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Plunge pool erosion in cohesive channels below a free overfall

van der Poel, Petrus W
http://rave.ohiolink.edu/etdc/view?acc_num=osu1202403267

Abstract Details

1985, Doctor of Philosophy, Ohio State University, Food Science and Nutrition.
A small-scale model was used to evaluate factors which influence plunge pool erosion below a free overfall in cohesive material. The model represented conditions near the head of discontinuous gullies with a small catchment area. A procedure was developed to prepare samples of known vane shear strength. Ground silica was compacted to a predetermined dry bulk density, and wetted under vacuum while its volume was kept constant. A relationship was established between the dry bulk density and the vane shear strength. The characteristic length of the model was the fall height, which equaled the gully height minus the tailwater depth. Using similitude principles, dimensionless plunge pool sizes were determined. They were found to vary with dimensionless terms which included the vane shear strength, discharge rate, upstream channel width, tailwater height and time. The fall height also influenced the scour hole dimensions. The slope and roughness of the upstream channel appeared to have no influence. In cohesive material, plunge pools below a free overfall differ from those below culvert outlets. The former were initially shallow and wide and reached only gradually a more constant shape (constant depth-length ratio), while other research reported the latter to have a uniform shape, independent of scour time. Relatively deep and narrow plunge pools developed for low values of the dimensionless terms which included the discharge rate, tailwater height, and width of the upstream channel. The dimensionless plunge pool size increased with the width of the dimensionless upstream channel width for low values (<0.6) of the latter term, while it decreased or remained more or less constant for higher values (>0.6). Plunge pools were found to decrease the stability of gully walls. The highest reductions occurred for long scouring times, material with a low vane shear strength, and low tailwater.
Glenn Schwab (Advisor)
261 p.

Recommended Citations

Citations

  • van der Poel, P. W. (1985). Plunge pool erosion in cohesive channels below a free overfall [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1202403267

    APA Style (7th edition)

  • van der Poel, Petrus. Plunge pool erosion in cohesive channels below a free overfall. 1985. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1202403267.

    MLA Style (8th edition)

  • van der Poel, Petrus. "Plunge pool erosion in cohesive channels below a free overfall." Doctoral dissertation, Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1202403267

    Chicago Manual of Style (17th edition)

osu1202403267
455
© 1985, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.