Temporal Pier Scour Evolution Under Stepped Hydrographs
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This study was aimed at measuring the temporal evolution of scour hole at a bridge pier under clear water scour condition. Scour tests were performed under steady flow conditions and stepped hydrographs. Multiple flood events were run in different sequences to determine how flood history affects scour hole development.

Various equilibrium scour depth equations and proposed temporal scour models were compared. The similarity of the scour hole profiles with time and flow history was evaluated. The order of flood events was found not to affect the final scour depth or scour hole shape. The scour hole maintained the same non-dimensional, longitudinal similarity regardless of flow history or time for both steady and unsteady flows. Best-fit power and logarithmic temporal scour depth equations were obtained from each steady state test. Using the method of superposition, these equations along with other proposed models were employed to predict scour depths under stepped hydrographs. For stepped hydrographs, the scour development for each event (or each step) followed the temporal scour evolution under steady flow conditions. It was determined that the power and logarithmic function accurately predicted final scour depths (? 10% and ? 12%, respectively) and temporal scour evolution under stepped hydrographs. The temporal scour models tested did not perform well in predicting scour evolution and final scour depth under stepped unsteady flow conditions.

Publication Summary

  • Geosyntec Authors: Mark Schillinger
  • All Authors: Mark W. Schillinger, Abdul A. Khan
  • Title: Temporal Pier Scour Evolution Under Stepped Hydrographs
  • Event or Publication: Sediment Transport: Monitoring, Modeling and Management
  • Practice Areas: Watershed and Stormwater Management, Erosion and Sediment Control
  • Citation: Schillinger, M.W. and Khan, A.A.(2013). Temporal Pier Scour Evolution Under Stepped Hydrographs. In Khan, A.A. and Wu, W. (Eds.), Sediment Transport: Monitoring, Modeling and Management. Nova Science Publishers.
  • Date: 2013