[Article in Italian] Rivista Acque Sotterranee compie 40 anni

Most countries that have technical guidelines or regulations for artificial recharge or managed aquifer recharge (MAR), that include water quality aspects are based on the establishment of standards or Maximum Allowable Concentrations (MACs) to regulate the quality of the water percolated or injected into an aquifer. The number of parameters in these guidelines vary considerably (from 6 in Spain to 156 in the USA) and often apply to all aquifers within administrative boundaries (e.g., national territory), regardless of the nature of the receiving medium, the depth of the water table, and other key factors. Eleven MAR systems in Spain have been studied (eight operational and three experimental, with limited number of data from three sites), characterising both, the recharge water quality and the water resulting from the interaction processes recharge water-soil-unsaturated zone-saturated zone of the aquifer. In all cases, an improved effect on groundwater quality is observed, even though some parameters in the recharge water don’t comply with the standards employed in some European countries, where this article focuses. The article suggests that regulating water quality for MAR through MACs at national level gives room for another alternative approach specific for each site. It might be recommendable to establish local standards at the regional or aquifer-wide level to better reflect the diversity of groundwater occurrence. As per the article, sectoral water authorities could receive more decision-making power on granting permits for MAR based on the quality of the hydrogeological and risk studies for each request. This would help reduce the application of the precautionary principle when in granting permission.

In previous studies, the mean geothermal gradient of the Tlemcen region has been estimated as low (3.7°C/100m). The existing boreholes in the Remchi plain (North of the Tlemcen Mountains) reveal thermal waters (26-48°C) and a remarkable artesianism. To understand the hydrodynamics and origin of thermalism of this groundwater, we merged geophysical and physical-chemical data. Geophysical data allowed us to improve the resolution of the fault network, to estimate the thickness of various sandstone beds connected with the thermal reservoir and to delimit the productive aquifer. Chemical characteristics of waters have been used for a statistical analysis, which displayed two independent water clusters resulting from two hydrodynamic patterns throughout the aquifer. The hydrothermal analysis identifies the depth reached by water and the relationship between water circulation and the fault network. Comparison with previous studies allowed us to build a schematic geological model, which explains hydrodynamics, origin and role of this structure in the groundwater flow.

The issue 175/1 of Acque Sotterranee – Italian Journal of Groundwater presents contributions from the Flowpath 2023 Conference which was held in Malta between the 14th and 16th of June. The scope of Flowpath focused on ensuring that hydrogeology can play an important role in supporting the development of groundwater management and protection policies; on strengthening the knowledge and research initiatives on emerging challenges to the groundwater environment and to highlight research initiatives undertaken in the Maltese islands, and improve technical cooperation between Maltese and Italian hydrogeologists. Flowpath brought together in Malta almost 200 hydrogeologists from Italy, Malta and six other countries who together contributed to 8 keynote speeches, 42 oral presentations and 45 posters. In fact this edition includes three papers from the Flowpath conference, two of which highlight joint work undertaken by researchers from Italy and Malta in the characterization of groundwater bodies.

[Article in Italian] Cosa c’è sotto? Breve storia dell’esplorazione dei fondali dei laghi vulcanici dell’area metropolitana di Roma Capitale (Italia centrale)

Water scarcity is a big issue in arid and semi-arid regions. This challenge is particularly evident in the Upper Cheliff plain in Algeria, where the alluvial aquifer plays a vital role in drinking water supply and supporting irrigation. This aquifer faces high demand and quality issues. A study was conducted in this context, employing a cartographic approach to assess potential groundwater recharge from precipitation into the alluvial aquifer. The current study aimed at mapping zones with potential natural groundwater recharge zones by applying the Analytic Hierarchy Process (AHP) integrated within a Geographic Information System (GIS) environment, combining various factors that can influence recharge, such as rainfall, surface soil type, slope degree, land use and land cover, unsaturated zone, groundwater depth, and curve number. The map resulting from the analysis indicates that only 22% of the assessed area covers zones with very low and low potential recharge, 35% with moderate potential recharge zones, and 43% with high and very high potential recharge zones. This map reveals that the eastern region of the plain, from the cities of Djendel to Ain Soltane, is moderately to highly favorable for recharge. This is due to the natural recharge from rainfall and watercourse infiltration during dam release periods, excess irrigation water, and recharge from the Miocene sandstone aquifer in areas with direct aquifer contact. A validation process was performed using data from 66 wells distributed in this plain and it indicated that 48 wells exhibited good agreement with the resulting map, while 18 wells showed slight deviations. The results indicate an agreement of 72.72% between expected and exist number value of wells which confirming the good prediction of the AHP technique.

The expansion of irrigated agriculture and the overexploitation of groundwater in the Tabeditt region lead to a serious deterioration of the chemical quality of water. The compilation of hydrogeological and geophysical studies is essential in order to assess the quality of the Plio-Quaternary waters and to determine the origin of the salinization of these waters. In this study, hydrochemical analyses were carried out on groundwater samples in the Tabeditt region. Hydrochemical data have shown that the salinity in this area could exceed 6 g/L. The interpretation of major ion analyses demonstrates that mineralization is controlled by natural processes. The mineralization process consists of the dissolu-tion of evaporite minerals, namely gypsum, anhydrite, and halite. The geoelectrical study is carried out to obtain information about the distribution and quality of water in the Plio-Quaternary. Interpreta-tion of the resistivity models show the presence of two main zones: the first, near Tabeditt Wadi, is characterized by low values, indicating the influence of salt water in the groundwater and the second, located on the right bank of Wadi Jmal, is characterized by variable resistivity values, generally high, indicating the lateral changes in lithological facies, and the presence of fresh water. In such an arid region suffering from scarcity and degradation (or depletion) of water resources, it is important to implement a master plan that keeps under control the number of wells both known and unknown ones taping these aquifers.

[Article in Italian] Acque sotterranee ed energia: geotermia superficiale, o geoscambio, in aree urbane