An introduction to determination of the location of fresh water-salt water interface in coastal zones

• 1、School of Water Resources and Environment, China University of Geosciences

Abstract：The classical Ghyben-Herzberg relation is widely used in determination of the location of fresh water-salt water interface based on the water table in a coastal zone but error exists in the results obtained. The Hubbert relation strictly describes the relationship between the heads and the location of the interface related to a sharp interface problem but is difficult in practical application. Examination of the equilibrium status of a point in the salt water zone and the description of piezometric heads at two points in both the salt water and fresh water zones reveals that the location of the fresh water-salt water interface in a coastal homogeneous, isotropic unconfined aquifer can be estimated based on piezometric heads at two points in the same vertical line tapping respectively the salt water zone (including the interface) and the fresh water zone (from the water table to the interface) when the groundwater flow system is in a steady state and satisfies the Dupuit assumption. The Ghyben-Herzberg relation is a special case of the method and the Hubbert relation is also a special case of the method. This method requires two nearest piezometric wells which respectively tap the fresh water and salt water zones.

Keywords： Coastal aquifer fresh water-salt water interface sea water intrusion tide Ghyben-Herzberg relation Hubbert relation