STUDY OF SUSPENDED SEDIMENT DISTRIBUTION IN THE COASTAL ZONE

In the present paper observations of the suspended sediment dynamics in the coastal zone of the Baltic, Black and Mediterranean Seas are briefly described. A special method for performing field experiments was developed. With this method a large amount of data have been collected during storms of various force. These data characterize concentration fields on a vast aquatory from the water edge to the significant depth of sediment movement. In the zone seaward of the breaker line, the changes in concentration at fixed levels follow directly the storm changes. A significant amount of sand and aleurite particles are suspended near the bottom at a depth of 30 m or even deeper. In the breaking zone, the concentration change with time is mostly governed by storm migration of the breaker location and not by a direct change of storm force. Here the distribution of mean grain size of sediment, dispersion, asymmetry and excess of composition coefficients is nearly uniform in the vertical direction, whereas on the adjacent sites variation in these quantities is significant. In the surf zone the amount of suspended material in the water is slightly but monotonously decreasing shoreward. Different types of vertical profiles of suspended sediment concentration are established for various locations in the coastal zone characterized by different deformation of surface waves. A method of predicting the suspended sediment distribution over a large part of the coastal zone was developed. Examples of concentration field calculations for different probabilities are presented for a site on the North African coast. © 1990.