302
6 Wave Transformation in Shallow Water
with the initial general direction of wave propagation being equal to 120°.
At the second point under consideration the relative increase of wave height
reaches 20 per cent. The greatest height is observed without any current, when
the initial wave direction is equal to 90°, and the height increase reaches 8 per
cent. The wavelength is decreased by 20-30 per cent at this point.
In conclusion it should be noted that the problem of wave spectrum transformation due to wave refraction in shallow water and in a non-uniform current without wind is studied in this chapter. As shown, the joint effect of
a non-uniform current and basin bottom unevenness can lead to such wave
field variations, which cannot be presented by simple superposition of the
effects caused by current and depth separately.
6.6 Wind Wave Spectrum 'fransformation According
to the Black Sea International Experiment
Description of the experiment.
The problems of wave transformation
due to the influence of bottom and current variations have been considered in
the monograph till now. At the same time wave refraction played a decisive
role, whereas the wind influence was neglected. Such an attitude was justified
in case of small wind speed and the non-linear effects could be neglected. In
reality a strong wind may have a considerable impact on wave evolution in
a coastal area. In this connection it is interesting to consider the results of
wind wave spectrum transformation, obtained with the Black Sea International Experiment (BSIE), in which the author of the present monograph
took part under the supervision of Prof. I.N. Davidan. The BSIE, devoted
to investigation of wave transformation in coastal shallow water at the area
south of Varna (Bulgaria), was held in November-December, 1999. Scientific
workers of the Oceanlogy Institute of the Bulgarian Academy of Sciences
(under the supervision of Prof. Z. Belberov), the Saint-Petersburg Branch of
the State Oceanography Institute, the Water Problem Institute of the Polish
Academy of Sciences and the Woods Hall Oceanography Institute (USA),
participated in the experiment.
The coastal area was suitable to produce reliable measurements of waves,
propagating from eastern and north-eastern directions without any coastal
or shallow disturbances on their way.
The bottom area made up a fiat slope surface with an averaged slope
about 0.025 in the depth zone 0-10 m, and 0.006 in the depth zone 10-20 m.
Submerged shoals were practically absent, so wave reflection could be neglected. The bottom profile is shown in Fig. 6.21.
The location of measuring devices is shown in Fig. 6.22. One-string wave
measuring equipment was installed on the platform along 250 m at eight
points, where the depth was 1.3, 1.6, 2.6, 2.8, 3.2, 3.4, 3.8, 4.2 m, correspondingly. A five-string wave measuring device was installed at the end of the
6 Wave Transformation in Shallow Water
with the initial general direction of wave propagation being equal to 120°.
At the second point under consideration the relative increase of wave height
reaches 20 per cent. The greatest height is observed without any current, when
the initial wave direction is equal to 90°, and the height increase reaches 8 per
cent. The wavelength is decreased by 20-30 per cent at this point.
In conclusion it should be noted that the problem of wave spectrum transformation due to wave refraction in shallow water and in a non-uniform current without wind is studied in this chapter. As shown, the joint effect of
a non-uniform current and basin bottom unevenness can lead to such wave
field variations, which cannot be presented by simple superposition of the
effects caused by current and depth separately.
6.6 Wind Wave Spectrum 'fransformation According
to the Black Sea International Experiment
Description of the experiment.
The problems of wave transformation
due to the influence of bottom and current variations have been considered in
the monograph till now. At the same time wave refraction played a decisive
role, whereas the wind influence was neglected. Such an attitude was justified
in case of small wind speed and the non-linear effects could be neglected. In
reality a strong wind may have a considerable impact on wave evolution in
a coastal area. In this connection it is interesting to consider the results of
wind wave spectrum transformation, obtained with the Black Sea International Experiment (BSIE), in which the author of the present monograph
took part under the supervision of Prof. I.N. Davidan. The BSIE, devoted
to investigation of wave transformation in coastal shallow water at the area
south of Varna (Bulgaria), was held in November-December, 1999. Scientific
workers of the Oceanlogy Institute of the Bulgarian Academy of Sciences
(under the supervision of Prof. Z. Belberov), the Saint-Petersburg Branch of
the State Oceanography Institute, the Water Problem Institute of the Polish
Academy of Sciences and the Woods Hall Oceanography Institute (USA),
participated in the experiment.
The coastal area was suitable to produce reliable measurements of waves,
propagating from eastern and north-eastern directions without any coastal
or shallow disturbances on their way.
The bottom area made up a fiat slope surface with an averaged slope
about 0.025 in the depth zone 0-10 m, and 0.006 in the depth zone 10-20 m.
Submerged shoals were practically absent, so wave reflection could be neglected. The bottom profile is shown in Fig. 6.21.
The location of measuring devices is shown in Fig. 6.22. One-string wave
measuring equipment was installed on the platform along 250 m at eight
points, where the depth was 1.3, 1.6, 2.6, 2.8, 3.2, 3.4, 3.8, 4.2 m, correspondingly. A five-string wave measuring device was installed at the end of the