Water movements in five harbour-models were assessed using (i) a Sontek-ADV to measure the velocity distributions and (ii) fluorometers to determine the local solute-concentrations under both tidal and steady flows. The width of the harbour entrance and the water-depth's amplitude influence significantly the flushing process for the narrow-entrance harbours. To achieve a high rate of flushing, as required in harbours in order to reduce the pollution concentration therein and the need for dredging, it is recommended that as wide as is feasible entry into the harbour is used: if a separate entry and exit are to be introduced, they should be well separated. Less expenditures of commercially-purchased energy will then be required for achieving these aims.