures implemented on the Loess Plateau have significantly reduced sediment load and concurrently exacerbated runoff declines, while the quantitative evaluation of the effects of SWC measures remains challenging. This study develops a sediment module which simulates the hillslope and in-stream sediment processes, and then incorporates the module into a Geomorphology-Based Ecohydrological Model (GBEHM). Besides, the model also couples with an explicit representation of different types of SWC measures, including both Hillslope SWC (HSWC) and River-network SWC (RSWC) measures. The newly developed hydro-sediment model is then applied to the Kuye River basin, a typical river basin on the Loess Plateau, and used for quantifying the effects of SWC measures on river discharge and sediment load during 1982–2019. Compared with Period 1 (1982–2000), the river discharge decreased by 48.7% in Period 2 (2001–2019), while the sediment load experienced a more substantial decrease of 95.3% between the two periods. Based on the numerical experiment results, HSWC and RSWC contributed to 25.4% (58 million m3/yr) and 28.9% (66 million m3/yr) of the annual runoff decline, as well as 58.1% (36 million t/yr) and 33.9% (21 million t/yr) of the annual sediment load reduction between the two periods, respectively. Besides, HSWC plays an increasingly important role in sediment reduction in recent years due to check dam silting. The model developed in this research is useful to evaluate the multi-faceted effects of existing SWC measures and to help with future SWC planning and policymaking. [ABSTRACT FROM AUTHOR]

Water erosion, a notorious major threat to food security and ecosystem sustainability, is strongly conditioned by spatial and temporal scale effects. This paper systematically reviews the scale issues in runoff and sediment delivery (SIRSD) as a research field by integrating the traditional review approach and bibliometric analysis. This review summarises SIRSD's roots and the scale effect on runoff and sediment delivery. Then, we provide quantitative insights into the SIRSD domain's development history, thematic structure, geographic distribution, international cooperation, and methodologies. Findings show that: i) SIRSD arises from the gap between the non-linearity of runoff and sediment delivery across scales and our ability to measure it. Point-based and short-term measurements cannot capture the non-linearities from the spatio-temporal heterogeneities and cross-scale interactions of factors or processes. ii) Previous literature provides evidence that the spatial scaling of specific runoff (r), soil erosion (SE), sediment yield (SSY), or sediment delivery ratio (SDR) with drainage area (A) or slope length (L) exhibits contrasting patterns due to distinct mechanisms. Infiltration-excess and saturation-excess processes account for inverse and positive r - A relations, respectively. Interrill-erosion and rill-erosion cause inverse and positive SE-L relations. Hillslope-erosion and channel/bank-erosion explain inverse and positive SSY-A relations. Downstream increasing deposition and additional sediment inputs drive inverse and positive SDR-A relations. These scaling relationships can be nonlinear or complex due to spatial heterogeneities in land use, vegetation, topography, climate, lithology, and soil characteristics. Hence, applying an empirical scaling equation developed from the region with distinct environmental contexts is not recommended. Furthermore, the existing scaling patterns or equations may require updating given global climate and land use change. iii) SIRSD is a complex and multidisciplinary issue investigated by scientists from 93 countries since 1928. International research has substantially facilitated the understanding of SIRSD; still, more collaboration should focus on less-developed countries with high soil and water loss risks and urgent conservation needs, such as those in Africa and South America under cropland expansion. iv) Scale mismatch and scale break have discredited large-scale erosion and sediment assessments. Incorporating gully and bank erosion into modelling, extending the scale range of the L factor, and expanding the sediment scaling scope from watershed to slope may make a difference. Therefore, more research with nested design incorporating multiple scales is necessary for cross-scale analysis and scalable modelling. Addressing global climate change requires improving real-time urban flood forecasting and integrating downscaled climate models with hydrology, erosion, and sediment transport models. • A bibliometric review of the global SIRSD research for the first time. • SIRSD is rooted in the gap between natural nonlinearity and our measuring ability. • Scaling of specific runoff, erosion, sediment yield, and SDR has diverse patterns. • Scale mismatch and scale break discredit large-scale modelling and assessments. [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]

• Mass movement is an important erosion mode and sediment source in gully network. • Mass movement increased sediment concentration and led to peak sediment concentration. • Mass movement was prone to be triggered by rainfall with a medium-duration and moderate-intensity. • Rainfall amount and slope gradiet determined the trigger and total volume of mass movement. Mass movement erosion on the gully sidewalls is recognized as an important erosion mode and sediment source in hilly and gully watersheds. However, the trigger of mass movement erosion and transport of gravity-detached material remain poorly understood. A series of rainfall simulation experiments were conducted on six loess gully sidewall models, with a height (1 m), three rainfall (60 mm, 48 mm and 24 mm) and two slope gradients (70° and 80°), to quantitatively explore the sensitivity factor and transport mechanisms of mass movement. Results revealed that the accumulation volume and initiation of the mass failure were significantly influenced by rainfall amount. The accumulative volume of failure events was observed to increase in a linear pattern with increasing rainfall amount. The minimum cumulative rainfalls for the initiation of mass failure on the loess gully sidewalls were approximately 43.6, 28.2 and 65.6 mm for short-duration and high-intensity, medium-duration and moderate-intensity and short-duration and moderate-intensity rainfalls, respectively. This implied that the initiation of mass failure was more prone to rainfall events with a medium-duration and moderate-intensity than those with a high intensity and short duration. Rainfall amount and initial slope gradient were the most sensitive elements driving the number and volume of the mass movement erosion. Mass movement erosion raised sediment concentration, but the eroded material was unable to be transported by runoff in a timely manner. Average sediment concentrations at the model outlet increased by 1.9–11.9 times following the occurrence of mass failures compared to those before. A low instantaneous sediment delivery ratio of 0.032 for the mass movement erosion. The experimental findings help comprehend the influence of mass movement erosion on sediment supply on the gully sidewall in the hilly and gully network, i.e. the Loess Plateau. [ABSTRACT FROM AUTHOR]

• A method for 3-D river networks extraction was proposed based on multi remote sensing. • A module for recognizing and retrieving cross section morphology was established. • An improved hydrological model was developed to enhance the simulation performance. Many rivers originating from mountainous areas cannot be adequately measured in the field to obtain sufficient basic data due to the challenging terrain, which poses difficulties for conducting relevant research such as hydrodynamic and sediment transport simulations, fluvial material fluxes. This study utilized a combination of 71 river cross sections extracted from multisource remote sensing data and 34 cross sections measured by hydrological stations between 2010 and 2018 to generate generalized cross sections for all river orders in the middle reaches of the Yellow River. By integrating the generalized cross sections, river surfaces, and traditional DEM river network, a comprehensive 3-D river network has been established to provide a more accurate representation of the morphological changes along the river channel. To tackle the challenge of simulating runoff in data-deficient areas, the Digital Yellow River Integrated Model (DYRIM), a potent distributed hydrological model, was enhanced by incorporating geometric parameters derived from a 3-D river network into almost all input parameters that can be obtained from multi-source remote sensing. This enhancement enabled the model to accurately simulate runoff in representative data-deficient rivers of the Loess Plateau. The Nash Efficiency coefficients for the simulated runoff exhibited improvement of 23% compared to previous studies, surpassing 0.8 for the period between 2010 and 2018. Additionally, the simulated errors for flow velocity and water depth were 7% and 9% respectively. This approach can provide essential data for the simulation of hydrological processes and improving hydrological models, as well as technical methodologies for related research such as sediment transport simulations and river carbon emissions. [ABSTRACT FROM AUTHOR]

• Rainfall and runoff explained 70–85% of sediment yield variability in two karst watersheds. • Specific rainfall and runoff variables affecting sediment yield the most were identified. • The PLSR model provides a convenient way of solving variable collinearity. As one of the largest and most typical continuous karst distribution belts in the world, Southwest China is vulnerable to soil erosion and rocky desertification because of its unique geological conditions and heterogeneous landscapes. Understanding the rainfall-runoff-sediment transport relationships is critical to effectively controlling soil erosion in karst watersheds. This study aims to evaluate the sediment yield variability at different temporal scales (daily, monthly/seasonal, and annual) from 2014 to 2019 and to further identify the rainfall and runoff variables most associated with sediment yield in the selected Mahuangtian (2.26 km2) and Muzhaihe (0.09 km2) karst watersheds. Since rainfall and runoff variables were highly codependent, the partial least squares regression (PLSR) model was used to quantify the relative importance of rainfall and runoff variables to sediment yield. The variable importance of the projection (VIP) scores>1 was considered to be the most influential predictor of the PLSR model. Results showed that sediment yield was greatly influenced by rainfall and runoff, which can explain 70% and 85% of the variation of sediment yield in the Mahuangtian and Muzhaihe watersheds, respectively. For rainfall variables, three-day antecedent precipitation (VIP = 1.41) and five-day antecedent precipitation (VIP = 1.28) were the main first-order factors controlling sediment yield in the Mahuangtian watershed. In contrast, the rainfall amount (VIP = 1.35) was the dominant factor influencing sediment yield in the Muzhaihe watershed. For runoff variables, runoff amount, runoff coefficient, and maximum discharge were the primary variables controlling the sediment yield in these two karst watersheds. By partially eliminating the co-dependency of the variables, the PLSR approach can conveniently determine the dominant factors controlling sediment yield in heterogeneous karst watersheds. [ABSTRACT FROM AUTHOR]

Research on factors affecting sediment regime in glacierized catchments under warming climates is still scarce despite its societal relevance. In particular, coarse bedload transport has never been quantitatively related to water runoff origin (snowmelt vs glacier melt), which provides important information on the role of different sediment sources (glaciers vs hillslopes and channel bed). Drawing on data from multiple spatial and temporal scales in a paradigmatic Alpine glacierized catchment, we show that glacier melt flows play a key role in coarse sediment transport dynamics. Bedload concentration measured during glacier melt flows is up to 6 orders of magnitude larger than during snowmelt. At the catchment scale and within the channel, however, minimal aggradation and degradation was detected over almost a decade. In addition, sedimentation rates at a hydropower weir, inferred from flushing frequency during the last four decades, are tightly associated to summer air temperature and not to precipitation trends, and most of sediment export occurred in July-August. However, sediment flushing frequency has been decreasing since the late 1990s despite very warm summers in the following decades. Collectively, these findings indicate that sediment is dominantly sourced from within glacier-covered areas and that transport rates are thus dictated by seasonal and multi-annual glacial dynamics. As glacier melt flows decrease due to ice mass loss, our results suggest that, for similar basins, a progressive shift from supply-limited (driven by glacier activity) to transport-limited (during rainfall-induced events) sediment transport will occur, disrupting the current near-equilibrium channel conditions. • Hydrograph separation coupled to bedload measurements in a glacierized catchment. • Bedload during glacier melt up to 6 orders of magnitude larger than during snowmelt. • Decadal channel bed equilibrium despite large bedload yields from glaciers. • Sediment export statistically related to summer air temperatures and not to precipitation. • Sediment export peaked in late 1990s despite rising temperatures in 21st century. [ABSTRACT FROM AUTHOR]

Patterns of sediment yield have been widely investigated across a variety of scales, but few of these studies have been carried out in urban watersheds. The design of this study represented a unique opportunity to use high-frequency sensor data to compare sediment yields across spatial and temporal scales in an urbanized watershed. Near real-time turbidity and discharge data were collected continuously for four years at five stream gages over three nested spatial scales in the highly impervious 14.2-km2 Dead Run watershed, located in Baltimore County, Maryland, USA. Monthly suspended sediment yields varied by over two orders of magnitude across all stations. Two mid-watershed stations on tributaries to the mainstem of Dead Run are located only about 500 m apart and about 500 m upstream of their confluence, yet displayed observable differences in the timing of their highest sediment yields. Average annual suspended sediment yield was higher at the headwater station with older development (78.2 t/km2/yr) than at the headwater station with more recent development (47.0 t/km2/yr). Average annual yields increased with watershed size from the headwater stations to the mid-watershed stations (87.0 t/km2/yr and 60.4 t/km2/yr). Additionally, yields at the station farthest downstream (81.7 t/km2/yr) were slightly larger than the yield calculated from the sum of both mid-watershed stations (74.6 t/km2/yr), which together represented about 80% of the upstream drainage area. Several additional patterns highlighting spatial heterogeneity of the system were observed. The ratio of sediment yields between the headwater stations increased steadily over time while the runoff ratio remained almost constant. Yields at one mid-watershed station were consistently higher than yields at the other mid-watershed station, despite similarity in runoff totals. Upstream watersheds show year-to-year variation in sediment yield. In contrast, yields at the farthest downstream station show minimal variation. This observation is consistent with the possibility that internal storage and remobilization tend to modulate downstream yields even with spatial and temporal variation in upstream sources. Observable inconsistencies in sediment yields between subwatersheds at monthly time scales suggest that there is a substantial degree of heterogeneity in terms of sediment response to large storm events. Despite significant internal variability, the overall range of sediment yield values at each site was consistent with values reported for multiple urban mid-Atlantic Piedmont watersheds. Comparison with global values indicates that sediment yields from Dead Run are in the same general range as the 25% quartile of urban sediment yields. • Urban sediment data collected from 5 gages at 3 nested scales for 4 years • Temporal patterns of sediment yield differ from temporal patterns of runoff. • Dominant sources of sediment vary spatially in a 14 km2 highly impervious catchment. • Downstream site exhibits lower variation in annual sediment yield than tributaries. • Storage has a substantial role in the sediment dynamics of a small, urban watershed. [ABSTRACT FROM AUTHOR]

Abstract The interactions between precipitation, runoff and sedimentation could reveal information about the processes of runoff and sediment production and the environmental evolution mechanisms of basins. Based on the hydrometeorological data collected over a long-term time series (1955–2012) which has been divided into five periods (P1 (1956–1969), P2 (1970–1979), P3 (1980–1989), P4 (1990–1999) and P5 (2000−2012)), changes and implications of the relationships between precipitation, runoff and sediment load (precipitation-runoff-sediment relationships) were studied in the Wuding River basin, China. Conclusions are as follows. (1) There is no obvious change occurs on the distribution of annual precipitation during 1955 to 2012. However, the annual runoff and sediment load are significantly decreased by 51.9% and 86.4%, respectively, from P1 to P5. (2) Under the same precipitation conditions, the runoff and sediment present overall decreasing trends. Decrease in the runoff was greater than that in the sediment load. The incoming sediment coefficient (ISC) reduced by 69.2%, indicating that the sediment transport ability per unit runoff was weakened. The significant reduction of ISC along with the decrease of the runoff amount caused the sediment brought into the Yellow River (STWY) decreased from P1 to P5. (3) Soil conservation measures played a critical role for the changes in precipitation-runoff-sediment relationships. Due to the rapid increases in the available storage of check dams in P2 and P5 and the areas of forest and grassland in P2, relationships among the precipitation, runoff and sediment has drastically changed. Decrease of the effects on sediment interception in check dams caused the sediment increased from P3 to P4. (4) Decreases of runoff and sediment load, and changes in their relationships would continue with the sustainable management of slopes and gullies. The potentially detrimental changes in the storage of check dams and those in runoff and sediment influenced by extreme weather conditions should be monitored and managed. Highlights • The annual runoff and sediment load have shown significant decreases (P < 0.05). • Human activities are the main driving factor of the changes in these relationships. • The decreasing effects of intercepting sediment led to the sediment increase in P4. • The STWY decreased because of the decreases in the ISC and runoff amount. • Changes in runoff and sediment under extreme weather should be considered. [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]

Highlights • This study analyzed the intensive fluctuations of runoff and sediment load at the upper Yellow River, which has not yet been studied clearly before. • Temporal variations in runoff and sediment load were discerned in terms of changing trend, abrupt change year, and multi-periods from the full measured datasets of all hydrological stations. • Impact of human activities on the hydrological variations was evaluated based on comparison of the measured and the reconstructed time series. Abstract Operations of amount of large and medium reservoirs have remarkably changed runoff and sediment loads, and consequently affected the fluvial processes intensively on the upper Yellow River. In this study, time series of runoff and sediment transport rates of four major hydrological stations on the upper Yellow River were used to analyze temporal and spatial variations of runoff and sediment loads. Mann-Kendall test and wavelet analysis were applied to analyze the datasets. Temporal variations in runoff and sediment loads were discerned in terms of changing trend, abrupt change year, and multi-periods from the time series. Additionally, a time series of runoffs was reconstructed based on a modeling scenario removing impact of reservoir impoundment and water diversion to indicate the status without human disturbances. Comparison of the measured and reconstructed datasets was conducted to evaluate the impact of reservoir impoundment and water diversion on hydrological variations. The measured runoff and sediment loads showed obvious decreasing trends due to impoundment and water diversion. However, the reconstructed runoffs regarded as only affected by climate change showed no significant changing trend at a 95% confidence level, confirming that, instead of climate change, human activities played the most important roles in variations. The measured datasets indicated that the reservoir construction and operation caused an abrupt change in runoff in 1986, while the reconstructed datasets indicated another abrupt change in 1995. Wavelet transform analysis distinguished the multi-periodical features of the time series. The first, second, and third dominant periodicities of the measured runoffs were 25–27, 16, and 8 years, respectively, whereas the first three dominant periodicities of the reconstructed runoffs were 26–31, 12, and 7 years, respectively. It was indicated that the high-frequency periodicities of runoffs decreased while the low-frequency periodicities increased, owing to reservoir impoundment and water diversion. [ABSTRACT FROM AUTHOR]

Prescribed fire is a common management practice in Mediterranean region to reduce the amount of fuel and to decrease the wildfire risk. The objective of this study is to assess the effect of a prescribed fire on some soil properties, hydrological response and vegetation recovery in experimental plots 5 years after. The results showed that: i) with the exception of electrical conductivity, the prescribed fire did not affect the analyzed soil properties, and ii) overland flow and sediment transport were increased during the first two years, returning to levels pre-fire, 5 years post-fire. The rainfall threshold for overland flow generation was lower during the following months after the prescribed fire owing to the depletion of the vegetation cover. Immediately after the fire, the vegetation cover was of 1.9%, being the three main soil surface components that dominated the hydrological response: charcoal and decayed wood; blackish and greyish ash, and bare soil. However, these areas decreased very rapidly during the second year following the fire, principally, owing to the regrowth of herbaceous plants and shrubs. In addition, the vegetation cover in burned plots was 16.1% higher than that measured in the unburned ones. Overall, the prescribed fire only had an impact on runoff and sediment transport in the two years post-fire, as consequence of vegetation removal. [ABSTRACT FROM AUTHOR]

Sediment is a major source of non-point pollution. Suspended sediment can transport nutrients, toxicants and pesticides, and can contribute to eutrophication of rivers and lakes. Modeling suspended sediment in rivers is of particular importance in the field of environmental science and engineering. However, understanding and quantifying nonlinear interactions between river discharge and sediment dynamics has always been a challenge. In this paper, we introduce a parsimonious probabilistic model to describe the relationship between Suspended Sediment Load (SSL) and discharge volume. This model, rooted in multivariate probability theory and Bayesian Network, infers conditional marginal distribution of SSL for a given discharge level. The proposed framework relaxes the need for detailed information about the physical characteristics of the watershed, climatic forcings, and the nature of rainfall-runoff transformation, by drawing samples from the probability distribution functions (PDFs) of the underlying process (here, discharge and SSL data). Discharge and SSL PDFs can be simplified into a joint distribution that describes the relationship between SSL and discharge, in which the latter acts as a proxy for different predictors of SSL. The joint distribution is created based on historical discharge and SSL data, and stores information about the discharge-SSL relationship and sediment transport process of the watershed of interest. We test this framework for seven major rivers in the U.S., results of which show promising performance to predict SSL and its likelihood given different discharge levels. [ABSTRACT FROM AUTHOR]

Soil and water loss from farmland causes land degradation and water pollution, thus continued efforts are needed to establish mathematical model for quantitative analysis of relevant processes and mechanisms. In this study, an approximate analytical solution has been developed for overland flow model and sediment transport model, offering a simple and effective means to predict overland flow and erosion under natural rainfall conditions. In the overland flow model, the flow regime was considered to be transitional with the value of parameter β (in the kinematic wave model) approximately two. The change rate of unit discharge with distance was assumed to be constant and equal to the runoff rate at the outlet of the plane. The excess rainfall was considered to be constant under uniform rainfall conditions. The overland flow model developed can be further applied to natural rainfall conditions by treating excess rainfall intensity as constant over a small time interval. For the sediment model, the recommended values of the runoff erosion calibration constant ( c r ) and the splash erosion calibration constant ( c f ) have been given in this study so that it is easier to use the model. These recommended values are 0.15 and 0.12, respectively. Comparisons with observed results were carried out to validate the proposed analytical solution. The results showed that the approximate analytical solution developed in this paper closely matches the observed data, thus providing an alternative method of predicting runoff generation and sediment yield, and offering a more convenient method of analyzing the quantitative relationships between variables. Furthermore, the model developed in this study can be used as a theoretical basis for developing runoff and erosion control methods. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are being used in many products as they have unique antimicrobial-biocidal properties. After disposal of these products AgNPs can reach the soil environment possibly affecting soil organisms and disrupting plants. This work aimed to study the transport of AgNPs by water and sediment during overland flow and soil erosion. This was done in a laboratory setting, using a flume and rainfall simulator. A low concentration of AgNPs (50 μg·kg − 1 ) was applied to two soil-flumes with slope percentages of 20% and 10%. The rainfall was applied in four events of 15 min each with a total amount of rainfall of 15 mm during each event. After applying the rainfall, samples of the non-transported background soil (BS) and the transported sediment (Sf) were collected from the flume surface. Runoff sediment (RS) and water (RW) were collected from the outlet. AgNPs were detected in all samples collected. However, concentration varied according to sample type (soil or water), time of collection (for runoff water and sediment) and the slope of the soil flume. Higher concentrations of AgNPs in soil were detected in the BS than in the Sf likely due to the BS having more fine particles (silt and clay). The AgNPs concentration in the runoff sediments increased with subsequent applied rain events. In addition, increasing the slope of the flume from 10% to 20% increased the total AgNPs transported with the runoff sediment by a factor 1.5. The study confirms that AgNPs can be transported by both overland flow and sediment due to erosion. [ABSTRACT FROM AUTHOR]

Runoff and sediment yield in semi-arid catchments are highly influenced by infrequent but very heavy rains. These events occur over short temporal scales, so runoff and sediment transport can only be understood using an event-based analysis. We applied a hydrological and soil-erosion model, LISEM, to the Gule catchment (~ 12 km 2 ) in northern Ethiopia. The objectives of the study were: (a) to evaluate the performance of LISEM in describing event-based hydrological processes and sediment yield in a catchment under the influence of different water harvesting techniques (WHTs), and (b) to study the effect of the WHTs on catchment-scale event-based runoff and sediment yield. The model performed satisfactorily (NSE > 0.5) for most of the events when discharge was calibrated at the main outlet (Gule) and at a sub-outlet (Misbar). Runoff coefficients for the Gule catchment and Misbar sub-catchment were expectedly low due to the implementation of WHTs, which can store runoff from the rains and increase infiltration into the soil. Simulated and measured sediment yields were of similar orders of magnitude. LISEM generally overestimated sediment yield compared to the measurements. The poor performance of LISEM in predicting sediment yield could be attributed to the uncertainty of several factors controlling soil erosion and the inadequacy of LISEM in describing soil erosion on steep slopes. Catchment-scale model simulations indicated that runoff and sediment yield could be effectively reduced by implementing WHTs. The model estimated 41 and 61% reductions in runoff and sediment yield at the Gule outlet, respectively. Similarly, runoff and sediment yield at the Misbar sub-outlet were reduced by 45 and 48%, respectively. LISEM can thus be used to simulate the effects of different existing or new WHTs on catchment hydrology and sediment yield. The results of scenario predictions could be useful for land-use planners who intend to implement different measures of catchment management. [ABSTRACT FROM AUTHOR]

• Physically based 2D hydrodynamic and sediment transport model, CCHE2D. • High resolution mesh, topography photogrammetry, experimental landform evolution. • Watershed hydrology, raindrop soil detachment, displacement, erosion and transport. • Distributed solution, tilled watershed, cornfield tillage ridge and furrow morphology. • Simulated runoff, sediment transport, landform evolution; channel network analysis. Soil and gully erosion is a critical threat to sustainable agricultural land management and productivity. Soil erosion by rain splash, sheet runoff, and concentrated flow are complex problems conditioned by the combined interactions of soil physical properties, hydrology, human activity, landscape topography, and climate. Effective management of erosion processes driven by rainfall and surface runoff requires a combined effort of field observation, physical experimentation, and numerical simulation. A physically-based hydrodynamic numerical model, CCHE2D with updated raindrop erosion effects, is applied to simulate landscape evolution processes as a result of raindrop impact and overland flow. The numerical model simulates a thin layer of runoff and concentrated flow over complex terrains, and predicts sediment transport due to raindrop splash detachment, transport and soil surface erosions. Soil erosion and landform evolution simulations due to rainfall are presented for an experimental landscape and a tilled large scale agricultural field. Photogrammetric field data were collected using an unmanned aerial system (UAS) following planting and subsequent rainstorms. Numerical simulation results agreed well with the observed experimental soil surface topography, sediment yield, and drainage network developments. The simulated soil and gully erosion in the tilled field also agreed well with observations. This research successfully demonstrates how high resolution spatial and temporal topographic measurements in experimental and field landscapes can be simulated and interrogated by 2D physically-based hydrodynamic and morphodynamic models. The accurate predictions of tillage field and gully erosion process in agriculture watersheds with complex tillage conditions also indicated the usefulness of the model for studying soil and landscape degradation. [ABSTRACT FROM AUTHOR]

• Factors contribution to runoff, sediment in different seasons and spatial scales. • Contribution of precipitation and underlying surface to runoff and sediment. • Assess the group relationships between different types of influencing factors. The changes in runoff and sediment are the most active parts of river systems. Identifying the effect of precipitation, vegetation coverage (VC), landscape metrics, land-use and land-cover changes (LUCC) on runoff and sediment variations is essential for understanding hydrological processes and the environmental evolution mechanisms of watersheds. This study selected four watersheds located in the Qinling Mountains in China to quantify the effects of different driving forces on runoff and sediment variations at different scales. The results showed that VC increased significantly in the study watersheds (p < 0.05) by more than 16 % since 1990. Obvious increases in forest area were the main features of land use change after 2000. The annual sediment transport and sediment concentration in the wet season showed downward trends. The change of underlying surface contributed more than 58 % to reductions in runoff and sediment concentration in controlled watersheds in Xiangjiaping and Jingziguan. The factors influencing runoff and sediment variations displayed obvious spatial and temporal differences. The 2000 m buffer scale could better explain the runoff and sediment variations than other spatial scales. Rainfall and VC were the main factors affecting runoff and sediment variations at different spatial scales during the wet season, while the aggregation index at the watershed-scale and VC were the main influencing factors in the dry season. Moreover, the intersections between precipitation and landscape pattern, between precipitation and LUCC & VC, and between landscape pattern and LUCC & VC in the dry season and wet season were −31.9 %, −27.6 %, −29.0 % and −18.7 %, −11.1 % and −2.3 %, respectively. Therefore, multi-scale differences in the impact of driving factors and the group relationships between measures should be considered for effective runoff and sediment regulation. [ABSTRACT FROM AUTHOR]

The Gulf of Alaska is a biologically productive ocean region surrounded by coastal mountains with high seasonal runoff from rivers and glaciers. In this complex environment, we measured the concentrations and size distributions of 2.5 µm–27 mm marine particles using the Laser in situ Scattering and Transmissometry device (LISST-DEEP) and the Underwater Vision Profiler 5 (UVP) during summer 2015. We analyzed the spatial distribution of particles across a wide range of size classes to determine the probable drivers. Spatially, total particle concentrations surpassed 1000 µl/l nearshore in the northeasternmost entrances and in the outflow of Cook Inlet, as well as offshore past the shelf break. These dual maxima suggest high lithogenic inputs nearshore and high biological production at and beyond the shelf break. Most large particles (> 0.5 mm) imaged by the UVP were detrital aggregates. In nearshore surface waters near river inputs, size distributions revealed small size classes (< 100 µm) to be most influential. At the shelf break, size distributions revealed a dual peak in both small (< 100 µm) and very large (> 2 mm) size classes. This study highlights the importance of lithogenic inputs from a mountainous margin to the coastal ocean and their potential to enhance sinking of biological material produced at the shelf break. [ABSTRACT FROM AUTHOR]

This study uses magnetic measurements to evaluate the heavy metal contamination of the surface sediments on Shilaoren Beach. The values of the laboratory magnetic measurements have a positive relationship with the concentrations of Fe, Mn, Cr, Ni, As and Pb. The field magnetic parameter provides an effective and rapid method for evaluating the distribution and dispersal of heavy metal. Sediments with higher heavy metal contents generally accumulate near higher and lower tide lines on the beach, reflecting the control of waves and tides. The sewage and stormwater outlets are the primary sources of the heavy metal contamination. Variations in seasonal waves and winds affect the sediment transport and the heavy metal distribution patterns. Based on the Australian ISQG-Low sediment quality criteria, Fe, Mn and Cr generally exhibit intermediate accumulation levels, whereas Pb and Zn exhibit higher accumulation levels because of the socioeconomic status of the area surrounding the beach. [ABSTRACT FROM AUTHOR]

High resolution water quality data has recently become widely available from numerous catchment based monitoring schemes. However, the models that can reproduce time series of concentrations or fluxes have not kept pace with the advances in monitoring data. Model performance at predicting phosphorus (P) and sediment concentrations has frequently been poor with models not fit for purpose except for predicting annual losses. Here, the data from the Eden Demonstration Test Catchments (DTC) project have been used to calibrate the Catchment Runoff Attenuation Flux Tool (CRAFT), a new, parsimonious model developed with the aim of modelling both the generation and attenuation of nutrients and sediments in small to medium sized catchments. The CRAFT has the ability to run on an hourly timestep and can calculate the mass of sediments and nutrients transported by three flow pathways representing rapid surface runoff, fast subsurface drainage and slow groundwater flow (baseflow). The attenuation feature of the model is introduced here; this enables surface runoff and contaminants transported via this pathway to be delayed in reaching the catchment outlet. It was used to investigate some hypotheses of nutrient and sediment transport in the Newby Beck Catchment (NBC) Model performance was assessed using a suite of metrics including visual best fit and the Nash-Sutcliffe efficiency. It was found that this approach for water quality models may be the best assessment method as opposed to using a single metric. Furthermore, it was found that, when the aim of the simulations was to reproduce the time series of total P (TP) or total reactive P (TRP) to get the best visual fit, that attenuation was required. The model will be used in the future to explore the impacts on water quality of different mitigation options in the catchment; these will include attenuation of surface runoff. [ABSTRACT FROM AUTHOR]

The impact of storm events on the sediment dynamics of the shallow groundwater fed estuaries of Cape Cod, Massachusetts, USA is little understood. To address this, the objectives of this study are to assess sediment dynamics during storm passage and determine whether shallow back-barrier lagoons like Waquoit Bay have the preservation potential for a sedimentary archive of hurricanes. When setting out in this study, it was unclear whether paleotempestological methods could be applied successfully to cores collected from the landward reaches of shallow estuaries of southern New England. Water level and bottom current data using Arm-and-Float tide gauges and SeaHorse Tilt Current Meters was collected during Tropical Storm Irene (2011) and coupled with storm surge modeling projections to better elucidate storm-induced sediment transport mechanisms. Three sediment cores were collected at the head of Waquoit Bay, located 2.8 km from the barrier beach. Grain size analysis of sediment cores was conducted with a laser particle size analyzer at 1 cm increments in order to identify coarse grain anomalies, which can act as a storm event proxy. Bayesian statistics were applied to develop age models of two of the cores based on three Pb pollution chronomarkers and 21 continuous flow 14 C AMS ages. The results yield variable sediment accumulation rates between 2 mm/yr to 10 mm/yr, with significantly higher rates occurring in the upper 1 m of sediments. Grain size results are highly variable, and contain numerous large amplitude, short duration fluctuations suggesting that during storm passage coarse sand is deposited in the coring site. The sensitivity of the site to both tropical and extratropical storm events, uncertainties in the age model, and the multiple sediment sources and transport pathways limits the utility of using the Waquoit sediments to determine long-term hurricane frequencies. Results nonetheless provide insights into how extreme storm events impact coastal lagoons. [ABSTRACT FROM AUTHOR]

• Linkage between soil surface microrelief and overland flow was examined. • Differently oriented wheel tracks served as water flow paths or as sediment sinks. • Increase of surface connectivity after a rain was shown by functional connectivity. • Structural connectivity showed reorganization of the surface runoff pathways. Although wheel tracks cover only a small portion of the surface of agricultural fields, their effect on surface runoff and sediment transport is substantial. Wheel tracks change the microrelief of the soil surface, and influence how the surface is further altered by rainfall and runoff. This study presents a plot-scale microrelief analysis of a tilled surface with wheel tracks under simulated rainfall. Digital elevation models of the microrelief with 1 cm spatial resolution were obtained using the Structure from Motion method. The random roughness, the structural connectivity, and functional connectivity were calculated for before-rainfall and after-rainfall soil surface conditions. The experiments were carried out on inclined, freshly-tilled plots (8 m long, 2 m wide). The wheel tracks were created by four passages of machinery in the slope direction (SWT) and in the contour-line direction (CWT). The experiments were compared to reference plots without wheel tracks (NWT). The wheel tracks increase water and sediment connectivity if they are oriented in slope-wise direction. Microrelief analysis shows that SWT drains water from the surrounding soil. The soil surface adjacent to SWT can also become more connected with the wheel track, due to changes in microrelief introduced by rainfall and runoff. The calculated higher connectivity in the SWT plot corresponded to the measured increased sediment loads. This suggests faster overland flow and therefore shorter flow pathways on the soil surface microrelief. CWT leads to a decrease in the water and sediment connectivity compared to the NWT and SWT plots. Although the surface runoff can overflow the CWT, the network of flow paths results in decreased flow velocity and a slower sediment transport rate. However, the CWT effect is not permanent, and declines as the wheel tracks become silted with the deposited sediment. It is shown that detailed microrelief data provide relevant information for a study of the changes in flow routing in a tilled agricultural field with the presence of a wheel track. SWT accelerates the runoff and especially the sediment transport. During a rainfall event, the hydraulic connection between the wheel track and the surrounding soil increases dramatically. CWT reduces the surface runoff and also the sediment transport. In the long term, rainfall events and surface runoff alter the microrelief connectivity, causing the soil surface to be more hydraulically connected, irrespective of the wheel track orientation. This study demonstrates the effect of wheel tracks on water and sediment transport. The results draw attention to the importance of appropriate soil protection measures, as a bare unprotected surface microrelief exposed to rainfall leads to increased sediment connectivity. [ABSTRACT FROM AUTHOR]

In this study, we quantified spatial patterns of sediment dynamics in a watershed of 311 km 2 over an extreme storm event using watershed modeling and statistical analyses. First, we calibrated a watershed model, Dynamic Watershed Simulation Model (DWSM) by comparing the predicted with calculated hydrograph and sedigraph at the outlet for this event. Then we predicted values of event runoff volume ( V ), peak flow ( Q peak ), and two types of event sediment yields for lumped morphological units that contain 42 overland elements and 21 channel segments within the study watershed. Two overland elements and the connected channel segment form a first-order subwatershed, several of which constitute a larger nested subwatershed. Next we examined (i) the relationships between these variables and area ( A ), precipitation ( P ), mean slope ( S ), soil erodibility factor, and percent of crop and pasture lands for all overland elements (i.e., the small spatial scale, SSS), and (ii) those between sediment yield, Q peak , A , P , and event runoff depth ( h ) for the first-order and nested subwatersheds along two main creeks of the study watershed (i.e., the larger spatial scales, LSS). We found that at the SSS, sediment yield was nonlinearly well related to A and P , but not Q peak and h ; whereas at the LSS, linear relationships between sediment yield and Q peak existed, so did the Q peak – A , and Q peak – P relationships. This linearity suggests the increased connectivity from the SSS to LSS, which was caused by ignorance of channel processes within overland elements. It also implies that sediment was transported at capacity during the extreme event. So controlling sediment supply from the most erodible overland elements may not efficiently reduce the downstream sediment load. [ABSTRACT FROM AUTHOR]

The relation between rainfall, runoff, erosion and sediment transport is highly variable in Mediterranean catchments. Their relation can be modified by land use changes and climate oscillations that, ultimately, will control water and sediment yields. This paper analyses rainfall, runoff and sediment transport relations in a meso-scale Mediterranean mountain catchment, the Ribera Salada (NE Iberian Peninsula). A total of 73 floods recorded between November 2005 and November 2008 at the Inglabaga Sediment Transport Station (114.5 km 2 ) have been analysed. Suspended sediment transport and flow discharge were measured continuously. Rainfall data was obtained by means of direct rain gauges and daily rainfall reconstructions from radar information. Results indicate that the annual sediment yield (2.3 t km − 1 y − 1 on average) and the flood-based runoff coefficients (4.1% on average) are low. The Ribera Salada presents a low geomorphological and hydrological activity compared with other Mediterranean mountain catchments. Pearson correlations between rainfall, runoff and sediment transport variables were obtained. The hydrological response of the catchment is controlled by the base flows. The magnitude of suspended sediment concentrations is largely correlated with flood magnitude, while sediment load is correlated with the amount of direct runoff. Multivariate analysis shows that total suspended load can be predicted by integrating rainfall and runoff variables. The total direct runoff is the variable with more weight in the equation. Finally, three main hydro-sedimentary phases within the hydrological year are defined in this catchment: (a) Winter, where the catchment produces only water and very little sediment; (b) Spring, where the majority of water and sediment is produced; and (c) Summer–Autumn, when little runoff is produced but significant amount of sediments is exported out of the catchment. Results show as land use and climate change may have an important role in modifying the cycles of water and sediment yields in Mediterranean mountain catchments. [ABSTRACT FROM AUTHOR]

• Under the action of concentrated flow, the change of surface runoff of karst gently sloping farmland is mainly controlled by the magnitude of concentrated flow. • Under the action of concentrated flow, the underground runoff of karst gentle slope farmland is significantly negatively correlated with the slope. • Concentrated flow can lead to severe soil erosion in karst gently sloping farmland. Exposed bedrock in karst areas considerably alters runoff paths causing partial runoff to converge into a concentrated flow, which is a potential source of soil erosion risk. However, research is lacking on how concentrated flow affects regional soil erosion. In this study, the surface and underground dual structure in karst areas was simulated in a steel tank. Combined with runoff plot monitoring, the runoff conversion process and erosion characteristics of gently sloping farmland in karst areas under different water discharge rates were examined through indoor concentrated flow discharge scouring tests, and the influence of concentrated flow changes on the runoff spatial distribution and sediment yield in gently sloping farmland was clarified. The results demonstrated the following: (i) there existed a significant positive correlation between surface runoff and the water discharge rate (p < 0.01); the partial correlation coefficient value reached 0.87. The higher the water discharge rate, the more surface runoff formation was facilitated. (ii) When the slope remained the same, the underground runoff was relatively high at 3 L/min. Given the same discharge, a significant negative correlation between underground runoff and slope was found (p < 0.05); the partial correlation coefficient value reached −0.71. (iii) In response to a water discharge rate of 5 L/min, surface soil erosion was serious, and the maximum sediment transport modulus was 174.088 g/min∙m2. A significant cubic function relationship existed between the scouring time and surface sediment yield. Overall, a critical flow rate occurred between 3 and 5 L/min, which controlled changes in surface runoff, subsurface runoff and surface sediment yield. Under highly concentrated flow, drastic soil erosion could occur. These results can provide a scientific basis for the control and prevention of concentrated flow-induced erosion in karst areas. [ABSTRACT FROM AUTHOR]

• SWAT hydrological model has high potential in the assessment of watershed changes. • Land use changes caused by forest fires affect hydrological response of watershed. • Significant increase in surface runoff and sediment load in the post-fire scenario. • Sediment yield increased by 6.5 times with the highest fire spatial distribution. • Forest fire scenarios help to limit hydrological impacts of fire on sediment load. Forest fires profoundly affect the nature of watershed responses to precipitation, increases in runoff rate and volume, and post-fire sediment discharge. A post-fire watershed assessment to identify potential trouble spots for soil erosion and flooding can help land managers for decision-making on deploy mitigation, remediation measures, and restoration action plans. Predicting the potential impact of fires on runoff and soil erosion requires distributed hydrological modeling methods. This study used the Soil and Water Assessment Tool (SWAT), a rainfall-runoff model, to investigate the hydrological consequences of forest fires and their impact on sediment load under different burnt scenarios. For the pre-fire (baseline) scenario, the watershed is calibrated by using the measured discharge and suspended sediment concentration data from the weather station during the time step to estimate post-fire changes at the sub-catchment scale. The total water and sediment yield for the selected sub-catchment in the post-fire scenario with the highest spatial distribution of forest fire, due to the excessive surface runoff (an increase of 14.5%) increased significantly, resulted in 6.5 times increase in sediment yield. The results obtained from the study indicate a significant increase in sediment transport into the stream in the post-fire scenario. A large volume of soil losses occurred during the time step. In contrast, due to removing trees and vegetation from the ground, less evapotranspiration and infiltration occurred in selected sub-catchment areas after forest fires. In terms of watershed management, understanding the consequences of forest fires on hydrological services will be an effective method for sediment budget control. Therefore, applying the rainfall-runoff and erosion models for the watershed with developing plausible forest fire scenarios can be a productive method to deal with the threats and hydrological risks such as soil erosion and sediment transfer to the downstream environment. [ABSTRACT FROM AUTHOR]

Integrated constructed wetlands (ICWs) were implemented to reduce nutrient and sediment transport from a confined-animal dairy operation in East Tennessee. The objectives of this study were to (1) characterize first flush concentrations of potential pollutants from a typical confined animal dairy operation, and (2) determine if two ICWs have acted as hydrologic and physicochemical buffers in agricultural drainages during the establishment phase (first year after construction). Nine events between the two ICWs were sampled within the first year of construction and flow rates were continuously measured at the inlets and outlets. First flush sampling showed that phosphorus concentrations exceeded critical levels in six of the eight sampled events and nitrogen concentrations exceeded critical levels in half of the sampled events. Suspended solids, organic carbon, and phosphate were the most commonly detected pollutants of concern carried by runoff leaving the dairy operation. The documented performance of ICWs indicated that the practices generally reduced sediment and nutrient concentrations in runoff flowing to receiving waterways during wet weather conditions during the first year following construction and acted to buffer hydrologic pulses by reducing peak flow rates. In four sampled storm events spanning the time of late summer through winter, a total of over 2200 kg of suspended solids and 0.22 kg of nitrogen were retained in one ICW. Organic carbon was exported from the ICW practices during most events. Overall, the practice removed significant amounts of suspended solids and nitrogen, and event-based phosphorus. [ABSTRACT FROM AUTHOR]

The effects arising from the inordinate use of the coastal zone are unfolding in a reduction or even elimination of the foredune systems. Therefore, rehabilitation programs of these systems are currently one of the priorities of the coastal managers. The proposal of this study is to assest the efficiency of the recuperation techniques of the foredune system, having as a starting point the performance of a stormwater runoff piping installation. The first stage of this work evaluated the methods utilized for the dune system recuperation through digital terrain models and the sediment volume variations in three distinct periods, discussing the unanticipated alterations due to the interventions performed. The second part established a correlation between the actual accumulation of sediments and the calculation of the potential aeolian sand transport, with the aim of choosing the empirical equation that best fits the aeolian sand transport in the Rio Grande do Sul State coast. The results obtained show the efficiency of Northeast and East-Northeast winds in the transport of sediments towards the foredunes, resulting, thus, in success in the dunes reconstruction. The alterations in the system by the interventions realized evidence the necessity for constant adaptation of the dunes recuperation project in function of the system responses. The equation of Bagnold (1941) is the most accurated to predict the potential aeolian sand transport to the study area. [ABSTRACT FROM AUTHOR]

Summary River dynamics in cold regions and the physical processes involving ice formation and release remain relatively understudied topics. Current research suggests that anchor ice forms in diurnal cycles and has the potential to move sediments when released from the bed. Given the importance of river ice dynamics, studies are needed to describe the physical processes of anchor ice and its impact on sediment transport. The study presented in this paper investigated in situ anchor ice formation on the Stoke River in Quebec, Canada. In the fall of 2012, we observed multi-day anchor ice formation cycles and release, which usually ended with a small runoff event. During a cycle, there was little or no release of anchor ice, thus allowing its gradual growth as the air temperature remained cold. Surface and anchor ice layers also often merged, leading to the formation of thick ice masses. Sediment transport was monitored using bed particles individually tagged with passive integrated transponders (PIT-tags). Movement of the experimental particles, measured after each multi-day cycle event, ranged from 0.5 to 4 m. Possible transport mechanisms include: (1) anchor ice rafting, (2) ice jam breakup creating a jave with high erosive capacity, (3) flow corridors through anchor ice masses with high erosive capacity, (4) mechanical pushing of particles by drifting ice blocks during ice breakup, and (5) entrainment by flow or drifting ice blocks of anchored ice with strong ice-pebble bonds. Given the coincidental occurrence of anchor ice release and runoff events, it is uncertain which specific mechanism caused the particles to move. This study is a step forward in understanding the behavior of anchor ice processes and ice-related sediment transport. [ABSTRACT FROM AUTHOR]

Surface runoff, channel activation and sediment transport processes in desert environments have been convincingly shown to strongly depend on the duration and intensity of local and convective rainfall events. Among these environments, the Atacama, considered the driest desert on Earth, is situated in a remote and rugged area, where documentation of historical and recent hydro-sedimentary processes is rare. We characterize the hydrological processes in an endorheic watershed of the Atacama's Altiplano Desert, where the occurrence of flash floods was evaluated on event-based signatures of water and sediment in a small ephemeral playa. Twelve pits were dug in the playa, with five identified event sediment couplets, each corresponding to computed flood volumes that gave rise to transport and depositional events occurring between 1978 and 2019. Detailed topography allowed reconstruction of a 3D terrain model, from which we estimated a 11.3 t/yr/km2 local historic sediment yield. The timing of the older identified events did not match local rainfall records, and proved to be uncorrelated with occurrences of El Niño–Southern Oscillation (ENSO). This suggests a high spatial patchiness of rainfall events in terms of depth and intensity, and implies that small playa records are not necessarily always helpful in reconstructing the regional climatic history of the recent past. The sediment concentration and volume of the reconstructed hypercontracted events are not well corrected with the magnitude of the rainfall event, suggesting the important role played by variable sediment availability and connectivity at basin scale. This spatiotemporal variability plays a major role in understanding the present and historic hydro-sedimentary processes in the Atacama's altiplano. [Display omitted] • Five recent sediment-laden flood events have been identified in sedimentary records in a playa in the Atacama Desert. • Events are not directly related to ENSO episodes nor to regional climatic events. • Sediment concentration does not correlate with the magnitude of the rainfall event. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shrub removal caused changes on water and sediment yields. • It increased base flow and decreased the length of the no-flow period. • Sediment production shifted from agricultural fields to treated forested area. • Overall sediment yield increased in the catchment outlet. • Dissolved yield was greater than suspended yield. Shrub removal works in the Gavarres massif (NE Spain) have impacted runoff and sediment transport in a first-order experimental catchment (2.5 km2), named Vernegà. These works have consisted in removing the shrub layer that grows under a typical mixture of cork oak tree and Mediterranean pine forest, and have been undertaken regularly since 2002 to reduce risk of forest fire and increase cork oak productivity. In 2005, the works affected the catchment headwaters, resulting in significant changes in runoff and sediment transport rates. This study aimed to assess short-term changes in runoff and sediment transport rates in the experimental catchment by comparing them to rates prior to 2005. Measurements were made at two monitoring stations within the basin: i) Bosc (1.6 km2), where the main land use is forest; and ii) Campàs (2.5 km2), the catchment outlet, where the main land use is agriculture. Mean annual runoff increased from 11.7 mm before 2005 to 33.1 mm after 2005 at the Bosc station. At the Campàs station, runoff increased from 81.9 mm to 92.2 mm. These changes can be observed in the flow duration curves of both stations. An increase on the frequency when low flows (<5 l/s) take place has been observed, while the occurrence of high flows remains unchanged. The low flow increase period had a concomitant reduction of the no flow period, which reduced about 30 days in Bosc station. Suspended sediment yield increased from 250 kg·km−2·yr−1 at Bosc and 430 kg·km−2·yr−1 at Campàs to 940 kg·km−2·yr−1 and 4,350 kg·km−2·yr−1 respectively after forest works. Dissolved sediment yield also increased but did so solely as a result of the increase in runoff rates rather than of the increase in dissolved concentrations. [ABSTRACT FROM AUTHOR]

Abstract: By altering the physical and chemical properties of a landscape, fire may increase its vulnerability to erosive processes. Whereas sediment transport by surface runoff after fires has been often investigated, less is known about the role of wind erosion in burned terrain. To examine how fire might increase a soil's vulnerability to aeolian transport, intact soil samples were collected from a chaparral landscape in southern California and heated with a propane torch with temperatures ranging from 250 to 1025°C and for durations of 5–60min to simulate a variety of burn severities. The samples were then subjected to simulated wind and the amounts of eroded sediment were measured. Results indicate a linear increase in the production of wind-erodible sediment with applied heat up to ~10MJ/m2. The increase was not due to a reduction in the threshold shear velocity of the soil surface but, instead, to the role of heat in detaching erodible material. In these soils, organic material may be an important binding agent destroyed at high temperatures. The relationship between fire and erodibility is complex, however, because heating may also help to aggregate soil particles. Experiments performed here also suggest a synergistic effect between fire and rain whereby heated soils are more vulnerable to the erosive power of raindrop impacts. Additionally, the soil heating experiments were used to measure and compare the thermal conductivities of intact and disturbed soils. Finally, it is concluded that soil heating may increase the emission of dust through the detachment of erodible particles, a result that may help in the anticipation of respiratory problems for those living downwind of burned areas. [Copyright &y& Elsevier]

Highlights: [•] Sediment particles were trapped by grassed filter strip. [•] Synthetic stormwater runoff was made from construction site. [•] The empirical equations were developed from experimental data. [•] The use of the equations can predict the efficiency of sediment traps. [•] New approaches have been proposed to investigate flow and sediment transport. [ABSTRACT FROM AUTHOR]

Earthworms are ecological engineers that play an important role in hydrological processes and soil erosion by their burrowing and casting activities. Little is known, however, about the ecological function of the activities of an anecic species (Metaphire guillelmi) from the Loess Plateau in China where the soil is severely eroded. We conducted rain-simulation experiments on artificial slopes (mesocosms) filled with soil from Loess Plateau. Two rain intensities (90 and 120 mm h−1) and slope gradients (5° and 15°) were used to investigate the influences of earthworm activity on runoff and soil loss under multiple conditions. Data from 15 d of earthworm activity and 1 h of rain indicated that earthworm activity significantly reduced runoff but aggravated soil erosion. Runoff initiation time increased 2.7–3.1-fold, contributing to the promotion of water infiltration, and the amounts and rates of runoff were 35.8–61.6% and 35.1–60.8% lower under earthworm activity than the controls, respectively. Earthworms greatly influenced the physical and chemical properties of the soil, and these properties were strongly correlated with runoff initiation time and cumulative runoff. The surface casts produced by the earthworms on the soil surface were completely dispersed, increasing the cumulative sediment by a maximum of 169%. Both rain intensity and slope gradient greatly influence runoff and soil detachment, but with earthworm activity, slope gradient was more influential due to its superior contribution to sediment transport. This study quantified the effects of M. guillelmi on runoff and soil erosion and provides basic data for developing a more integrated control of soil erosion on the Loess Plateau. • The increase in infiltration related to earthworm activities decreases runoff. • Soil erosion is aggravated by the low stability of surface cast under intense rainfall. • Earthworm impact on soil loss is larger at lower rain intensity and steeper slope. [ABSTRACT FROM AUTHOR]

• Flow/sediment routing strongly controlled by interactions with landscape elements. • Despite this, observed routes replicated using only DEM and steepest-descent model. • But other attributes of flow, controlled by landscape elements, not well simulated. • Therefore models need explicit representation of interaction with landscape elements. • Inadequate representation explains findings of previous model validation studies. Field-to-river flow of runoff and sediment in a lowland arable catchment in the south of England is explored from both field and modelling perspectives. Routes observed to be taken by flow and sediment on five study areas include many interactions between flow and 'landscape elements' (LEs), including those (field boundaries, paths, roads) of anthropogenic origin. We were able to satisfactorily replicate observed flow routes using a simple steepest-descent-with-overtopping model with a 5 m DEM. This was unexpected, considering the narrowness of linear LEs such as paths and tracks. However LE attributes showed considerable sensitivity: changing just one attribute of a single FE-flow interaction notably altered the route taken by simulated flow, while changing LE attributes notably affected synthetic hydrographs for flow reaching the river, suggesting similar impacts upon transported sediment reaching the river. Thus while simple steepest-descent and overtopping permits satisfactory replication of observed flow routes, it is likely that more explicit representation of LE-flow interactions is necessary in order to adequately capture the dynamics of field-to-river runoff and sediment transport, as must be done by catchment-scale erosion models. This will enable such models to better represent runoff speed and volume, and the flux and size distribution of transported sediment, with the aim of overcoming some broad limitations of such models as noted in earlier model validation studies. Finally, we consider the representation of some LE-flow interactions in several catchment-scale models, and discuss the ways in which such representation might be improved. [ABSTRACT FROM AUTHOR]

• This paper presents new data on the intensity fluctuations in natural rainfall. • Literature review demonstrates the importance of intensity profile to rainfall simulation research. • The origin and landsurface process relevance of intensity profile are reviewed. • Recommendations are suggested that could enhance the utility of rainfall simulation research. The temporal sequence of fluctuating rainfall intensities during an event - the intensity profile or 'rainfall pattern' - is known to affect water partitioning at the ground surface and associated erosional processes. There can be large differences in runoff ratios and runoff rates between early-peak and late-peak events, and hence in the depth, speed, and sediment transport capacity of resulting overland flow. Whilst rainfall intensity may fluctuate continually during all IPs in natural rainfall, there is little information on the rates of such intensity fluctuations that can be used to guide the design of rainfall simulation experiments. This review analyses relevant data derived from published high-resolution rainfall records and also from new analyses of data from Australian ground observing stations. Both sources confirm the occurrence of rates of intensity change of greater than 500 mm h−1 min−1. It is suggested that the fluctuating intensities characteristic of natural rainfall need to be employed in rainfall simulation experiments in order to generate results applicable to natural landsurface processes like infiltration or soil removal. Constant-intensity rain, as commonly used in rainfall simulation experiments, lacks both the kinds of rapid intensity fluctuations seen in natural rainfall, as well as any representation of natural intensity profiles. These unrepresentative conditions can result in lower runoff rates and larger proportions of infiltration than when intensity fluctuations are present. There is thus a strong case for changing the design of rainfall simulation to reflect more closely natural intensity fluctuations and intensity profiles and their influence on key surface processes such as overland flow and soil erosion. [ABSTRACT FROM AUTHOR]

Abstract: Different hydraulic parameters, including the hydraulic shear stress, unit length shear force, steam power, unit steam power, and effective stream power were used to quantify flow detachment. Most former studies were conducted for flow detachment under uniform slope surface conditions, while a few studies compared different slope surface conditions. The uniform bare loess was prepared in laboratory experiments. Natural fallowed soil loess with stone covers was prepared in field experiments. The objective of this study was to assess the differences in hydraulic parameters and sediment detachment under these different soil surface conditions. Our results show that the unit sediment load (Rs ) has a good linear relationship with the unit runoff rate (Rr ) for the flume and field experiments, and the relationship can be expressed as the function: Rs =0.262Rr −0.802 (R 2 =0.947). The rate of Manning roughness coefficient to mean flow depth (n/h) is a good hydraulic indicator like as the stream power and Reynolds number for predicting the sediment load. Hydraulic parameters n/h, Re, and ω are good indicators for the unit area sediment load for both the flume and field experiments, while Fr, f, and τ are good indicators for the unit area sediment load only when the flume experiments and field experiments are individually analyzed. Among the three good indicators (ω, Re , and n/h), n/h is better than the other two for predicting sediment load in rill erosion for both flume and field experiments, as well as for the unit solute transport rate (MBr ). The parameter of n/h probably is not only a good hydraulic parameter as an indicator for both sediment and solute transport, but also a good hydraulic parameter which link with runoff energies. The parameter n/h represents the flow wave of runoff and is an important factor to represent the energy for water and sediment transport, and the flow wave celerity (vw ) is related to n/h by: vw =1.585(n/h)−0.527 (R 2 =0.978). [Copyright &y& Elsevier]

Summary: Under the influence of climate and human activities, fluvial systems have natural ability to make adjustments so that the river hydrology, sediment movement, and channel morphology are in dynamic equilibrium. Taking the Changjiang (Yangtze River) for example. In the early stages after the Three Gorges Dam (TGD) began operational ten years ago, the suspended sediment content (SSC) and fluxes in the middle and lower reaches of the river decreased noticeably. At present, they appear to be in a stable state on the decadal scale. Although the river runoff has not shown any trends, the water level in the river decreased appreciably in time. In the meantime, channel down cutting along the thalweg almost existed throughout the river course. The riverbed has turned from depositional before the dam construction to erosional afterwards. In other words, the riverbed had turned from being sediment sinks to sediment sources. In the main channel of the Changjiang between Yichang and Nanjing, a distance of 1300km, the riverbed sedimentation mode displays strong, intermediate, and weak erosion depending on the closeness to the TGD. [ABSTRACT FROM AUTHOR]

Abstract: During runoff on soil surface, aggregates travel, abrade, and produce finer and more transportable particles, resulting in a significant effect on sediment transport, water infiltration and soil erosion. This study was to assess the effects of stability, transport distance and two hydraulic parameters on aggregate abrasion using Ultisols in subtropical China. Aggregate stability was investigated for soils from two parent materials (Shale and Quaternary red clay) with different land uses using LB methods. They were studied with a series of aggregate abrasion experiments in a 3.8m long flume with a fixed bed. Results indicated that slaking and mechanical breakdown were probably the main mechanisms of aggregate breakdown in these study soils. Two stages of aggregate abrasion process could be distinguished via the coefficient α in different transport distances. Aggregates were first rapidly abraded, became round, and was predominantly broken apart into smaller fragments, followed by weakly abrasion of smaller fragments and round aggregates, making them even light and less angular. A good multiple regression equation was obtained for estimating aggregate abrasion in overland flow with consideration of mechanical breakdown index RMI and transport distance x. From two selected Ultisols (SX3 and QX1) and under the combination of five slopes and five discharges, exponential relationships were found between aggregate abrasion and flow depth or friction factor. This research makes a good attempt at analyzing the aggregate abrasion in overland flow from simple laboratory experiments settings, and the results of the analysis could be valuable for the development of adequate soil erosion models. [Copyright &y& Elsevier]

Abstract: A rainfall simulator is an ideal tool for infiltration, soil erosion, and other related research areas for replicating the process and characteristics of natural rainfall. In this study, a laboratory-scale rainfall simulator is developed. Rainfall characteristics including the rainfall intensity and its spatial uniformity, raindrop size, raindrop velocity, and kinetic energy confirm that natural rainfall conditions are simulated with sufficient accuracy. Pressure nozzles are used to spray water corresponding to rainfall intensities ranging from 45 to 105mmh−1. The simulator produces rainfall with uniformity coefficient changing between 82 and 89%. The raindrops falling with an initial velocity from a height of 2.43m have median diameters of 2.2–3.1mm. The impact velocities of the median size raindrops deviate from their terminal velocities with a relative error between 6 and 15%. The accompanying erosion flume can be given slope up to 20% in lateral and longitudinal directions. During the experiments, flow measurement is taken from two outlets at the end of the flume to distinguish the contribution of interrill areas into rills. Experiments result in typical rainfall-induced hydrographs and sedigraphs observed under natural conditions. This shows the ability of the rainfall simulator for use in sediment transport processes over hillslopes. [Copyright &y& Elsevier]

Abstract: A combination of different process monitoring, lake sediment coring and sediment analysis methods and techniques was applied in the 17.5km2 Sætrevatnet sub-catchment in the upper Bødalen drainage basin (Nordfjord, western Norway) in order to define hydro-meteorological controls on runoff, suspended sediment transfer and sediment accumulation, and to determine the role of Lake Sætrevatnet within the drainage basin-wide sediment routing system. The proglacial system shows the typical seasonal and weather-depended runoff variations for glacierized drainage basins. Significant suspended sediment transport is associated to summer glacier melt (when 61.9% of the annual suspended sediment yield was recorded in 2010) as well as to single rainfall events (when 19.8% of the annual suspended sediment yield was recorded in 2010). The intensity of atmospheric energy input and the frequency of heavy rainfall events were found to be critical for the rate of suspended sediment transport within the Sætrevatnet sub-catchment. The computed annual suspended sediment yield from the proglacial area was 24.2tkm−2, which is notably lower as compared with a number of other glacierized basins worldwide. Delta accumulations rates from 2009 (4cmyr−1) and 2010 (3cmyr−1) as well as average annual delta advance ranging from 3.8m to 4.6m confirm the calculated high annual lake sedimentation rate of 1.7cmyr−1. Lake Sætrevatnet (0.02km2) currently traps about 80–85% of the sediments delivered from the upstream-located glacial system highlighting the importance of small ephemeral proglacial lakes within larger valley–fjord sediment routing systems. [Copyright &y& Elsevier]

Summary: The impact of rainfall characteristics on runoff generation and soil erosion are not fully understood despite their importance. In this study, a series of laboratory experiments, systematically considering different rainfall intensities, durations, moving directions, rainfall positions, and no-rainfall intervals, were conducted to investigate the impacts of rainfall characteristics on runoff generation and soil erosion. Significant differences, including hydrograph, sediment graph, soil water content, and infiltration depth (depth of wetting front), were observed. The following conclusions are drawn for the studied rainfall characteristics and soil from this study: (1) when compared with moving upstream rainfall scenarios (MURSs), moving downstream rainfall scenarios (MDRSs) can generally be characterized by hydrographs with a later rise and higher runoff peak for most of the rainfall events; (2) surface sealing changes the infiltration pattern so that MURS generally produce more total runoff than MDRS, and for some rainfall events MDRS generate lower runoff peak than MURS, which is different from what has been widely reported; (3) with the increase in the runoff peak, the erosion peak increases first and then decreases, indicating a switch from transport-limited erosion to detachment-limited erosion; (4) the increase ratio of underground water content for MURS is lower than MDRS; (5) rainfall duration is an important factor in soil crack occurrence. Not only does this study expand the understanding of hydrologic response and erosion, it also provides an important database for the hydrology community. [Copyright &y& Elsevier]

Abstract: Fine sediment supply has been identified as an important factor contributing to the initiation of runoff-generated debris flows after fire. However, despite the significance of fines for post-fire debris flow generation, no investigations have sought to quantify sources of this material in debris flow affected catchments. In this study, we employ fallout radionuclides (137Cs, 210Pbex and 239,240Pu) as tracers to measure proportional contributions of fine sediment (<10μm) from hillslope surface and channel bank sources to levee and terminal fan deposits formed by post-fire debris flows in two forest catchments in southeastern Australia. While 137Cs and 210Pbex have been widely used in sediment tracing studies, application of Pu as a tracer represents a recent development and was limited to only one catchment. The ranges in estimated proportional hillslope surface contributions of fine sediment to individual debris flow deposits in each catchment were 22–69% and 32–74%. The greater susceptibility of 210Pbex to apparent reductions in the ash content of channel deposits relative to hillslope sources resulted in its exclusion from the final analysis. No systematic change in the proportional source contributions to debris flow deposits was observed with distance downstream from channel initiation points. Instead, spatial variability in source contributions was largely influenced by the pattern of debris flow surges forming the deposits. Linking the tracing analysis with interpretation of depositional evidence allowed reconstruction of temporal sequences in sediment source contributions to debris flow surges. Hillslope source inputs dominated most elevated channel deposits such as marginal levees that were formed under peak flow conditions. This indicated the importance of hillslope runoff and fine sediment supply for debris flow generation in both catchments. In contrast, material stored within channels that was deposited during subsequent surges was predominantly channel-derived. The results demonstrate that fallout radionuclide tracers may provide unique information on changing source contributions of fine sediment during debris flow events. [Copyright &y& Elsevier]

Abstract: We quantified the sediment volume transported by a major debris flow event in the Halltal, Austrian Alps, using a combination of terrestrial (TLS) and airborne laser scanning (ALS) which has rarely been carried out before. A digital terrain model (DTM) derived from ALS data (pre-event surface) was combined with a DTM derived from TLS data (post-event surface). Both datasets were aligned and compared in a cut and fill analysis estimating differential volumes. The main focus lay on the evaluation and accuracy assessment of the applied method. Tie-point based registration of both datasets proved to be insufficient; additional alignment by Multi Station Adjustment was necessary to minimise the averaged height error between both datasets, amounting for a volumetric error of less than 10% which is comparable to pure ALS-campaigns. Larger errors were estimated for complex terrain with low scanning resolutions. A particular problem in data processing was the low and dense shrub vegetation in the study area which required a specifically adapted filter algorithm. An insufficient ground representation was observed for the ALS-data overestimating ground heights for averaged 70cm. Despite these limitations, the approach proved to be suitable for accurate extreme event quantification. The starting zones of the debris flows lie at the bedrock-debris interface where runoff is concentrated. Volumes of 5000 to 12,000m3 were assessed. Volume estimation worked better for the erosional than for the depositional features; this is because the erosional gullies are relatively deep and the calculation is not affected by pre-event vegetation. While erosion and sedimentation are balanced for one of the three catchments investigated, the deposited volumes are higher than the detected eroded volumes for the other two. The reasons are not fully understood. The magnitude of the flows was determined by catchment size, topographical characteristics and deforestation by a major wildfire in 1946. [Copyright &y& Elsevier]

Abstract: We examined runoff and sediment transport associated with large-scale construction projects in Fujian Province, China. Six experimental plots, comprised of four plot types, were designed to mimic typical conditions immediately following disturbance. It was found that natural vegetative cover reduces both runoff and erosion by approximately 36 and 7457 times over bare ground, and 16 and 1801 times over typically planted grasses, respectively. The increase in erosion associated with the replacement of native vegetation with bare ground or grasses due to large-scale infrastructure projects in Fujian from 1999 to 2004, amounted to an estimated loss of 1.76×107 tonnes of top soil and 3.04×108 m3 of surface runoff from the province during the bare soil construction phase, and an additional 4.25×106 tonnes of top soil and 1.35×108 m3 of surface runoff from the province associated with the first year of operation for each project. This has implications for frequency and occurrence of landslides and other geographic hazards, the transport of chemicals into waterways, the transport of goods through shipping passages, and the fertility of land in Fujian. [Copyright &y& Elsevier]

Abstract: Water erosion is a very dynamic process with direct and indirect consequences on ecosystem functioning. While the processes of sediment (SED) and soil organic carbon (SOC) detachment and transport are well recognized, it is however difficult to assess and interpret their impact on SED and SOC detachment, transport and sedimentation within a given landscape. In this study of a tropical area of the Mekong Basin, our main objective was to evaluate sediment (SED), soil organic carbon (SOC) and runoff (R) delivery from various spatial scales from 1m² to 10km² and to interpret these results in term of erosion processes operating within the landscape. Deliveries from nested scales of microplots (1×1m²; n=12 installed at different topographic positions and soils of a hillslope), plots (1×2.5m²; n=8), hillslope (60×100m²) and catchment (30, 60, and 1000ha) were assessed during an entire rainy season. To improve understanding of soil erosion at landscape level, delivery of mobilized water, sediment and SOC from one surface area to the following one in the nested experimental design were confronted to environmental information on rainfall characteristics (rainfall intensity, I; maximum 6-min rainfall intensity, Imax; rainfall amount, R; rainfall depth Dur; cumulative yearly rainfall prior to the event, Cum), slope gradient (S), soil thickness (T) and soil crusting (Crust), antecedent soil water content (SWC), and depth to the water table (DWT). These data were finally compared to extensive mapping of the thickness and the type of the soils in an attempt to validate these results and to evaluate the longer term consequences of erosion processes on soil distribution. The mean sediment delivery from 1×1m² plots was 899gm−2 y−1 with standard error (SE) of 26gm−2 y−1. The SED delivery decreased to 275±63gm−2 y−1 on 1×2.5m2 plots and to 4.3gm−2 y−1 at the hillslope level but then increased to 16.6gm−2 y−1 at the basin level. The slight decrease in SED delivery flux from 899gm−1 y−1 on 1m long plots to 688±157gm−1 y−1 on 2.5m2 long plots and to 468gm−1 y−1 on the 100m long hillslope revealed that SED detachment and transport in slopes is mainly controlled by splash. The ratio of plot to microplot deliveries for R increased significantly as Crust increased (r=0.91) but decreased with increasing Cov (r=−0.88) while the ratio for SOC correlated the most with S (r=0.97) and Cov (r=−0.58). The R delivery ratio from hillslope to plot and from river to hillslope increased as soils get wetter and the water table rose while higher ratios for SED and SOC occurred at longer event duration and larger rainfall depth amount and at larger yearly antecedent rainfall in the case of the within catchment delivery. The large accumulations of SED and SOC at the lower parts of hillslopes confirms the observed erosion dynamics longer-term, (i.e., removal and transport of SED and SOC mainly by splash because of high infiltration occurring in slopes) thus suggesting a potential long-term sequestration of the SOC deposited in the lower parts of hillslopes while deposition in the river network appeared ephemeral. [Copyright &y& Elsevier]

Abstract: The application of polymer for controlling erosion and the associated nutrient transport has been well documented. However, comparatively less information is available on the effect of polymer application together with soil amendments. In this study, the effect of polyacrylamide (PAM) in combination with surface application of gypsum and Milorganite™ (MILwaukee ORGAnic NITtrogEn) biosolid for reducing sediment and phosphorus transport under laboratory rainfall simulations was investigated. The treatments considered were bare soil, gypsum, Milorganite™, gypsum+Milorganite™, PAM-coated gypsum and PAM-coated Milorganite™. Application rates for gypsum and Milorganite™ were 392kgha−1 (350lb/acre) and 726kgha−1 (650lb/acre), respectively. The PAM was coated on gypsum and Milorganite™ at an application rate of 11.2kgha−1 (10lb/acre) and 22.4kgha−1 (20lb/acre), respectively. Rain simulation experiments were conducted using a rainfall intensity of 6.0cmh−1 for 1h on a 10% slope. Surface runoff was collected continuously from each soil box over 10min intervals and leachate was collected continuously over the 60min simulation. The reduction in runoff or in leachate for all treatments was not significantly different from the bare soil control. The sediment loss for PAM coated Milorganite™ was reduced by 77%, when compared to bare soil. However, the sediment loss was not significantly reduced for any other treatment compared to bare soil. The PAM-coated gypsum was not effective for erosion control in our study, and there appears to be a correlation between effectiveness and prill size. However, the gypsum (coated and uncoated) contributed about half of the dissolved reactive phosphorus (DRP) export (in the runoff) compared to bare soil. The PAM-coated Milorgante™ reduced the DRP and total phosphorus (TP) export to 0.3–0.5 times that of Milorganite™ and to levels similar to bare soil. The decreased sediment and phosphorus export for the PAM-coated Milorganite™ treatment is a signal for a potential management practice for controlling erosion and nutrient transport in fertilized agricultural landscapes. [Copyright &y& Elsevier]