Assessing the backwater rise of floating barriers with racks for various blockages in open channels

Abstract One major risk in the stream is thought to be debris. The general effects of debris spreading have a detrimental effect on water infrastructure and water activities. A rack (curtain) with float units on top is the component of a floating barrier with a rack that is used in Egypt to trap the stream debris. It is installed upstream of water structures to collect debris and protect such structures from clogging. Units of the steel barrier that float have racks that do not extend or rest to the level of the channel bed. The majority of earlier researches examined the hydraulics of trash racks; however, there is a lack of knowledge involving the hydraulic performance of floating barriers and racks with debris blocking. One hundred experiments were conducted to study the hydraulic performance of such floating barriers in open channels, regarding the effects of discharges, flow depths, and blockage rack ratios which was defined as the rack blocked area relative to the projected area of the rack. The findings show that backwater rise (Δ h ) increased through the rack with increasing Froude numbers and rack blockage ratio. Whilst, increasing water depth caused a decrease in Δ h at a constant blockage ratio of the rack. A new equation is developed with the tested parameters to predict Δ h of floating barrier with rack for the range of 0.013 ≤ F o ≤ 0.077, 0.25 ≤ B r ≤ 1, and 0.063 ≤ B c ≤ 0.40. The developed Δ h values for the tested limits and flow conditions were considered minor in terms of practical applicability, with Δ h ≤ 100 mm in the prototype. Consequently, this type of floating barrier is considered the optimal choice for trapping debris before reaching the body of the structure, serving as a primary line of defense.