On the Behaviors of suspended sediments near a silt screen and the screen efficiency in a microtidal area

Abstract

The behaviors of suspended sediment concentration (SSC) near a silt screen in a microtidal coastal area was measured with associated hydrodynamic conditions. The current speed at the mid-layer of about 30 m downstream of the screen reduces to about the half of that at the same distance of the upstream. It is presumably responsible for the contraction of the vertical section due to the screen. Even for a relatively weak storm period, the SSC increases up to the value caused by dredging. Section-averaged SSC of the downstream is higher by about 60 % than that of the upstream, which means the silt screen plays adverse effect in the viewpoint of reducing SSC generated by dredging. Maximum efficiency of the screen in terms of vertically integrated SSC flux is about 30 %, while the average is only 5 %.