Search results for "erosion"
showing 10 items of 637 documents
Analysis of rill step–pool morphology and its comparison with stream case
2021
In this paper, the morphology of step–pool features is analysed using rill measurements and literature data for streams. Close-range photogrammetry was used to carry out ground measurements on rills with step–pool units, shaped on a plot having slope equal to 14, 15, 22, 24 and 26%. Data were used to compare the relationships between H/L, in which H is the step height and L is the step length, and the mean gradient of the step–pool sequence, Sm, for streams or the slope of the step–pool unit, S, for rills. The relationship of H/L against Sm is widely used to test the occurrence of the maximum flow resistance condition in streams, which is associated with the range 1 ≤ (H/L)/Sm ≤ 2. Further …
Scour around a Permeable Groin Combined with a Triangular Vane in River Bends
2019
River restoration refers to the environmental and ecological aspect of river engineering and aims to improve the natural habitat of a river system using eco-friendly methods. This paper introduces a new river restoration technique for bank protection and restoration of meander bends by combining a permeable groin with a triangular vane. Nine different combinations of permeable groins with triangular vane including three different effective lengths and three angles of vane were investigated in a 180 degrees mild laboratory flume bend in clear water conditions. Based on experimental tests, scour geometrical patterns were analyzed, classified, and compared with each other. This analysis showed…
Effect of Vegetation on Fluvial Erosion Processes: Experimental Analysis in a Laboratory Flume
2013
Abstract The plane evolution of a meander wave is determined by the erosion processes at the banks. Particularly, the outer- bank is considerably vulnerable to the erosion processes. Indirect techniques, which act upon the reduction of the effect of the cross-circulation motion, have been recently proposed to limit the outer-bank erosion. This paper shows preliminary results on the role played by vegetation on cross-circulation motion. The analysis is conducted on the basis of experimental data collected in a large amplitude meandering channel constructed at the hydraulic laboratory of DICAM. Maps describing the cross-stream flow, both over the no-vegetated bed and over the vegetated bed, a…
Applying the bootstrap technique for studying soil redistribution by caesium-137 measurements at basin scale
2000
Abstract The use of the bootstrap technique to estimate the reference level of137 Cs in an uneroded site is tested. The analysis is developed using 137Cs measurements made in a small experimental Sicilian basin. In the reference area the 137Cs activity is normally distributed with a known sample mean value, m equal to 94.4 mBq cm−2. The influence of137 Cs reference site sampling was determined generating samples having a fixed size, N and six different values of the sample coefficient of variation, CV, by a Monte Carlo technique. Then, for each size N, the probability distribution of the mean μ of the sequences generated by Monte Carlo technique is defined. The soil redistribution is determ…
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…
Evaluation of the SEDD model for predicting sediment yield at the Sicilian experimental SPA2 basin
2007
In this paper a spatially distributed model of the hillslope sediment delivery processes, named the sediment delivery distributed (SEDD) model, is initially reviewed; the model takes into account the sediment delivery processes due to both the hillslope sediment transport and the effects of slope curvature. Then the rainfall and sediment yield events measured at the experimental SPA2 basin, in Sicily, are used both to calibrate the SEDD model and to verify the predictive capability of the distributed sediment delivery approach at event scale. For the SPA2 basin discretized into morphological units and stream tubes, the SEDD model is calibrated at event scale using the measurements carried o…
Effect of plot size on measured soil loss for two Italian experimental sites
2011
The objective of this investigation was to determine empirically the plot width and length effects on runoff volume, Ve, soil loss, Ae, and sediment concentration, Ce, by using data collected, at the temporal scale of the erosive event, on bare plots differing in width (2 to 8 m) and length (11 to 22 m) for two Italian stations (Masse, Umbria; Sparacia, Sicily). Mean results differed by a maximum factor of 1.6 for Ve, 1.8 for Ae and 1.2 for Ce when plots differing in width were compared and by a maximum factor of 1.4 for Ve, 1.2 for Ae and 1.3 for Ce when comparison between plot lengths was conducted. Differences between two plot widths or two plot lengths were not statistically significant…
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…
Establishing a soil loss threshold for limiting rilling
2015
In this paper a frequency analysis of event soil loss measurements collected in the period 1999–2012 at the microplots and plots of the Sparacia Experimental Area in Sicily, southern Italy, was developed. The analysis was carried out using the annual maximum soil loss measurements normalized by the mean soil loss measured at a given temporal and spatial scale. The empirical frequency distribution of the normalized variable was well fitted by two Gumbel’s theoretical probability distributions discriminated by a value of the normalized variable equal to 2. This last value discriminates between the relatively low and frequent values of the normalized variable and the high and rare ones. The an…
Response to ‘comment on “predicting event soil loss from bare plots at two Italian sites”’
2014
In this paper, a response to the comment by Dr. Kinnell on “Predicting event soil loss from bare plots at two Italian sites”’ (Bagarello et al., Catena 109, 96–102, 2013) is provided.