The influence of driftwood debris in accelerating the regional scour near the bridge pier

Abstract

Flood disasters caused by driftwood debris are increasing and becoming more severe due to rising rainfall, shifting forest conditions, and increased trees along rivers. Driftwood buildup in rivers leads to sedimentation, erosion, and rising water levels, necessitating precise prediction of its behavior to mitigate its harmful effects. This study utilizes a three-dimensional numerical model to investigate the influence of piled-up driftwood debris on the acceleration of local scour development in front of the bridge pier. Depending on their density, driftwood blockages can be deposition types, such as floating, suspended, and submerged materials. The floating driftwood debris types yielded broader and deeper scour holes, while the suspended driftwood debris produced narrower but deeper ones. The submerged driftwood debris obstructed the pier perimeter; consequently, the plunging and spiral horseshoe patterns deteriorated as the flow approached the pier. The horseshoe vortex’s intensity and diving flow are likely lower, producing shallower local erosion around the bridge pier.