Behaviour of a puff of resuspended sediment: a conceptual model

The particulate matter concentration above the seabed is usually assumed to decrease with height, following an exponential or Rouse profile. Many part iculate matter concentration profiles with a peak were found on the North M editerranean bottom water at a few tens of metres above the bottom. A parti cle size signal at the same altitude was found in this area and on the New York Eight shelf. It is assumed that this unexpected shape is due to a clou d of resuspended cohesive sediments originating from an impulse resuspensio n process. A simplified three-dimensional numerical model is proposed to de scribe the behaviour of resuspended particulate matter that originates from a sediment impulse vertically injected in the bottom water. This model rep roduces the concentration profile shape observed, and it gives indications concerning the length and time characteristics of such a cloud, depending o n the water velocity and bottom boundary layer properties. (C) 2000 Elsevie r Science B.V. All rights reserved.