Modeling the fate of chemical constituents such as cations and anions, organic and inorganic ligands, etc., is essential to understand the long-term utility of groundwater for various purposes. The chemical modeling helps to describe the chemical characteristic of an aqueous system to solve a simultaneous set of equations, which explains the equilibrium reactions and mass balance on dissolved element for the output consists of theoretical distribution of aqueous species for dissolved elements. The book in total includes ten papers dealing with the instrumentation techniques for the analysis of various major, minor ions and trace elements and focuses on the geochemical modeling to get a prime idea about the different concepts adopted in modeling and the evolution of different geochemical models. The chapters cover the speciation of different ions, case studies by using inverse and forward modeling in different Indian scenarios, application of GIS and biogeochemical modeling to get a comprehensive overview of the applications of the geochemical models in water research.