This volume covers the theories and practices of sea water intrusion in coastal aquifers. The subjects range from basics, such as the physical background and the mathematical theory, to technologies in geophysical and geochemical survey, monitoring, exploitation and restoration of aquifers, planning and management. For engineers, quantitative tools such as analytical solutions, numerical techniques, and stochastic analysis methodologies are provided. Several numerical codes that include two popular USGS computer programs SHARP and SUTRA, written by the original developers, and other advanced codes, are available for sharp interface and density-dependent transport modeling. Case studies include those of the USA, the Netherlands, Israel, and Egypt.