Ballast
Définition
Sens commun
Large capacity water tank used on boats. It is to be filled or emptied to optimise navigation (buoyancy and stability control)
Source
according to Wikipedia
Fishing carried out by vessels absent from port more than 24 hours and 96 hours maximum.
Structure in concrete, earth or rock, or a mere (compacted or not) earthen dike or levee for: channelling a stream and possibly protect its surroundings (floodplain) against flooding, and/or protect a defined objective, more or less specific (urban, industrial, agricultural) and sometimes surround it, and/or serve as a barrier for a water abstraction in the stream.