Effects of Surface Roughness and Rainfall Impact on Overland Flow
Publication: Journal of Hydraulic Engineering
Volume 121, Issue 7
Abstract
Bed roughness and rainfall impact affect hydraulic friction in overland flow. The relationship between friction, velocity, discharge, and channel slope was examined for the case of shallow, spatially varied flow on rough surfaces. Rainfall was simulated on artificially roughened surfaces in a laboratory. Measured flow velocities were compared to theoretical velocities computed from a dynamic equation for spatially varied flow and from the Darcy-Weisbach uniform flow equation. The measurements showed that the constant that relates the Darcy-Weisbach friction coefficient to Reynolds number can become larger than the theoretical value for smooth laminar flow. An analysis of the dynamic equation showed that frictional forces were much larger than forces resulting from changes in hydrostatic pressure and momentum. Water-surface profiles based on the Darcy-Weisbach friction equation nearly matched those from the dynamic equation for spatially varied flow. A regression was developed from the Darcy-Weisbach equation. The regression accurately predicted flow velocity when absolute roughness, rainfall rate, channel discharge, slope, slope length, and viscosity were known.
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References
1.
Chen, C. L.(1976). “Flow resistance in broad shallow grassed channels.”J. Hydr. Div., ASCE, 102(3), 307–322.
2.
Chow, V. T. (1959). Open channel hydraulics . McGraw-Hill, New York, N.Y.
3.
Eisenlohr, W. S.(1945). “Discussion of `The surface profile of overland flow,' by C. F. Izzard.”Trans., Am. Geophysical Union, 25(6), 959.
4.
Emmett, W. W. (1970). “The hydraulics of overland flow on hillslopes.”Geological Survey Professional Paper 662-A, U.S. Government Printing Ofc., Washington, D.C.
5.
Foster, G. R., Neibling, W. H., and Nattermann, R. A. (1982). “A programmable rainfall simulator.”ASAE Paper No. 82-2570. Am. Soc. of Agric. Engrs. (ASAE), St. Joseph, Mich.
6.
Izzard, C. F. (1946). “Hydraulics of runoff from developed surfaces.”Proc., Hwy. Res. Board, Nat. Res. Council, Nat. Acad. Sci., 26th Annu. Meeting, Washington, D.C.
7.
Izzard, C. F.(1945). “The surface profile of overland flow.”Trans., Am. Geophysical Union, 25(6), 959–968.
8.
Katz, D. M. (1990). “The effects of surface roughness and rainfall impact on the hydraulics of overland flow,” MS thesis, Univ. of Idaho, Moscow.
9.
Keulegan, G. H.(1945). “Spatially variable discharge over a sloping plane.”Trans., Am. Geophysical Union, 25(6), 956–958.
10.
Meyer, L. D., and Harmon, W. C.(1979). “Multiple-intensity rainfall simulator for erosion research on row hillslopes.”Trans., ASAE, 22(2), 100–103.
11.
Moore, I. D., Hirschi, M. C., and Barfield, B. J.(1983). “Kentucky rainfall simulator.”Trans., ASAE, 26(4), 1085–1089.
12.
Phelps, H. O.(1975). “Shallow laminar flows over rough granular surfaces.”J. Hydr. Div., ASCE, 101(3), 367–384.
13.
Roberson, J. A., and Crowe, C. T. (1993). Engineering fluid mechanics, 5th Ed., Houghton-Mifflin Co., Boston, Mass.
14.
SAS Institute, Inc. (1987). SAS user's guide: basics . Cary, N.C.
15.
Savat, J. (1980). “Resistance to flow in rough supercritical sheet flow.”Earth Surface Proc., Vol. 5, 103–122.
16.
Shen, H. W., and Li, R. M.(1973). “Rainfall effect on sheet flow over smooth surface.”J. Hydr. Div., ASCE, 99(5), 771–792.
17.
Woo, D. C., and Brater, E. F.(1962). “Spatially varied flow from controlled rainfall.”J. Hydr. Div., ASCE, 88(6), 31–57.
18.
Woo, D. C., and Brater, E. F.(1961). “Laminar flow in rough rectangular channels.”J. Geophysical Res., 66(12), 4207–4217.
19.
Yoon, Y. N., and Wenzel, H. G.(1971). “Mechanics of sheet flow under simulated rainfall.”J. Hydr. Div., ASCE, 97(9), 1367–1387.
Information & Authors
Information
Published In
Journal of Hydraulic Engineering
Volume 121 • Issue 7 • July 1995
Pages: 546 - 553
Copyright
Copyright © 1995 American Society of Civil Engineers.
History
Published online: Jul 1, 1995
Published in print: Jul 1995
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