The combined effect of climate change and increased water demand has put significant strain on groundwater resources globally. Managed aquifer recharge (MAR) has become an effective approach for addressing groundwater depletion problems and sustainable management of groundwater resources. This review article provides an extensive insight into the existing knowledge of MAR, including the main objectives and applications, implementation techniques (surface spreading, sub-surface, and induced recharge) being practiced over the years, risks and challenges associated with the MAR, and the developments in the field of MAR. This review also explores the potential of MAR in the Friuli Venezia Giulia (FVG) region, north-eastern Italy. An average increase in temperature and a decrease in precipitation and piezometric levels in the region suggest the development of a proper MAR plan to manage water resources in the decades to come. Additionally, a comparative analysis of studies published over the last 20 years, focusing on the quantitative and qualitative aspects of water resource management, is conducted to analyze the research trends in the field of MAR. The reviewed literature reveals a notable research trend towards the quantitative aspect compared to the qualitative one. This review also identifies a notable disparity in qualitative studies during the analysis of water quality parameters considered in different MAR studies. Based on this review, a prospective viewpoint to address the challenges and expand the scope of the field is presented. This calls for an optimized strategy that considers both water quality and quantity issues, along with incorporating environmental and socio-economic aspects within the framework of MAR.

Managed aquifer recharge (MAR) is becoming a common practice worldwide. MAR is carried out in different environments from coastlands to highlands, in megalopolis, farmlands and pristine areas, and in arid and humid regions. Pre‐Alpine aquifers represent an optimal target when MAR is aimed at storing large amounts of high‐quality waters. In fact, pre‐Alpine aquifers are generally characterized by high permeability and a thick unsaturated zone, with the catchments crossed by watercourses rich of high‐quality water. Here, we focus the attention to a representative pre‐Alpine aquifer system located in the Friuli region, northeastern Italy. A 1‐year long MAR test was carried out through a ~700 m² infiltration basin recharged by water diverted from a nearby channel. The site was characterized from the hydrogeological viewpoint, and the MAR test was monitored through time‐lapse hydrogeophysics, water level and piezometric records, and physicochemical water characterization. The data set was used to calibrate a local groundwater flow model, showing that MAR recharged the 50 m deep phreatic aquifer with 1,000 m³/day. Hydrogeologic data made available by previous studies were processed to develop a groundwater model of the regional aquifer that allowed for estimating the natural groundwater recharge of the phreatic system and, subsequently, evaluating the MAR effects in the context of the natural balance. If a single MAR site, like the tested one, plays a certain effect at a local scale only, the MAR implementation on several gravel pits and large‐diameter wells scattered in the region could store several million cubic meters of water per year, significantly raising the water table and improving the groundwater quality.

The Mereto di Tomba area in the upper Friuli plain was selected to evaluate the impacts of artificial recharge (AR) and to develop reliable models for managing AR activities using an infiltration basin, about 5.5 m deep and 45×7 m² wide. Alluvial deposits compose the unconfined aquifer with an estimated thickness no less than 100 m. The depth to the water table averages 50 m. Hydrogeological and geophysical investigations were performed supporting the aquifer conceptual model. The expected AR efficiency has been simulated by a three-dimensional variably-saturated finite-element model. Preliminary data of AR testing are presented.

The Friuli Venezia Giulia (FVG) region in northeastern Italy has experienced an imbalance in the hydrogeological system over the years, resulting in the lowering of groundwater levels. Reduced and erratic precipitation patterns, rising temperatures, and increased abstraction have all contributed to the decline in piezometric levels in the Friuli Plain's phreatic aquifers. These changes in the hydrogeological system have resulted in a decrease in direct infiltration and an increase in the surface run-off and evapotranspiration rate, thus affecting both the surface and groundwater resources in the region. The groundwater of the region is also polluted by nitrate content, whose concentrations in some parts of the region exceed the threshold value (50 mg/l as per Italian legislation) for potable use. To address declining water resources and improve underground storage of high-quality surface waters, three recharge sites (Carpeneto, Mereto di Tomba, and Sammardenchia), in the upper Friuli plain have been suggested for MAR practice. MAR potential in this pre-Alpine region is characterized by the availability of high-quality surface waters (primarily from rivers), a highly permeable thick aquifer system, and numerous existing structures such as pits and large-diameter wells. The present study aims to investigate the effect of MAR on groundwater levels and quality through an infiltration pond at Sammardenchia site. Modflow is applied to simulate the aquifer’s response to natural and artificial recharge through MAR by means of water from the nearby Ledra channel. The initial results show a positive effect of MAR on the groundwater levels at the local scale. The study further aims to simulate the solute transport and water quality changes resulting from the recharge operation, with the ultimate goal of predicting future hydrogeological variations in the aquifer system.