Monitoring water column and sediments using DAS

Coastal regions such as estuaries and river deltas are often susceptible to large bathymetrial changes due to sediment transport. Monitoring the water depth in these areas can be challenging due to the size, shipping traffic, mixing of water layers, and the high dynamic environment. Nevertheless, there is a need for high accuracy depth measurements, to enable marine traffic, for water management, and to understand sediment transport. Even though the importance of coastal regions only increases, due to increasing trade and population growth in or near these regions, accurate shallow marine depth measurements remain challenging. We show how distributed acoustic sensing can be used to measure the water level, flow velocity, and water-sediment interface based on frequency and amplitude content. We show this using both vertical fibres, coiled around a mantle on a pole, and horizontal fibres, spanning between two poles.