Search results for "soil erosion"

Roughness effect on the correction factor of surface velocity for rill flows

2021

Flow velocity is one of the most important hydrodynamic variables for both channelized (rill and gullies) and interrill erosive phenomena. The dye tracer technique to measure surface flow velocity Vs is based on the measurement of the travel time of a tracer needed to cover a known distance. The measured Vs must be corrected to obtain the mean flow velocity V using a factor αv = V/Vs which is generally empirically deduced. The Vs measurement can be influenced by the method applied to time the travel of the dye-tracer and αv can vary in different flow conditions. Experiments were performed by a fixed bed small flume simulating a rill channel for two roughness conditions (sieved soil, gravel)…

A Comprehensive Check of Usle-Based Soil Loss Prediction Models at the Sparacia (South Italy) Site

2020

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, b2 = 1), USLE-M (b1 = b2 = 1), USLE-MB (b1 ≠ 1, b2 = 1), USLE-MR (b1 = 1, b2 ≠ 1), USLE-MM (b1 = b2 ≠ 1) and USLE-M2 (b1 ≠ b2 ≠ 1) can be defined using REFe. Then, the different expressions of REFe were simultaneously tested against a dataset of normalized bare plot soil losses, AeN, collected at the Sparacia (south Italy) site. As expected, the poorest AeN predict…

Modelling sediment delivery using connectivity components at the experimental SPA2 basin, Sicily (Italy)

2018

Sediment delivery ratio can be used as a measure of sediment connectivity and it can be linked to the structural connectivity (morphological unit, slope length, slope steepness, travel time) of a basin and to the functional connectivity (rainfall-runoff processes at morphological unit scale). In this paper the sediment connectivity approach was applied at basin scale both using Sediment Delivery Distributed (SEDD) model, which takes into account the hillslope sediment transport, and sediment yield measurements carried out at SPA2 experimental basin (Sicily, Italy). The expression of the sediment delivery ratio SDRi of a morphological unit was modified for highlighting two components corresp…

Measuring soil erosion by field plots: Understanding the sources of variation

2006

Soil erosion plots of different types and sizes are widely used to investigate the geomorphological processes related to soil erosion. This field method has provided a variety of results, depending on the characteristics of the plots, on their suitability to reflect the ecosystem's characteristics and on the objectives of each particular research. The coupling of real soil loss at patch and slope scale within a landscape and the values obtained by field plots depend, among other things, on how good the methodology performs over a set of ecosystem properties, such as those related with temporal and spatial scale issues, disturbance and representation of natural conditions, and the ability to…

Towards More Efficient Incentives for Agri-environment Measures in Degraded and Eroded Vineyards

2015

Evaluating the economic damage caused by soil erosion is important. In addition to increasing the awareness of the problem among farmers and policy makers, evaluation of the economic damage caused by erosion can promote the implementation of more sustainable soil management practices. In the present study, we describe a new approach to evaluate incentives for the adoption of agri-environment measure (AEM) in degraded and eroded vineyards. To estimate this incentive, the replacement cost (RC) and the loss of income are calculated when the vineyard is managed with conventional tillage versus a cover crop (AEM). Our findings show that the incentive could range from the loss of income due to AE…

On the variation of the correction factor of surface velocity with the measurement vertical for shallow flows over rough beds

2023

Considering that water flow energy affects the detachment of soil particles, the transport and deposit of the detached particles, the flow velocity is a key variable governing the soil erosion processes at the hillslope scale. The simple dye-tracer technique for measuring mean flow velocity can be applied in non-controlled field applications for which some measurement difficulties (e.g. due to sediment transport, and shallow flows) can occur. The correction factor is usually obtained as the ratio between the mean velocity, deriving from measurements of flow discharge and water depth, and surface velocity. Alternatively, the possibility of using the velocity profile in a given vertical to de…

Comparing Logistic Regression and MARS approaches for gully erosion susceptibility evaluation in central-northern Sicily

2012

Application of 3D Photo-reconstruction techniques in Geomorphology: Examples through different landforms and scales

2014

Recent developments made in tri-dimensional photo-reconstruction techniques (3D-PR), such as the use of Structure from Motion (SfM) and MultiView Stereo (MVS) techniques together, have allowed obtaining high resolution 3D point clouds. In order to achieve final point clouds with these techniques, only oblique images from consumer un-calibrated and non-metric cameras are needed. Here, these techniques are used in order to measure, monitor and quantify geomorphological features and processes. Three different applications through a range of scales and landforms are presented here. Firstly, five small gully headcuts located in a small catchment in SW Spain were monitored with the aim of estimat…

Assessment of hydro-erosive processes in small steep coastal basins in Liguria and Sicily, Italy

2015

The steep Mediterranean catchments underwent drastic socio economic changes in the last decades. Moreover, these basins are also subject to climate variability and potential future climate change effects. Due to mechanization in agriculture a lot of surfaces changed from terraced vineyards and olive growth to abandoned land. The terraced areas are less productive and more cost and labour intensive and hence cannot compete with a highly mechanized agriculture. Furthermore, tourism based on the natural and cultural heritage of the region is more and more important for the income of the inhabitants. The abandonment has effects on the entire landscape system in terms of hydrological dynamics, s…

Application of RUSLE model for the assessment of soil erosion in the western sector of Palermo Mountains (north-western Sicily)

2009

The aim of this work is to study the impact of vegetation cover on water erosion phenomena by exploiting an integrated approach to the assessment of soil loss rates. The investigated area is located in the western portion of the mountainous group named “Monti di Palermo” and occupies an area of approximately 475 km2; this area, which extends from sea level up to about 1,300 m, is mainly characterized by the presence of lithosols and luvisols laying above carbonate and terrigenous substrates. The assessment of erosion intensity was indirectly obtained by applying the RUSLE model, that allowed to estimate soil loss produced by rill-interrill erosion phenomena. Starting from topographical and …