Boundary Integral Solution to Seawater Intrusion Into Coastal Aquifers

Abstract

The boundary integral equation method is used to solve problems of seawater intrusion into a freshwater aquifer that is being pumped. The transient problem of intrusion (lens type) into a deep aquifer is solved, as is the steady state problem of intrusion (wedge type) into a shallow aquifer. Both cases are compared with analytical solutions that are available for simple geometries. The numerical models uses the Dupuit‐Forchheimer approximation to reduce the three‐dimensional problem to two dimensions. It then uses the Ghyben‐Herzberg approximation, which simplifies the treatment of flow in the saltwater region. A “special potential“ eliminates the need to track explicitly the freshwater‐saltwater interface. The numerical program adds to the capability of the general groundwater basin model, which was based on the same techniques.