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Nikolaus J Kuhn - One of the best experts on this subject based on the ideXlab platform.
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effects of Interrill Erosion on the distribution of soil organic and inorganic carbon in different sized particles of mediterranean calcisols
Soil & Tillage Research, 2020Co-Authors: Laura Quijano, Nikolaus J Kuhn, Ana NavasAbstract:Abstract In this study, the potential effect of the selective transport and deposition by Interrill Erosion on the spatial distribution of eroded soil and associated soil organic (SOC) and inorganic carbon (SIC) in carbonate-rich soils was investigated in Mediterranean cultivated Calcisols. Particular attention was paid to the role of calcium carbonate in the stabilization of SOC and its impact on soil structure and the settling behavior of soil particles in suspension. The settling velocity is a key variable in controlling the transport and fate of eroded sediment and sediment-associated carbon, which accounts for soil particle / aggregate size and density. The objectives were to analyze the settling behavior of cultivated soils at two contrasting slope positions, representative of Erosion and deposition sites, in an Interrill area and compare with those of uncultivated and undisturbed soils (not affected by deposition or Erosion processes). Besides we examined the distribution of SOC and SIC associated with different particle size classes. Soils were fractionated into five size classes (>250, 125–250, 63–125, 32–63 and ≤32 μm) using a settling tube procedure and carbon contents (SOC and SIC, %) were measured at each settling size classes. The results indicated that the particle size selectivity of Interrill Erosion affects the distribution of soil particles and associated SOC and SIC spatial variability. As a result of Erosion processes, cultivated soil at the upper part of the slope was enriched in finer fractions compared to the lower part where mainly coarse particles were deposited and the finer material was transported and washed out. Cultivation leads to a depletion of SOC and of the >250 μm fraction in comparison with uncultivated and undisturbed soil, where the SOC content was two times higher than in cultivated soil. Lighter and smaller settling size classes (≤63 μm) had the highest SOC content in uncultivated and cultivated downslope soils. This is contrary to what occurs with SIC that acts as a cementing agent and promotes aggregation formation affecting soil structure. Therefore, sand-sized and silt-sized carbonates were accumulated in coarser size fractions in these soils, mainly in downslope positions. This study provides a first insight into the role of selective processes by Interrill Erosion and their impact on soil organic/inorganic carbon distribution affected by different particle selective transport process, soil aggregate size distribution and associated carbon in Mediterranean agroecosystems.
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assessment of crusting effects on Interrill Erosion by laser scanning
PeerJ, 2020Co-Authors: Wolfgang Fister, Nikolaus J KuhnAbstract:Background Crust formation affects soil Erosion by raindrop impacted flow through changing particle size and cohesion between particles on the soil surface, as well as surface microtopography. Therefore, changes in soil microtopography can, in theory, be employed as a proxy to reflect the complex and dynamic interactions between crust formation and Erosion caused by raindrop-impacted flow. However, it is unclear whether minor variations of soil microtopography can actually be detected with tools mapping the crust surface, often leaving the interpretation of Interrill runoff and Erosion dynamics qualitative or even speculative. Methods In this study, we used a laser scanner to measure the changes of the microtopography of two soils placed under simulated rainfall in experimental flumes and crusting at different rates. The two soils were of the same texture, but under different land management, and thus organic matter content and aggregate stability. To limit the amount of scanning and data analysis in this exploratory study, two transects and four subplots on each experimental flume were scanned with a laser in one-millimeter interval before and after rainfall simulations. Results While both soils experienced a flattening, they displayed different temporal patterns of crust development and associated Erosional responses. The laser scanning data also allowed to distinguish the different rates of developments of surface features for replicates with extreme Erosional responses. The use of the laser data improved the understanding of crusting effects on soil Erosional responses, illustrating that even limited laser scanning provides essential information for quantitatively exploring Interrill Erosion processes.
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temporal variation of soc enrichment from Interrill Erosion over prolonged rainfall simulations
Agriculture, 2013Co-Authors: Wolfgang Fister, Nikolaus J KuhnAbstract:Sediment generated by Interrill Erosion is commonly assumed to be enriched in soil organic carbon (SOC) compared to the source soil. However, the reported SOC enrichment ratios (ERSOC) vary widely. It is also noteworthy that most studies reported that the ERSOC is greater than unity, while conservation of mass dictates that the ERSOC of sediment must be balanced over time by a decline of SOC in the source area material. Although the effects of crusting on SOC Erosion have been recognized, a systematic study on complete crust formation and Interrill SOC Erosion has not been conducted so far. The aim of this study was to analyze the effect of prolonged crust formation and its variability on the ERSOC of sediment. Two silty loams were simultaneously exposed to a rainfall simulation for 6 h. The ERSOC in sediment from both soils increased at first, peaked around the point when steady-state runoff was achieved and declined afterwards. The results show that crusting plays a crucial role in the ERSOC development over time and, in particular, that the conservation of mass applies to the ERSOC of sediment as a consequence of crusting. A “constant” ERSOC of sediment is therefore possibly biased, leading to an overestimation of SOC Erosion. The results illustrate that the potential off-site effects of selective Interrill Erosion require considering the crusting effects on sediment properties in the specific context of the interaction between soil management, rainfall and Erosion.
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Interrill Erosion of carbon and phosphorus from conventionally and organically farmed devon silt soils
Catena, 2012Co-Authors: Nikolaus J Kuhn, Elizabeth K Armstrong, Amy C Ling, Kathryn L Connolly, Goswin HeckrathAbstract:Abstract Globally, between 0.57 and 1.33 Pg of soil organic carbon (SOC) may be affected by Interrill processes. Also, a significant amount of phosphorus (P) is contained in the surface soil layer transformed by raindrop impact, runoff and crust formation. In the EU, the P content of a crusted (2 mm) surface layer corresponds to 4 to 40 kg ha− 1 of P on arable land (1.094 mil km2). Therefore, the role of Interrill processes for nutrient cycling and the global carbon cycle requires close attention. Interrill Erosion is a complex phenomenon involving the detachment, transport and deposition of soil particles by raindrop impacted flow. Resistance to Interrill Erosion varies between soils depending on their physical, chemical and mineralogical properties. In addition, significant changes in soil resistance to Interrill Erosion occur during storms as a result of changes in surface roughness, cohesion and particle size. As a consequence, Erosion on Interrill areas is selective, moving the most easily detached small and/or light soil particles. This leads to the enrichment of clay, phosphorous (P) and carbon (C). Such enrichment in Interrill sediment is well documented, however, the role of Interrill Erosion processes on the enrichment remains unclear. Enrichment of P and C in Interrill sediment is attributed to the preferential Erosion of the smaller, lighter soil particles. In this study, the P and organic C content of sediment generated from two Devon silts under conventional (CS) and organic (OS) soil management were examined. Artificial rainfall was applied to the soils using two rainfall scenarios of differing intensity and kinetic energy to determine the effects on the P and C enrichment in Interrill sediment. Interrill soil erodibility was lower on the OS, irrespective of rainfall intensity. Sediment from both soils showed a significant enrichment in P and C compared to the bulk soil. However, sediment from the OS displayed a much greater degree of P enrichment. This shows that the net P export from organically farmed soils is not reduced by a similar degree than soil Erosion compared to conventional soil management. The enrichment of P and C in the Interrill sediment was not directly related to SOC, P content of the soil and soil Interrill erodibility. A comparison of soil and sediment properties indicates that crusting, P and C content as well as density and size of eroded aggregate fragments control P and C enrichment. Due to complex and dynamic interactions between P, SOC and Interrill Erosional processes, the nutrient and C status of sediments cannot be predicted based on soil P content, SOC or Interrill erodibility alone. Clearly, further research on crust formation and the composition of fragments generated by aggregate breakdown and their transport in raindrop impacted flow under different rainfall conditions is required. Attaining this critical missing knowledge would enable a comprehensive assessment of the benefits of organic farming on nutrient budgets, off-site effects of Interrill Erosion and its role in the global C cycle.
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Erodibility of soil and organic matter: independence of organic matter resistance to Interrill Erosion
Earth Surface Processes and Landforms, 2007Co-Authors: Nikolaus J KuhnAbstract:The enrichment of organic matter in Interrill sediment is well documented; however, the respective roles of soil organic matter (SOM) and Interrill Erosion processes for the enrichment are unclear. In this study, organic matter content of sediment generated on two silts with almost identical textures, but different organic matter contents and aggregations, was tested. Artificial rainfall was applied to the soils in wet, dry and crusted initial conditions to determine the effects of soil moisture and rainfall and drying history on organic matter enrichment in Interrill sediment. While Erosional response of the soils varied significantly, organic matter enrichment of sediment was not sensitive to initial soil conditions. However, enrichment was higher on the silt with a lower organic matter content and lower Interrill erodibility. The results show that enrichment of organic matter in Interrill sediment is not directly related to either SOM content or soil Interrill erodibility, but is dominated by Interrill Erosion processes. As a consequence of the complex interaction between soil, organic matter and Interrill Erosion processes, erodibility of organic matter should be treated as a separate variable in Erosion models. Further research on aggregate breakdown, in particular the content and fate of the organic matter in the soil fragments, is required. Copyright © 2007 John Wiley & Sons, Ltd.
Bin Wang - One of the best experts on this subject based on the ideXlab platform.
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rare earth elements tracing Interrill Erosion processes as affected by near surface hydraulic gradients
Soil & Tillage Research, 2020Co-Authors: Chenfeng Wang, Bin Wang, Yunqi Wang, Yujie Wang, Wenlong Zhang, Xunchang J ZhangAbstract:Abstract Understanding Interrill Erosion processes is important for the development of process-based Interrill Erosion models. The objectives of this study were to identify dominant Interrill Erosion processes and to improve Interrill Erosion predictive equations. Six rare earth elements (REEs) were applied in different slope segments and soil layers to track sediment movement and deposition in order to gain insights into the near-surface hydraulic gradient-affected (drainage, saturation, and seepage conditions) Interrill Erosion processes under three rainfall intensities of 30, 60, and 90 mm h−1. The results showed that the contributions of Interrill soil losses from each tracer segment to the total soil loss first increased and then decreased along the slope under drainage/saturation conditions, while they continuously increased under seepage conditions. Transport by raindrop-induced and sheet flow-driven rolling, creeping, or sliding was the dominant transport mode. The dominant process of Interrill Erosion was transport-limited under drainage/saturation conditions and detachment-limited under seepage conditions. Under transport-limited conditions, raindrop-induced transport was more relevant than raindrop-impacted sheet flow-driven transport. However, the raindrop-impacted sheet flow-driven transport was more important than raindrop-induced transport under detachment-limited conditions. The response relationships of sediment transport capacity and soil detachment rate to the near-surface hydraulic gradient, rainfall intensity, slope gradient, and slope length could be described well via power equations (R2 ≥ 0.81). The R2 values of the power equations were 2.5 %–1840.0 % higher than those calculated with existing Interrill Erosion empirical equations, and the average absolute relative error (RME) derived in this study decreased by 38.0 %–87.2 %. In addition, Interrill erodibility should be further divided into Interrill sediment transportability under transport-limited conditions and Interrill detachability under detachment-limited conditions.
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Improved Interrill Erosion prediction by considering the impact of the near-surface hydraulic gradient
Soil and Tillage Research, 2020Co-Authors: Chenfeng Wang, Bin Wang, Yunqi Wang, Yujie Wang, Wenlong ZhangAbstract:Abstract The mechanism of the Interrill Erosion process is still unclear under complex conditions. Spatio-temporal variations of the near-surface hydraulic gradient are a common occurrence; however, few attempts have been made to characterize the near-surface hydraulic gradient for Erosion prediction. Therefore, the objective of this study is to determine the influence of exogenic Erosional forces (rainfall, overland flow, and seepage) on Interrill Erosion processes by considering the impact of the near-surface hydraulic gradient. Five near-surface hydraulic gradients (70 % of field capacity, field capacity, saturation, artesian seepage at 0.20 and 0.40 m of the hydrostatic pressure head) were applied in clay loam soil at two representative slope gradients of 8.7 % and 17.6 % under three rainfall intensities of 30, 60, and 90 mm h−1. The results showed that the near-surface hydraulic gradient was the dominant factor in the Interrill Erosion process in addition to rainfall intensity (I), runoff (Q), and slope gradient (S). There was a significant improvement in the prediction accuracy of the Interrill Erosion rate when the factor of near-surface hydraulic gradient was introduced into the Interrill Erosion prediction equation based on the Water Erosion Prediction Project (WEPP) concept (R2 = 0.92, Nash-Sutcliffe simulation efficiency (NSE) = 0.92). The R2 and NSE values were 22.4 %–210.0 % higher than those of existing empirical equations (main parameters: I, I&S, I&Q, I&S&Q). The correlation matrix results indicated that the flow velocity was a key hydraulic parameter for predicting the Interrill Erosion rate. The Interrill Erosion rate was predicted well by a simple power function of the flow velocity (R2 = 0.88, NSE = 0.88), although this relationship lacks clear physical meaning. We also found that the Interrill Erosion rate increased as a power function with the runoff depth, rainfall intensity, hydrostatic pressure head, and slope gradient (R2 = 0.88, NSE = 0.88). Considering the integrated effect of the exogenic Erosional dynamics on Interrill Erosion, a power function that included the physical description of the hydrodynamic parameters, rainfall intensity, and hydrostatic pressure head was used to predict the Interrill Erosion rate (R2 ≥ 0.85, NSE ≥ 0.86). The results of this research provide new insights into developing process-based and mechanistic models for Interrill Erosion processes.
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impact of rainfall pattern on Interrill Erosion process
Earth Surface Processes and Landforms, 2017Co-Authors: Bin Wang, Jean L Steiner, Fenli Zheng, Prasanna H GowdaAbstract:The impact of rainfall pattern on the Interrill Erosion process is not fully understood despite its importance. Systematic rainfall simulation experiments involving various rainfall intensities, stages, intensity sequences, and surface cover conditions were conducted in this study to investigate their effects on the Interrill Erosion process. Five rainfall patterns designed with the same total kinetic energy/precipitation (increasing, decreasing, rising–falling, falling–rising and constant patterns) were randomly delivered to a pre-wet clay loam soil surface at a 10° slope gradient. Significant differences in soil losses were observed among the different rainfall patterns and stages, but there was no obvious difference in runoff. Kinetic energy flux (KEr) was a governing factor for Interrill Erosion, and constant rainfall pattern (CST) produced nine times greater soil loss than runs with no KEr. Varied-intensity patterns had a profound effect on raindrop-induced sediment transport processes; path analysis results indicated that said effect was complex, interactive and intensity-dependent. Low hydraulic parameter thresholds further indicated that KEr was the dominant factor in detaching soil particles, while overland flow mainly contributed to transporting the pre-detached particles. This study not only sheds light on the mechanism of Interrill sediment transport capacity and detachability, but also may provide a useful database for developing event-based Interrill Erosion prediction models. Copyright © 2017 John Wiley & Sons, Ltd.
Zhanli Wang - One of the best experts on this subject based on the ideXlab platform.
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plot based experimental study of raindrop detachment Interrill wash and Erosion limiting degree on a clayey loessal soil
Journal of Hydrology, 2019Co-Authors: Qingwei Zhang, Zhanli Wang, Nan Shen, Qi Guo, Naling Tian, June LiuAbstract:Abstract Better understanding of raindrop detachment, Interrill wash and Erosion-limiting degree in Interrill processes is critical for accurately modelling Interrill Erosion and implementing proper anti-Erosion strategies. Simulated rainfall experiments were conducted on a clayey loessal soil at three rainfall intensities (42, 60 and 90 mm h−1), five slope gradients (7°, 10°, 15°, 20° and 25°) and rainfall duration of 40 min. Results showed that raindrop detachment rate initially decreased rapidly within a few minutes and then reached a relative steady state during rainfall. The initial and steady raindrop detachment rate increased with increased rainfall intensity. Interrill wash rate peaked early and then decreased to a relative constant rate during the rainfall. The initial, maximum and steady Interrill wash rate increased with increased rainfall intensity and slope gradient. Erosion-limiting degree (ELD), defined as the ratio of Interrill wash rate to raindrop detachment rate, ranged from 10.99% to 35.70% under experimental conditions, indicating that Interrill Erosion system was transport-limited. The ELD decreased with rainfall intensity and increased linearly (R2 = 0.90) with slope gradient. The higher the rainfall intensity, the stronger the transport-limiting in Interrill Erosion processes; the steeper the slope gradient, the weaker the transport-limiting in Interrill Erosion processes. Raindrop detachment is the dominant process in detaching soil particles, whereas Interrill flow contributes to washing out detached sediments. The findings of this study, especially ELD, largely improved the understanding of Interrill Erosion processes.
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identifying sediment transport capacity of raindrop impacted overland flow within transport limited system of Interrill Erosion processes on steep loess hillslopes of china
Soil & Tillage Research, 2018Co-Authors: Qingwei Zhang, Zhanli Wang, Bing Wu, Nan ShenAbstract:Abstract Interrill Erosion processes typically involve such scientific issues as detachment-limited and transport-limited Erosion behaviour. An accurate estimation of the sediment transport capacity (Tc) by raindrop-impacted overland flow is critical for Interrill Erosion modelling and for evaluating sediment budgets under Erosion-limiting conditions. Simulated rainfall experiments with rainfall intensities from 0.8 to 2.5 mm min−1 over a three-area soil pan with slope gradients from 12.7% to 46.6% were conducted to identify the transport-limited cases and determine Tc by raindrop-impacted overland flow within the transport-limited systems of Interrill Erosion processes. Results indicated that Tc increased as a power function of rainfall intensity and slope gradient (R2 = 0.84, NSE = 0.75), and Tc was more sensitive to rainfall intensity than to slope gradient. In terms of R2 and NSE, stream power was the key hydraulic parameter that influenced Tc among flow velocity (R2 = 0.64, NSE = 0.39), shear stress (R2 = 0.53, NSE = 0.23), stream power (R2 = 0.76, NSE = 0.52) and unit stream power (R2 = 0.49, NSE = 0.16). The addition of rainfall physical parameters in response equations of Tc in addition to hydraulic parameter, could improve an accuracy of Tc modelling. Stream power combined with rainfall kinetic energy can best describe the Tc of raindrop-impacted overland flow within the transport-limited system of Interrill Erosion processes by a power-exponent function (R2 = 0.90, NSE = 0.72). Rainfall kinetic energy can reduce the Darcy-Weisbach resistance coefficient of raindrop-impacted overland flow and thus benefit sediment transporting. This study provides another method for directly identifying the Tc of raindrop-impacted overland flow in Interrill Erosion processes on steep loess slopes, and points out that rainfall impacts should be particularly considered when studying Tc by raindrop-impacted overland flow.
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distinguishing transport limited and detachment limited processes of Interrill Erosion on steep slopes in the chinese loessial region
Soil & Tillage Research, 2018Co-Authors: Qingwei Zhang, Zhanli Wang, Nan ShenAbstract:Abstract Distinguishing transport- and detachment-limited processes of Interrill Erosion on the basis of the ratio of Interrill Erosion rate ( Q ) to splash detachment rate ( D ) was investigated to fully understand Interrill Erosion processes. A modified experimental device was used to measure Interrill Erosion and splash detachment rates simultaneously at 12.23%, 17.63%, 26.8%, 36.4%, 40.40% and 46.63% slope gradients under rainfall intensities of 48 and 120 mm h −1 . Results showed that the transport-limited ( Q D ), detachment-limited ( Q > D ), and transport- and detachment-limited ( Q D & Q > D ) processes were respectively included in individual rainfall event, which were influenced by slope gradient and rainfall intensity, and the transport-limited process changed to a detachment-limited process early when the slope gradients were steep. Furthermore, the ratio of Interrill Erosion rate to splash detachment rate under rainfall intensities of 48 and 120 mm h −1 increased from 0.006 to 36.91 and from 0.14 to 15.65 as the slope gradient increased from 12.23% to 46.63%, respectively. The research findings emphasise the importance of quantifying transport- and detachment-limited processes on steep slopes.
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validating and improving Interrill Erosion equations
PLOS ONE, 2014Co-Authors: Zhanli Wang, Fengbao Zhang, Mingyi YangAbstract:Existing Interrill Erosion equations based on mini-plot experiments have largely ignored the effects of slope length and plot size on Interrill Erosion rate. This paper describes a series of simulated rainfall experiments which were conducted according to a randomized factorial design for five slope lengths (0.4, 0.8, 1.2, 1.6, and 2 m) at a width of 0.4 m, five slope gradients (17%, 27%, 36%, 47%, and 58%), and five rainfall intensities (48, 62.4, 102, 149, and 170 mm h(-1)) to perform a systematic validation of existing Interrill Erosion equations based on mini-plots. The results indicated that the existing Interrill Erosion equations do not adequately describe the relationships between Interrill Erosion rate and its influencing factors with increasing slope length and rainfall intensity. Univariate analysis of variance showed that runoff rate, rainfall intensity, slope gradient, and slope length had significant effects on Interrill Erosion rate and that their interactions were significant at p = 0.01. An improved Interrill Erosion equation was constructed by analyzing the relationships of sediment concentration with rainfall intensity, slope length, and slope gradient. In the improved Interrill Erosion equation, the runoff rate and slope factor are the same as in the Interrill Erosion equation in the Water Erosion Prediction Project (WEPP), with the weight of rainfall intensity adjusted by an exponent of 0.22 and a slope length term added with an exponent of -0.25. Using experimental data from WEPP cropland soil field Interrill erodibility experiments, it has been shown that the improved Interrill Erosion equation describes the relationship between Interrill Erosion rate and runoff rate, rainfall intensity, slope gradient, and slope length reasonably well and better than existing Interrill Erosion equations.
Chi Hua Huang - One of the best experts on this subject based on the ideXlab platform.
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Effects of soil surface roughness on Interrill Erosion processes and sediment particle size distribution
Geomorphology, 2017Co-Authors: Wenfeng Ding, Chi Hua HuangAbstract:Abstract Soil surface roughness significantly impacts runoff and Erosion under rainfall. Few previous studies on runoff generation focused on the effects of soil surface roughness on the sediment particle size distribution (PSD), which greatly affects Interrill Erosion and sedimentation processes. To address this issue, a rainfall-simulation experiment was conducted with treatments that included two different initial soil surface roughnesses and two rainfall intensities. Soil surface roughness was determined by using photogrammetric method. For each simulated event, runoff and sediment samples were collected at different experimental times. The effective (undispersed) PSD of each sediment sample and the ultimate (after dispersion) PSD were used to investigate the detachment and transport mechanisms involved in sediment movement. The results show that soil surface roughness significantly delayed runoff initiation, but had no significant effect on the steady runoff rate. However, a significant difference in the soil loss rate was observed between the smooth and rough soil surfaces. Sediments from smooth soil surfaces were more depleted in clay-size particles, but more enriched in sand-size particles than those from rough soil surfaces, suggesting that Erosion was less selective on smooth than on rough soil surfaces. The ratio of different sizes of transported sediment to the soil matrix indicates that most of the clay was eroded in the form of aggregates, silt-size particles were transported mainly as primary particles, and sand-size particles were predominantly aggregates of finer particles. Soil surface roughness has a crucial effect on the sediment size distribution and Erosion processes. Significant differences of the enrichment ratios for the effective PSD and the ultimate PSD were observed under the two soil surface roughness treatments. These findings demonstrate that we should consider each particle size separately rather than use only the total sediment discharge in assessing and modeling Interrill Erosion processes.
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mechanics of Interrill Erosion with wind driven rain
Earth Surface Processes and Landforms, 2013Co-Authors: Gunay Erpul, Chi Hua Huang, Dennis C Flanagan, Donald Gabriels, Darrell L Norton, S M VisserAbstract:The vector physics of wind-driven rain (WDR) differs from that of wind-free rain, and the Interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the Interrill component of the WEPP model for WDR events. The Interrill delivery rates were measured in the wind tunnel facility of the International Center for Eremology (ICE), Ghent University, Belgium with an experimental setup to study different raindrop impact velocity vectors. Synchronized wind and rain simulations with wind velocities of 6, 10 and 14 m s–1 were applied to a test surface placed on windward and leeward slopes of 7, 15 and 20%. Since both rainfall intensity and raindrop impact velocity varied greatly depending on differences in the horizontal wind velocity under WDRs, the resultant kinetic energy flux (KEr, in J m–2 s–1) was initially used in place of the WEPP model intensity term in order to incorporate the effect of wind on impact velocity and frequency of raindrops. However, our results showed only minor improvement in the model predictions. For all research data, the model Coefficients of Determination (r2) were 0·63 and 0·71, when using the WEPP and the KEr approaches, respectively. Alternately, integrating the angle of rain incidence into the model by vectorally partitioning normal kinetic energy flux (KErn, in J m–2 s–1) from the KEr greatly improved the model's ability to estimate the Interrill sediment delivery rates (r2?=?0·91). This finding suggested that along with the fall trajectory of wind-driven raindrops with a given frequency, raindrop velocity and direction at the point of impact onto the soil surface provided sufficient physical information to improve WEPP sediment delivery rate predictions under WDR
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Interrill soil Erosion as affected by tillage and residue cover
Soil and Tillage Research, 1994Co-Authors: Joe M. Bradford, Chi Hua HuangAbstract:No-till cropping systems are effective in reducing soil Erosion. The objective of this study was to determine whether high infiltration rates and low runoff and soil loss under long-term, no-till conditions in loessial regions of the Midwest US result from both the well-structured, porous condition of the soil and the protective cover of crop residue or primarily from residue cover. Soil loss, runoff, and infiltration were measured using a rainfall simulator on Interrill Erosion plots with and without residue cover on a conventional and two no-till systems in central Illinois. For both conventional till and no-till conditions, removing surface residue significantly decreased infiltration rates and increased soil loss. Tilling the no-till surface while maintaining an equal surface cover as with the no-till system slightly increased Interrill Erosion. Removing residue on a no-till system, however, increased soil loss significantly. A no-till soil condition without adequate residue cover will seal, crust, and erode with extremely high soil losses following surface drying. © 1994.
Rorke B Bryan - One of the best experts on this subject based on the ideXlab platform.
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drying soil surface condition and Interrill Erosion on two ontario soils
Catena, 2004Co-Authors: Nikolaus J Kuhn, Rorke B BryanAbstract:Abstract Interrill erodibility summarizes the resistance of soil to rainsplash, sheetwash and rainflow Erosion and incorporates changes in infiltration, roughness and resistance to detachment and transportation. Resistance to Interrill Erosion varies during storms, reflecting the effect of wetting, sealing, crusting, and Erosion on surface conditions. Significant changes in soil conditions also occur as a result of progressive drying between storms, producing considerable uncertainty in event-based Erosion prediction. However, a clear link between drying, primary soil properties and soil condition, as well as Interrill Erosion during subsequent storms has not been established. In this study, soil condition and Interrill Erosion of soils from southern Ontario were examined in detail during a sequence of simulated rainstorms, and linkages between primary soil properties, drying, surface soil structure, and Interrill Erosion were established. Interrill Erosion after drying differed depending on the persistence of the changes in soil structure caused by drying. Pronounced stabilization of aggregates on drying led to an increase of erodibility, indicating a transition from a coherent to granular structure, requiring lower stresses for particle detachment. The sensitivity of soil erodibility to drying appears to be determined by the tendency of a soil to form aggregates. The results show that a better understanding of the linkages between primary soil properties, rainfall and drying history, soil condition and Interrill Erosion is required for effective event-based erodibility assessment. However, the wide range of possible initial soil conditions and the complex nature of soil–climate interaction are likely to limit the effectiveness of erodibility assessment.
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seal formation and Interrill Erosion on a smectite rich kastanozem from ne mexico
Catena, 2003Co-Authors: Nikolaus J Kuhn, Rorke B Bryan, Jose NavarAbstract:Abstract On-site and off-site effects of Interrill Erosion can be highly significant for river and reservoir sedimentation and can cause serious water contamination. Interrill Erosion changes during storms, reflecting the effect of seal formation on soil resistance to Interrill Erosion. Swelling clay soils appear to be particularly complex in their response to rainfall. Assessment of Interrill Erosion hazards on such soils requires effective quantitative description of the effects of seal formation on Interrill Erosion. However, short-term changes of seal properties are not reflected well in current event-based Erosion models, leading to poor prediction quality. The objective of this study was to identify the changes in seal condition relevant to temporal change in Interrill Erosion on a smectite-rich Kastanozem from NE-Mexico. Formation and removal of a non-coherent washed-out layer, consisting of stable aggregates, was the most apparent change in seal condition associated with Interrill Erosion dynamics. The progressive exposure of a more cohesive washed-in layer resulted in reduced Interrill Erosion, which is attributed to lower erodibility of the washed-in layer. The results demonstrate that seal formation and Interrill Erosion dynamics of a freshly tilled Kastanozem are strongly linked. The amount of rainfall required for the removal of the washed-out layer (180 mm) shows that seal formation lasts for a significant part of the rainy season. The changes of Interrill Erosion caused by seal formation on the Kastanozem are not represented adequately in current methods of erodibility assessment and improving the quality of event-based Erosion prediction remains difficult for two reasons. First, relationships between soil properties, seal formation and Erosion dynamics are not well understood. Second, the quantitative description of seal property dynamics relevant for Interrill Erosion is characterized by strong spatial and temporal variability. Therefore, it is likely that even with best modeling efforts, the quality of event-based Erosion prediction will be limited by the high uncertainty about erodibility.
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soil erodibility and processes of water Erosion on hillslope
Geomorphology, 2000Co-Authors: Rorke B BryanAbstract:Abstract The importance of the inherent resistance of soil to Erosional processes, or soil erodibility, is generally recognized in hillslope and fluvial geomorphology, but the full implications of the dynamic soil properties that affect erodibility are seldom considered. In Canada, a wide spectrum of soils and Erosional processes has stimulated much research related to soil erodibility. This paper aims to place this work in an international framework of research on water Erosion processes, and to identify critical emerging research questions. It focuses particularly on experimental research on rill and Interrill Erosion using simulated rainfall and recently developed techniques that provide data at appropriate temporal and spatial scales, essential for event-based soil Erosion prediction. Results show that many components of Erosional response, such as partitioning between rill and Interrill or surface and subsurface processes, threshold hydraulic conditions for rill incision, rill network configuration and hillslope sediment delivery, are strongly affected by spatially variable and temporally dynamic soil properties. This agrees with other recent studies, but contrasts markedly with long-held concepts of soil credibility as an essentially constant property for any soil type. Properties that determine erodibility, such as soil aggregation and shear strength, are strongly affected by climatic factors such as rainfall distribution and frost action, and show systematic seasonal variation. They can also change significantly over much shorter time scales with subtle variations in soil water conditions, organic composition, microbiological activity, age-hardening and the structural effect of applied stresses. Property changes between and during rainstorms can dramatically affect the incidence and intensity of rill and Interrill Erosion and, therefore, both short and long-term hillslope Erosional response. Similar property changes, linked to climatic conditions, may also significantly influence the stability and resilience of plant species and vegetation systems. Full understanding of such changes is essential if current event-based soil Erosion models such as WEPP and EUROSEM are to attain their full potential predictive precision. The complexity of the interacting processes involved may, however, ultimately make stochastic modelling more effective than physically based modelling in predicting hillslope response to erodibility dynamics.
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the relationship of soil loss by Interrill Erosion to slope gradient
Catena, 2000Co-Authors: Dennis Fox, Rorke B BryanAbstract:Abstract The influence of slope gradient on Erosion rate differs for rill and Interrill conditions. Rill Erosion increases substantially more with increasing slope gradient than Interrill Erosion. Combining the two Erosion processes into single data sets led to the development of regression equations (e.g., USLE) that overestimated the effect of slope gradient on Erosion rate for low slope gradients and short slopes. This study investigated the change in Interrill Erosion rate with slope gradient and examined its relationship to runoff velocity. A sandy loam (grey brown luvisol) was packed in 100×40×10 cm3 soil trays and subjected to simulated rainfall for a period of 75 min. Rain-impacted flow Erosion and downslope splash were monitored, and runoff velocity measurements were made at three positions within the flume. Downslope splash Erosion never accounted for more than 20% of the total Erosion. Rain-impacted flow Erosion peaked early in the simulation then decreased to a constant rate; Erosion rate was therefore probably detachment-limited. For a constant runoff rate, rain-impacted flow Erosion increased roughly with the square root of slope gradient, as did the runoff velocity. Soil loss was correlated (0.81) with runoff velocity under the experimental conditions.
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laboratory experiments on surface seal development and its effect on Interrill Erosion processes
European Journal of Soil Science, 1992Co-Authors: M C Slattery, Rorke B BryanAbstract:SUMMARY Despite extensive research, the processes involved in seal and crust formation are not yet fully understood. This paper provides detailed information on the dynamics of surface sealing and its effect on the Erosion process. Seal development of an artificial soil mixture was investigated by measuring changes in splash detachment, soil bulk density and near-surface soil strength, and by detailed observation and analysis of thin-section photomicrographs taken at different sealing stages. Raindrop impact was found to be the principal force governing the formation of the surface seal. The sequence of seal development was as follows: (i) rapid disruption of surface aggregates by direct raindrop impact; (ii) rearrangement of disrupted fragments and textural separates; and (iii) compaction of surface material by continued drop impact. Eventually, an ‘equilibrium’ complete seal of the surface was established. Other micro-morphological characteristics included (i) a mean seal thickness of 0.3–0.8 mm, (ii) a complex void structure dominated by compound packing voids and vughs, (iii) an absence of any ‘washing-in’ of fine material, and (iv) development of miniature soil pedestals (micro-hoodoos), micro-depressions and micro-knolls formed by drop impact. Measured changes in splash detachment and soil bulk density were consistent with the observed fabric changes. Splash detachment increased during the early seal stages but thereafter decreased rapidly with incorporation of material into the developing seal. The decrease was matched by an overall increase in soil bulk density. Contrary to expectations, soil shear increased only during the initial wetting phase, and subsequently decreased to give minimum values coincident with maximum seal development. After the initial wetting phase shear strength had a negative linear relationship with soil moisture content. It is concluded that soil shear strength may not be a reliable indicator of seal development.
