Authors promote research on estimation of SS concentration in the effluent from diked containment areas to be reclaimed. As a part of the research, field studies were conducted at four ports where pump dredgers worked for dredging and reclamation. SS concentration distribution in the basin, quality of sediment and working performance were investigated to consider sedimentation behavior of soil particles.
　Following became clear by the studies; SS concentration near the inlet was changed greatly with dredging operation or appearance of water path. In case that particle size had wide distribution from clay to sand, around the inlet zone appeared sedimentary delta with gentle slope with progress of reclamation. In case that inlet pipe was set high from water surface, SS concentration of upper part was high according to the turbulence of water surface. As for the vertical distribution of SS concentration in the basin, at the points which were moved 50 m far from inlet pipe, that of lower part was higher than that of upper part under the over flow rate of 1.0×10-5m/s. But this tendency was not seen in the basin where over flow rate was small as 0.2 ×10-5 m/s.