A time scale for long-term salt intrusion in well-mixed estuaries

Abstract

The one-dimensional equation for dispersion of sail in a well-mixed estuary is analyzed to obtain an estimate of the departure from the quasi-steady distribution of the tidally averaged salinity in the case of a gradually varying fresh water discharge. A time scale for the adaptation of the salinity to a new situation is defined, and is found to be less than the time a fictitious particle travelling with the fresh water velocity would need to traverse the estuary.