Improvement of water environment using tidal or wave energy
In order to improve water quality in a semi-enclosed bay, we proposed the new
method to activate substance transport and tidal exchange by control and
creation of tidal residual current using bottom roughness with directional
resistance properties. A pattern of the tidal residual current is to be
realized by arranging many pieces of the artificial bottom roughness.
To confirm the validity of this method, not only numerical calculations,
laboratory experiments but also a prototype test in an actual bay were carried
out. As a result of these experiments, it becomes clear that it is possible to
produce and control the tidal residual current and to activate tidal exchange
In addition, by applying the similar principle to wave motion we succeeded in
producing and controlling a wave-induced residual current near seabed, which
can control sediment transport in a coastal area. Through numerical and field
experiments, we have confirmed that this BANK method is an effective
countermeasure against beach erosion and burial of passage by sedimentation.