Development of ALTUS, a high frequency acoustic submersible recording altimeter to accurately monitor bed elevation and quantify deposition or erosion of sediments

In order to accurately measure the level variations of the bed in muddy dominant environments, a selfcontained device has been specifically designed to be used in shallow waters. The submersible developed system is of small size and can be easily deployed by hand on intertidal areas, and eventually be placed on a submerged frame in water. It acts as an echo sounder located at a desired place while emitting 2 MHz acoustic waves towards the bottom. Altitude data corresponding to various detection thresholds are recorded. This device has been designed to precisely survey and quantify short or long-term changes of bed elevation at locations where deposition of (fine) sediments or erosion measurements are of greatest interest for general hydrosedimentological studies and investigation of physical processes, in order to validate relevant numerical models and particularly sediment transport ones. This system has been deployed in association with a multiparameter probe on intertidal mudflats in bay and estuary