Search Results (68)

The interaction of the Almone River with groundwater in the Caffarella area (Rome, Italy) was investigated using a multi-method approach based on hydrogeological and radon analyses. Eleven measurement stations were established along the river at distances of approximately 270 m from one another. Stream discharge, water physicochemical properties, and radon levels were measured from June 2024 to March 2025. The contribution of two tributaries of the Almone was evaluated, but it was found to be negligible in terms of radon contribution. Except for an average increase of 40 L/s between stations 1A and 2A, the Almone’s discharge (corrected for the streams input) was constant (around 150 L/s) in June and slightly increasing from 6A to 11A in March due to heavier rainfalls. The increased discharge between stations 1A and 2A was interpreted as groundwater overflow from the volcanic aquifer into the alluvial body and in turn into the river due to a change in geometry and volume of the volcanic aquifer. In that part of the river, radon concentration increased only in March, due to the fast transition of the groundwater from a high to a lower radon emanation unit. Radon decreased along the valley due to atmospheric evasion, as confirmed by pH growth due to CO₂ degassing. Full article

In the Republic of Djibouti (Horn of Africa), fractured volcanic aquifers serve as the primary water resource. The country’s climatic characteristics (arid climate, average rainfall of 140 mm/year, and absence of surface water) have led to intensive groundwater exploitation to meet increasing water demands. This study focuses on the Dalha basalts aquifer in the Dikhil region. The Dikhil region, located in the southwest of Djibouti and bordering Ethiopia, spans 7200 km². Its population is estimated at 112,000 inhabitants. The Dalha aquifer is intensively exploited to supply the region and its capital, the city of Dikhil (35,000 inhabitants). The primary objective of this work is to assess the current resources of this aquifer using numerical modeling and its capacity to meet future water demands under the impact of climate change. The RCP 2.6 (Representative Concentration Pathway) was used to simulate the climate scenario up to 2100. Superficial recharge is estimated at 3.86 × 10⁶ m³/year. The current wellfield abstraction amounts to 2.34 × 10⁶ m³/year, accounting for 60% of the aquifer’s recharge. The simulation under RCP 2.6 indicates a declining trend in the water table. These findings highlight the fragile state of the Dalha aquifer, which is critical for the socioeconomic stability of the region. Given its current vulnerability, any increase in exploitation is unsustainable, despite the growing water demand in the Dikhil region. To tackle this challenge, we recommend conducting further studies to deepen the understanding of this system and implementing a real-time monitoring network to track aquifer changes. Full article

Groundwater resources from the volcanic aquifers of northern Latium (central Italy) are widely used to supply local water needs and are mainly captured through wells. Nevertheless, despite the detailed hydrogeological knowledge of these aquifers, not enough information is available on the long-term pumping yield necessary to define the sustainable yield of a well. In this study, data from about 230 pumping tests (mainly step-drawdown and a few constant-flow-rate tests) performed in the volcanic aquifers of the Latium region were analyzed. Specifically, the aquifer formations intercepted by the wells are the fall and flow pyroclastic deposits of the Vico, Vulsini, and Sabatini volcanic districts; lava from the Vico, Cimino, and Vulsini volcanic districts; and Ignimbrite Cimina, one of the main pyroclastic products of the Cimino eruptions. These aquifers were grouped and analyzed by considering the type of permeability, hydrostratigraphic succession, and frequency and thickness of the aquifer horizons intercepted by wells. The results obtained in terms of specific capacity and transmissivity values are comparable among the identified different aquifer formations, showing a good correlation between the two parameters, a strong hydraulic heterogeneity (variability within five orders of magnitude), and variable responses regarding drawdown to pumping. This study highlights that the analysis of drawdown over time at a constant flow is fundamental in heterogeneous hydrogeological environments such as volcanic ones, where the trend in drawdown is often affected by the reduced spatial continuity of the most productive aquifer formations. Knowledge of the trend in drawdown over time, the thickness of the aquifer intercepted by the well, and the operating time of the well is an essential element in defining the sustainable yield of a well. Full article

This study provides a comprehensive analysis of the groundwater potential of hard rock aquifers in five diverse African case study areas: Lake Tana Basin and Beles Basin in northwestern Ethiopia and Mount Meru in northern Tanzania (comprising volcanic aquifers); the Mekelle area in northern Ethiopia and Jifarah Plain in Libya (consisting of sedimentary aquifers). The evaluation of recharge, transmissivity, and water quality formed the basis of qualitative and quantitative assessment. Multiple methods, including water table fluctuation (WTF), chloride mass balance (CMB), physical hydrological modeling (WetSpass), baseflow separation (BFS), and remote sensing techniques like GRACE satellite data, were employed to estimate groundwater recharge across diverse hydrogeological settings. Topographic contrast, fractured orientation, lineament density, hydro-stratigraphic connections, hydraulic gradient, and distribution of high-flux springs were used to assess IGF from Lake Tana to Beles Basin. The monitoring, sampling, and pumping test sites took into account the high hydromorphological and geological variabilities. Recharge rates varied significantly, with mean values of 315 mm/year in Lake Tana Basin, 193 mm/year in Mount Meru, and as low as 4.3 mm/year in Jifarah Plain. Transmissivity ranged from 0.4 to 6904 m²/day in Lake Tana Basin, up to 790 m²/day in Mount Meru’s fractured lava aquifers, and reached 859 m²/day in the sedimentary aquifers of the Mekelle area. Water quality issues included high TDS levels (up to 3287 mg/L in Mekelle and 11,141 mg/L in Jifarah), elevated fluoride concentrations (>1.5 mg/L) in 90% of Mount Meru samples, and nitrate pollution in shallow aquifers linked to agricultural practice. This study also highlights the phenomenon of inter-basin deep groundwater flow, emphasizing its role in groundwater potential assessment and challenging conventional water balance assumptions. The findings reveal that hard rock aquifers, particularly weathered/fractured basalt aquifers in volcanic regions, exhibit high potential, while pyroclastic aquifers generally demonstrate lower potential. Concerns regarding high fluoride levels are identified in Mount Meru aquifers. Among sedimentary aquifers in the Mekelle area and Jifarah Plain, limestone intercalated with marl or dolomite rock emerges as having high potential. However, high TDS and high sulfate concentrations are quality issues in some of the areas, quite above the WHO’s and each country’s drinking water standards. The inter-basin groundwater flow, investigated in this study of Beles Basin, challenges the conventional water balance assumption that the inflow into a hydrological basin is equivalent to the outflow out of the basin, by emphasizing the importance of considering groundwater influx from neighboring basins. These insights contribute novel perspectives to groundwater balance and potential assessment studies, challenging assumptions about groundwater divides. Full article

The purpose of this study was to enhance the understanding and sustainable groundwater management of volcanic aquifer systems by estimating key hydrogeological parameters. The transmissivity of a volcanic aquifer system was estimated using analytical solutions based on 68 constant rate and recovery data sets collected from various sources. A combination of hydro-lithostratigraphy and diagnostic plots was employed to identify the aquifer types and flow conditions, which facilitated model selection. Transmissivity of the confined aquifer was modeled using both Theis and Cooper–Jacob methods, with the Theis residual drawdown solution utilized for estimation. For the unconfined aquifer, the Neuman method was used, and the Hantush/Jacob method was employed for leaky aquifers. The results showed that the transmissivity of the Tertiary basalt varied from 0.38 m²/d to 860 m²/d, while the Quaternary aquifer system ranged from 2.33 m²/d to 1.8 × 10⁴ m²/d, indicating an increase in transmissivity with younger volcanic flows. Specific capacity (SC) was estimated for 74 wells and the values ranged from 0.62 to 5860 m²/d. This wide variation of specific capacity and transmissivity showed significant heterogeneity within the volcanic aquifers. This study introduces the innovative application of derivative diagnostic plots in groundwater research, offering an efficient approach for analyzing and interpreting pumping test data to characterize aquifer systems in various hydrogeologic units. This study focuses on aquifer characterization in hard rock formation, demonstrating methods that can be applied to similar geological environments globally. For the Blue Nile basin in general and for the Lake Tana basin in particular, the study result of aquifer characterization will contribute to exploration, development, and improved groundwater management in the region. Full article

The sustainable management of groundwater in the Jimma area is complicated by a lack of comprehensive studies on its chemical makeup and the geochemical processes influencing its hydrochemistry. This research aims to fill that gap by examining 51 groundwater samples from various sources, including deep groundwaters, shallow groundwaters, hand-dug well groundwaters, surface waters, and springs within the area primarily consisting of complex volcanic rocks. The goal is to describe the hydrogeochemical characteristics and determine the key processes affecting groundwater composition in this volcanic area. The study identifies clear patterns in cation and anion concentrations. For deep groundwaters, the average cation concentration is ranked as Na⁺ > Ca²⁺ > Mg²⁺ > K⁺, while shallow groundwaters, hand-dug well groundwaters, surface waters, and springs show a ranking of Ca²⁺ > Na⁺ > Mg²⁺ > K⁺. The major anions are typically ordered as HCO₃⁻ > NO₃⁻ > Cl⁻ > SO₄²⁻. The quantitative hydrogeochemical analysis indicates that the freshwater types in the region are primarily Ca-HCO₃ and Ca-Mg-HCO₃, with some highly mineralized Na-HCO₃ waters also detected. The weathering of silicate minerals mainly drives the geochemical processes affecting groundwater chemistry. An increase in mineralization, suggested by saturation indices, points to a longer residence time underground, with deep groundwaters exhibiting the highest saturation levels and springs the lowest. This mineralization is especially significant for Mg-silicates and carbonates. Stability diagrams for feldspar minerals further demonstrate groundwater evolution along flow paths, revealing that shallow systems are in equilibrium with minerals like gibbsite, whereas deeper systems achieve stability with albite, Ca-montmorillonite, and microcline. Higher CO₂ levels (10^−1.5 to 10^0.5 atm), likely from mantle-magma degassing, add more HCO₃⁻ to the deeper aquifers. This study offers the first thorough characterization of the groundwater composition in the Jimma area and provides important insights into the Jimma area’s hydrogeochemical development, establishing a basis for enhanced groundwater management within this intricate volcanic aquifer system. Full article

This study aimed to determine the amount of As and Pb in the water in the Meoqui-Delicias’ aquifer and their spatiotemporal dynamics. Twenty-one water sampling points were selected. Seventeen samples were from wells and four were from surface water; two were used for human consumption and the rest for agricultural use. The samples were taken from May 2019 to January 2020 in four sampling events, one for each climatological season of the year. The studied geochemical anomalies seem to be linked to the nature and mechanism of volcanic emplacement. Several samples exhibited high concentrations of arsenic ranging from 1.20 to 156.54 ppb, unlike lead, with low values being the maximum value of 26.32 ppb. These elements (As and Pb) are in the water in Naica, part of the mining district where tons of Au, Ag, Pb, Cu, and Zn were obtained. From a geographical standpoint, it is impossible to establish that these elements are related, even though these elements (As and Pb) are present in the water in Naica, a mining zone where tons of Au and Ag were historically mined. Full article

Freshwater, vital for life and ecosystems, accounts for only 2.5% of Earth’s water, and is primarily located in polar caps, underground reservoirs, and surface water. Its quality varies due to environmental interactions, especially in groundwater. Tenerife, located in the Canary Islands, Spain, relies mainly on underground aquifers and tunnels capturing 51.6 cubic hectometers annually. Ensuring safe drinking water is a global challenge due to health risks from poor water quality, including diseases and cancer. Fluoride, sodium, and potassium are essential for health, and are mainly derived from groundwater as fluoride ions (F⁻) and sodium and potassium cations (Na⁺, K⁺). However, excessive F⁻, Na⁺, and K⁺ in drinking water is harmful. The World Health Organization limits F⁻ to 1.5 mg/L, Na⁺ to 8.70 meq/L, and K⁺ to 0.31 meq/L. Geological, climatic, and human factors control the presence and transport of F⁻, Na⁺, and K⁺ in groundwater. Seismic events can impact water quality, with long-term effects linked to aquifer structure and transient effects from gas and fluid expansion during earthquakes. This study was motivated by a 3.8 mbLg earthquake in Tenerife in 2012, which allowed its impact on groundwater quality, specifically F⁻, Na⁺, and K⁻ concentrations, to be examined. Post-earthquake, F⁻ levels alarmingly increased to 8.367 meq/L, while Na⁺ and K⁺ showed no significant changes. This research quantifies the influence of earthquakes on increasing F⁻ levels and evaluates F⁻ reduction during low seismic activity, emphasizing the importance of water management on volcanic islands. Full article

Understanding the recharge–discharge system of a catchment is key to the efficient use and effective management of groundwater resources. The present study focused on the estimation of groundwater recharge using Soil Moisture Balance (SMB) and Baseflow Separation (BFS) methods in the Gilgel Gibe catchment where water demand for irrigation, domestic, and industrial purposes is dramatically increasing. The demand for groundwater and the existing ambitious plans to respond to this demand will put a strain on the groundwater resource in the catchment unless prompt intervention is undertaken to ensure its sustainability. Ground-based hydrometeorological 36-years data (1985 to 2020) from 17 stations and satellite products from CHIRPS and NASA/POWER were used for the SMB method. Six BFS methods were applied through the Web-based Hydrograph Analysis Tool (WHAT), SepHydro, BFLOW, and Automated Computer Programming (PART) to sub-catchments and the main catchment to estimate the groundwater recharge. The streamflow data (discharge) obtained from the Ministry of Water and Energy were the main input data for the BFS methods. The average annual recharge of groundwater was estimated to be 313 mm using SMB for the years 1985 to 2020 and 314 mm using BFS for the years 1986 to 2003. The results from the SMB method revealed geographical heterogeneity in annual groundwater recharge, varying from 209 to 442 mm. Significant spatial variation is also observed in the estimated annual groundwater recharge using the BFS methods, which varies from 181 to 411 mm for sub-catchments. Hydrogeological conditions of the catchment were observed, and the yielding capacity of existing wells was assessed to evaluate the validity of the results. The recharge values estimated using SMB and BFS methods are comparable and hydrologically reasonable. The findings remarkably provide insightful information for decision-makers to develop effective groundwater management strategies and to prioritize the sub-catchments for immediate intervention to ensure the sustainability of groundwater. Full article

A multidisciplinary study, involving hydrogeological, geochemical, and mineralogical analyses, was conducted to define the evolution of thermal mineral springs in the Sabatini Volcanic District (SVD) (Central Italy) in a historic period. The outcomes were integrated with the archeological findings to improve the knowledge of the evolution of Veii, a settlement established since the Iron Age and later expanded by Etruscans and Romans. During the archeological excavations, water-related buildings were identified, especially at the Campetti Southwest site in the Veii settlement. Votive inscriptions also suggest the presence of buildings linked to sacred waters, even if a clear definition of the source and type of water is missing. In the SVD, some low-flow thermal mineral springs are present as a result of the mixing of thermal and CO₂-rich groundwater from the deep carbonate aquifer and the cold, shallow volcanic aquifer. Mineralogical and chemical analyses characterized the travertine and Fe-hydroxide deposits on Roman tanks and walls in Campetti Southwest and in a nearby ancient Roman bath along the Valchetta River. These deposits showed different relative concentrations of sedimentary and volcanic-related elements, testifying a geochemical evolution of the groundwater mixing and the presence of a paleothermal mineral spring in Campetti Southwest. Full article

A geophysical method, electrical resistivity tomography, was applied to identify potential groundwater-bearing zones around Nubutautau village on Viti Levu island, Fiji. Apparent resistivity data of the subsurface were collected through an electrode assembly along survey lines by injecting current into the subsurface using an ABEM Terrameter LS2. The apparent resistivity data were inverted using Res2DINVx64 software to produce the final electrical resistivity through an iterative process to compare the resistivity of layers and draw analogical hydrogeological results. Analysis revealed the presence of two potential groundwater-bearing zones as potential targets for future drilling. The two targets indicated the presence of potentially saturated vertical fractures through which infiltrating rainwater percolates through the volcanic rock towards a deeper basal aquifer. The identification of the two potential targets demonstrated great potential of this geophysical technique to effectively inform drilling operations. A scientific approach can increase the successful delivery of water security interventions in remote, drought-prone communities of the Pacific. Full article

Geodiversity, comprising both endogenous and exogenous geological processes, plays a crucial role in shaping the structure and functionality of natural systems, alongside its substantial impact on human well-being. However, the often-overlooked interconnection between geodiversity components limits our comprehension of geosystems. In the Chinchiná River Basin (CRB) in Colombia, located in the northern Andes in South America, we established criteria to differentiate geodiversity classes, calculated indices to understand the distribution of geological elements, and discussed systemic relationships. This comprehensive approach lays the foundation for a holistic comprehension of the territory’s structure and functionality. Our findings revealed the convergence in an area of 1052 km² of 10 rock types, 7 slope ranges, 13 landforms, 5 drainage density features, 610.4 km of faults with 9 kinematic tendencies, 5 soil orders, 5 climate types, a 3328 km surface drainage network with 7 hydrographic orders, 1 underground aquifer, 4 areas with lakes, 2 zones with glaciers, 27 polygenetic and monogenetic volcanoes, and several thermal springs. This discussion explores the implications of various methodologies used to establish the value of the general geodiversity index while also examining the relationships between abiotic elements and their distribution patterns. This forms a fundamental basis for understanding the geosystem services of the basin in terms of regulation, support, and provisioning processes, as well as the culture and knowledge derived from geodiversity. These conceptual elements are indispensable for enhancing the sustainability of a region that is susceptible to the impacts of climate change. Furthermore, they serve as the foundations for the objective’s achievement, as set by the UNESCO Global Geopark project “Volcán del Ruiz”, currently ongoing within the region. Full article

In this study, we present the hydrogeological, hydrogeochemical and isotopic characterisation and monitoring activity of a closed landfill located in the northern sector of the Phlegrean Fields groundwater body in the Campania Region (Southern Italy). The aim of the study is to distinguish between natural enrichments (e.g., geogenic sources) and anthropogenic pressures (e.g., leakages from the landfill body) causing anomalously high concentrations of some metals (As, F, Fe, Mn) in groundwater. Major anions, cations, metals, water-stable isotopes, carbon isotopes and tritium were analysed. The results show that high As, F and Fe concentrations are due to adsorption–desorption processes occurring in the aquifer hosted in the volcanic rocks/deposits or the occurrence of upwelling hydrothermal fluids related to the volcanic activity of the Phlegrean Fields, which may cause metal mobilisation. High localised Mn concentrations cannot be solely related to natural processes or to groundwater contamination due to leachate leakage from the landfill body. Instead, we hypothesise a leakage from the landfill gas system. The outcomes of this study show the advantages of the coupled use of physico-chemical and isotopic analyses in improving the comprehension of geochemical processes in areas characterised by the presence of municipal landfills. Full article

The study of aquifers of the Lece andesite complex (LAC) and its surroundings yielded a new procedural stepwise analysis that allowed the assessment of the origin of elements, particularly in areas affected by both anthropogenic and natural influences. The methodology uses the mineralogical composition of the rocks, including the elements available in rocks and groundwater. This study analyzes the element ratios B/Cl⁻, Na⁺/Ca²⁺, Ca^2+/Mg²⁺, HCO₃⁻/Cl⁻, and Na⁺/Na⁺ + Cl⁻; the correlations are coupled with a statistical analysis. In addition to reevaluating the already published water content, we provide an important new dataset. The results show that the main source of the water contamination with the elements B, F, U, As, Cu, Fe, Zn, Co, and Ni is the processes occurring at the contact between the groundwaters and non-altered/altered (propylitized) andesite rocks. This is also observed in the waters extracted from crystalline schists. The results may help develop an efficient use and assessment of the qualitative water potential of the LAC reservoirs. Similarly, the results highlight the applicability of the groundwaters, facilitating their regional research and use, further encouraging new initiatives for the preservation and protection of human and animal health. Full article

The shallow volcanic aquifer is the major rural water supply source in the Ethiopian highlands. A significant number of hand pump wells in these aquifers experience a rapid decline in yield and poor performance within a short period of time after construction. Hence, reliable estimation of groundwater flow velocity is important to understand groundwater flow dynamics, aquifer responses to stresses and to optimize the sustainable management of groundwater resources. Here, we propose the geospatial technique using four essential input raster maps (groundwater elevation head, transmissivity, effective porosity and saturated thickness) to investigate groundwater flow velocity magnitude and direction in the shallow volcanic aquifers of the Ethiopian highlands. The results indicated that the high groundwater flow velocity in the Mecha site, ranging up to 47 m/day, was observed in the fractured scoraceous basalts. The Ejere site showed groundwater flow velocity not exceeding 7 m/day in the fractured basaltic aquifer and alluvial deposits. In the Sodo site, the groundwater flow velocity was observed to exceed 22 m/day in the fractured basaltic and rhyolitic aquifers affected by geological structures. The Abeshege site has a higher groundwater flow velocity of up to 195 m/day in the highly weathered and fractured basaltic aquifer. In all study sites, aquifers with less fractured basalt, trachyte, rhyolite, welded pyroclastic, and lacustrine deposits exhibited lower groundwater flow velocity values. The groundwater flow velocity directions in all study sites are similar to the groundwater elevation head, which signifies the local and regional groundwater flow directions. This work can be helpful in shallow groundwater resource development and management for rural water supply. Full article