Mapping Seabed Vegetation with Sidescan Sonar

Abstract : Beds of marine vegetation such as seagrass and the larger algae may, if dense enough, mask the presence of seabed mines. An investigation is underway in Sydney Harbour of the extent to which seabed vegetation is discernable on sidescan sonar images. To date it has been found that, in some cases, sidescan sonar images provide very similar coverage to air photographs of seagrass beds. When seagrass is seen this readily on sidescan it is likely to be a problem for mine hunting. In those cases where sonar images and air photographs disagree, it is probable that the seagrass is relatively sparse, but this requires further investigation. At most sites the presence of the larger marine algae could not be discerned on sidecsan imagery, suggesting in many cases, but one cannot say all, that algae will not present a problem for mine hunting.