Settling velocity determination using the BIGDAN settling tube and the Owen settling tube

The BIGDAN tube for measuring the in situ settling velocity of suspended particulate matter (SPM) is introduced, and its handling and subsampling method described. BIGDAN was conceived for measurements in the marine environment where the water current is weak and the SPM concentration low. BIGDAN is an alternative to the instruments of the well-known Owen tube type generally used in estuaries or in rivers. Recommendations for use of the Owen tube are given and the results of some fundamental tests presented. Finally it is recommended to quantity the results of settling tests not only by the SPMʹs median settling velocity, but also by mass portions of settling velocity fractions.