Numerical Modeling of Managed Aquifer Recharge (MAR) Systems

The depletion of water in aquifers, driven by exploitation for agricultural, energy, and urban purposes to meet overall demand, is accelerating globally. This phenomenon is further exacerbated by climate change, which has significantly affected the hydrological cycle in various parts of the world, directly impacting aquifers that are an integral part to this cycle. To address this issue, engineering systems such as Managed Aquifer Recharge (MAR) have been developed and implemented in various parts of the world, particularly in arid regions and areas where water stress is caused by excessive agricultural use. These systems are characterized based on their specific structures and various configurations can be employed based on the needs, considering installation and management costs as well as construction. To understand the factors that are crucial for the implementation of these systems, numerical models are widely used. These models allow for a simplified and concrete representation of reality and provide valuable information for the development of these systems. This study presents the results obtained from a sensitivity analysis performed using FEFLOW numerical model. Specifically, the response of an unconfined aquifer to seasonal injection through an MAR system was analysed in two configurations. The analysis focused on identifying which factors used in the model implementation most significantly influence aquifer recharge, thereby contributing to an increase in extraction rates during the irrigation season. The hydraulic conductivity turned out to be the most influential factor on recharge, while the distance of the extracting well from the MAR system had a minor influence. In contrast, the hydraulic gradient and the type of MAR system had a negligible influence.