Effect of shoreline irregularities on streamwise dispersion in estuaries and other embayments

Abstract

Irregularities in the shoreline of an embayment act as a trap for water properties such as an introduced pollutant. The exchange of water between the trap and the main body may lead to an effective longitudinal dispersion of these properties. A mathematical model for this problem is developed, in which the exchange process between the trap and main body can be parameterized by the geometry of the system as well as by an exchange rate coefficient. In effect, the trap system behaves as a localized source-and-sink of substance for the main body of water. The model enables us to discuss the moments of the substance distribution. It is shown that, depending upon the values of parameters chosen, the presence of a trap may enhance or suppress the rate of dispersion in the main stream. This study suggests that the entrapment phenomenon may be a process of practical importance in longitudinal dispersion of substance in estuaries and coastal waters.