Scour-inducing stilling basin flow patterns

Document Type

Conference Proceeding

Publication Date



Bed scour downstream of stilling basins continues to threaten the stability of water control structures. A 1/30 scale physical model of one such structure operated by the South Florida Water Management District was constructed at Michigan Tech to further study this problem. Detailed flow measurements were taken on a flow scenario corresponding approximately to the prototype design flow, which resulted in high scour, namely that of a high flow rate and upstream headwater depth and a low tailwater depth. Equilibrium bed scour and velocity measurements were taken using an Acoustic Doppler Velocimeter. Velocity data was used to construct a vector plot in order to identify which flow components contribute to the scour hole. Flow entering the scour region exhibited an aerated nappe and was comprised of a strong-velocity region exiting the stilling basin that induced a standing wave and split into a downward roller with a near-bed component flowing upstream inducing near-structure scour and a plunging region downstream of the structure inducing far-field scour and continuing downstream to form a vertically contracting region far downstream as the flow returned to normal conditions after the local scour effects were dissipated. In addition, slowly-rotating vertical flow-separation eddies in the corners of the structure-channel banks intersection were formed. © 2011 ASCE.

Publication Title

World Environmental and Water Resources Congress 2011: Bearing Knowledge for Sustainability - Proceedings of the 2011 World Environmental and Water Resources Congress