Search Results (3,286)

The Po River, the largest watercourse in northern Italy, represents a fundamental resource for the socio-economic system of the Padanian Plain. Between February 2022 and February 2023, the basin was affected by exceptional climatic anomalies, with unprecedented high temperatures, marked precipitation deficits, and the most severe hydrological drought documented in the instrumental record. Po river waters sampled during this period showed variable increases (Na⁺, K⁺, Mg²⁺, HCO₃⁻, Cl⁻, SO₄²⁻) or decreases (Ca²⁺, NO₃⁻) in the geochemical composition of major ions compared to data from previous decades collected under various climatic and hydrological conditions In contrast, the water stable isotope composition (δ²H and δ¹⁸O) of the period 2022–2023 displayed distinct and peculiar signatures, ranging from −64.1 to −53.5‰ for δ²H and from −9.4 to −5.7‰ for δ¹⁸O, compared to historical averages for 1998–2014 (−71.3 to −58.0‰ and −10.0 to −8.7‰, respectively). These values indicate a strong enrichment in heavy isotopes, reflecting warmer and drier climatic conditions, comparable only to those observed during the severe drought of 2015. Two groups of data were identified: Group 1, showing affinities with Eastern Mediterranean precipitation, and Group 2, characterized by pronounced evaporative isotopic enrichment due to prolonged drought, as evidenced by strongly negative d-excess and LC-excess values, consistent with those from arid and semi-arid regions worldwide. This study demonstrates how climate change and increasing hydrological stress are altering the isotopic composition of one of Europe’s most important river systems. Stable isotopes provide a sensitive tool for tracing moisture sources, quantifying evaporative processes, and assessing drought impacts, confirming their role as Essential Climate Variables (ECVs) in climate and water-resource studies. Full article

Groundwater quality in the semi-arid region of Oum El Bouaghi, Northeastern Algeria, was assessed for irrigation suitability using hydrogeochemical analyses, water quality indices, and GIS techniques. The study analyzed 23 groundwater samples during dry and wet seasons in 2022–2023, several physicochemical parameters were measured. Results revealed neutral to slightly alkaline pH levels, except for one acidic sample, with salinity (EC: 527–5001 µS·cm⁻¹) exceeding WHO guidelines, particularly during the dry season due to evaporation and anthropogenic activities. Hydrogeochemical facies showed dominance of Na⁺-HCO₃⁻ and Ca²⁺-Cl⁻/SO₄²⁻ water types, indicating rock–water interactions and evaporation control, as confirmed by Gibbs plots. The IWQI classified water into five categories, with severe restrictions (IWQI < 40) in 13% of samples during the dry season, improving slightly in the wet season. Indices such as SAR, Na%, and RSC indicated low to moderate sodium hazard, while KR and PS highlighted salinity risks in specific areas. Spatial analysis revealed localized pollution hotspots, with the (GPI) identifying minimal to high contamination levels, linked to agricultural and geogenic sources. These findings underscore needs for sustainable groundwater management, including monitoring, optimized irrigation practices, and mitigation of anthropogenic impacts, to ensure long-term agricultural viability in this water-scarce region. Full article

This study looks into the parameters that affect the heat transfer coefficient (h₂) on the wet surfaces of vertical tube indirect evaporative coolers (VTIEC). An experimental platform was used to investigate the impact of secondary-to-primary airflow ratios (AFR) and spray water density on the HTC. The findings show that raising the primary air temperature drop, expanding the outside dry-bulb and wet-bulb temperature differences, and decreasing the air-to-water ratio improve heat transmission. The HTC of the wet sides ranged from 34.79 to 924.5 W/(m²·°C) throughout testing. To achieve optimal performance, aim for a spray water density of 2.07 to 3.46 m³/(m²·h), an AFR of 0.5 to 0.6, and a primary air temperature drop of at least 6 °C. These factors help keep the h₂ above 350 W/(m²·°C). Full article

The Organic Rankine Cycle (ORC)-based waste-heat recovery system represents an important technological pathway toward decarbonization in the maritime industry. This study focuses on the design and optimization of a multi-heat-source Organic Rankine Cycle (MHSORC) power generation system specifically developed for large marine diesel engines, which simultaneously utilizes exhaust gas, cylinder jacket water, and scavenging air as heat sources. Unified thermodynamic, economic, and environmental models are constructed to evaluate the coupled performance of the system.Eight low GWP working fluids are assessed, and a multi-objective optimization is performed to balance efficiency, cost, and environmental impact. The optimal design point is subsequently identified using a decision-making algorithm. The results indicate that, for the MHSORC, higher evaporating temperatures and lower condensing temperatures improve system performance, and the heat-source temperature exerts a direct and substantial influence on that performance. Among the candidate fluids, R601 exhibits the best overall performance, whereas R1234ze performs the worst. With R601 as the working fluid, the MHSORC achieves an exergy efficiency of 41.69%, a LCOE of 0.0495 $/kWh, and greenhouse gas emissions of 0.8019 kt of CO_2,eq. Full article

Within the scope of this article is the presentation of a modelling and measurement approach for the effects of roof greenings and the application of the approach to evaluate the influence of roof greenings upon the thermal conditions inside a typical residential building. It is shown that overheating in summer can be reduced, and thermal comfort for inhabitants can be increased. The cooling is caused by the transpiration of plants and by the evaporation of water from the substrate. Other relevant physical effects are the shading of plants and the increase in the heat capacity of the building. In state-of-the-art buildings, a layer with a high insulating effect is incorporated into the envelope. This leads to the effect that a huge fraction of the cooling power is taken from the outside of the building and only a smaller part is taken from the inside. In order to mitigate this decoupling, a hydraulic connection between the greening and the interior of the building is introduced. To evaluate the effect of the inside cooling, the difference in the number of yearly hours with overheating in residential buildings is estimated. In addition, the reduction in energy demand for the climatisation of a typical residential building is calculated. The used methods are as follows: (1) Performance of laboratory and free field measurements. (2) Simulation of a typical residential building, using a validated approach. In summary, it can be said that green roofs, in particular with hydraulic connections, can significantly increase the interior thermal comfort and potentially reduce the energy required for air conditioning. Full article

To mitigate the impact of north–south strip errors inherent in Gravity Recovery and Climate Experiment (GRACE) spherical harmonic coefficient solutions, this research develops a state-space model to generate a more robust solution. The efficacy of the state-space model is demonstrated by comparing its performance with that of conventional filtering methods and hydrological modeling schemes. The method is subsequently applied to estimate the GRACE Groundwater Drought Index in the California Central Valley basin, a region significantly affected by drought during the GRACE observation period. This analysis quantifies the severity of droughts and floods while investigating the direct influences of precipitation, runoff, evaporation, and anthropogenic activities. By incorporating the El Niño–Southern Oscillation (ENSO) and the Pacific Decadal Oscillation, the study offers a detailed causal analysis and proposes a novel methodology for water resource management and disaster early warning. The results indicate that a moderate-duration flood event in 2006 resulted in a recharge of 19.81 km³ of water resources in the California Central Valley basin, whereas prolonged droughts in 2008 and 2013, lasting over 15 months, led to groundwater depletion of 41.53 km³ and 91.45 km³, respectively. Precipitation and runoff are identified as the primary determinants of local drought and flood conditions. The occurrence of ENSO events correlates with sustained precipitation variations over the subsequent 2–3 months, resulting in corresponding changes in groundwater storage. Full article

Salt lakes on the Tibetan Plateau (TP) are vital repositories of China’s strategic mineral resources, including boron and lithium. The Budongquan Salt Lake (BDQSL) in eastern Hoh Xil Basin (HXB) represents a hypersaline system with combined geothermal recharge and intense evaporation, yet its hydrochemical characteristics and B-Li enrichment mechanisms remain poorly understood. Through systematic hydrochemical and isotopic analysis (δD, δ¹⁸O, d-excess) of 69 surface samples, 14 depth-stratified profiles, and 131 regional water samples, we reveal that: (1) BDQSL exhibits extremely saline Na-Cl brines (TDS: 192,700–220,700 mg/L) significantly enriched in B and Li (45–54 mg/L), with overall spatial homogeneity and complete vertical mixing; (2) B and Li demonstrate strong correlation (R² = 0.95), controlled by coupled hydrothermal input, water–rock interaction, and evaporative concentration, with hydrothermal delivery as the predominant source; (3) depleted isotopic signatures (δ¹⁸O = −1.4‰, d-excess = −5‰) confirm intense evaporation, while upstream cascade connectivity and climate warming drive lake expansion and brine dilution, indicating transition toward lower salinity; (4) a distinctive hydrothermal–evaporative composite mineralization model differentiates BDQSL from regional mono-evaporative systems. This study elucidates B-Li enrichment mechanisms in hydrothermally active plateau salt lakes, providing geochemical constraints for resource assessment and predictive frameworks for evaluating mineral evolution under climate change. Full article

As a critical ecological barrier in the arid and semi-arid regions of northwestern China, the spatio-temporal evolution of vegetation carbon sequestration in the Hexi Corridor is of great significance to the ecological security of this region. Based on multi-source remote sensing and meteorological data, this study integrated second-order partial correlation analysis, ridge regression, and other methods to reveal the spatio-temporal evolution patterns of Gross Primary Productivity (GPP) in the Hexi Corridor from 2003 to 2022, as well as the response characteristics of GPP to air temperature, precipitation, and Vapor Pressure Deficit (VPD). From 2003 to 2022, GPP in the Hexi Corridor showed an overall increasing trend, the spatial distribution of GPP showed a pattern of being higher in the east and lower in the west. In the central oasis region, intensive irrigation agriculture supported consistently high GPP values with sustained growth. Elevated air temperatures extended the growing season, further promoting GPP growth. Due to irrigation and sufficient soil moisture, the contributions of precipitation and VPD were relatively low. In contrast, desert and high-altitude permafrost areas, constrained by water and heat limitations, exhibited consistently low GPP values, which further declined due to climate fluctuations. In desert regions, high air temperatures intensified evaporation, suppressing GPP, while precipitation and VPD played more significant roles. This study provides a detailed analysis of the spatio-temporal change patterns of GPP in the Hexi Corridor and its response to climatic factors. In the future, the Hexi Corridor needs to adopt dual approaches of natural restoration and precise regulation, coordinate ecological security, food security, and economic development, and provide a scientific paradigm for carbon neutrality and ecological barrier construction in arid areas of Northwest China. Full article

Based on a cloud water resources (CWR) diagnostic dataset with a 1° × 1° resolution over China from 2000 to 2019, this study systematically analyzes the spatiotemporal patterns of CWR in the complex terrain of the North China Region. The results indicate the following: (1) CWR-related physical quantities exhibit significant seasonal differences, with most being highest in summer and lowest in winter; water vapor convergence is strongest in summer and weakest in autumn, while hydrometeor convergence is smallest in summer and largest in winter; and the water surplus (precipitation minus evaporation) is minimal and negative in spring, indicating severe spring drought. (2) At the annual scale, precipitation is highly correlated with cloud condensation (r > 0.99), and CWR variation is primarily controlled by hydrometeor influx (r > 0.99). (3) The regional annual CWR and precipitation increase at rates of 34.8 mm/10 years and 49.2 mm/10 years, respectively, but exhibit seasonal asynchrony—CWR increases in all four seasons, while precipitation shows a slight decreasing trend in winter. (4) Spatially, CWR show a pattern of “more in the south and north, less in the central region; more in the east, less in the west,” with significant increases in the central–southern parts (southern Shanxi and Hebei, Beijing, and Tianjin). (5) Empirical orthogonal function (EOF) analysis reveals two dominant modes of CWR anomalies: a “region-wide consistent pattern” and a “north–south out-of-phase dipole pattern,” the latter being related to terrain-induced differences in water vapor transport and uplift condensation. The results statistically elucidate the distribution patterns of CWR under the influence of complex topography in NCR, providing a scientific reference for the development and utilization of regional CWR. Full article

Oil production generates approximately 250 million barrels of produced water (PW) daily, nearly three times the volume of oil, with salinity levels reaching up to 300,000 ppm. Improper management of this wastewater causes significant environmental degradation, including soil salinization and aquatic toxicity. To address these impacts, this study applies circular economy (CE) principles to PW management through flash vaporization and resource recovery. Implementing this approach enables 85–90% water recovery and reduces salinity to below 1000 ppm, allowing reuse for irrigation. Simultaneously, residual brine processed via evaporation ponds yields 15–25% potash (KCl) and 30–40% halite (NaCl), thereby transforming waste into valuable products. As a result, the integrated CE process can reduce wastewater disposal by 80%, cut greenhouse gas emissions by 25–30%, and lower treatment costs by 20–35%, while generating additional revenue of $150–300 per ton of recovered potash. These outcomes demonstrate that adopting CE strategies in PW management not only mitigates environmental degradation but also strengthens economic resilience and resource efficiency. The framework offers a scalable pathway for achieving the UN Sustainable Development Goals (SDG 6 and 12) and advancing sustainability within the oil and gas industry. Full article

Reverse osmosis (RO) water purifiers produce a large volume of reject water, which is typically discarded, leading to water wastage and resource inefficiency. This work proposes a novel approach to reusing RO effluent as a cooling medium in a water-cooled condenser integrated into a residential hot-and-cold water purifier. The system replaces a conventional air-cooled condenser with a water-cooled unit and was evaluated under controlled laboratory conditions (ambient temperature 25 °C). Experiments were conducted at various RO effluent flow rates ranging from 0.5 to 2.5 L per minute (LPM). Key performance metrics, including the coefficient of performance (COP), cooling time, and energy consumption, were measured and compared. Results showed that replacing a conventional air-cooled condenser with a water-cooled condenser configuration reduces energy consumption by up to 37.5% and shortens cooling times by up to 33%. Performance was maintained under intermittent RO effluent supply. However, an excessive flow rate (2.0 LPM) caused evaporator frosting and efficiency loss, indicating the importance of flow control. These findings demonstrate that internally reusing an RO effluent offers a sustainable, compact, and energy-efficient solution for next-generation water purifiers. Full article

This study presents a detailed evaluation of the energy performance and design optimization of a novel four-stage indirect evaporative cooler (IEC) enhanced with a supplementary humidifier, examined under the summer design conditions of Riyadh. Although previous research has demonstrated the system’s high thermal effectiveness, its energy efficiency—expressed through the coefficient of performance (COP)—and the influence of key design parameters have not been thoroughly explored. To address this gap, we integrate a validated thermal model with a comprehensive energy consumption model to assess the COP of the system under varying operational and geometric conditions. Results show that the baseline design achieves a maximum COP of 14.3. Through parametric optimization of heat exchanger depth and air velocity, the maximum COP increases to 20.4—a 43% improvement, associated with a supply temperature of 13.2 °C and specific water consumption of 2.5 kg/kWh at a return ratio of 0.3. The optimal parameters—a heat exchanger depth of 1.5 m and a humid-path air velocity of 1 m/s—ensure both high efficiency and practical feasibility. Overall, the findings highlight the considerable potential of the optimized multistage IEC system as a highly energy-efficient and sustainable alternative to conventional vapor-compression cooling technologies, contributing to reduced energy consumption and enhanced environmental sustainability in hot and dry climates. Full article

The Pantanal, considered the world’s largest tropical wetland, is increasingly threatened by intensifying droughts driven by climate variability and climate change. Using Multi-Source Weather data (MSWX), and bias-corrected multi-model means from five Coupled Model Intercomparison Project Phase 6 (CMIP6) simulations for the years 1980–2100, we assessed historical and future drought conditions under SSP2-4.5 and SSP5-8.5 scenarios for the Pantanal. Drought conditions were identified through the Standardised Precipitation Index (SPI) and the Standardised Precipitation–Evapotranspiration Index (SPEI) across multiple timescales, and with different reference periods. A historical analysis revealed a significant drying trend, culminating in the extreme droughts of 2019/2020 and 2023/24. Future projections indicate a dual pressure of declining precipitation and rising temperatures, intensifying the severity of dry conditions. By the late 21st century, SSP5-8.5 shows persistent, severe multi-year droughts, while SSP2-4.5 projects more variable but still intensifying dry spells. The SPEI highlights stronger drying than the SPI, underscoring the growing role of evaporative demand, which was confirmed through risk ratios for drought occurrence across temperature anomaly bins. These results offer multi-scalar insights into drought dynamics across the Pantanal wetland, with critical implications for biodiversity, water resources, and wildfire risk. Thus, they emphasise the urgency of adaptive management strategies to preserve ecosystem integrity under a warmer, drier future climate. Full article

In arid environments such as the Namib Desert, non-rainfall water sources—including dew and fog—constitute indispensable yet understudied components of the regional hydrological cycle. These moisture inputs play a critical role in sustaining ecological functionality and biogeochemical processes, but remain among the least quantified facets of desert ecohydrology. The present study investigates multi-year trends in morning dew formation within the Namib Desert, utilizing observations from the Gobabeb–Namib Research Institute between 2015 and 2022. Meteorological data from the Southern African Science Service Centre for Climate and Adaptive Land Management (SASSCAL), in conjunction with direct field observations of dew, were used to develop an empirical equation to estimate dew occurrence. A sensitivity analysis verified the robustness of this formulation, and subsequent validation using field data confirmed its reliability (84.84% accuracy). During this eight-year period, the annual number of days with morning dew decreased from 170 in 2015 to 140 in 2022, representing an overall decline of approximately 18%. However, the total daily dew occurrence across 24 h remained relatively constant, indicating that the observed decline is confined primarily to morning condensation events. Dew formation was most prevalent during the wet season (December–May). Both monthly and annual analyses revealed a discernible declining trend in morning dew occurrence across this hyperarid ecosystem (p < 0.05). This decline corresponded with a gradual increase in both air and soil temperatures (approximately +0.03 °C yr⁻¹) and a slight but consistent decrease in relative humidity (approximately −0.26% yr⁻¹) between 2015 and 2022. The principal drivers of this decline include rising soil and air temperatures and decreasing atmospheric humidity. The analysis further identified an inverse relationship between air temperature and dew formation, implying that climatic warming intensifies evaporative demand and thereby suppresses dew condensation. Random forest analysis identified soil temperature, air temperature, and relative humidity as the most important predictors influencing dew occurrence, whereas wind speed and direction played lesser roles. Collectively, these findings underscore the vulnerability of dew-dependent ecosystems to anthropogenic climate change and highlight the imperative to continue investigating non-rainfall moisture dynamics in desert environments. Full article

Investigating ecological irrigation risks associated with mine water utilization is of great significance for alleviating water resource shortages in arid mining regions of western China, thereby supporting efficient coal extraction and coordinated ecological development. In this study, a representative mining area in Xinjiang was investigated to reveal the evolution patterns of mine water quality under arid geo-environmental conditions in western China and to systematically assess environmental risks induced by ecological irrigation. Surface water, groundwater, and mine water samples were collected to study ion ratio coefficients, hydrochemical characteristics, and evolution processes. Based on this, a multi-index analysis was employed to evaluate ecological irrigation risks and establish corresponding risk control measures. The results show that the total dissolved solids (TDS) of mine water in the study area are all greater than 1000 mg/L. The evolution of mine water quality is mainly controlled by water–rock interaction and is affected by evaporation and concentration. The main ions Na⁺, Cl⁻, Ca²⁺, and SO₄²⁻ originate from the dissolution of halite, gypsum, and anorthite. If the mine water is directly used for irrigation without treatment, the soluble sodium content, sodium adsorption ratio, salinity hazard, and magnesium adsorption ratio will exceed the limits, leading to the accumulation of Na⁺ in the soil, affecting plant photosynthesis, and posing potential threats to the groundwater environment. Given the evolution process of mine water quality and the potential risks of direct use for irrigation, measures can be taken across three aspects: nanofiltration combined with reverse osmosis desalination, adoption of drip irrigation and intermittent irrigation technologies, and selection of drought-tolerant vegetation. These measures can reduce the salt content of mine water, decrease the salt accumulation in the soil layer, and lower the risk of groundwater pollution, thus reducing the environmental risks of ecological irrigation with mine water. The research will provide an important theoretical basis for the scientific utilization and management of mine water resources in arid areas by revealing the evolution law of mine water quality in arid areas and clarifying its ecological irrigation environmental risks. Full article