Search results for " soil loss"
showing 10 items of 37 documents
Establishing soil loss tolerance: an overview
2016
Soil loss tolerance is a criterion for establishing if a soil is potentially subjected to erosion risk, productivity loss and if a river presents downstream over-sedimentation or other off-site effects are present at basin scale. At first this paper reviews the concept of tolerable soil loss and summarises the available definitions and the knowledge on the recommended values and evaluating criteria. Then a threshold soil loss value, at the annual temporal scale, established for limiting riling was used for defining the classical soil loss tolerance. Finally, some research needs on tolerable soil loss are listed.
Testing the “physical model concept” by soil loss data measured in Sicily
2012
The best possible model to predict the erosion from an area of land has been suggested to be a physical model of the area that has similar soil type, land use, size, shape, slope and erosive inputs. Therefore, a replicated plot has to be considered the best possible, unbiased, real world model. In this paper the physical model concept was tested by using soil loss data collected on plots of different length at the experimental station of Sparacia, in Sicily (South Italy). This investigation supported the conclusions that i) a coefficient of determination between measured and predicted soil loss values of 0.77 has to be considered as the best-case prediction scenario and ii) an uncalibrated …
Deducing the USLE mathematical structure by dimensional analysis and self-similarity theory
2010
The Universal Soil Loss Equation (USLE) was originally deduced by a statistical analysis of a large data set of soil loss measurements. The multiplicative structure of the model has been criticised due to the considerable interdependence between the variables. Using the soil erosion representative variables and the reference condition adopted in the USLE, the aim of this paper was to apply dimensional analysis and self-similarity theory to deduce the functional relationship among the selected variables. The analysis yielded a multiplicative equation, similar to the USLE. Therefore, this study suggested that the USLE has a logical structure with respect to the variables used to simulate the …
A comprehensive analysis of Universal Soil Loss Equation-based models at the Sparacia experimental area
2020
Improving Universal Soil Loss Equation (USLE)‐based models has large interest because simple and reliable analytical tools are necessary in the perspective of a sustainable land management. At first, in this paper, a general definition of the event rainfall‐ runoff erosivity factor for the USLE‐based models, REFₑ = (QR)ᵇ¹(EI₃₀)ᵇ², in which QR is the event runoff coefficient, EI₃₀ is the single‐storm erosion index, and b₁ and b₂ are coefficients, was introduced. The rainfall‐runoff erosivity factors of the USLE (b₁ = 0 and b₂ = 1), USLE‐M (b₁ = b₂ = 1), USLE‐MB (b₁ ≠ 1 and b₂ = 1), USLE‐MR (b₁ = 1 and b₂ ≠ 1), USLE‐MM (b₁ = b₂ ≠ 1), and USLE‐M2 (b₁ ≠ b₂ ≠ 1) can be defined using REFₑ. Then t…
Soil erosion assessment and control in Northeast Wollega, Ethiopia
2018
Soil erosion is the main driver of land degradation in Ethiopia, and in the whole region of East Africa. This study was conducted at the Northeast Wollega in West Ethiopia to estimate the soil losses by means of the Revised Universal Soil Loss Equation (RUSLE). The purpose of this paper is to identify erosion spot areas and target locations for appropriate development of soil and water conservation measures. Fieldwork and household survey were conducted to identify major determinants of soil erosion control. Six principal factors were used to calculate soil loss per year, such as rainfallerosivity, soil erodiblity, slope length, slope steepness, crop management and erosion-control practices…
Practical thresholds to distinguish erosive and rill rainfall events
2019
Abstract In this paper, 1017 rainfall events from 2008 to 2017 are used to identify the rainfall threshold that produces upland erosion at the Masse (central Italy) and Sparacia (southern Italy) experimental stations. The rainfall events are classified into three classes: non-erosive, interrill-only and rill. The threshold values for separating as correctly as possible the erosive rains (case I) and the rill rains (case II) are derived solely from the hyetograph. Each threshold value is obtained by imposing that the long-term erosivity of the events above the threshold is equal to the long-term erosivity of all erosive events (case I) or only rill events (case II). The performances of selec…
Statistical check of USLE-M and USLE-MM to predict bare plot soil loss in two Italian environments
2018
The USLE-M and the USLE-MM estimate event plot soil loss. In both models, the erosivity term is given by the runoff coefficient, QR, times the single-storm erosion index, EI30. In the USLE-MM, QREI30is raised to an exponent b1> 1 whereas b1= 1 is assumed in the USLE-M. Simple linear regression analysis can be applied to parameterize both models, but logarithmically transformed data have to be used for USLE-MM. Parameterizing the USLE-MM with nonlinear regression of untransformed data could be a more appropriate procedure. A statistical check of the two suggested models (USLE-M and USLE-MM), considering two alternative parameterization procedures for the USLE-MM, was carried out for the Mass…
Evaluating the Effectiveness of Forest Crop to Mitigate Erosion Using a Sediment Delivery Distributed Model
1998
In this paper sediment yield data, measured from 1978 to 1997 in a small experimental Calabrian basin reafforested with Eucalyptus trees (Eucalyptus occidentalis Engl.), and RUSLE (Revised Universal Soil Loss Equation) coupled with a sediment delivery distributed model are used to evaluate the antierosive effects of this forest cover. At first, the soil loss measureinents carried out in two experimental plots, located in the basin, are used to evaluate the crop and management factor C of RUSLE far Eucalyptus coppice. The reliability of the selected C factor value is verified by comparing, at an event scale, the measured and the calculated sediment yield values at the basin outlet. Then, a M…
Uso del método mejorado del uso del injerto (Isum) como herramienta para determinar el valor de factores topográficos alternativos en la estimación d…
2020
Made available in DSpace on 2020-12-12T02:01:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-15 The Improved Stock Unearthing Method (ISUM) was initially designed to assess soil mobilisation rates in vineyards; however, other grafted crops such as citrus orchards could also be successfully used. The results obtained from ISUM have been used for several goals, but have not yet been applied for computing the LS factor (length and slope) as a part of the Universal Soil Loss Equation (USLE), which could give useful information to improve soil management system plans. This investigation was conducted in an 8-year old clementine field located in Canals (Valencia, Spain) and values of…
A pedotransfer function for estimating the soil erodibility factor in Sicily
2009
The soil erodibility factor, K, of the Universal Soil Loss Equation (USLE) is a simple descriptor of the soil susceptibility to rill and interrill erosion. The original procedure for determining K needs a knowledge of soil particle size distribution (PSD), soil organic matter, OM, content, and soil structure and permeability characteristics. However, OM data are often missing and soil structure and permeability are not easily evaluated in regional analyses. The objective of this investigation was to develop a pedotransfer function (PTF) for estimating the K factor of the USLE in Sicily (south Italy) using only soil textural data. The nomograph soil erodibility factor and its associated firs…