Artykuły w czasopismach na temat „Rainfall detachment”
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1
Tan, Soon-Keat. "Rainfall and soil detachment". Journal of Hydraulic Research 27, nr 5 (wrzesień 1989): 699–715. http://dx.doi.org/10.1080/00221688909499119.
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Proffitt, APB, CW Rose i CJ Lovell. "A comparison between modified splash-cup and flume techniques in differentiating between soil loss and detachability as a result of rainfall detachment and deposition". Soil Research 27, nr 4 (1989): 759. http://dx.doi.org/10.1071/sr9890759.
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Temporal changes in soil loss rates as a result of rainfall detachment were measured in modified splash-cups (kc) for two contrasting soil types with 5 mm depth of surface water at two constant rainfall rates (56 and 100 mm h-1). Results were compared with those from a flume (kf) for the same rainfall duration, rainfall rates, soil types and water depth. Reasons are given why soil loss rate commonly measured from splash-cups is not a true measure of soil detachment by rainfall when surface water is present. In order to yield the true rate of soil detachment, the measured net rate of soil loss must be augmented by a correction accounting for the rate of deposition. Theory for the net outcome of rainfall detachment and sediment deposition was used to interpret net soil loss data at equilibrium from splash-cups to yield true soil detachment rates (eTc), and compared those from a flume (eTf ). The two soil types were a cracking clay (black earth or Vertisol) and a slightly dispersive sandy clay loam (solonchak or Aridisol). Splash-cup modification allowed the proportion of sediment lost as airsplash (and therefore not deposited within the splash-cup) to be quantified to allow calculation of true soil detachment rates, and hence true soil detachabilities. Under constant rainfall rates and water depth, kc decreased significantly (5% level) with time until an equilibrium detachment rate was reached. This decrease was attributed to the development of a deposited layer on the soil surface, coarser in texture than the original soil. Values of kc were higher for the solonchak than the black earth, and increased with rainfall rate. At equilibrium, eTc and qf were approximately three orders of magnitude greater than kcand kf, illustrating the importance of recognizing the deposition process in determining true rates of soil detachment and soil detachabilities. There was no significant difference (5% level) between kc and kf at equilibrium for the black earth, but values of kc were significantly higher (5% level) than kf for the solonchak. There were no significant differences (5% level) between qc and eTf for both soil types at the low rainfall rate, but eTc were significantly lower than eTf for both the black earth (5% level) and solonchak (0.1% level) at the high rate.
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Proffitt, APB, i CW Rose. "Soil erosion processes. I. The relative importance of rainfall detachment and dunoff entrainment". Soil Research 29, nr 5 (1991): 671. http://dx.doi.org/10.1071/sr9910671.
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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.
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Di Napoli, Mariano, Diego Di Martire, Giuseppe Bausilio, Domenico Calcaterra, Pierluigi Confuorto, Marco Firpo, Giacomo Pepe i Andrea Cevasco. "Rainfall-Induced Shallow Landslide Detachment, Transit and Runout Susceptibility Mapping by Integrating Machine Learning Techniques and GIS-Based Approaches". Water 13, nr 4 (13.02.2021): 488. http://dx.doi.org/10.3390/w13040488.
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Rainfall-induced shallow landslides represent a serious threat in hilly and mountain areas around the world. The mountainous landscape of the Cinque Terre (eastern Liguria, Italy) is increasingly popular for both Italian and foreign tourists, most of which visit this outstanding terraced coastal landscape to enjoy a beach holiday and to practice hiking. However, this area is characterized by a high level of landslide hazard due to intense rainfalls that periodically affect its rugged and steep territory. One of the most severe events occurred on 25 October 2011, causing several fatalities and damage for millions of euros. To adequately address the issues related to shallow landslide risk, it is essential to develop landslide susceptibility models as reliable as possible. Regrettably, most of the current land-use and urban planning approaches only consider the susceptibility to landslide detachment, neglecting transit and runout processes. In this study, the adoption of a combined approach allowed to estimate shallow landslide susceptibility to both detachment and potential runout. At first, landslide triggering susceptibility was assessed using Machine Learning techniques and applying the Ensemble approach. Nine predisposing factors were chosen, while a database of about 300 rainfall-induced shallow landslides was used as input. Then, a Geographical Information System (GIS)-based procedure was applied to estimate the potential landslide runout using the “reach angle” method. Information from such analyses was combined to obtain a susceptibility map describing detachment, transit, and runout. The obtained susceptibility map will be helpful for land planning, as well as for decision makers and stakeholders, to predict areas where rainfall-induced shallow landslides are likely to occur in the future and to identify areas where hazard mitigation measures are needed.
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J. P. Schultz, A. R. Jarrett i J. R. Hoover. "Detachment and Splash of a Cohesive Soil by Rainfall". Transactions of the ASAE 28, nr 6 (1985): 1878–84. http://dx.doi.org/10.13031/2013.32535.
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Ekwue, E. I., i J. O. Ohu. "A model equation to describe soil detachment by rainfall". Soil and Tillage Research 16, nr 3 (maj 1990): 299–306. http://dx.doi.org/10.1016/0167-1987(90)90103-k.
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Parsons, Anthony J., i Alan M. Gadian. "Uncertainty in modelling the detachment of soil by rainfall". Earth Surface Processes and Landforms 25, nr 7 (2000): 723–28. http://dx.doi.org/10.1002/1096-9837(200007)25:7<723::aid-esp127>3.0.co;2-x.
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Palis, RG, G. Okwach, CW Rose i PG Saffigna. "Soil erosion processes and nutrient loss. II. The effect of surface contact cover and erosion processes on enrichment ratio and nitrogen loss in eroded sediment". Soil Research 28, nr 4 (1990): 641. http://dx.doi.org/10.1071/sr9900641.
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Thirty-five erosion experiments, involving four levels of surface contact cover by corn stalks and corn leaves (the latter represented by flat metal sheets) on three slopes, were carried out under simulated rainfall to investigate the effect of fractional surface contact cover and type on the loss and enrichment ratio (ER) of nitrogen in eroded sediment. All experiments were in a tilting flume of the simulated rainfall facility with a sandy clay loam soil. Experiments with rainfall detachment as the only erosion process were conducted on a low slope of 0.1%, to prevent entrainment occurring. The simulated rainfall rate was 100 mm h-1, and sediment samples were collected at the flume exit for up to 40 min. In experiments with entrainment as the only erosion process, clear water was applied as runon at the top of the flume. A stream power of 0 33 W m-2 was used and maintained with entrainment alone and in experiments with rainfall and runon combined for both 3 and 6% slopes. Sediment samples were fractionated through a series of sieves and total nitrogen was analysed for each size range to give the enrichment ratio (ER). The aggregate size or settling velocity characteristics, enrichment ratio (ER), and total nitrogen loss of the eroded sediment varied considerably with slope and cover types for the different erosion experiments. As cover by corn stalks increased, the settling velocity characteristics of eroded sediment became finer; the degree of this fineness was greater than when simulated leaves provided the same cover. For the rainfall detachment alone experiments, values of ER were greater than unity for both cover types and slopes, and greater than values for all other experiments. For the combined rainfall and runon experiments, ER was higher for corn stalks than simulated leaves. For experiments with entrainment alone, values of ER were close to unity for both cover types and slope, even by the early sampling time of 0.6 min. It may be concluded that the effectiveness of cover in reducing nutrient loss lies in reducing sediment loss, not in reducing ER. When rainfall detachment and entrainment were applied together, sediment concentration and total nitrogen loss were substantially increased over the sum of the contribution of rainfall detachment and entrainment acting alone. This finding indicates synergism in nutrient loss between these two erosion processes.
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Brodie, I. M. "Prediction of stormwater particle loads from impervious urban surfaces based on a rainfall detachment index". Water Science and Technology 55, nr 4 (1.02.2007): 49–56. http://dx.doi.org/10.2166/wst.2007.094.
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This paper makes use of Non-Coarse Particle (NCP) data collected from three different impervious surfaces in Toowoomba, Australia. NCP is defined as suspended solids less than 500 μm in size. NCP loads (in mg/m2) were derived for 24 storms from a galvanized iron roof, a concrete car park and a bitumen road pavement. A scatter plot analysis was used to identify potential correlations between NCP loads and basic rainfall parameters such as rainfall depth and intensity. An exponential-type trend, consistent with many washoff models, was evident between load and average rainfall intensity for all surfaces. However, load data for some storms did not fit this general trend. Various indices, comprising different combinations of basic rainfall parameters, were evaluated as an alternative to rainfall intensity. A composite index, referred to as the Rainfall Detachment Index, was found to be better than average rainfall intensity in explaining a relationship between NCP load and storm rainfall characteristics. The selected rainfall index utilizes 6-minute rainfall intensities and is a variant of the well known Rainfall Erosivity Index (EI30) used for soil erosion estimation.
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Ranaivoson, Andry Z., i John F. Moncrief. "Filtration capacity of a gravel inlet system under low accumulation conditions". International Journal of Hydrology 4, nr 5 (14.10.2020): 257–68. http://dx.doi.org/10.15406/ijh.2020.04.00253.
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Filtration models were applied to a gravel inlet system to estimate attachment and/or detachment of particles onto collectors (gravel grain). Two methods were used to estimate total solidstrapping efficiency at the gravel inlet: mass concentration and particle count. The first method provided trapping estimate between 11% and 22% based on two averaging computations. The second method, particle count, showed that detachment of total solids occurred mostly with the clay size category and early duringrainfall events. Detachment reveals the quality of effluent and can be interpreted as particles being detached either from previous total solids deposit or not being retained by the collector. Based on a model by Rajagopalan and Tien, trapping ability of gravel inlet was expected to be relatively low (<50%) for particles and aggregates smaller than 100 μm. Five rainfall events in 2002 were analyzed and showed that the first event had a retention capacity of 32% with a significant statistical difference between pairs of samples from “above” and “below” the gravel, based on a paired t-test. The following rainfall events had not seen any significant difference based on the same statistical test between the above and below water samples; however, the pattern of retention within pairs of samples showed that large filtration values were associated with incoming large solids concentrations, which, in turn, are related to rainfall bursts. The laser diffractometer technique allowed the particle count method to estimate number of particles retained or detached with respect to the gravel media. Particle count was obtained by direct measurement in the fine silt and clay size region and by extrapolation of measured data for large size in the silt-sand region including small particles and aggregates. Two rainfall events (August 3 and 21) showed important detachment based on particle counting method.
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Hussein, Mohammad H. "A sheet erodibility parameter for water erosion modeling in regions with low intensity rain". Hydrology Research 44, nr 6 (16.01.2013): 1013–21. http://dx.doi.org/10.2166/nh.2013.029.
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Soil erodibility reflects the soil effect on the detachment process by rainfall and runoff; an evaluation of this parameter for single storm events was carried out using natural runoff plot data collected for two rainfall seasons in northern Iraq. The region is characterized by a semiarid Mediterranean-type climate with normal rainfall intensity below 20 mm/h and dominant sheet erosion on agricultural land. The plots were three 30 × 3 m and three 10 × 3 m, in fallow, situated on a 6% uniform slope; the soil at the site has a silty clay loam texture and belongs to the Calciorthid suborder. Sheet erosion rate was assumed linearly proportional to the storm power and the sheet flow power; a steady-state turbulent and kinematic sheet flow was also assumed. The results indicated a dominant detachment by rainfall with a substantial variability in storm by storm calculated sheet erodibility. The two-parameter lognormal probability distribution fitted the obtained sheet erodibility values reasonably well. Using this probability distribution, a representative sheet erodibility value of 0.056 × 10−3kg/J was obtained for use at the experimental site.
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Zumr, David, Danilo Vítor Mützenberg, Martin Neumann, Jakub Jeřábek, Tomáš Laburda, Petr Kavka, Lisbeth Lolk Johannsen i in. "Experimental Setup for Splash Erosion Monitoring—Study of Silty Loam Splash Characteristics". Sustainability 12, nr 1 (24.12.2019): 157. http://dx.doi.org/10.3390/su12010157.
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An experimental laboratory setup was developed and evaluated in order to investigate detachment of soil particles by raindrop splash impact. The soil under investigation was a silty loam Cambisol, which is typical for agricultural fields in Central Europe. The setup consisted of a rainfall simulator and soil samples packed into splash cups (a plastic cylinder with a surface area of 78.5 cm2) positioned in the center of sediment collectors with an outer diameter of 45 cm. A laboratory rainfall simulator was used to simulate rainfall with a prescribed intensity and kinetic energy. Photographs of the soil’s surface before and after the experiments were taken to create digital models of relief and to calculate changes in surface roughness and the rate of soil compaction. The corresponding amount of splashed soil ranged between 10 and 1500 g m−2 h−1. We observed a linear relationship between the rainfall kinetic energy and the amount of the detached soil particles. The threshold kinetic energy necessary to initiate the detachment process was 354 J m−2 h−1. No significant relationship between rainfall kinetic energy and splashed sediment particle-size distribution was observed. The splash erosion process exhibited high variability within each repetition, suggesting a sensitivity of the process to the actual soil surface microtopography.
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Boussaadi, Mounia, i Liatim Mouzai. "Vegetation cover effects on sediment concentration and overland flow under artificial rainfall intensity". Journal of the Geographical Institute Jovan Cvijic, SASA 71, nr 2 (2021): 135–50. http://dx.doi.org/10.2298/ijgi2102135b.
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Soil erosion depends on a number of factors including rainfall intensity, density of plant cover, and area cover. The objective of this study is to investigate the impact of these factors on flow velocity, overland flow regimes, sediment concentration, and absolute soil detachment. The soil used in this study was sandy remolded agricultural soil. The soil is packed in a tray of 1 m2 fixed on a slope of 3%; five different intensities were simulated under different vegetation cover (density and area). The results indicated that the overland flow velocity with vegetation cover was best described by polynomial function. The mean flow velocity varied from 0.021 to 1.244 m/s. Overland flow regime is subcritical and laminar. However, there are significant relationships between the vegetation cover density and sediment concentration and absolute soil detachment. The sediment concentration ranged from 1.38 to 5.65 kg/m3 whereas the absolute soil detachment ranged from 0.021?10-3 to 1.244?10-3 kg/m2/s. Finally, the vegetation cover presented a good protector to soil sediment from erosion.
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Naves, Juan, Jose Anta, Joaquín Suárez i Jerónimo Puertas. "Development and Calibration of a New Dripper-Based Rainfall Simulator for Large-Scale Sediment Wash-Off Studies". Water 12, nr 1 (4.01.2020): 152. http://dx.doi.org/10.3390/w12010152.
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Rainfall simulators are useful tools for controlling the main variables that govern natural rainfall. In this study, a new drop-forming rainfall simulator, which consists of pressure-compensating dripper grids above a horizontal mesh that breaks and distributes raindrops, was developed to be applied in wash-off experiments in a large-scale physical model of 36 m2. The mesh typology and size, and its distance to drippers, were established through a calibration where rain uniformity and distributions of raindrop sizes and velocities were compared with local natural rainfall. Finally, the rain properties of the final solution were measured for the three rain intensities that the rainfall simulator is able to generate (30, 50 and 80 mm/h), obtaining almost uniform rainfalls with uniformity coefficients of 81%, 89% and 91%, respectively. This, together with the very suitable raindrop size distribution obtained, and the raindrop velocities of around 87.5% of the terminal velocity for the mean raindrop diameter, makes the proposed solution optimal for wash-off studies, where rain properties are key in the detachment of particles. In addition, the flexibility seen in controlling rain characteristics increases the value of the proposed design in that it is adaptable to a wide range of studies.
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Palis, RG, G. Okwach, CW Rose i PG Saffigna. "Soil erosion processes and nutrient loss. 1. The interpretation of enrichment ratio and nitrogen loss in runoff sediment". Soil Research 28, nr 4 (1990): 623. http://dx.doi.org/10.1071/sr9900623.
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The ratio of nutrient concentration in eroded sediment to that in the original soil (the enrichment ratio, ER) commonly varies with the accumulated soil loss. The objective of this study was to investigate possible factors contributing to this change in ER when erosion was accompanied by a significant depth of water. The enrichment ratio was directly measured on sediment from a sandy clay loam soil. ER was followed as a function of time for eight erosion experiments in which the mix of erosion processes and the fractional surface cover was varied. By using a simulated rainfall tilting flume facility, experiments covered low slope (0.1%), when rainfall detachment was the only erosion process, and 3% soil surface slope, where the processes of rainfall detachment and entrainment occurred. The type and extent of fractional surface cover was varied for the experiments with the 3% slope. In all cases, the rainfall rate was 100 mm h-1and the drop size was 2.2 mm. A new analytical framework is described, showing that ER can be interpreted from the product of two component distributions. The first component distribution is the concentration of sediment as a function of sediment size (a distribution found to vary with time and mix of erosion processes). The second distribution is nitrogen concentration (largely organic) as a function of size (found to be much less time-variable than sediment size). The conclusions reached, after analysis of these experimental data by using this framework, were: (i) time variation in ER was largely due to time variation in the first component distribution; (ii) values of ER different from unity require some variation with sediment size (or settling velocity) in the concentration of the nutrient sorbed to the soil or closely associated with the soil organic matter; (iii) the more that rainfall detachment dominates runoff erosion as the major erosion process, the more likely it is that ER is greater than unity.
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R. P. C. Morgan. "Effect of Corn and Soybean Canopy on Soil Detachment by Rainfall". Transactions of the ASAE 28, nr 4 (1985): 1135–40. http://dx.doi.org/10.13031/2013.32401.
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TRUMAN, CLINTON C., i JOE M. BRADFORD. "EFFECT OF ANTECEDENT SOIL MOISTURE ON SPLASH DETACHMENT UNDER SIMULATED RAINFALL". Soil Science 150, nr 5 (listopad 1990): 787–98. http://dx.doi.org/10.1097/00010694-199011000-00005.
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Ekwue, E. T. "Quantification of the effect of peat on soil detachment by rainfall". Soil and Tillage Research 23, nr 1-2 (luty 1992): 141–51. http://dx.doi.org/10.1016/0167-1987(92)90010-9.
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Defersha, M. B., S. Quraishi i A. Melesse. "Interrill erosion, runoff and sediment size distribution as affected by slope steepness and antecedent moisture content". Hydrology and Earth System Sciences Discussions 7, nr 4 (31.08.2010): 6447–89. http://dx.doi.org/10.5194/hessd-7-6447-2010.
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Abstract. Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by erosive agents such as flowing water. The rate at which erosion occurs depends upon the individual as well as interactive effects of different parameters responsible for soil erosion. The study discusses results of a laboratory analysis and evaluates the effect of slope steepness and antecedent moisture content on sediment yield (wash) and runoff rate. Interrill sediment yield, splash detachment, runoff, and sediment size distribution were measured in laboratory erosion pans under simulated total duration of 90 min. Rainfall intensity at 120 mm/hr, 70 mm/hr, and 55 mm/hr were applied sequentially at 9, 25, and 45% slope steepness for three soils (Alemaya Black soil, Regosols, and Cambisols) varied from clay to sandy clay loam in texture with wet and dry antecedent water contents. As slope steepness increased from 9 to 25% splash increased for five treatments and decreased for the remaining treatment; washed sediment increased for all treatments. As slope increased from 25 to 45% splash decreased for five treatments but increased for one treatment, and washed sediment increased for three treatments but decreased for the other three treatments. Pre-wetting decreased splash detachment for all soil treatments and rate of reduction was high for the highly aggregated soil, Alemaya Black soil and low for the less aggregated soil Regosols. Splash sediment and sediment yield was not correlated. Change in splash with increase in slope steepness was also not correlated with change in sediment yield. Change in runoff rate with increase in slope steepness was correlated (r=0.66) with change in sediment yield. For Alemaya Black soil and Regosols, splashed sediment size distribution was correlated with washed sediment size distribution. Interrill erosion models that include runoff and rainfall intensity parameters were a better fit for these data than the rainfall intensity based model. The exponent term, b, values in (E=a Ib) model did not approach 2.00 for all treatments. For the same slope steepness factor, both rainfall and rainfall-runoff based models provided different erodibility coefficients at different levels of slope and moisture contents.
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Proffitt, A. P. B., C. W. Rose i P. B. Hairsine. "Rainfall Detachment and Deposition: Experiments with Low Slopes and Significant Water Depths". Soil Science Society of America Journal 55, nr 2 (1991): 325. http://dx.doi.org/10.2136/sssaj1991.03615995005500020004x.
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Onyelowe, Kennedy C., Ahmed M. Ebid i Light Nwobia. "Evolutionary Prediction of Soil Loss from Observed Rainstorm Parameters in an Erosion Watershed Using Genetic Programming". Applied and Environmental Soil Science 2021 (20.09.2021): 1–15. http://dx.doi.org/10.1155/2021/2630123.
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Various environmental problems such as soil degradation and landform evolutions are initiated by a natural process known as soil erosion. Aggregated soil surfaces are dispersed through the impact of raindrop and its associated parameters, which were considered in this present work as function of soil loss. In an attempt to monitor environmental degradation due to the impact of raindrop and its associated factors, this work has employed the learning abilities of genetic programming (GP) to predict soil loss deploying rainfall amount, kinetic energy, rainfall intensity, gully head advance, soil detachment, factored soil detachment, runoff, and runoff rate database collected over a three-year period as predictors. Three evolutionary trials were executed, and three models were presented considering different permutations of the predictors. The performance evaluation of the three models showed that trial 3 with the highest parametric permutation, i.e., that included the influence of all the studied parameters showed the least error of 0.1 and the maximum coefficient of determination (R2) of 0.97 and as such is the most efficient, robust, and applicable GP model to predict the soil loss value.
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Angulo-Martínez, M., i S. Beguería. "Trends in rainfall erosivity in NE Spain at annual, seasonal and daily scales, 1955–2006". Hydrology and Earth System Sciences Discussions 9, nr 5 (16.05.2012): 6285–309. http://dx.doi.org/10.5194/hessd-9-6285-2012.
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Abstract. Rainsplash – the detachment and transport of soil particles by the impact of raindrops on a bare soil – is a major mechanism of soil degradation and erosion on semiarid areas and agricultural lands. Rainfall erosivity refers to the ability of precipitation to erode soil, and depends on the characteristics of the raindrops – size and velocity – and on the rainfall intensity and duration. Despite the relevance of rainfall erosivity for soil degradation prevention very few studies addressed its spatial and temporal variability. On this study the time variation of rainfall erosivity in the Ebro valley (NE Spain) is assessed for the period 1955–2006. The results show a general decrease in annual and seasonal rainfall erosivity, which is explained by a decrease of very intense rainfall events whilst the frequency of moderate and low events increased. This trend is related to prevailing positive conditions of the main atmospheric teleconnection indices affecting the West Mediterranean, i.e. the North Atlantic Oscillation (NAO), the Mediterranean Oscillation (MO) and the Western Mediterranean Oscillation (WeMO).
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Alaimo, Andrea, Mauro De Marchis, Gabriele Freni, Antonio Messineo i Dario Ticali. "Concept of a New Pluviometer for Metering Rainfall Erosivity". Advanced Materials Research 452-453 (styczeń 2012): 316–20. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.316.
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Rainfall is the main driver of several natural phenomena having a large impact on human activities. Its monitoring is then very important for natural disaster prevention and for the preservation of the environment. One important phenomenon is related to soil displacement due to rainfall impact. The intensity of physical soil degradation, detachment and transport of soil particles by raindrop splash and interrill erosion is largely controlled by rainfall characteristics. There is still a lot of debate as to whichparameter expresses the best rainfall erosivity. Due to the limited data ondrop-size distribution of natural rainfall and the time consuming nature of methods to obtain these data, rain erosivity parameters are commonly obtained from empirical relationships based on rainfall intensity. This paper describes an a new pluviometer able to measure several raindrop variables and assess rainfall kinetic energy at the impact with the ground. It enables one to measure drop size and drop velocity in real time and thus any parameter linked to rainfall erosivity. The pluviometer is based on the combination of optical and electrical sensors and it is based on cheap technologies in order to allow the easy distribution of several monitoring station on the analyzed area. A description of the device and of its sensor is presented in the present paper.
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Mineo, Claudio, Elena Ridolfi, Benedetta Moccia, Fabio Russo i Francesco Napolitano. "Assessment of Rainfall Kinetic-Energy–Intensity Relationships". Water 11, nr 10 (25.09.2019): 1994. http://dx.doi.org/10.3390/w11101994.
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Raindrop-impact-induced erosion starts when detachment of soil particles from the surface results from an expenditure of raindrop energy. Hence, rain kinetic energy is a widely used indicator of the potential ability of rain to detach soil. Although it is widely recognized that knowledge of rain kinetic energy plays a fundamental role in soil erosion studies, its direct evaluation is not straightforward. Commonly, this issue is overcome through indirect estimation using another widely measured hydrological variable, namely, rainfall intensity. However, it has been challenging to establish the best expression to relate kinetic energy to rainfall intensity. In this study, first, kinetic energy values were determined from measurements of an optical disdrometer. Measured kinetic energy values were then used to assess the applicability of the rainfall intensity relationship proposed for central Italy and those used in the major equations employed to estimate the mean annual soil loss, that is, the Universal Soil Loss Equation (USLE) and its two revised versions (RUSLE and RUSLE2). Then, a new theoretical relationship was developed and its performance was compared with equations found in the literature.
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Hairsine, P. B., i C. W. Rose. "Rainfall Detachment and Deposition: Sediment Transport in the Absence of Flow-Driven Processes". Soil Science Society of America Journal 55, nr 2 (1991): 320. http://dx.doi.org/10.2136/sssaj1991.03615995005500020003x.
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Wirtz, S., T. Iserloh, G. Rock, R. Hansen, M. Marzen, M. Seeger, S. Betz i in. "Soil Erosion on Abandoned Land in Andalusia: A Comparison of Interrill- and Rill Erosion Rates". ISRN Soil Science 2012 (14.11.2012): 1–16. http://dx.doi.org/10.5402/2012/730870.
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The present paper is based on several field investigations (monitoring soil and rill erosion by aerial photography, rainfall simulations with portable rainfall simulators, and manmade rill flooding) in southern Spain. Experiments lead now to a closer understanding of the dynamics and power of different soil erosion processes in a gully catchment area. The test site Freila (Andalusia, Spain) covers an area of 10.01 ha with a rill density of 169 m ha−1, corresponding to a total rill length of 1694 m. Assuming an average rill width of 0.15 m, the total rill surface can be calculated at 250 m2 (0.025 ha). Given that, the surface covered by rills makes up only 0.25% of the total test site. Since the rill network drains 1.98 ha, 20% of the total runoff comes from rills. The rills’ sediment erosion was measured and the total soil loss was then calculated for detachment rates between 1685 g m−2 and 3018 g m−2. The interrill areas (99.75% of the test site) show values between 29 and 143 g m−2. This suggests an important role of rill erosion concerning runoff and soil detachment.
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Silva, Thaís Rayane Gomes da, João Pedro Scholze de Oliveira, Márcio Aurélio Lins dos Santos, Marcelo Rodrigues Barbosa Júnior, Fabiana Fontes da Silva, Valdevan Rosendo dos Santos i Cícero Gomes dos Santos. "Estimate of the rain erosivity in the municipality of Piaçabuçu-AL". COLLOQUIUM AGRARIAE 17, nr 6 (19.12.2021): 45–56. http://dx.doi.org/10.5747/ca.2021.v17.n6.a468.
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Soil erosion is a process caused by several factors, including precipitation. Causing the water erosive process, through the detachment and transport by surface runoff of soil particles.This phenomenon depends on the intensity, frequency and duration of eventsin a given region. Thus, the objective was to determine the rainfall erosivity indices through rainfall data. The period of rainfall data used was between the years 1943 to 1985, for the municipality of Piaçabuçu, located in the lower São Francisco Alagoano region. These data were tabulated to calculate rainfall, rainfall coefficient and its relation to erosivity using six equations. The municipality of Piaçabuçu has an average annual rainfall distribution of 1128.52 mm for the observation period of 42 years, with a wide variation in the distribution of rainfall over the years, with the rainy season concentrated in the months of March to August , presenting average values above the average, in this period it precipitated more than 70% of the rains for the municipality.Todos os seis modelos de estimativas da erosividade apresentaram correlação considerada alta, o que os capacita para a estimativa da erosividade do município em estudo.All six erosivity estimation models presented a high correlation, which enables them to estimate the erosivity of the municipality under study.
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Patriche, Cristian Valeriu, Bogdan Roșca, Radu Gabriel Pîrnău, Ionuț Vasiliniuc i Liviu Mihai Irimia. "Simulation of Rainfall Erosivity Dynamics in Romania under Climate Change Scenarios". Sustainability 15, nr 2 (12.01.2023): 1469. http://dx.doi.org/10.3390/su15021469.
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Soil erosion is triggered by rainfall through the detachment of soil particles and their transport downslope, playing a key role in soil erosion models. Together with the vegetation cover, rainfall is a temporal dynamic factor, inducing corresponding time variations of erosion rates. Under current climate change, rainfall is also changing its characteristics and our study aimed to reveal whether these changes will significantly affect rainfall erosivity in Romania, and implicitly the soil erosion. To achieve this purpose, we developed a statistical non-parametric model for predicting rainfall erosivity on the basis on the modified Fournier index and applied it to future precipitation evolution scenarios. The precipitation data were extracted from the CHESLA database for the Romanian territory for two climate change contrasting scenarios (RCP 4.5 and 8.5). Average predictions from five selected climate models were used in order to minimize prediction uncertainty. The results show that rainfall erosivity is likely to increase, at least during the 2041–2060 period, especially in the south-western, western and eastern part of the country, which may cause a corresponding increase in soil erosion rates, with an average of 1–2 t ha−1 yr−1. During the 2061–2080 period, rainfall erosivity is likely to decrease in central and eastern Romania.
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Adewumi, Johnson Kayode, John Jiya Musa, Olayemi Johnson Adeosun, Otuaro Ebierin Akpoebidimiyen, Adebola Adekunle i Babafemi Sunday Adewumi. "Soil Detachment with Organic Mulching Using Rainfall Simulator in Comparison with a Short Duration Natural Rainfall for Effective Soil Conservation". Journal of Environmental Protection 11, nr 06 (2020): 457–69. http://dx.doi.org/10.4236/jep.2020.116027.
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de Luna, E., A. Laguna i J. V. Giráldez. "The role of olive trees in rainfall erosivity and runoff and sediment yield in the soil beneath". Hydrology and Earth System Sciences 4, nr 1 (31.03.2000): 141–53. http://dx.doi.org/10.5194/hess-4-141-2000.
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Abstract. The modification of raindrops by the canopy of olive trees increases the kinetic energy of the rain per unit area. The kinetic energy computed from the measured drop size distribution under the tree canopy in simulated rainfall experiments is greater than that received in the open, 17.1 J mm-1, as against 15.7 J mm-1 . This causes higher soil detachment and loss than that observed outside the canopy. Tillage treatments of the soil modify its erodibility, accelerate soil detachment and reduce, simultaneously, the velocity of runoff. Both effects reduce the amount of sediment compared to that observed in the non-tilled soil. The average values of soil lost per unit of rain depth and unit area were 5.81 g mm-1 m-2 (conventional tillage) and 4.02 g mm-1 m-2 (zero tillage) under the canopy compared to 0.89 g mm-1 m-2 (conventional tillage) and 0.95 g mm-1 m-2 (zero tillage) in the open.
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Johannsen, Lisbeth Lolk, Nives Zambon, Peter Strauss, Tomas Dostal, Martin Neumann, David Zumr, Thomas A. Cochrane i Andreas Klik. "Impact of Disdrometer Types on Rainfall Erosivity Estimation". Water 12, nr 4 (28.03.2020): 963. http://dx.doi.org/10.3390/w12040963.
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Soil erosion by water is affected by the rainfall erosivity, which controls the initial detachment and mobilization of soil particles. Rainfall erosivity is expressed through the rainfall intensity (I) and the rainfall kinetic energy (KE). KE–I relationships are an important tool for rainfall erosivity estimation, when direct measurement of KE is not possible. However, the rainfall erosivity estimation varies depending on the chosen KE–I relationship, as the development of KE–I relationships is affected by the measurement method, geographical rainfall patterns and data handling. This study investigated how the development of KE–I relationships and rainfall erosivity estimation is affected by the use of different disdrometer types. Rainfall data were collected in 1-min intervals from six optical disdrometers at three measurement sites in Austria, one site in Czech Republic and one site in New Zealand. The disdrometers included two disdrometers of each of the following types: the PWS100 Present Weather Sensor from Campbell Scientific, the Laser Precipitation Monitor from Thies Clima and the first generation Parsivel from OTT Hydromet. The fit of KE–I relationships from the literature varied among disdrometers and sites. Drop size and velocity distributions and developed KE–I relationships were device-specific and showed similarities for disdrometers of the same type across measurement sites. This hindered direct comparison of results from different types of disdrometers, even when placed at the same site. Thus, to discern spatial differences in rainfall characteristics the same type of measurement instrument should be used.
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Terry, James P. "A rainsplash component analysis to define mechanisms of soil detachment and transportation". Soil Research 36, nr 3 (1998): 525. http://dx.doi.org/10.1071/s97078.
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Rainsplash is a term that has been used to describe a wide variety of effects caused by the impact of raindrops on soils. This is because rainsplash, even by individual drops, is not a single process but a combination of several discrete but interacting soil particle detachment and transport mechanisms. Because there are a number of possible rainsplash sub-processes that may operate on soils, some of the terminology used in splash studies is inconsistent. In response, this paper reviews some of the past research on raindrop{soil interactions, as well as incorporating observations by the author, in order to clarify the definitions used to describe soil dispersal mechanisms during drop impact. Five main mechanisms are identified, and defined as (1) aggregate breakdown, (2) cratering, (3) splashing, (4) splash saltation, and (5) splash creep, several of which are illustrated with photographic and video techniques under laboratory splash tests. For rainfall in field conditions, an integrated ‘component approach’ introduces a more expansive and flexible approach to rainsplash on soils than is currently available, by considering this geomorphological process as a suite of discrete but interacting mechanisms, varying with changing rainfall and soil characteristics during storms. Some implications of this concept for erosion studies in splash-prone areas are examined.
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DAS, SUSANTA, RANJIT DAS, PRADIP KUMAR BORA i MANISH OLANIYA. "Estimation of rainfall erosivity (R) using Geo-spatial technique for the state of Tripura, India: A comparative study". Indian Journal of Agricultural Sciences 92, nr 7 (4.04.2022): 831–35. http://dx.doi.org/10.56093/ijas.v92i7.104246.
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The principal-agent of soil detachment is rainfall kinetic energy (KE), which must be assessed to understandthe nature of erosion, particularly in high rainfall regions, and is designated as a rainfall erosivity index (R). Thepresent study aimed to develop and choose an appropriate model for estimating the R factor in the Indian state ofTripura. The study employed the following three models: KE>25 index model, average annual rainfall model, andmonthly and average annual rainfall model. The rainfall data were collected from MOSDAC and https://www.worldweatheronline.com for the calculation of point R-value. The interpolation technique (Kriging) in the ArcGISenvironment was adopted to find the spatial variation of the rainfall and R factor over the region. The average annual R factor of the study area was 1089.89, 533.17, and 2452.27 MJ mm/ha/h/y as calculated by Model-1, Model-2,and Model-3, respectively, for the study period (2008–17). The results show that Tripura has high rainfall erosivitywhich may lead to soil erosion. The comparative analysis shows Model-2 has underestimated approximately 70%whereas Model-3 has overestimated about 15% of the R factor values by considering Model-1 as base. The resultsdemonstrate that Model-2 can be used as an alternative for estimation of rainfall erosivity in an area where the dailyrainfall data is not available. These findings may help researchers to select a suitable method for the calculation ofrainfall erosivity factor in mountainous catchments.
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Cucchi, A., I. Q. Valsecchi, M. Alberti, P. Fassi, M. Molari i G. Mannucci. "The alerting system for hydrogeological hazard in Lombardy Region, northern Italy: rainfall thresholds triggering debris-flows and "equivalent rainfall" method". Natural Hazards and Earth System Sciences Discussions 3, nr 1 (8.01.2015): 269–90. http://dx.doi.org/10.5194/nhessd-3-269-2015.
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Abstract. The Functional Centre (CFMR) of the Civil Protection of the Lombardy Region, North Italy, has the main task of monitoring and alerting, particularly with respect to natural hazards. The procedure of early warning for hydrogeological hazard is based on a comparison of two quantities: thresholds and rainfall, both referred to a defined area and an exact time interval. The CFMR studied 52 landslide events (1987–2003) in Medium-Low Valtellina and derived a model of the critical detachment rainfall, in function of the local slope and the Curve Number CN (an empirical parameter related with the land cover and the hydrological conditions of the soil): it's physically consistent and allows a geographically targeted alerting. Moreover, rainfall thresholds were associated with a typical probability of exceedance. The processing of rainfall data is carried out through the "equivalent rainfall" method, that allows to take into account the antecedent moisture condition of the soil: in fact the hazard is substantially greater when the soil is near to saturation. The method was developed from the CN method and considers the local CN and the observed rainfall of the previous 5 days. The obtained value for the local equivalent rainfall, that combines rainfall (observed and forecasted) and local soil characteristics, is a better parameter for the evaluation of the hydrogeological hazard. The comparison between equivalent rainfall and thresholds allows to estimate the local hydrogeological hazard, displayed through hazard maps, and consequently to provide a reliable alerting activity (even localized to limited portions of the region).
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Defersha, M. B., S. Quraishi i A. Melesse. "The effect of slope steepness and antecedent moisture content on interrill erosion, runoff and sediment size distribution in the highlands of Ethiopia". Hydrology and Earth System Sciences 15, nr 7 (22.07.2011): 2367–75. http://dx.doi.org/10.5194/hess-15-2367-2011.
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Abstract. Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by the flowing water. This study discusses the results of laboratory experiments in which for three soils, the runoff depth, sediment yield, splash erosion and sediment size were measured. Rainfall intensity, slope and antecedent moisture contents were varied in the experiment. The soil types ranged from clay to sandy clay loam (Alemaya Black soil, Regosols and Cambisols). Rainfall was applied for six sequential 15-min periods with rainfall intensities varying between 55 and 120 mm h−1. The three slopes tested were 9, 25, and 45 %. Results show that as slope increased from 9 to 25 %, splash erosion and sediment yield increased. An increase in slope from 25 to 45 % generally decreases in splash erosion. Sediment yield for one soil increased and one soil decreased with slope and for the third soil the trend was different between the two initial moisture contents. Sediment yield was correlated (r = 0.66) with runoff amounts but not with splash erosion. Interrill erosion models that were based on the flowing water and rainfall intensity fitted the data better than when based on rainfall intensity solely. Models that assume a positive linear relationship between erosion and slope may overestimate sediment yield.
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Kaiser, A., F. Neugirg, M. Schindewolf, F. Haas i J. Schmidt. "Simulation of rainfall effects on sediment transport on steep slopes in an Alpine catchment". Proceedings of the International Association of Hydrological Sciences 367 (3.03.2015): 43–50. http://dx.doi.org/10.5194/piahs-367-43-2015.
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Abstract. The Alps represent a young, high mountain range which displays strong geomorphological activity. As the major source area in Central Europe, they deliver large quantities of sediment to the lowlands. However, our knowledge on process differentiation is still not sufficient to distinguish between the summer and winter periods of denudation. To increase our understanding of soil detachment, artificial rainfall experiments were carried out to generate data for the physically-based soil erosion model EROSION 2D/3D. Additionally, state-of-the-art, close-range remote sensing methods were applied to validate the results. The first rainfall simulations showed promising results for predicting denudation during the summer period, thus indicating the applicability of this experimental approach. However, further research is required for seasonal dynamics during other times of the year.
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Ngezahayo, Esdras, Michael P. N. Burrow i Gurmel S. Ghataora. "Rainfall induced erosion of soils used in earth roads". E3S Web of Conferences 92 (2019): 17006. http://dx.doi.org/10.1051/e3sconf/20199217006.
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Earth roads in rural areas of the developing world are key engines to the development of countries. They give access to education and health services, sustain agriculture and businesses, and promote social interactions between communities. However, earth roads suffer substantially from poor engineering and funding for construction and maintenance. Rainfall is probably their most dangerous enemy resulting in soil particle detachment leading to the loss of surface material. A laboratory rainfall simulator was used to identify the performance of an earth road surface compacted at the maximum dry density against rainfall energy and surface flow. Under the rain intensity of 30mm/hr, erosion increased with rain duration from 0 to 30 minutes. Fine sand (0.06 – 0.02mm) and medium sand (0.02 – 0.6mm) particles eroded faster than coarse sand (0.6 – 2mm) and gravel (> 2mm) particles of the sediments collected at 5 minutes intervals of time. Additionally, a 20cm x 20cm photograph at the same place was analysed using ImageJ software and showed reduction in number of particles from 18554 at 10 min to 5803 at 25 min as smaller particles had eroded in the meantime.
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Mafrica, Rocco, Amalia Piscopo, Alessandra De Bruno i Marco Poiana. "Effects of Climate on Fruit Growth and Development on Olive Oil Quality in Cultivar Carolea". Agriculture 11, nr 2 (10.02.2021): 147. http://dx.doi.org/10.3390/agriculture11020147.
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Trees of the olive (Olea europaea L.) cultivar Carolea grown in Calabria (Italy) in three sites with different main climate traits (temperatures, rainfall, Growth Degree Days seasonal variations) were studied for three years to see the ripening time course and quality of the oils. The optimal harvesting time for obtaining the best-quality olive oils was defined for each site. The effect on quality indexes of three harvesting periods was also considered, linking this to the observed various thermal regimes. The different climates largely affected the growth and the development of fruits and the quality of obtained oils. Lower temperatures and higher rainfall slow down fruit growth and development and delay ripening. Olive oils of good quality (free acidity, fatty acid composition, antioxidant components and oxidative stability were obtained in the site with lower temperatures and higher rainfall when fruits were still yellow-green ripe and had a detachment index between 1.9 and 1.5. Climate change, evidenced by rising temperatures, led to the movement of olive groves from the high-temperature coastal plain to the intern foothills.
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Wuddivira, Mark N., Reynold J. Stone i Edwin I. Ekwue. "Clay, Organic Matter, and Wetting Effects on Splash Detachment and Aggregate Breakdown under Intense Rainfall". Soil Science Society of America Journal 73, nr 1 (styczeń 2009): 226–32. http://dx.doi.org/10.2136/sssaj2008.0053.
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Yang, Ting, Quanjiu Wang, Laosheng Wu, Guangxu Zhao, Yanli Liu i Pengyu Zhang. "A mathematical model for soil solute transfer into surface runoff as influenced by rainfall detachment". Science of The Total Environment 557-558 (lipiec 2016): 590–600. http://dx.doi.org/10.1016/j.scitotenv.2016.03.087.
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Ekwue, E. I. "The effects of soil organic matter content, rainfall duration and aggregate size on soil detachment". Soil Technology 4, nr 3 (wrzesień 1991): 197–207. http://dx.doi.org/10.1016/0933-3630(91)90001-4.
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Cerdà, Artemi, Óscar González-Pelayo, Antonio Giménez-Morera, Antonio Jordán, Paulo Pereira, Agata Novara, Eric C. Brevik i in. "Use of barley straw residues to avoid high erosion and runoff rates on persimmon plantations in Eastern Spain under low frequency–high magnitude simulated rainfall events". Soil Research 54, nr 2 (2016): 154. http://dx.doi.org/10.1071/sr15092.
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Soil and water losses due to agricultural mismanagement are high and non-sustainable in many orchards. An experiment was set up with rainfall simulation at 78 mm h–1 over 1 hour on 20 paired plots of 2 m2 (bare and straw covered) in new persimmon plantations in Eastern Spain. Effects of straw cover on the control of soil and water losses were assessed. An addition of 60% straw cover (75 g m–2) resulted in delayed ponding and runoff generation and consequently reduced water losses from 60% to 13% of total rainfall. The straw cover reduced raindrop impact and thus sediment detachment from 1014 to 47 g plot–1 h–1. The erosion rate was reduced from 5.1 to 0.2 Mg ha–1 h–1. The straw mulch was found to be extremely efficient in reducing soil erosion rates.
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Clift, Peter D., i A. Alexander G. Webb. "A history of the Asian monsoon and its interactions with solid Earth tectonics in Cenozoic South Asia". Geological Society, London, Special Publications 483, nr 1 (18.07.2018): 631–52. http://dx.doi.org/10.1144/sp483.1.
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AbstractAlthough there is some evidence for an Eocene monsoon, the most important intensification of rainfall appears to start at c. 24 Ma in the Early Miocene. Many palaeoceanographical proxies for monsoon intensity are linked to wind and do not correlate well with humidity of the continental climate over tectonic timescales. Rainfall peaked in the middle Miocene (c. 15 Ma) with strong drying after 8 Ma. This timing does not correlate well with either initial uplift of the Tibetan Plateau or with the retreat of shallow seas from central Asia. The c. 24 Ma onset of strengthening rainfall is associated with the initiation of rapid erosion and cooling of Himalayan metamorphic rocks. The progressive detachment of the subducting Indian lithosphere from the eastern and western syntaxes at c. 25 Ma to the east-central Himalaya at c. 13–11 Ma would have produced corresponding propagation of rising Himalayan topography following release of the weight of the detached slab. Rapid uplift of the Himalayan barrier, blocking moisture-laden winds, is considered the most likely trigger for a stronger summer monsoon in South Asia, which in turn allowed faster erosion and exhumation of the Greater Himalaya after 24 Ma.
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Beguería, Santiago, Marta Angulo-Martínez, Leticia Gaspar i Ana Navas. "Detachment of soil organic carbon by rainfall splash: Experimental assessment on three agricultural soils of Spain". Geoderma 245-246 (maj 2015): 21–30. http://dx.doi.org/10.1016/j.geoderma.2015.01.010.
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Misra, RK, i CW Rose. "An examination of the relationship between erodibility parameters and soil strength". Soil Research 33, nr 4 (1995): 715. http://dx.doi.org/10.1071/sr9950715.
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Erosion rate of soil by the impact of raindrops and overland flow of water is often considered to be affected by the shear strength of surface soil. Physically based erosion models indicate a link between defined erodibility parameters and soil strength. The objectives of this paper are to determine erodibility parameters with the process-based erosion model GUEST for a. krasnozem soil of two contrasting strengths, and to examine the influence of soil strength on erodibility parameters. Soil beds of width 1 m and length 5.8 m, with and without compaction, were exposed to simulated, constant rate rainfall. A range of slopes was used. Detachment trays of width 300 mm and downslope length 200 mm containing soils of identical strength were placed at the same slope and exposed to the same rain in order to determine the effects of rainfall-driven processes alone on erosion. Soil strength was measured with a hand vane tester and a pocket penetrometer to determine whether compaction was effective in modifying soil strength. Temporal variation in sediment concentrations (c) for the large soil beds and detachment trays was measured for each slope and soil strength. The settling velocity characteristic of soil, with and without exposure to rain, was determined with the modified bottom withdrawal tube technique. Values of c decreased with increase in soil strength. The relationship between c and slope was influenced by soil strength in a manner consistent with the theoretical expectation of the role of soil strength in controlling erosion. Rilling during erosion was absent only when the soil was compacted. The average settling velocity of the soil exposed to rain (i.e. its depositability) was significantly lower than for the same soil not subjected to rain, indicating a breakdown of soil aggregates as a result of raindrop impact. Rainfall detachability parameters (estimated with GUEST) Were lower when soil strength was high. Runoff-driven erodibility parameters, namely the specific energy of entrainment (J), increased and the approximate erodibility parameter (�) decreased with increase in soil strength. The Variation in these erodibility parameters with soil strength was consistent with the theory implemented in GUEST. Detailed analysis of the relative contribution of rainfall- and runoff-driven processes to c at varying stream powers and soil strengths indicated that, at high soil strength, uncertainty in the values of J and � is high because of the higher contribution to c of rainfall-driven rather than runoff-driven processes. The adequacy of in situ measurement of soil strength as an indicator of soil erodibility is discussed in relation to the results presented.
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Scherer, U., i E. Zehe. "Predicting land use and soil controls on erosion and sediment redistribution in agricultural loess areas: model development and cross scale verification". Hydrology and Earth System Sciences Discussions 12, nr 3 (31.03.2015): 3527–92. http://dx.doi.org/10.5194/hessd-12-3527-2015.
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Abstract. This study quantifies soil and land use controls on sediment mobilisation and redistribution in cultivated loess soil landscapes, as these landscapes are frequently used for intensive cultivation and are highly susceptible to erosion. To this end we developed and verified a process based model named CATFLOW-SED at the plot, hillslope and catchment scales. The model relies on an explicit representation of hillslopes and their dominant physiographical characteristics which control overland flow formation, particle detachment and sediment redistribution (transport and sedimentation). Erosion processes are represented by means of the steady state approximation of the sediment continuity equation, their interaction is conceptualized based on the sediment transport capacity of overland flow. Particle detachment is represented by means of a threshold approach accounting for the attacking forces of rainfall and overland flow which need to exceed a threshold in soil erosion resistance to mobilize soil particles (Scherer et al., 2012). Transport capacity of overland flow is represented as proposed by Engelund and Hansen (1967). Top soil particles and aggregates are detached and transported according to their share in the particle size distribution. Size selective deposition of soil particles is determined based on the sink velocity of the various particle size classes. CATFLOW-SED was verified on the plot, hillslope and catchment scale, where either particle detachment or lateral redistribution or sedimentation is the limiting factor, to check whether the respective parameterizations are transferable for simulations at the next higher scale. For verification we used the Weiherbach data set providing plot scale rainfall simulation experiments, long term monitoring of sediment yields on a selected hillslope as well as observed sediment fluxes at the catchment outlet. Our findings corroborate that CATFLOW-SED predicted the sediment loads at all scales within the error margin of the measurements. An accurate prediction of overland flow turned out as being necessary and sufficient to guarantee spatial transferability of erosion parameters optimized at smaller scales to the next higher scale without need for further calibration. Based on the verified model setup, we investigate the efficiency of land use management to mitigate measures in erosion scenarios for cultivated loess landscapes.
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Williams, C. Jason, Frederick B. Pierson, Peter R. Robichaud, Osama Z. Al-Hamdan, Jan Boll i Eva K. Strand. "Structural and functional connectivity as a driver of hillslope erosion following disturbance". International Journal of Wildland Fire 25, nr 3 (2016): 306. http://dx.doi.org/10.1071/wf14114.
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Hydrologic response to rainfall on fragmented or burnt hillslopes is strongly influenced by the ensuing connectivity of runoff and erosion processes. Yet cross-scale process connectivity is seldom evaluated in field studies owing to scale limitations in experimental design. This study quantified surface susceptibility and hydrologic response across point to hillslope scales at two degraded unburnt and burnt woodland sites using rainfall simulation and hydrologic modelling. High runoff (31–47 mm) and erosion (154–1893 g m–2) measured at the patch scale (13 m2) were associated with accumulation of fine-scale (0.5-m2) splash-sheet runoff and sediment and concentrated flow formation through contiguous bare zones (64–85% bare ground). Burning increased the continuity of runoff and sediment availability and yield. Cumulative runoff was consistent across plot scales whereas erosion increased with increasing plot area due to enhanced sediment detachment and transport. Modelled hillslope-scale runoff and erosion reflected measured patch-scale trends and the connectivity of processes and sediment availability. The cross-scale experiments and model predictions indicate the magnitude of hillslope response is governed by rainfall input and connectivity of surface susceptibility, sediment availability, and runoff and erosion processes. The results demonstrate the importance in considering cross-scale structural and functional connectivity when forecasting hydrologic and erosion responses to disturbances.
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Sheridan, G. J., i C. J. Rosewell. "An improved Victorian erosivity map". Soil Research 41, nr 1 (2003): 141. http://dx.doi.org/10.1071/sr02030.
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The impact of raindrops on the soil surface and surface water runoff are two of the agents of soil detachment and sediment transport. The magnitude of these erosion processes is a function of the erosive potential, or erosivity of a rainstorm. The erosivity of rainfall is commonly quantified using the R factor developed for the universal soil loss equation. R is the average of the annual sum of the individual storm erosivity values and can be estimated from published relationships between the storm energy and the rainfall intensity. Currently the most likely source of R-values in Victoria is a hand-drawn contour map produced more than 20 years ago by an expert panel and published in an out-of-print handbook. A new R-value contour map for Victoria is presented, developed from current empirical relationships between rainfall intensity–frequency–duration and R. The R contours vary in value across the state by about a factor of 4, from <800 MJ.mm/ha.h.year in the north-west, to >2700 MJ.mm/ha.h.year in the eastern ranges. The new map improves the resolution and accuracy of erosivity values for Victoria, especially in steeper, forested areas, and will assist in the prediction and modelling of erosion and water quality.
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Henorman, Hanna Mariana, Duratul Ain Tholibon, Masyitah Md Nujid, Hamizah Mokhtar, Jamilah Rahim i Azlinda Saadon. "The Functional Relationship of Sediment Transport under Various Simulated Rainfall Conditions". Fluids 7, nr 3 (15.03.2022): 107. http://dx.doi.org/10.3390/fluids7030107.
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Sediment removed in the detachment process is transported by overland flow. Previous experimental and field works studied that sediment transport is influenced by hydraulic properties of flow, physical properties of soil, and surface characteristics. Several equations in predicting sediment transport have been developed from previous research. The objective of this paper was to establish the selected parameters that contribute to the sediment transport capacity in overland flow conditions under different rainfall pattern conditions and to evaluate their significance. The establishment of independent variables was performed using the dimensional analysis approach that is Buckingham’s π theorem. The final results obtained are a series of independent parameters; the Reynolds number (Re), dimensionless rainfall parameter iLν, hydraulic characteristics QLν that related to the dependent parameters; and dimensionless sediment transport qsρv. The relationship indicates that 63.6% to 72.44% of the variance in the independent parameters is in relation to the dependent parameter. From the iteration method, the estimation of constant and regression coefficient values is presented in the form of the general formula for linear and nonlinear model equations. The linear and nonlinear model equations have the highest model accuracy of 93.1% and 81.5%, respectively. However, the nonlinear model equation has the higher discrepancy ratio of 54.9%.
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Li, Guang-lu, Teng-hui Zheng, Yu Fu, Bai-qiao Li i Teng Zhang. "Soil detachment and transport under the combined action of rainfall and runoff energy on shallow overland flow". Journal of Mountain Science 14, nr 7 (lipiec 2017): 1373–83. http://dx.doi.org/10.1007/s11629-016-3938-y.
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