Search Results (552)

Identification of recharge sources in the Mekelle area is controversial, as some studies indicate that precipitation is the only source of recharge, while others indicate the existence of inter-catchment/inter-basin groundwater transfers with the possibility of intermediate-to-regional flow system recharge sources. The objectives of this study were, therefore, to identify the sources of recharge, quantify the groundwater recharge and develop a local meteoric waterline (LMWL) for the Mekelle area using the stable isotopic compositions (δ¹⁸O and δ²H) of rainwater. To that end, 13 precipitation, 34 groundwater, and two surface water samples were analyzed for δ¹⁸O and δ²H signatures. Accordingly, the local meteoric water line (LMWL: δ²H = 6.78 δ¹⁸O + 9.83) was developed from ten monthly accumulated precipitation samples and three rainfall event samples. Moreover, the spatial variations in the isotopic compositions of the groundwater with respect to the LMWL showed the existence of three zones/groups with different groundwater flow conditions, namely, shallow, intermediate, and deep flow systems. Two groundwater recharge sources were also identified from the dual-isotope slope of the groundwater isotope lines with respect to the LMWL. Furthermore, the groundwater recharge was estimated to be 49 mm/year using the chloride mass balance (CMB) method. Full article

Quantifying groundwater storage in karst aquifers remains challenging because of their heterogeneous structure and the scarcity of direct observations. This study proposes a pragmatic approach for characterizing storage and water availability in karst systems at the regional scale using long-term hydrographs from 16 Swiss karst springs and rivers. We distinguish between seasonal storage, associated with recharge events, and low-water storage, which sustains discharge during periods without significant recharge. Seasonal storage was estimated at approximately 30–70 mm for most investigated systems, while total storage reached up to about 140 to 180 mm at some sites, based on recharge–discharge modelling. Low-water storage was estimated to be on the order of 200 mm across most investigated systems, despite differences in hydrogeological settings. Analysis of low-water recession curves showed that most natural springs analyzed in this study followed a similar master recession curve, with low-water conditions defined as beginning at a specific transition discharge of 11.25 L s⁻¹ km⁻². This similarity provides the basis for a regional drought index that estimates the volume of remaining groundwater storage and forecasts discharge several weeks in advance. The results also support a conceptual model in which epikarstic, epiphreatic, and deeper storage compartments attenuate short-term discharge variability while sustaining low-water discharge over prolonged periods. Comparison with non-karst catchments shows that karst hydrogeological systems dampen peak flows but sustain baseflow through distinct storage reservoirs. This approach delivers quantitative indicators to assess drought, manage groundwater, and foresee water shortages in karst regions. Future work will test its validity outside the Swiss dataset. Despite discussed uncertainties in discharge measurements and catchment delineation, results demonstrate that dedicated hydrograph-based analyses can yield robust and transferable insights into karst groundwater storage at regional scales. Full article

This study proposes an innovative framework that combines hydroclimatic and agro-environmental predictors, including nitrate concentration and NDVI, with climatic factors such as Rainfall, temperature, and evapotranspiration to forecast piezometric level variations in the Saïss Basin, Morocco. Eight Machine Learning (ML) models were benchmarked, and feature importance was assessed using Shapley Additive exPlanations (SHAP) to ensure model transparency and interpretability. In parallel, the PELT algorithm was applied to detect structural change points, while Sen’s slope estimator and the Mann–Kendall test were used to quantify long-term trends. The Extra Trees (ET) model achieved the best performance (R² = 0.92), with Rainfall emerging as the most influential predictor, followed by nitrate concentration, confirming the added value of hydrochemical indicators for groundwater forecasting. Change-point analysis revealed significant declines during the 1980s and 1990s, followed by lower-amplitude fluctuations since the late 2000s. Projections toward 2050 suggest partial stabilization in the central part of the basin under favorable recharge conditions, whereas persistent declines are expected to continue in peripheral areas subjected to sustained groundwater abstraction pressure. These findings provide a robust and transferable decision-support tool for the sustainable management of groundwater resources in semi-arid agricultural area. Full article

Water security is a significant challenge for the Saudi Arabia Kingdom’s development and stability, affecting other economic sectors beyond the water sector. Insufficient water resources are causing economic and social crises; addressing this issue is crucial for the country’s growth and stability. This study aims to manage water resources in central Saudi Arabia (Wadi AS SAHBAA) through a two-level approach. The first level involves extracting rainfall amounts from satellite imagery to predict future rainfall intensity using PERSIANN-CCS-CDR data. The second level focuses on monitoring groundwater recharge using geographic information systems (GIS) and remote sensing techniques. The study further seeks to understand rainstorm behavior influenced by climate variability and applies geomatics techniques for quantitative analysis. The results show that the Wadi AS SAHBAA basin receives an annual precipitation of 116.6 mm/year and mean annual precipitation of 9.7 mm. The year 2019 experienced the highest recorded precipitation, reaching 222.3 mm and mean annual precipitation of 18.5 mm. Between 2013 and 2019, the AS SAHBAA region experienced increased rainfall driven by intense storm events; however, it declined during the period 2020–2022. Moreover, 2021 recorded the lowest annual precipitation of 53.8 mm with mean annual precipitation of (4.5 mm), possibly linked to reduced storm activity due to the COVID-19 pandemic. The study uses several methods to estimate groundwater recharge from rainfall and concludes that the average infiltration during 2013–2022 was varying from 1.59–36.63 mm, representing about between 1.03 and 28.5% of total rainfall. This is reflected in groundwater storage capacity, which ranges from approximately 1.65 to 38.27 million m³ yearly. This study provides a framework for monitoring precipitation and groundwater recharge and offers practical recommendations for regional development and sustainable water management. Full article

Monthly precipitation distributions provide screening-level hydroclimatic information relevant to regional water-resource assessment that is not captured by annual or seasonal means alone. This study evaluates observed and projected shifts in monthly precipitation distributions across the nine NOAA Climate Regions of the contiguous United States using PRISM observations and NEX-GDDP-CMIP6 projections. Observed changes were assessed using PRISM monthly precipitation for 1941–2020 by comparing 1941–1980 with 1981–2020, with sensitivity tests using 1981–2014 and an alternative bootstrap block length. Future changes were evaluated using five NEX-GDDP-CMIP6 models under four SSP scenarios, relative to each model’s 1981–2014 historical reference. To strengthen the statistical and water-resource interpretation, the analysis additionally evaluates historical CMIP6 performance against PRISM, tests explicit hypotheses using permutation/bootstrap procedures with Benjamini–Hochberg false-discovery-rate control, and introduces a categorical Hydroclimatic Screening Matrix. The selected models reproduced the regional monthly climatological cycle well, with monthly climatology correlations of 0.943–0.969 and monthly climatology Kling–Gupta Efficiency values of 0.834–0.886, although raw monthly time-series skill was lower. Observed PRISM results show robust mean increases in the Northeast, Upper Midwest, and Ohio Valley, while monthly Q95 increased robustly in the Northeast and South. Future projections indicate broad late-century increases in monthly mean and upper-tail precipitation, especially under SSP5-8.5. Statistical testing showed that late-century SSP5-8.5 projected changes fell outside the empirical PRISM historical-change envelope in 14 of 18 region-metric pairs, whereas upper-tail amplification was not FDR-significant across regions. The Hydroclimatic Screening Matrix identifies aligned planning-relevant signals, emerging upper-tail concerns, seasonal-storage follow-up priorities, and directional-uncertainty cases. These results support precipitation-based screening for identifying where detailed hydrologic impact modeling may be warranted, without treating monthly precipitation metrics as direct runoff, recharge, reservoir-operation, or flood-risk estimates. The observational endpoint of 2020 was selected to form two equal 40-year periods, thereby keeping the sample lengths balanced for distributional comparisons. Full article

Estimating transmissivity and hydraulic conductivity is crucial for groundwater resource assessment, flow modeling, pollution remediation, and sustainability studies. In the volcanic highlands of Ethiopia, millions rely on hand-dug wells and springs for drinking and irrigation, yet the hydraulic properties of these shallow aquifers remain largely uncharacterized. This study provides the first comprehensive estimation of transmissivity and hydraulic conductivity for the shallow groundwater aquifers in the Lake Tana Basin through integrated analyses of pumping and slug tests. The effective dataset comprised 31 tests, unevenly distributed among four aquifer types: eight in Quaternary basalt, 13 in weathered basalt regolith, seven in pyroclastic deposits, and three in alluvio-lacustrine sediments. Time-series groundwater level data were additionally used to characterize seasonal recharge responses and recession behaviors. Quaternary basalt aquifers showed high transmissivity values of 117–1064 m²/d, with a geometric mean of 235 m²/d, reflecting the influence of open and hydraulically connected fractures. Weathered basalt regolith aquifers had transmissivity values of 0.27–71 m²/d, with a geometric mean of 3.09 m²/d, whereas pyroclastic aquifers ranged from 0.17 to 11 m²/d, with a geometric mean of 0.96 m²/d. The alluvio-lacustrine aquifers ranged from 1.68 to 173 m/d, with a geometric mean of 8.56 m²/d; however, this estimate should be interpreted cautiously because it is based on only three tests. This study reveals strong heterogeneity within and across aquifers. Pumping tests were generally more applicable to the relatively transmissive Quaternary basalt aquifers, whereas slug tests provided a practical approach for characterizing shallow weathered regolith, pyroclastic, and alluvio-lacustrine aquifers. Seasonal groundwater level patterns varied with geology and topographic position: aquifers on slopes and plateaus generally showed rapid recharge and recession responses, whereas those at foothills and floodplains exhibited more sustained groundwater levels, probably because of lateral inflow and interactions with river water. The findings provide preliminary hydraulic-property ranges for groundwater assessment and indicate that fractured Quaternary basalt aquifers may represent promising targets for water-supply development. Full article

This study investigates the spatiotemporal dynamics of Land Use/Land Cover (LULC) along precipitation gradients across Türkiye by integrating high-resolution satellite-based precipitation datasets (CHIRPS, TerraClimate, and TRMM) with the European Space Agency (ESA) WorldCover (10 m) product and multi-sensor Normalized Difference Vegetation Index (NDVI) composites (Landsat, MODIS, Sentinel-2). Türkiye’s heterogeneous climate, characterized by a sharp contrast between humid coastal belts and semi-arid interiors, serves as a natural laboratory to assess ecosystem responses to moisture availability. The results reveal a systematic and non-linear transformation of LULC classes as precipitation increases. In low-rainfall zones (200–400 mm), agricultural activities and bare surfaces predominate, reflecting human-induced land management in water-constrained environments. A critical ecological threshold was identified between 400 mm and 700 mm, where grassland areas expand rapidly, becoming the dominant class. Beyond the 900 mm isohyet, forest cover exhibits a sharp increase, approaching nearly 100% dominance in regions exceeding 1200 mm, effectively displacing other LULC categories. Comparative analysis of precipitation products shows that while all datasets capture the “coastal-wet/inland-dry” pattern, TRMM tends to overestimate winter precipitation (exceeding 100 mm), whereas CHIRPS and TerraClimate provide more conservative estimates (75–80 mm). Overlay analyses between seasonal NDVI and precipitation confirm a pronounced “time-lag effect” in vegetation phenology. Despite peak precipitation occurring in winter (~75 mm), NDVI reaches its minimum (~0.03) due to thermal limitations and dormancy. Conversely, vegetation greenness peaks during the dry summer months (NDVI ~0.14 to 0.40), utilizing antecedent soil moisture stored during the spring recharge. High-resolution Sentinel-2 data proved superior in delineating micro-topographic vegetation responses compared to Landsat and MODIS. These findings provide a scientific baseline for sustainable land management and climate adaptation strategies, highlighting that precipitation thresholds are the primary determinants of Türkiye’s ecological boundaries. Full article

The Dongting Basin in central China has experienced increasing pressure on water resources due to intensified industrial and agricultural activities and increasingly frequent droughts. Therefore, reliable estimates of groundwater recharge are essential for evaluating the sustainability of groundwater resources in this region. An integrated approach combining the water table fluctuation (WTF), groundwater age, and chloride mass balance (CMB) was applied to estimate groundwater recharge in the Quaternary aquifer of the Zishui Plain, a sub-basin of the Dongting Basin. The mean recharge values derived from these methods were 268.2, 226.2, and 167.03 mm/year, respectively. The corresponding mean R/P ratios were 19.4%, 16.5%, and 12.2%. Differences between the recharge estimates reflect methodological differences among the three approaches and suggest that lithology, river seepage, and human activities contribute to the observed spatial variability in groundwater recharge. The WTF method generally produced the highest recharge estimates, whereas the CMB and groundwater age methods tended to provide lower estimates because of their respective methodological limitations. The integrated application of these methods may provide a more comprehensive assessment of groundwater recharge and may serve as a useful reference for groundwater management in the Dongting Basin. Full article

Modern scientific research approaches to studying the hydrological cycle of water in nature, in addition to the mathematical modeling of hydrological–hydraulic processes that have expanded in recent years, increasingly include isotope hydrology on a global scale. This paper presents the preliminary results of research in the Vardar River basin. The research is in the field of isotope hydrology with the analysis of stable isotopes of hydrogen (δ²H) and oxygen (δ¹⁸O) in precipitation (P), surface water (SW) and groundwater (GW). For this purpose, a network for taking water samples in the Vardar River basin has been established. The isotopic composition of precipitation shows a relatively wide variability, with δ²H values ranging from −83.7‰ to −12.4‰ and δ¹⁸O values from −11.65‰ to −2.99‰. In contrast, groundwater samples exhibit a considerably narrower isotopic range, with δ¹⁸O values between −10.98‰ and −10.1‰ and δ²H values between −73.3‰ and −68.1‰. Surface water samples show δ¹⁸O values ranging from −10.7‰ to −9.11‰ and δ²H values from −70.6‰ to −61.6‰. The results of the study show that the waters in the Vardar River basin are predominantly of meteoric origin, with their isotopic composition being strongly influenced by climatic factors and altitude, varying from approximately 1400 m and 2000 m a.s.l. The study confirms that precipitation is the primary source of both surface and groundwater. Evaporation is the dominant process that modifies isotopic signatures during rainfall, surface runoff and groundwater recharge. Due to good fit and nearly parallel meteoric lines observed in the three different locations, preliminary LMWLs and RMWL were estimated. A similar isotopic composition of surface water (SW) and groundwater (GW) in some locations indicates the presence of a direct and active hydrological connection between these water bodies, which need to be investigated in more detail in future research. However, one of the groundwater sampling locations suggest more depleted isotopic composition, which is probably related to different recharge altitudes, but also possibly very interesting relationship between Vardar River, alluvial aquifers and karst aquifer in the Žeden massif. Full article

Greenhouse gas emissions from heavy-duty vehicles (HDVs) must be drastically reduced. Battery electric trucks (BETs) are the main option for low-carbon road freight transport, but they require recharging infrastructure. However, a thorough cost analysis of public charging is lacking, especially for the Megawatt Charging System (MCS). This study estimates the infrastructure-related levelised cost of megawatt charging for battery electric trucks in Europe based on simulated truck operations and techno-economic modelling. The analysis combines empirical driving data with cost assumptions for MCS infrastructure. The reported values are infrastructure-only costs and include annualised capital expenditure, installation costs, grid connection costs and operating expenditure. They exclude electricity prices, taxes, levies, land costs and operator margins. Low- and high-cost scenarios differ in assumed charger hardware and installation costs, while grid connection costs and utilisation assumptions are held constant across scenarios. The results show that utilisation is the key driver of cost reductions over time. The infrastructure-related levelised cost of MCS declines to 0.03–0.07 EUR/kWh by 2050 under the analysed cost assumptions. The total annual infrastructure costs for Europe are estimated at 6.6–10.8 billion EUR, or 2.9–4.7 EUR cents/km. The results support policy decisions on infrastructure deployment and highlight the importance of coordinated rollout and demand growth. Full article

This paper presents the design, construction, and experimental evaluation of a low-cost, portable solar tracking system for monitoring ultraviolet solar radiation in real time. It integrates a Raspberry Pi Zero 2W as the embedded control unit, an AS7331 spectral sensor to measure UVA, UVB, and UVC irradiance, two 270° servomotors to position the system toward the sun, an NEO-6M GPS module to geolocate the system, and a DS3231 real-time clock to synchronize the time. To enable autonomous outdoor operation, a multistage power supply architecture based on a solar panel, a rechargeable battery, and LM2596 and MP1584EN DC-DC regulators was implemented. The tracking algorithm uses astronomical equations to estimate the solar azimuth and elevation and updates the sensor orientation during daylight hours. This allows the UV sensor to remain approximately normal to the incoming solar radiation. Experimental tests were conducted in Arequipa, Peru. The recorded data included UVA, UVB, and UVC irradiance; sensor temperature; geographic coordinates; time; and solar angles. The measured UV profiles exhibited the anticipated diurnal behavior: maximum values around solar noon, higher UVA levels than UVB levels, and minimal UVC levels due to atmospheric absorption. We compared the radiometric response with reference information from EarthKit, PVGIS 5.3, SAMPA, and a Davis Vantage Pro 2 weather station. We evaluated the solar positioning performance against Stellarium, NOAA, and the NREL Solar Position Algorithm. Across the complete five-day validation at three daily evaluation times, the maximum percentage errors were 0.0584% for azimuth and 0.5059% for elevation relative to the NREL SPA, NOAA, and Stellarium reference calculations. The results demonstrate that the proposed system constitutes an embedded, portable, autonomous, and low-cost platform for in situ monitoring of solar ultraviolet radiation. Due to its modular architecture, georeferencing capability, time synchronization, and independent power supply, the prototype can be used as a mobile measurement unit or as part of a distributed network of UV stations at various locations in Arequipa. In this regard, the system enables multipoint measurement campaigns, complements fixed weather stations, validates solar models, and generates local experimental data for the spatial and temporal assessment of the solar UV resource under real-world field conditions. Full article

Progressive climate change and rapid urbanization are placing increasing pressure on water resources, highlighting the need for local stormwater retention and reuse in residential areas. This study aimed to evaluate the influence of geological-engineering and geotechnical conditions on the design of stormwater management systems and to develop a conceptual solution for a residential property in Kraków, Poland. Geological, hydrogeological, hydrological, and topographic conditions were assessed using archival data verified through field investigations. Rainfall data from the Kraków-Balice meteorological station (2014–2023) were used to estimate rainwater harvesting potential and evaluate system performance. The proposed system consists of surface and subsurface drainage, two storage tanks, and an infiltration well. The first tank collects roof runoff for non-potable domestic use, whereas the second stores water from the drainage system and paved surfaces for irrigation. The annual rainwater harvesting potential was comparable to the non-potable water demand of a five-person household, while water collected from the drainage system and paved surfaces was sufficient for irrigation. Monthly precipitation analysis revealed pronounced seasonal variability, with winter shortages and summer surpluses. Integrating the storage tanks with the infiltration well enabled effective management of excess stormwater while supporting groundwater recharge. The results demonstrate that consideration of geological-engineering conditions is essential for the effective and sustainable design of residential stormwater management systems. Full article

Highland pastures in Montenegro, known as katuns, are seasonal settlements without grid power or network coverage and which are located where conventional monitoring is unfeasible. This study presents a solar-powered, off-grid system for livestock and environmental monitoring. It integrates, into a single portable unit, a solar power station, an edge-AI computer, a camera, environmental sensors, a LoRaWAN gateway, and a cellular router for backhaul. All parts are pre-wired in a modular enclosure, deployable by one operator in under 30 min. Data are fed to the agroNET farm-management platform and a purpose-built mobile web application; livestock detection runs on-device using a model from our earlier work. The system was evaluated at three sites, including a highland katun near Žabljak (~1450 m), under a two-phase energy-measurement protocol. During field logging it drew ~75 W on average against ~125 W solar input—a measured surplus that is used to recharge the battery—with a daily monitoring load of ~1560 Wh. The four-panel array’s nameplate potential in summer is an estimated ~3700 Wh/day, indicating substantial headroom relative to the measured load. At 80% depth of discharge the battery gives ~20 h autonomy, and the detection pipeline ran continuously, processing ~10,000 frames at under 3 s latency. The results demonstrate the feasibility of off-grid precision livestock farming, reaching TRL 6. Full article

River–aquifer exchange during floods controls groundwater recharge and bank storage, yet its sensitivity to floodplain geometry, flood duration, and subsurface permeability remains insufficiently quantified. A coupled model integrating one-dimensional surface-water flow, two-dimensional groundwater flow, and vertically resolved unsaturated floodplain infiltration was parameterized using observation-derived bank-storage estimates from Hungarian Danube floods. Idealized scenarios evaluated the effects of floodplain width, flood duration, and aquifer and soil permeability on river–aquifer exchange, bank storage, and flood attenuation. Simulations indicated that, under the investigated conditions, vertical floodplain infiltration dominates exchange processes, accounting for approximately 82–92% of total exchange and bank storage, whereas horizontal riverbed exchange remains secondary. Floodplain geometry and flood duration exerted influences on bank storage and flood attenuation comparable to those of subsurface permeability. Wider floodplains enhanced infiltration, storage capacity, and flood attenuation. Short floods produced high but transient infiltration and strong peak attenuation, whereas longer floods promoted sustained infiltration, larger bank storage, and delayed attenuation. Subsurface permeability regulated exchange efficiency but exhibited a nonlinear influence on bank storage. These results demonstrated that flood attenuation during overbank flooding depends not only on river–aquifer exchange magnitude, but also on its partitioning and the temporal evolution of subsurface storage. Full article

The Shangri-La area lies within the Yunnan-Tibet geothermal belt, characterized by intense tectonic activity and abundant geothermal resource potential. However, existing studies have largely focused on individual hot springs, and a regional scale understanding of geothermal geology and fluid circulation mechanisms remains lacking. This study systematically elucidates the geological setting, hydrogeological characteristics, circulation mechanisms, and resource potential of the geothermal systems by integrating hydrogeological surveys with hydro chemical and isotopic analyses. The results indicate that the Zhongxiao Fault Zone and its associated secondary structures are the primary controllers of geothermal water distribution, serving as both thermal conduits and hydrogeological boundaries. The primary heat source is attributed to the natural geothermal gradient, supplemented by additional contributions from magmatic activity. The geothermal waters are classified as Na-HCO₃ or Ca-HCO₃ types and are notably rich in fluoride. The mean values of δD and δ¹⁸O for geothermal water were −127.86‰ and −15.53‰, respectively, exhibiting isotopic depletion compared with non-thermal water. The geothermal water samples plot near both the Global and Local Meteoric Water Lines while exhibiting a distinct mean ¹⁸O shift of +1.24‰, indicating that the systems are recharged by atmospheric precipitation and have subsequently undergone intense water–rock interaction. Analysis using the Na-K-Mg triangle diagram reveals that most geothermal water samples are immature waters. Thus, the quartz geothermometer provides more reliable estimates of reservoir temperatures. Calculations yield reservoir temperatures ranging from 70 °C to 123 °C, characterizing the system as a medium-to-low temperature resource. With an annual exploitable energy of 5.9 × 10¹⁴ J and high fluoride content, these resources can offer substantial potential for clean energy and balneotherapy. Full article