Abstract

Experimental results on scour around a cylinder embedded in a sediment bed are presented. A novel measuring technique for the non-intrusive measurement of the spatio-temporal development of scour was designed and implemented. The sediment material studied was coarse sand, with diameters ranging from 0.6 to 2.0 mm. The experiment was conducted in a 26-m long, 2-m wide, and 1-m deep flume. The circular cylinder was 20 cm in diameter. During the experiment, which lasted 20 hours, scour around the cylinder was continuously measured. Results show the spatio-temporal development of the bed topography around the cylinder and the scouring mechanism. They are also useful for calibration, validation, and verification of hydro-morphologic numerical models. Correlations between the geometric properties of the scour hole and the maximum scour depth at the front of the cylinder are presented. The optimal shape of the potentially scoured region is determined. This is important for the purpose of bed replacement with rip-rap material in order to reduce scour. The positioning of sensors for scour monitoring is proposed.