Scientists and Environmentalists are very concerned with the health of Seagrasses as they play a vital role in our ecosystem. Using a combination of technologies we are able to not only locate the position of the sea grasses, we can also measure the height and density. Combining this data over a number of years can be used to highlight and monitor any changes.
Clients may also require information on where sensitive seagrasses are located inside their various project areas. Protecting this vegetation will determine how any project plans in that area may or may not proceed. Completed projects may also be required to provide continued monitoring of the seagrass to ensure that the localised environment is not adversely affected.
We use various techniques to map sea grasses including, Sidescan Sonar (SSS), Single Beam Echo Soundings (SBES), Remotely Operated Vehicles (ROV), drop cameras and Multibeam back scatter (true pics). No one method is better than the other and quite often a combination of the disciplines is used.
The Sidescan data is a useful tool in depicting the location and boundary of the concerned seagrass areas with high resolution. The Sidescan captures the whole of the sea floor making the differences between rock, sand and seagrass easy to distinguish. The boundary data can be plotted on CAD systems and monitored over time to chart any reduction or growth of the vegetated areas.
Single Beam is also useful, unlike the Sidescan, the Single Beam depicts a cross section of the seabed collected, and inside that data we can define the edge of the vegetated areas as well as the height and density of the vegetation. This is also useful in monitoring seasonal growth where the amount of sea grass may be sparser.
Remotely Operated Vehicles (ROVs) and drop cameras are suitable for collecting pictorial images of the grasses. Location information can be embedded into the images to define areas of interest.
It is also possible to detect sea grass areas with Multibeam and back scatter data (similar to Sidescan). The Multibeam collects xyz points of the seabed with a dense point cloud. Generally sandy seabeds are quite smooth and uniform, while Multibeam data over seagrass areas are irregular. These areas are clearly defined and upon exporting a solid TIN surface to a CAD program a 2D poly line can plot the areas for that particular survey and be used in comparisons with future surveys.