Water Wave Motions in the Bottom Layer of Shallow Water Areas (on the Example of the Vistula Lagoon in the Baltic Sea)

A. K. Ambrosimov, Sh. Kh. Yakubov, A. N. Babakov, and B. V. Chubarenko

Synchronous instrumental measurements of the characteristics of bottom currents and surface waves in the shallow Vistula Lagoon in the Baltic Sea were carried out for the first time from May 15 to June 17, 2009. It is proved experimentally that the bottom gradient currents which can have the direction up to the opposite one to the wind impact, are formed in the enclosed and semi-enclosed water bodies. This is caused by the water surface denivellation formed in the case of the long impact of wind with the same direction. Bottom water oscillations induced by surface waves cause the bottom current velocity modulation and favor increase in the horizontal velocity component. The typical values of horizontal and vertical oscillations of bottom water are estimated for the most active storm during the measurement period that was registered on June 12, 2009 (the southwestern wind with the average speed up to 10.5 m/s, the mean wave height is 0.6–0.8 m).