Advances in Hydrus-Based Modelling for Water Flow and Solute Transport in Variably-Saturated Porous Media: A Review

Abstract

The HYDRUS program has become an essential tool for modelling water flow and contaminant transport in variably saturated porous media, and is widely used in environmental sciences, hydrology, and agricultural engineering. This review synthesizes recent advancements and applications of HYDRUS, examining how they simulate complex subsurface processes with high precision and adaptability. Special attention is given to HYDRUS-based applications in the agricultural, environmental, and industrial sectors, as well as the model's integration with other technologies, current challenges, and future prospects for enhancing prediction accuracy in sustainable water management. The review observed  challenges pertaining to surface type modelling, parameter definition, calibration and validation, and the representation of highly reactive pollutants are given particular consideration. Additionally focus has been given to integration with GIS, machine learning, and artificial intelligence to improve the data uses, precision and effectiveness of simulations.  The review also emphasises to enhance user interfaces and promote open-source cooperation in order to increase the application of HYDRUS. Lastly, future prospects for sustainable water and environmental resource management are outlined by exploring how HYDRUS-based simulations can assist policy and decision-making through environmental monitoring and management.