Search results for "soil erosion."
showing 10 items of 146 documents
Testing flow resistance equation for rill flow
2018
At first, in this paper a flow resistance equation for rill flow, deduced applying dimensional analysis and self-similarity theory, is presented. The incomplete self-similarity hypothesis is used for establishing the flow velocity distribution whose integration gives the theoretical expression of the Darcy-Weisbach friction factor. Then the deduced theoretical resistance equation, which is calibrated by some measurements of flow velocity, water depth, cross section area, wetted perimeter and bed slope carried out in 106 reaches of some rills modelled on an experimental plot, is tested using the literature data by Abrahams et al. (1996), Strohmeier et al. (2014) and Peng et al. (2015) for ri…
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…
Assessing dye-tracer technique for rill flow velocity measurements
2018
Abstract Rill erosion is considered one of the most important processes affecting soil because of the large amount of soil loss. The rill network acts as sediment source and is able to transport both rill flow-detached particles and those delivered from the interrill areas. Small flow depth in a rill and steep slope values of its bed affect significantly flow hydraulics. When rill flow velocity is measured using a dye-tracing method, the mean velocity is calculated by multiplying the measured surface velocity of the leading edge of the tracer plume by a correction factor. The main uncertainty of the dye-tracing technique stands in the relationship between mean and surface flow velocity. In …
Comment on “Effects of different tillage practices on the hydraulic resistance of concentrated flow on the loess plateau in China” by J. Sun et al
2020
Abstract For concentrated flows, which are characterized by small water depth and steep sloping beds, hydraulic conditions different from those typical of streams and rivers occur. In this study a new theoretically deduced flow resistance equation was tested using the experimental data by Sun et al. for three different tilled surfaces (Manual Dibbling, MD, Manual Hoeing, MH, and Contour Drilling, CD). At first, the profile parameter-relationship, which is the relationship between the velocity profile parameter Γ, the channel slope and the flow Froude number, was calibrated using rill flow data by Di Stefano et al. Then, the applicability of this relationship was tested by the measurements o…
Testing GIS-morphometric analysis of some Sicilian badlands
2014
Abstract Calanchi badlands are erosion landforms characterized by areas with scarce or absent vegetation, steep slopes, knife-edge divides and high erosion rates. They are originated by a combination of morphogenetic processes, partly similar to those shaping bigger fluvial landforms, and therefore can be considered as field “laboratories.” This paper presents the results of an investigation carried out in two badland sites located in Sicily, where the geometry of 25 calanchi has been characterized using Digital Elevation Models having a mesh size equal to 2 m. For each landform, a power length–volume relationship is established. This relationship demonstrates that length of calanchi channe…
A new empirical model for estimating calanchi Erosion in Sicily, Italy
2015
Abstract Calanchi (plural of calanco) are typical badland landforms of the Italian landscape. They consist of dense networks of V-shaped valleys, with a sparse or absent vegetation cover, which frequently develop on unconsolidated or poorly consolidated clayey deposits. In this paper, the dimensional analysis and the incomplete self-similarity theory were used to deduce a model relating the volume of sediments eroded from the calanchi area to a set of geometric attributes of their tributary areas. The morphometric characteristics of 209 calanchi basins were used to calibrate and validate the model. The predictive skill of the model was assessed by calculating the mean square error and the N…
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…
Experiments for testing soil texture effects on flow resistance in mobile bed rills
2018
Abstract In this paper a recently theoretically deduced rill flow resistance equation, based on a power-velocity profile, was tested experimentally on plots of varying slopes and soil texture in which mobile bed rills are incised. Measurements of flow velocity, water depth, cross section area, wetted perimeter and bed slope conducted in rill reaches incised on experimental plots, having different slope values (9, 14, 22, 24 and 26%) and soil texture (clay fraction ranging from 42 to 73%), and literature data were used to calibrate the flow resistance equation. In particular, the relationship between the velocity profile parameter Γ, the channel slope, the flow Froude number and texture frac…
Soil Erosion on Mountain Trails in Eastern Iberian Peninsula
2020
A review on trial erosion shows that soil erosion rates are one to three orders of magnitude higher than the ones recommended as sustainable. This is threatening the sustainable managements of mountain terrains, mainly in the popular hiking paths. The warm temperatures characterize Eastern Spain in winter, which results in visitors from northern Europe to walk in the coastal land mountainous terrain. This increases the pressure to the currently highly visited most popular paths. We selected representative transects of the trails of Serra de Bérnia, Puigcampana, Penyagolosa, Montcabré, Serra del Sit, Aitana, Les Tres Creus, Caroig, Cupurutxo and Circ de la Safor. All the selected study sites…