On the behaviour of tidal current directions due to the presence of submarine sand waves
Hennings, I.; Lurin, B.; Vernemmen, C.; Vanhessche, U. (2000). On the behaviour of tidal current directions due to the presence of submarine sand waves. Mar. Geol. 169(1-2): 57-68. dx.doi.org/10.1016/S0025-3227(00)00049-9
In: Marine Geology. Elsevier: Amsterdam. ISSN 0025-3227; e-ISSN 1872-6151, more
|  |
| Keyword |
|
| Author keywords |
tidal current; sand wave; megaripple; side-scan sonar; radar image; |
| Authors | | Top |
- Hennings, I.
- Lurin, B.
- Vernemmen, C., more
- Vanhessche, U., more
|
|
|
| Abstract |
Side-scan sonar records reveal that the crestlines of megaripples in the troughs as well as on both sides of the slopes of sand waves form an angle with the crestline of the sand waves itself. The existence of such an angle between the crestline of megaripples and sand waves indicates that changes of the (tidal) current direction across sand waves can be expected. Direct evidence that such (tidal) current direction changes occur above sand waves is derived from measurements of the Air-Sea Interaction Drift Buoy (ASIB) system at the sea surface and from side-scan sonar records of the sea bed. Both systems were operated from on hoard research vessels during two C-STAR field experiments in the Hoek van Holland study area off the Dutch coast in April 1996 and in April 1997. Measurements performed by electrical resistance wires on board the ASIB system indicate that variations of the short and moderate wave direction and the wave directional spread are associated with changes of the (tidal) current direction at the sea surface. According to the results of the measurements derived from the ASIB system and the side-scan sonar records it can be summarised that the variation of the direction of short and moderate period water waves as well as changes of the (tidal) current speed and direction across large sand waves must be considered for correct modelling of the wave-current interaction mechanism. |
|
