On the Fixed Rainfall Intensity: Effects on Overland Flow Resistance, Shear Velocity and on Soil Erosion
Raindrops and overland flow both are erosive parameters but they do not act by the same way. The overland flow alone tends to shear the soil horizontally and concentrates into rills. In the presence of rain, the soil particles are removed from the soil surface in the form of a uniform sheet layer. In addition to this, raindrops falling on the flow roughen the water and soil surface depending on the flow depth, and retard the velocity, therefore influence shear velocity and Manning’s factor. To investigate this part, agricultural sandy soil, rainfall simulator and a laboratory soil tray of 0.2x1x3 m were the base of this work. Five overland flow depths of 0; 3.28; 4.28; 5.16; 5.60; 5.80 mm were generated under a rainfall intensity of 217.2 mm/h. Sediment concentration control is based on the proportionality of depth/microtopography. The soil loose is directly related to the presence of rain splash on thin sheet flow. The effect of shear velocity on sediment concentration is limited by the value of 5.28 cm/s. In addition to this, the rain splash reduces the soil roughness by breaking the soil crests. The rainfall intensity is the major factor influencing depth and soil erosion. In the presence of rainfall, the shear velocity of the flow is due to two simultaneous effects. The first, which is horizontal, comes from the flow and the second, vertical, is due to the raindrops.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3299913Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 191
 Moussouni A., Mouzai L. and Bouhadef M., 2012, Laboratory experiments: influence of rainfall characteristics on runoff and water erosion. World Academy of Science, Engineering and Technology, 68, pp. 1540-1543.
 Madi H., Mouzai L. and Bouhadef M., 2013, Plants cover effects on overland flow and on soil erosion under simulated rainfall intensity. World Academy of Science, Engineering and Technology, Vol. 7, n°8, pp. 561-565.
 Moss, A.J., 1979, Thin flow transportation of solids in arid and non-arid areas: a comparison of processes. Proc. Camberra Symposium IAHS, vol. 128, pp. 435-445.
 Foster G.R, Meyer, L.D. and Onstad, C.A., 1977, An erosion equation derived from basic erosion principles. Transactions, ASAE, vol. 20, part 4, pp. 678-682.
 Govers, G., 1985, Selectivity and transport capacity of thin flows in relation to rill erosion. Catena, vol. 12, pp. 35-49.
 Raws G.V. and Govers G., 1988, Hydraulic and soil mechanical aspects of rill generation on cultural soils. J. of Soil Science, vol. 39, pp. 111-124.
 Moss A.J., Walker P.H. and Hutka. J., 1979, Raindrop stimulated transportation in shallow water flows: An experimental study Sedimentary Geology, vol.22, pp. 165-184.
 Savat J. Laboratory experiments on erosion and deposition of loess by laminar sheet and turbulent rill flow. Proceedings, Seminar on agricultural soil erosion in temperate Non-Mediterranean climate, Strasbourg, Colmar, Pp. 39-43.
 Guy B.J., Dickinson W.T. and Rudra R.P., 1990, Hydraulics of sediment-laden sheet flow and the influence of simulated rainfall. Earth Surface Processes and Landforms, vol. 15, pp. 101-118.
 Torri D., Sfalanga M. and Ghisci G., 1987, Threshold conditions for incipient rilling. Catena Supplement 8, pp. 97-105.
 Verhaegen T., 1987, The use of small flumes for the determination of soil erodibility. Earth Surface Processes, vol. 12, pp. 185-194.
 Nearing M.A., Norton L.D., Bulgarov D.A., Larinov G.A., West L.T. and K.M. Dontsova, 1997, Hydraulics and erosion in eroding rills. Water Resources Research, Vol. 33, No. 4, pp. 865-876.
 Emmett, W.D., 1970, The hydraulics of overland flow on hillslopes. Geological Survey Professional paper 662-A.
 Savat J., 1980, Resistance to flow in rough supercritical sheet flow. Earth Surface Processes. Vol. 5, pp. 103-122.
 Ramser C.E., 1934, Dynamics of erosion in controlled channels. Transaction Amer. Geophys. Union pp. 488-494.
 Kramer L.A., Meyer L.D., 1969, Small amounts of surface mulch reduce runoff velocity and erosion, Transactions of the ASAE, 12, pp. 638-645.
 Walker O.H., Kinnell P.I.A. and Green P., 1978, Transport of a non-cohesive sandy mixture in rainfall and runoff experiments, Soil Sci. Soc. Ameri. J., vol. 42, pp. 793-801.