GROUNDWATER MODELING AND ITS CONCEPTS, CLASSIFICATIONS, AND APPLICATIONS FOR SOLUTE TRANSPORT SIMULATION IN SATURATED POROUS MEDIA Masoud Saatsaz * Department of Earth Sciences, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran Saeid Eslamian Department of Water Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, Iran Saatsaz, M., & Eslamian, S. (2020). Groundwater Modeling and Its Concepts, Classifications, and Applications for Solute Transport Simulation in Saturated Porous Media. In Eslamian & Eslamian, Advances in Hydrogeochemistry Research (2020), Nova Science Publishers, Inc. ABSTRACT Numerical modeling of flow and solute transport has received increased attention during the last three decades. Groundwater models can offer the most accurate representation, characterization, and prediction of the hydrogeologic processes. This chapter discusses (i) the basic concept of groundwater modeling, (ii) the classification of groundwater models (general view), (iii) the application of solute transport models, (iv) the identification of hydrogeochemical processes, (v) the governing equation of solute transport, (vi) the guide for the development of coupled flow and solute transport numerical models, (vii) the applicability of various kinds of models to simulate the fate and transport of the major ions, (viii) the inverse estimation of solute transport properties, and (ix) the evaluation of approaches for modeling groundwater contamination (specific view). One clear conclusion of this study is that groundwater models should consider a series of hypothesizes, assumptions, constraints, and simplifications based on the model objective, modeling techniques, model reliability, solution complexity, data availability, * Corresponding Author address Email: saatsaz@iasbs.ac.ir