This line item refers to the volume of seawater intrusion into the three primary groundwater stores (water table aquifers and the underlying aquifers - Leederville and Yarragadee) within the Perth region from the ocean. The PRAMS and PHRAMS models estimate a net annual volume of flow from the aquifers into the ocean during the reporting period. That is, seawater intrusion is zero.
It should be noted that the interface between the aquifer and the ocean moves throughout the year. During the summer months, when levels in the water table aquifers are relatively low, the saltwater interface moves towards the coastline. Despite this, no salt water intrusion occurs within the aquifer.