Special Issue of Transport in Porous Media on ‘Seawater Intrusion in Coastal Aquifers’

Abstract

A large proportion of the world’s population (about 70%) dwells in coastal zones. In the last half-century, population and economic growth have greatly increased freshwater demands, which has led to the over-exploitation of groundwater in many parts of the world. Consequently, the encroachment of seawater into coastal aquifers has become a common problem. A basic explanation and understanding of the steady-state balance between saltwater and freshwater in a coastal aquifer has been known for over one hundred years (at least since the independent studies and publications of Badon Ghyben and Herzberg). Their theories, however, assume that the saltwater is static and a sharp interface is maintained, which is not strictly true. During the past 50 years, significant advances have been made in understanding the dynamic balance of saltwater and freshwater in coastal aquifers, wherein the role of dispersion and seawater circulation are better described. During the past 25 years, the greatest category of advance has been in the development and application of numerical models to these types of problems. Such numerical methods can solve the governing variable-density flow and transport equations for problems having complex boundary conditions and heterogeneous aquifer properties. In spite of these significant advances, there is still much to learn about processes and predictions. Thus, an international conference was organized to focus on the present state-of-the-art and the future research needs. This conference, ‘SaltWater Intrusion and Coastal Aquifers: Monitoring, Modeling, and Management’ (or ‘SWICA-M3’), held in Essaouira, Morocco, in April 2001, was intended to