Drop Height Influence on Outlet Scour
Publication: Journal of Hydraulic Engineering
Volume 120, Issue 12
Abstract
A study was conducted to determine how fall distance, or drop height, beneath a culvert outlet affects the dimensions of localized scour. Eighteen experiments were performed in which flow discharged from a circular, 4‐in.‐diameter pipe onto a near‐horizontal bed for 316 min. The bed material was relatively uniform sand with median grain diameter, . The scour hole dimensions, depth, width, length, and volume, were documented for drop heights of 0, 1, 2, and 4 times the culvert diameter above the bed. A series of expressions were developed correlating the dimensionless scour hold parameters of depth, width, length, and volume to the modified discharge intensity, , and to the drop height. It was determined that culverts placed above the bed result in deeper, wider, and shorter scour holes than culverts placed adjacent to the bed. Criteria for adjusting the existing U.S. Department of Transportation scour hole prediction procedure for drop height is presented in this paper.
Get full access to this article
View all available purchase options and get full access to this article.
References
1.
Abt, S. R., Ruff, J. F., Doehring, F. K., and Donnell, C. A. (1987). “Influence of culvert shape on outlet scour.” J. Hydr. Engrg., ASCE, 113(3), 393–400.
2.
Blaisdell, F. W., and Anderson, C. L. (1989). Scour at cantilevered outlets: plunge pool energy dissipator design criteria; Vol. 76. U.S. Department of Agr., Agric. Res. Service (ARS), 76, Washington, D.C.
3.
Blaisdell, F. W., and Anderson, C. L. (1988a). “A comprehensive generalized study of scour at cantilevered pipe outlets. I: background.” J. Hydr. Res., 26(4), 357–376.
4.
Blaisdell, F. W., and Anderson, C. L. (1988b). “A comprehensive generalized study of scour at cantilevered pipe outlets. II: results.” J. Hydr. Res., 26(5), 509–524.
5.
Blaisdell, F. W., Anderson, C. L., and Hebaus, G. G. (1981). “Ultimate dimensions of.local scour.” J. Hydr. Engrg., ASCE, 107(3), 327–337.
6.
Bohan, J. P. (1970). “Erosion and riprap requirements at culvert and storm‐drain outlets.” Hydr. Lab. Investigation; Rep. H‐70‐2, U.S. Army Wtrwy. Experiment Station, Vicksburg, Miss.
7.
Doddiah, D. (1950). “Comparison of scour caused by hollow and solid jets of water,” MS thesis, Colorado A&M College, Fort Collins, Colo.
8.
Doehring, F. K. (1987). “The influence of drop height on outlet scour,” MS thesis, Colorado State University, Fort Collins, Colo.
9.
Fletcher, B. P., and Grace, J. L. Jr. (1972). “Practical guidance for estimating and controlling erosion at culvert outlets.” Hydr. Lab. Investigation; Rep. H‐72‐50, U.S. Army Wtrwy. Experiment Station, Vicksburg, Miss.
10.
Hallmark, D. E. (1955). “Scour at the base of a free overfall,” MS thesis, Colorado A&M College, Fort Collins, Colo.
11.
Laursen, E. M. (1952). “Observations on the nature of scours.” Proc., 5th Hydr. Conf., Bull. 34, Univ. of Iowa, Iowa City, Iowa, 179–197.
12.
Milt, W. C., and Kabin, J. (1983). “Impingement of water jets on nonuniform stream bed.” J. Hydr. Engrg., ASCE, 109(4), 536–548.
13.
Rajaratnam, N., and Beltaos, S. (1977). “Erosion by impinging circular turbulent jets.” J. Hydr. Engrg., ASCE, 14, 571–576.
14.
Robinson, A. R. (1971). “Model study of scour from cantilevered outlets.” Trans. ASAE, Vol. 14, 571–581.
15.
Rouse, H. (1938). “Experiments on the mechanics of sediment suspension.” Proc., 5th Int. Congr. for Appl. Mech., John Wiley and Sons, Inc., New York, N.Y.
16.
Ruff, J. F., Abt, S. R., Mendoza, C., Shaikh, A., and Kloberdanz, R. (1981). “Scour at culvert outlets in mixed bed materials.” Rep. for the Ofc. of Res. and Development; Contract DOT‐FH‐11‐922‐7, Federal Hwy. Administration (FHWA), Washington, D.C.
17.
Smith, G. L. (1957). “Scour and energy dissipation below cantilevered outlets.” Rep. No. CER No. 57 GLS 16, 122, Colorado A&M College, Fort Collins, Colo.
18.
Thomas, R. K. (1953). “Scour in a gravel bed,” MS thesis, Colorado A&M College, Fort Collins, Colo.
19.
Thomas, Z. (1975). “Time development of the dimensions of a local scour and deposit.” Rep., Agricultural Research Service, U.S. Department of Agriculture (USDA), Washington, D.C.
20.
U.S. Dept. of Transp. (1983). “Hydraulic design of energy dissipators for culvert and channels.” Chapter V; Hydr. Engrg. Circular No. 14, Ofc. of Engrg., Federal Hwy. Administration (FMWA), Washington, D.C.
Information & Authors
Information
Published In
Copyright
Copyright © 1994 American Society of Civil Engineers.
History
Received: Jan 17, 1994
Published online: Dec 1, 1994
Published in print: Dec 1994
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.