Determining coastal inlet flushing times: a practical expression for use in aquaculture and pollution management

It is often necessary to compare the flushing of coastal inlets in selecting sites for aquaculture or in making recommendations on pollution hazards. We derive an expression for a reference flushing time.

in which h is the mean depth of the inlet, (E‐R) is the net evaporation rate, S₁ is the salinity of the open ocean, S₂ is the (volume) average salinity in the inlet and ΔS = S₂‐S_1o is easily evaluated from simply obtained data sets, especially in a steady‐state situation, or for an harmonic annual cycle. We show that _o is a good estimate of the flushing time for sources within the body of the inlet.