The underwater video system VIS

An underwater video system (Video In Situ: VIS) is described that determines sizes and settling velocities of suspended mud flocs in situ, without disturbing large fragile aggregates. Some results are presented from the Ems estuary, showing macroflocs of 200 to 700 μm (up to 1 mm) diameter with settling velocities in the range of 0.5 to 8 mm·s−1. They survived high current velocities of > 1 m·s−1.