Near-Nature Ecological Technique for Pier Scour Countermeasure in a Submerged Overfall

Abstract

This paper proposes a near-nature ecological technique, which can consist of a wide range of materials, to protect against pier scouring. The proposed technique can involve the use of many long strips that behave like water weeds. This paper studied a protection method against pier scour by using long strips in a submerged overfall, particularly for a pier located at the maximum depth area of overfall scour. The length and size of the strips were chosen as factors to study their protective effect. Our results showed that this approach slowed the flow velocity between the installed strips and bed. The sediment in flow might accordingly move slowly or even settle down. Thus, the pier could be kept stable and safe by the installation of those strips. Experimental results show that the protective effect is more efficient when the strip length is closer to the pier and has a small diameter. Moreover, the maximum protective effect reached 45.5% scour reduction. Varied lengths provided different protective effects against overfall scour. These findings show that this near-nature ecological technique could be a good and economical solution for pier protection in submerged overfalls.