In-channel managed aquifer recharge: a review of current development worldwide and future potential in Europe

Managed aquifer recharge (MAR) schemes often employ in-channel modifications to capture flow from ephemeral streams, and increase recharge to the underlying aquifer. This review collates data from 79 recharge dams across the world and presents a reanalysis of their properties and success factors, with the intent of assessing the potential of applying these techniques in Europe. This review also presents a narrative review of sand storage dams, and other in-channel modifications, such as natural flood management measures, which contribute to the retardation of the flow of flood water and enhance recharge. The review concludes that in-channelMARsolutions can increase water availability and improve groundwater quality to solve problems a ecting aquifers in hydraulic connection with temporary streams in Europe, based on experiences in other parts of the world. Therefore, to meet the requirements of the Water Framework Directive (WFD), in-channel MAR can be considered as a measure to mitigate groundwater problems including saline intrusion, remediating groundwater deficits, or solving aquifer water quality issues.European Union (EU) 814066info:eu-repo/semantics/publishedVersio

Decision-support groundwater modelling of managed aquifer recharge in a Coastal Aquifer in South Portugal

The Vale do Lobo sector of the Campina de Faro aquifer system in the Algarve (Portugal) is at risk of seawater intrusion. Managed Aquifer Recharge (MAR) is being considered to avoid groundwater quality deterioration. Numerical modelling was undertaken to assess the feasibility of several proposed MAR schemes. Although some data is available, many aspects of system behaviour are not well understood or measured. We demonstrate the use of a structurally simple but parametrically complex model for decision-making in a coastal aquifer. Modelling was designed to facilitate uncertainty reduction through data assimilation where possible, whilst acknowledging that which remains unknown elsewhere. Open-source software was employed throughout, and the workflow was scripted (reproducible). The model was designed to be fast-running (rapid) and numerically stable to facilitate data assimilation and represent prediction-pertinent uncertainty (robust). Omitting physical processes and structural detail constrains the type of predictions that can be made. This was addressed by assessing the effectiveness of MAR at maintaining the fresh-seawater interface (approximated using the Ghyben-Herzberg relationship) below specified thresholds. This enabled the use of a constant-density model, rather than attempting to explicitly simulating the interaction between fresh and seawater. Although predictive uncertainty may be increased, it is outweighed by the ability to extract information from the available data. Results show that, due to the limit on water availability and the continued groundwater extraction at unsustainable rates, only limited improvements in hydraulic heads can be achieved with the proposed MAR schemes. This is an important finding for decision-makers, as it indicates that a considerable reduction in extraction in addition to MAR will be required. Our approach identified these limitations, avoiding the need for further data collection, and demonstrating the value of purposeful model design.info:eu-repo/semantics/publishedVersio

Report on the performance of optimal MAR designs

Managed Aquifer Recharge (MAR) is a promising technique for water management. It comprises a group of technologies that enhance the infiltration of various water sources into aquifers. The water stored underground can serve different uses, such as irrigation, industrial and drinking water supply, and the recovery or preservation of environmental assets. The uptake of MAR is rapidly increasing worldwide under the threat of multiple pressures, including climate change, the decline in aquifer storage and environmental degradation. The present report is part of the Horizon 2020 MSCA "Managed Aquifer Recharge Solutions Training Network" (MARSoluT ITN, 2019-2023), which aimed at training experts in MAR (https://www.marsolut-itn.eu/). Report D4.4 deals with the objectives of work package 4 (WP4) and seeks to evaluate the performance of MAR sites across the Mediterranean using monitoring data. D4.4 continues a line of research started in the FP7 project "Demonstrating Managed Aquifer Recharge as a Solution to Water Scarcity and Drought" (MARSOL, 2013-2016) through MARSOL work package 13 (WP13) and its Deliverables D13.1 and D13.3, which provided technical solutions for MAR. The performance of six MAR sites across the Mediterranean was evaluated, namely, The Algarve, Portugal (UAlg); The Los Arenales MAR sites, Spain (TRAGSA); the Suvereto MAR site, Italy (SSSA); the Pwales MAR site, Malta, (EWA); the Argolis Field, Greece (NTUA); and the Menashe streams MAR site, Israel (ARO). The performance was evaluated in terms of seven categories: yearly recharge volumes, impacts on groundwater levels, impacts on water quality, infiltration rates and clogging, site upgrade, financial aspects, and other aspects. The site performance evaluation involved research conducted primarily within the framework of the MARSoluT project. In general, the sites show satisfactory performance after several years of operations. In the Algarve, MAR could help to palliate some of the current issues, but other measures are also required. In addition, a calculation for the unintentional recharge of groundwater caused by transversal structures (dykes and dams) has been conducted as a starting point for a future more accurate estimation. The volume infiltrated from the about 27,600 in-river structures ranges between 800 and 1,200 Mm3/year for the Spanish territory, representing a starting point for this new line of action about (un)managed aquifer recharge at a large scale. The obtained figures will be fine-tuned in the future of this initial figure. The site performance evaluation research involves multiple tools and diverse approaches, including numerical groundwater modelling, analytical hydrochemical characterisation, field and laboratory experiments, and geospatial analysis. A total of 20 technical solutions were added to the list that started in MARSOL with Deliverable D13.1. These technological solutions are related to multiple aspects of MAR, such as operation, planning, maintenance, and site upgrade. The advances in MAR sciences and engineering reflected in this report showcase successful MAR experiences and provide technical solutions that can support the market penetration of MAR in the Mediterranean region and beyond