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Modelling sediment delivery using connectivity components at the experimental SPA2 basin, Sicily(Italy)
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作者 costanza di stefano Vito FERRO 《Journal of Mountain Science》 SCIE CSCD 2018年第9期1868-1880,共13页
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 funct... 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 corresponding to the structural(SDR_(L,i)) and functional(SDR_(F,i)) sediment connectivity, respectively. For SPA2 basin the frequency distribution of the travel time of each morphological unit was used to estimate the coefficient βL of the structural component of the sediment delivery ratio of each morphological unit. Then, using the sediment yield measurements carried out at the outlet of the experimental SPA2 basin in the period April 2000-March 2015, the SEDD model was calibrated at event scale for estimating the coefficient βF of the functional component of the sediment delivery ratio. At event scale the developed analysis stated that the functional connectivity is dependent on the magnitude of erosion events. Intermediate and high events, which were characterized by the lowest values of the functional coefficient, determine a more high functional connectivity and are characterized by a more efficient sediment transport along the hillslopes. Finally, at annual scale, the model was calibrated for the period 2000-2015 and relationships for estimating the coefficient βF,a of the functional component of the sediment delivery ratio taking into account the intensity of erosion events occurring in each year were determined. At annual scale, the analysis demonstrated that the functional coefficient was always greater than the landscape coefficient and the sediment connectivity was always controlled by the low values of the functional component. 展开更多
关键词 Soil erosion Sediment delivery Sediment connectivity Experimental basin SEDD
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Plot investigation on rill flow resistance due to path tortuosity
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作者 Francesco G.Carollo costanza di stefano +3 位作者 Alessio Nicosia Vincenzo Palmeri Vincenzo Pampalone Vito Ferro 《International Soil and Water Conservation Research》 SCIE CSCD 2023年第4期602-609,共8页
The path tortuosity t is an indicator of rill morphology accounting for the deviation of the thalweg from a straight alignment.The effect of t on flow resistance has been little investigated for rills.This paper repor... The path tortuosity t is an indicator of rill morphology accounting for the deviation of the thalweg from a straight alignment.The effect of t on flow resistance has been little investigated for rills.This paper reports the results of a plot investigation aimed to establish the suitable accuracy of the rill thalweg measurement to determine the tortuosity parameter and to test the reliability of a theoretical flow resistance law.Four rills were incised in clay soil(CS)and clay-loam soil(LS)and shaped by a clear flow discharge.The three-dimensional Digital Terrain Models were created by the Structure from Motion technique.For rills on LS,an approximate thalweg was tracked by photo-interpretation,and a specific calculation routine was applied to identify the cross sections with a constant spacing d.The actual rill thalweg was obtained as the line joining the lowest points of these cross-sections.Among the different tested d values,d=0.075 m was chosen to determine t.For both CS and LS,the Darcy-Weisbach friction factorffeatured a non-monotonic relation with t,which was explained as the result of three additive components due to bed roughness,sediment transport,and localized energy losses due to curves.The effect of the former two components onff contrasts that of the third,resulting in a linearly decreasing f-t relationship and constant flow velocity for the three lowest tortuosity values,and an increased friction factor and reduced flow velocity for the highest tortuosity value.The flow resistance law was positively tested,and the predicted friction factor was dependent on t. 展开更多
关键词 Rill erosion TORTUOSITY Rill morphology Friction factor Rill flow resistance
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