Soil erosion processes. I. The relative importance of rainfall detachment and dunoff entrainment

Soil Research ◽  
1991 ◽  
Vol 29 (5) ◽  
pp. 671 ◽  
Author(s):  
APB Proffitt ◽  
CW Rose

Experiments carried out in a simulated-rainfall tilting-flume facility are reported in which sediment concentrations (c) in runoff water resulting from overland flow only, or from a combination of rainfall and overland flow, were measured under controlled conditions using a series of slopes (0.1, 05, 1, 3 and 5%). The mixture of rainfall (of rate 100 mm h-1) and runon of water at the top of the flume were arranged to provide a constant volumetric flux (1.0x10-3 m3 m-l s-1) at exit from the 5.8 m long flume. Two contrasting soil types were studied: a cracking clay (black earth or vertisol), and a slightly dispersive sandy clay loam (solonchak or aridisol). Two major processes which can contribute to soil erosion under rainfall are rainfall detachment and runoff entrainment. For both soil types, c was generally highest for the steepest slope and decreased with slope. For constant rainfall and/or runoff conditions, c generally decreased with time until an equilibrium concentration was reached. At this equilibrium, the relative importance of rainfall detachment and entrainment in terms of soil loss was dependent on soil type and streampower which incorporates effects of slope and water flux. For streampowers <0.1 W m-2 for the black earth, and <0.3 W m-2 for the solonchak, the greatest contribution to c was by rainfall detachment, whilst at greater streampowers entrainment was the dominant contributor to c. At any streampower, the contribution by rainfall detachment was greater for the weakly structured solonchak than for the well aggregated black earth. At lower strearnpowers, the interaction between erosion processes was found to give higher c than the sum of both sediment concentrations resulting from the separately occurring processes. At streampowers greater than approximately 0.5 W m-2, rainfall reduced eroded sediment concentration by suppressing rill development. The findings in this study suggest that both runoff entrainment and rainfall detachment can contribute to sediment concentration from 'interrill' areas.

Soil Research ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 1359 ◽  
Author(s):  
B. Fentie ◽  
C. W. Rose ◽  
K. J. Coughlan ◽  
C. A. A. Ciesiolka

We examined, both experimentally and theoretically, whether rilling results in higher soil erosion than would have occurred without rilling. The possibility of rilling occurs when overland flow-driven erosion processes are dominant over erosion due to raindrop impact, and that is the situation assumed in this paper. Stream power (or a quantity related to stream power such as shear stress) is commonly used to describe the driving variable in flow-driven erosion. Five flume experiments were designed to investigate the relationship between stream power and sediment concentration and how this relationship is affected by the ratio of width to depth of flow (r), and the frequency or number of rills per metre width (N) of rectangular rills. This paper presents the results of these experiments and uses a physically based soil erosion theory to show that the results of the 5 flume experiments are in accord with this theory. This theory is used to investigate the effect of all possible rectangular rill geometries and frequencies on the maximum possible sediment concentration, i.e. the sediment concentration at the transport limit, by developing general relationships for the influence of r and N on sediment concentration. It is shown that increased stream power, which can be due to rilling, does not necessarily result in higher sediment concentration.


Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 109 ◽  
Author(s):  
MJ Singer ◽  
PH Walker

The 20-100 mm portion of a yellow podzolic soil (Albaqualf) from the Ginninderra Experiment Station (A.C.T.) was used in a rainfall simulator and flume facility to elucidate the interactions between raindrop impact, overland water flow and straw cover as they affect soil erosion. A replicated factorial design compared soil loss in splash and runoff from 50 and 100 mm h-1 rainfall, the equivalent of 100 mm h-1 overland flow, and 50 and 100 mm h-1 rainfall plus the equivalent of 100 mm h-' overland flow, all at 0, 40 and 80% straw cover on a 9% slope. As rainfall intensity increased, soil loss in splash and runoff increased. Within cover levels, the effect of added overland flow was to decrease splash but to increase total soil loss. This is due to an interaction between raindrops and runoff which produces a powerful detaching and transporting mechanism within the flow known as rain-flow transportation. Airsplash is reduced, in part, because of the changes in splash characteristics which accompany changes in depths of runoff water. Rain-flow transportation accounted for at least 64% of soil transport in the experiment and airsplash accounted for no more than 25% of soil transport The effects of rainfall, overland flow and cover treatments, rather than being additive, were found to correlate with a natural log transform of the soil loss data.


1998 ◽  
Vol 130 (4) ◽  
pp. 473-488 ◽  
Author(s):  
P. A. JAMES ◽  
R. W. ALEXANDER

Studies of soil erosion in upland and marginal upland Britain are reviewed. Processes affecting soil erosion and runoff are described in marginal upland improved pastures of differing age in the Clwydian Hills, including one which was cultivated twice during the study period. A Gerlach-type trough was designed for trapping sediment and filtered runoff from bounded plots and for operating under grazing. Erosion and runoff amounts are interpreted in the light of ground cover, rainfall amounts and intensity, the action of grazing stock and other animals, and other influences. The chief erosion processes are the action of animals and surface wash by unconcentrated overland flow; no rilling occurred. The significance of particle size of eroded sediment is discussed.


2018 ◽  
Vol 46 (2) ◽  
pp. 553-562 ◽  
Author(s):  
Ataollah KAVIAN ◽  
Leila GHOLAMI ◽  
Maziar MOHAMMADI ◽  
Velibor SPALEVIC ◽  
Moghadeseh FALAH SORAKI

Soil erosion is one of the key challenges in soil and water conservation. Vegetation that covers soil and organic and inorganic mulch is very useful for the control of erosion processes. This study examined treatment with wheat residual (as agriculture mulch) on infiltration, time to runoff, runoff coefficient, sediment concentration and soil erosion processes. The study has been conducted for sandy-loam soil taken from summer rangeland (Northern Iran) with simulated rainfall intensities of 50 and 100 mm h-1. The experiment was conducted in slopes of 30% in three replications with two amounts of wheat residual of 50 and 90 %. The results showed that conservation percent of soil erosion for wheat residual 50 and 90% was 61.68 and 73.25%, respectively (in rainfall intensity of 50 mm h-1). Also, the conservation percent of soil erosion for wheat residual of 50 and 90% cover was 70.68 and 90.55, respectively (in rainfall intensity of 100 mm h-1). It was concluded that the conservation treatments could reduce runoff coefficient, sediment concentration and soil erosion and increase the time to runoff and infiltration coefficient. This effect was significant on time for infiltration, sediment concentration and soil erosion variables (R2=0.99), time to runoff and runoff coefficient variables (R2=0.95). The interaction effects of rainfall intensity and soil conservation was significant for sediment concentration and soil erosion variables (R2=0.99).


Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 1183
Author(s):  
A. S. Wiranatha ◽  
C. W. Rose ◽  
M. S. Salama

The spatial pattern of net soil loss on 6 downslope transects in a small semi-tropical sub-catchment was measured in 1990—91 using the resident caesium-137 deficit technique. The sub-catchment consisted of 2 opposing hillslopes which shed water to an intermittent stream in the valley bottom of the sub-catchment. There were 3 transects on each of the opposing hillslopes, and measurement indicated net soil loss from all 6 transects. Furthermore, the spatial pattern of caesium-137 deficit did not indicate the accumulation of soil expected due to the slope decrease toward the bottom of the valley. Possible explanations of this finding could be the effect of periodic flooding of the intermittent valley stream, or seepage-accelerated erosion. Pineapple cultivation in the sub-catchment since 1950 included intensive cultivation at 4-year intervals by downslope-moving rotary hoe. The paper develops a theoretical prediction of the spatial pattern of net soil loss expected due to such cultivation, as well as the expected pattern of soil loss due to overland flow on the hillslopes. The spatial patterns of soil loss due to these 2 different soil erosion mechanisms were then compared with the pattern of net soil loss indicated by caesium-137 depletion to provide an assessment of their likely relative importance in contributing to soil loss. In the upper part of each hillslope, this comparison of spatial trends did not allow the dominant cause of soil erosion to be distinguished. Both the model of erosion due to cultivation and that due to hillside overland flow predicted soil accumulation in the lower valley sides where slope decreased. Neither model represented the net loss of such accumulated soil indicated by caesium-137 deficit, and this loss possibly occurred during periodically observed flooding of the valley floor, or due to surface burial with caesium-137 depleted subsoil.


2021 ◽  
Author(s):  
Rosolino Ingraffia ◽  
Gaetano Amato ◽  
Vincenzo Bagarello ◽  
Francesco G. Carollo ◽  
Dario Giambalvo ◽  
...  

Abstract. Microplastic is recognized as a factor of global change affecting many environmental compartments. Agricultural soils are likely hotspots of microplastic contamination in terrestrial ecosystems and are of particular concern due to their role in food production. Microplastic has already been shown to be able to affect soil properties, but its effect on different soil types is poorly understood. Moreover, no information is available on how the presence of this pollutant can affect soil water erosion processes, which are extremely important issues in many environments. In the light of this, we performed two experiments (a microcosm and a mesocosm study) to investigate how the presence of polyester microplastic fibers affects soil physical and hydrological parameters and processes such as aggregate formation and soil erosion in three different agricultural soil types. Our data show that the effects of polyester microplastic on soil physical parameters (including soil aggregation and erosion) are strongly dependent on soil type. We found that microplastic contamination can decrease the formation of new aggregates but at the same time increase their stability in water, with effects on soil erosion stronger as the intrinsic erodibility of soil increases. Overall, our results highlight the importance of broadly exploring soil properties such as texture, mineralogy, and organic carbon content to better understand how the various soil types respond to microplastic contamination.


2021 ◽  
Vol 9 ◽  
Author(s):  
Bingbing Zhu ◽  
Zhengchao Zhou ◽  
Zhanbin Li

The Loess Plateau has long been suffering from serious soil erosion of which erosion from the slope-gully system is now dominant. The slope-gully system is characterized with distinctive erosion distribution zones consisting of inner and inter gully areas wherein erosion patterns spatially vary, acting as both sediment source and the dominant sediment and water transport mechanism. In this paper, a substantial body of research is reviewed concentrating on the soil erosion processes and control practices in the slope-gully system. The inner gully area is identified as the main sediment source while runoff and sediment from the inter-gully upland is found to significantly affect down slope erosion processes. Correspondingly, the protective vegetation pattern and coverage should be strategically designed for different erosion zones with an emphasis on the critical vegetation cover and pattern to reduce sediment yield of the whole slope-gully system. Check-dam could change the base level of erosion and reduce the slope length of the gully side, which will further decrease the possibility and magnitude of gravity erosion. We concluded that understanding the erosion processes and implementing erosion practices for the slope-gully system are of importance and require more research efforts that emphasize: 1) the influence of upland runoff on erosion processes at downslope; 2) the relationship between hydraulic characteristics of overland flow and erosion process at a slope-gully system scale; 3) physical mechanisms of different vegetation patterns on the slope-gully erosion process.


Author(s):  
Banglin Luo ◽  
Zhen Han ◽  
Jing Yang ◽  
Qing Wang

Soil erosion of sloped lands is one of the important sources of substantive sediments in watersheds. In order to investigate erosion characteristics of sloped lands during rainfall events in the Three Gorges Reservoir Area, erosion processes of purple and yellow soils under different slope gradients and rainfall intensities were studied by using a rainfall simulator. The results showed that the sediment concentration in runoff was closely correlated with rainfall intensity. The sediment concentration in runoff gradually rose to a peak with time, and then gradually declined and approach a steady rate during simulation rainfall events. The particle size distribution of surface soils before the rainfall was different from that after the rainfall. Soil erosion mainly resulted in the loss of fine particles of surface soil through runoff, and the fine particles of soil were enriched in sediments. Soil erosion rates were gradually increased with the slope gradient when the slope gradient was less than 10°, and significantly increased when the slope gradient was more than 10°. The slope factor of yellow soil could be fitted well to that calculated by the formula of Universal Soil Loss Equation (USLE). The trend of the slope factor of purple soil was similar to that of the slope factor that was derived from USLE. Therefore, the effect of slope gradients on soil erosion need to be further researched when USLE was applied to predict erosion in purple soil area.


Soil Research ◽  
2001 ◽  
Vol 39 (2) ◽  
pp. 219 ◽  
Author(s):  
A. S. Wiranatha ◽  
C. W. Rose ◽  
M. S. Salama

The spatial pattern of net soil loss on 6 downslope transects in a small semi-tropical sub-catchment was measured in 1990—91 using the resident caesium-137 deficit technique. The sub-catchment consisted of 2 opposing hillslopes which shed water to an intermittent stream in the valley bottom of the sub-catchment. There were 3 transects on each of the opposing hillslopes, and measurement indicated net soil loss from all 6 transects. Furthermore, the spatial pattern of caesium-137 deficit did not indicate the accumulation of soil expected due to the slope decrease toward the bottom of the valley. Possible explanations of this finding could be the effect of periodic flooding of the intermittent valley stream, or seepage-accelerated erosion. Pineapple cultivation in the sub-catchment since 1950 included intensive cultivation at 4-year intervals by downslope-moving rotary hoe. The paper develops a theoretical prediction of the spatial pattern of net soil loss expected due to such cultivation, as well as the expected pattern of soil loss due to overland flow on the hillslopes. The spatial patterns of soil loss due to these 2 different soil erosion mechanisms were then compared with the pattern of net soil loss indicated by caesium-137 depletion to provide an assessment of their likely relative importance in contributing to soil loss. In the upper part of each hillslope, this comparison of spatial trends did not allow the dominant cause of soil erosion to be distinguished. Both the model of erosion due to cultivation and that due to hillside overland flow predicted soil accumulation in the lower valley sides where slope decreased. Neither model represented the net loss of such accumulated soil indicated by caesium-137 deficit, and this loss possibly occurred during periodically observed flooding of the valley floor, or due to surface burial with caesium-137 depleted subsoil.


2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Gebreyesus Brhane Tesfahunegn ◽  
Lulseged Tamene ◽  
Paul L. G. Vlek

Even though scientific information on spatial distribution of hydrophysical parameters is critical for understanding erosion processes and designing suitable technologies, little is known in Geographical Information System (GIS) application in developing spatial hydrophysical data inputs and their application in Morgan-Morgan-Finney (MMF) erosion model. This study was aimed to derive spatial distribution of hydrophysical parameters and apply them in the Morgan-Morgan-Finney (MMF) model for estimating soil erosion in the Mai-Negus catchment, northern Ethiopia. Major data input for the model include climate, topography, land use, and soil data. This study demonstrated using MMF model that the rate of soil detachment varied from <20 t ha−1y−1to >170 t ha−1y−1, whereas the soil transport capacity of overland flow (TC) ranged from 5 t ha−1y−1to >42 t ha−1y−1. The average soil loss estimated by TC using MMF model at catchment level was 26 t ha−1y−1. In most parts of the catchment (>80%), the model predicted soil loss rates higher than the maximum tolerable rate (18 t ha−1y−1) estimated for Ethiopia. Hence, introducing appropriate interventions based on the erosion severity predicted by MMF model in the catchment is crucial for sustainable natural resources management.


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