Research on tidal scour is largely centered at Elkhorn Slough in California.[2][better source needed] The slough was directly exposed to tidal flux beginning in 1947 with the creation of the
Moss Landing Harbor.[2][better source needed][5] Multiple studies have been done on the slough since tidal exposure to catalog the morphological change and determine how long it will take for the system to reach equilibrium.[2][better source needed][5]
Formation
Tidal scours are formed in tide-dominated
deltas and
estuaries with the changing of the tide. As the tide changes from low to high or high to low, water is transported through the channel taking sediment with it. With increasing erosion, there is increasing tidal volume creating a self-perpetuating system.[2][better source needed] Tidal scour is most apparent when a
barrier is breached due to natural or
anthropogenic forcing.[2][better source needed][3]
Anatomy
Bathymetry
Tidal scour can be determined by looking at the change in
bathymetry over time. Bathymetry of tidal channels is determined using
multi-beam sonar or
LiDAR. By comparing
cross-sections of channel bathymetry over several years and at various distances in the tidal channel, the amount of tidal scour can be quantified.[2][better source needed][4][7]
Grain Size Distribution
Sediment grab samples show that in areas demonstrating tidal scour, there is an increase in
grain size from surrounding areas.[5]
Ecological Significance
With direct influence from the Ocean, slough
morphology can change significantly making it difficult for native species to persist.[2][better source needed] This can be seen in:
Increased transport of
agricultural runoff, such as DDT-laden sediment, introduced by increased tidal scour.[8]