Precision surveys of topography both below and above the water level
Mapping of sediments, analyses of natural risk zones, searches
Investigations of sand transport, shoreline change, and channel siltation
Measurements of suspended matter erosion and accumulation
Studies of floating islands from drowned peat in reservoirs
Assessment of natural risks: turbidity currents, mass movements, etc
Studies of polluted sediments and possible remedies
State-of-the-Art Tools and Methods
Caicos Islands, B.W.I.
We have the expertise for scientific quality under water mapping, using depth and sediment echo-sounder, side scan sonar, sub-bottom profiler, and precision positioning systems. The shoreline and beach can be added from air photos, or by land surveying with a (laser) total station. The bathymetric data can be delivered as regular maps, a digital elevation model, or in DXF format to be used in a CAD system.
Sediment and morphology mapping
The side scan sonar data can be processed in a computer to form a mosaic of the bottom. Sediment samples, cores, and sub-bottom profiles are used as complements in the interpretation. Sonar maps provide a wealth of information, but a skilled interpreter is needed for the analysis. Our sonar expert has over 15 years of experience from working with rectifying side scan sonar, in a wide range of climates and environments.
A side scan sonar mosaic is invaluable in interpreting the sediment dynamics of an area. It greatly facilitates a correct interpretation by revealing the spatial variability of key variables, such as grain size, gas content, bedrock exposures, patches of temporarily deposited organic sediments, and turbidity current routes.
The morphological mapping also provides information needed for the identification of areas with slope instabilities and under-water screes, conditions that pose a threat to underwater installations such as cables, pipelines, and oil plattforms. Furthermore, features such as wrecks, cables, and pipelines, can be mapped.
Bed-load sediment transport
In the sea the bed-load transport is of much higher relative importance than in rivers or reservoirs. To measure the bed-load directly is very difficult--but we can offer a couple of methods to find an estimate. The patented Sedimeter® was invented by one of our consultants for this very purpose. The bed-load transport can also be calculated using the MESTSEM model.
Example: A Floating Island Study
A drowned peat area was mapped using side scan sonar, and the sonographs combined in a computer to form a mosaic map of the bottom
The red dots mark holes in the bottom left by the floating islands - 12% of the peat area is red
The study also resulted in a buoyancy forecasting model, to be used as a planning tool to minimise the problems (blue line=water level input, red line=buoyancy output)