Global advances in managed aquifer recharge: a systematic synthesis

The rising water crisis requires effective and innovative techniques to safeguard the dwindling groundwater resources. Managed aquifer recharge (MAR) is a groundwater management approach to minimize groundwater depletion and ensure water security across a range of climatic regions. It is implemented globally to maximize aquifer storage, reduce saltwater intrusion, prevent land subsidence, reduce flooding hazards, and enhance agricultural production, while ensuring better water quality and quantity. This synthesis followed the PRISMA 2020 guidelines to systematically select relevant publications from scientific databases between 1980 and 2023. Systematic review and bibliometric synthesis indicate that river water (surface water runoff to streams and rivers), stormwater, and reclaimed wastewater were the main water sources for MAR. Tracers, water balance, and numerical modeling methods were commonly used approaches for evaluating MAR systems. Global studies on MAR reveal a significant relationship with the aridity index, indicating that highly arid areas experience negligible recharge due to the limited availability of excess water for recharge. These regions are prone to groundwater depletion but hold potential for MAR using sources such as treated wastewater, stormwater, and desalinated water. MAR projects have been established worldwide for agricultural and domestic needs at different regional scales. MAR not only increases groundwater storage but also has global benefits, including water security, environmental enhancement, economic benefits, technological advancement, climate change mitigation, and community engagement. The challenges of MAR include financial, technical, and hydrogeological issues, social acceptance, ecological concerns, and climate change. Our systematic synthesis highlights the advantages of MAR in addressing the pressing issue of water scarcity for agriculture and domestic use. This underscores the importance of an integrated, well-informed, and region-specific strategy and policies to fully harness MAR's capabilities in guiding the world toward a sustainable future.