This technical note describes a study that was conducted to determine how drop height beneath a culvert outlet affects the dimensions of localized scour. A total of 18 experiments were performed in which flow discharged from a circular pipe onto a near-horizontal bed for 316 minutes. Relatively uniform sand with median grain comprised the bed material. The scour hole dimensions, depth, width, length, and volume were noted for drop heights of 0, 1, 2, and 4 times the culvert diameter above the bed. Researchers developed a series of expressions to correlate the dimensionless scour hole parameters of depth, width, length, and volume to the modified discharge intensity and to the drop height. Study data indicate 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 scour hole prediction procedure for drop height (United States Department of Transportation) is presented.


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  • Accession Number: 00675525
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Mar 20 1995 12:00AM