Physical Oceanography, Vol. 15, No. 6, 2005
STRUCTURE OF THE WAVE BOTTOM BOUNDARY LAYER
OVER SMOOTH AND ROUGH BOTTOMS
V. M. Kushnir
The comparison of six well-known models of the wave bottom boundary layer shows that they
are identical in the case of a smooth bottom but exhibit serious differences for the other types of
conditions. The thickness of the wave bottom boundary layer and the coefficient of vertical dif-
fusion of momentum are studied by using the relations of the
-model. The validity of these
estimates is checked by comparing the measured and computed values of the friction velocity.
This comparison demonstrates fairly good agreement between the results characterized by a co-
efficient of correlation equal to
Simple estimates demonstrate that, in the presence of storm waves whose heights are equal to
the amplitudes of velocity of the bottom wave currents are equal to
at a depth of
at depths of
m. For great wave heights and large periods, their influence in the
near-bottom zone can be traced down to depths of
Hence, the wave bottom boundary layer (WBBL)
can be found in vast shelf zones of the World Ocean. At present, these are the regions of intense economical ac-
tivities, including the extraction of mineral resources, construction and exploitation of hydraulic structures, and
the presence of health-resort zones and zones of aquaculture.
The urgency of investigation of the structure of WBBL is determined by the following factors:
1. The bottom layer is characterized by the processes of transformation of the mineral suspension and det-
ritus into biogenic elements whose vertical flows actively affect the primary parameters of production.
2. The vertical flows of oxygen in the bottom domain determine the rates of the processes of oxidation in
this zone, the living conditions of various bottom superorganisms, the possibility of hypoxia, and, hence,
the quality of water media.
3. As a rule, the pollutants appearing in the bottom layer undergo various transformations and then their
propagation in water media is determined by the parameters of diffusion flows.
4. The WBBL strongly affects the laws of formation of the layer of sediments, the dynamics of sediments,
and bottom friction, which should be taken into account in the hydrodynamic models of shallow-water
The urgency of investigation of the WBBL structure is determined not only by these factors but also by the
necessity of solution numerous applied problems of building and operation of various hydraulic structures in the
sea, the development of aquaculture and health-resort zones, and the offshore extraction of mineral resources.
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
54–67, November–December, 2005. Original article submitted August
26, 2004; revision submitted November 3, 2004.
370 0928-5105/05/1506–0370 © 2005 Springer Science+Business Media, Inc.