Search results for "Versa"
showing 10 items of 1490 documents
Estudio multivariante de la calidad del agua: Aplicación al río Júcar en el período 1990-2013
2014
SUMMARY A study of the Jucar River’s water quality in the period 1990-2013 is performed using multivariate analysis tools. This study is both of longitudinal and transversal nature, ie, water quality is assessed along the river, thus observing the variations in its characteristics
Testing the long term applicability of USLE-M equation at a olive orchard microcatchment in Spain
2016
Abstract Universal Soil Loss Equation USLE-based erosion models have been used extensively to complement erosion measurements, to understand the interactions of the different geophysical features into erosion processes and to assess adequate alternative management practices and scenarios analyses. Despite its proved usefulness on different land-uses around the world, there is an urgent need to set up simple tools which do not require an advanced management expertise in terms of both choose of model parameters and calculation ability and which are accurate particularly at the event scale. In this paper the suitability of the Modified USLE (USLE-M) model at the event and the annual scale were…
Analysis of soil loss data from plots of differing length for the Sparacia experimental area, Sicily, Italy
2010
Widely used models of the soil erosion process, such as the empirical universal soil loss equation (USLE) and revised USLE (RUSLE), suggest that soil loss, i.e. the mass of soil lost by water erosion per unit surface area, increases with slope length, λ, although contrasting experimental results may be found in the literature. Experiments were carried out at the Sparacia site, Sicily, to establish the influence of plot length on soil loss. This was tested using data characterised by a high number of replicated, bare plots of different lengths (0.25, 0.4, 1, 2, 5, 11, 22, 33 and 44 m), simultaneously operating in the 1999–2008 period. Event soil losses did not vary significantly with λ or ev…
SW—Soil and Water
2000
Abstract Recent research has directed attention to the properties of the eroded material because of its influence in deposition phenomena and in carrying capacity of pollutant materials. In this paper, the spatial distribution of the content of nitrogen, phosphorus and total organic carbon is firstly deduced using the measurements carried out in 129 soil samples well distributed over the Sicilian Sparacia Basin and a Kriging interpolation method. Then the load of each chemical was calculated at morphological unit and basin scale using the above-mentioned spatial distributions and sediment yield values calculated by a parametric approach such as the revised universal soil loss equation (RUSL…
Predicting unit plot soil loss in Sicily, south Italy
2008
Predicting soil loss is necessary to establish soil conservation measures. Variability of soil and hydrological parameters complicates mathematical simulation of soil erosion processes. Methods for predicting unit plot soil loss in Sicily were developed by using 5 years of data from replicated plots. At first, the variability of the soil water content, runoff, and unit plot soil loss values collected at fixed dates or after an erosive event was investigated. The applicability of the Universal Soil Loss Equation (USLE) was then tested. Finally, a method to predict event soil loss was developed. Measurement variability decreased as the mean increased above a threshold value but it was low als…
Length Slope Factors for applying the Revised Universal Soil Loss Equation at Basin Scale in Southern Italy
2000
In this paper, for a basin divided into morphological units, a distributed model based on the Revised Universal Soil Loss Equation (RUSLE), with different expressions for the topographic factors, and on the sediment delivery ratio of each morphological unit is used. At first, the caesium-137 data available from a Sicilian basin are calibrated with two different models [the Proportional Method (PM), the Simplified Mass Balance (SMB) model] to provide net soil loss data for each morphological unit. Then, for a selected expression of the topographic factor, the slope length exponent is calculated for each morphological unit, equating the calculated sediment yield with the net soil loss. The an…
Linking sediment yield and caesium-137 spatial distribution at basin scale
1999
Abstract Identifying areas of the landscape that are most sensitive or susceptible to erosion stimulated the study of within-basin variability of the sediment delivery processes and the use of spatially distributed models coupled with Geographic Information Systems. The progress of sediment delivery distributed modelling is also dependent on the availability of measurements able to establish the link between eroded soil leaving an area and the patterns of erosion and deposition occurring along the hydraulic path from the considered area to the nearest stream reach. In this paper, the tracer technique using the radionuclide137Cs and its employment in sediment yield studies at basin scale are…
Estimating the USLE soil erodibility factor in Sicily, South Italy
2012
The Universal Soil Loss Equation (USLE) is used by professionals and technicians to predict soil loss by water erosion and to establish soil conservation measures. One of the key elements of the USLE is the K factor, which is a measure of the soil erodibility. Given the difficulty in collecting sufficient data to adequately measure K, early in the USLE's history the soil erodibility nomograph method was developed to allow estimation of K based on standard soil properties. Since the nomograph approach was developed based on a small number of soils in the United States, it is necessary for other contexts to check the nomograph's ability to predict the soil's true erodibility. Considering that…
Time Scale Effects and Interactions of Rainfall Erosivity and Cover Management Factors on Vineyard Soil Loss Erosion in the Semi-Arid Area of Souther…
2019
Several authors describe the effectiveness of cover crop management practice as an important tool to prevent soil erosion, but at the same time, they stress on the high soil loss variability due to the interaction of several factors characterized by large uncertainty. In this paper the Revised Universal Soil Loss Equation (RUSLE) model is applied to two Sicilian vineyards that are characterized by different topographic factors
Testing alternative erosivity indices to predict event soil loss from bare plots in Southern Italy
2009
Methods for predicting unit plot soil loss for the ‘Sparacia’ Sicilian (Southern Italy) site were developed using 316 simultaneous measurements of runoff and soil loss from individual bare plots varying in length from 11 to 44 m. The event unit plot soil loss was directly proportional to an erosivity index equal to (QREI30)1·47, being QREI30 the runoff ratio (QR) times the single storm erosion index (EI30). The developed relationship represents a modified version of the USLE-M, and therefore it was named USLE-MM. By the USLE-MM, a constant erodibility coefficient was deduced for plots of different lengths, suggesting that in this case the calculated erodibility factor is representative of a…