Search Results (1,595)

Climate change is altering the global hydrological cycle, which, combined with human interventions, such as reservoir operation, further disrupts river flows. Given the heterogeneity and importance of these impacts, and the particularities of each basin, regional studies are essential to assess local vulnerabilities. This study focuses on the upper Miño basin (NW Iberian Peninsula), together with the Belesar reservoir, to evaluate projected changes in streamflow between historical (1985–2014) and future (2070–2099) periods under the SSP5-8.5 and the SSP2-4.5 scenarios. Neural networks were applied to model the hydrological cycle, estimating flow from temperature and precipitation data, as well as to simulate reservoir operation, achieving successful validation. Results for SSP5-8.5 reveal a projected intensification of the hydrological cycle, with the 10th percentile (defining low-flow conditions) projected to decrease by approximately −10%, while the 99.997th percentile (defining high-flow conditions) is expected to increase by about +5%. Mean streamflow is projected to decline by more than −15%. Under the more moderate SSP2-4.5 scenario, changes are less pronounced, with the low-flow percentile expected to decrease by roughly −5% and mean streamflow showing a projected decline not reaching −15%. In contrast, the high-flow percentile exhibits an opposite trend, with a projected decrease of about −30% relative to the historical period. The analysis of reservoir operation was conducted under the most extreme emission scenario (SSP5-8.5), to assess its regulatory capacity under the harshest projected hydrological conditions. Results show that reservoir operation helps moderate the projected impact by redistributing water from wetter to drier periods, more than doubling projected summer flows downstream relative to upstream, and lowering winter flows, with the one-year return period value (99.997th percentile) projected to be reduced by approximately −15% by reservoir operation. Although natural future conditions are projected to become more critical, both the adoption of a more moderate emission pathway and an adequate reservoir operation will contribute to alleviating the most adverse hydrological impacts. Full article

The utilization of treated dredged sludge as a partial replacement for natural sand and gravel in construction projects offers a promising approach to reducing the exploitation of natural resources. The conventional vacuum preloading (VP) method, while widely used for soft soil improvement, is often associated with prolonged consolidation periods and high energy consumption in its later stages. Conversely, the electroosmosis (EO) technique is effective in enhancing drainage in low-permeability soft clays but is constrained by issues including anode corrosion, high operational costs, and uneven soil reinforcement. This study presents an experimental investigation into an alternating vacuum preloading and electroosmosis method for sludge treatment based on the underlying reinforcement theory. A series of laboratory model tests was conducted using a self-made vacuum–electroosmosis alternating test device. The reinforcement efficiency was assessed through the continuous monitoring of key performance indicators during the tests, including water discharge, surface settlement, electric current, electrode corrosion, and energy consumption. Post-test evaluations of the final soil shear strength and moisture content were also performed. The test results demonstrate that the alternating vacuum–electroosmosis yielded more significant improvement than their synchronous application. Specifically, the alternating vacuum–electroosmosis increased total water discharge by 46.1%, reduced final moisture content by 20.8%, and enhanced shear strength by 35.6% relative to the synchronous mode. Furthermore, an alternating VP-EO mode was found to be particularly advantageous during the electroosmosis phases, facilitating a more stable and sustained dewatering process. In contrast, the application of vacuum preloading alone resulted in inefficient performance during the later stages, coupled with relatively high energy consumption. Full article

Highland urban wetlands are primarily located in high-altitude, low-temperature regions, possessing unique ecological and regulatory functions. Following ecological restoration and supplemented by artificial interventions, wetlands in Xining City play a significant role in carbon sequestration, oxygen release, and water purification. Against the backdrop of China’s “carbon peak and carbon neutrality” goals, investigating carbon cycling processes in high-altitude urban wetlands has emerged as a current research focus. However, systematic exploration integrating the three elements-“high-altitude,” “urban ecosystems,” and “sediment carbon pools”-remains largely unexplored. This study examines the sediment carbon pools in Xining’s wetlands—specifically Haihu (semi-artificial wetland), Ninghu (artificial wetland), and Beichuanhe (riverine wetland)—within the Hangsui River Wetland Park. Key findings include: (1) The short-term sedimentation rate was determined to be 0.50–0.75 cm·a⁻¹ based on the “inflection point” of biogenic elements in wetland sediments. (2) Significant differences (p < 0.05) in average TOC content were observed across different wetland sediments during distinct periods. Sediment TOC content is higher under plant cover than without plant cover. (3) The mean sediment carbon density ranged from 6.58 ± 1.38–13.02 ± 3.91 g·cm⁻², with sediment organic carbon burial rates between 0.67–1.65 g·cm⁻²·a⁻¹. (4) The sediment carbon stock in the wetland was 20,856.09 Mg·C. Full article

Saltwater intrusion increasingly jeopardizes groundwater in low-lying coastal plains worldwide, where the combined effects of sea-level rise, land subsidence, and hydraulic regulation further exacerbate aquifer vulnerability and threaten the long-term sustainability of freshwater supplies. To move beyond sparse and fragmented piezometric observations, we propose “integrated coastal supersites”: wells equipped with multiparametric sensors and multilevel piezometers that couple high-resolution vertical conductivity–temperature–depth (CTD) profiling with continuous hydro-meteorological time series to monitor the hydrodynamic behavior of coastal aquifers and saltwater intrusion. This study describes the installation of two supersites and presents early insights from the first monitoring period, which, despite a short observation window limited to the summer season (July–September 2025), demonstrate the effectiveness of this approach. Two contrasting supersites were deployed in the coastal plain between the Brenta and Adige Rivers (Italy): Gorzone, characterized by a thick, laterally persistent aquitard, and Buoro, where the aquitard is thinner and discontinuous. Profiles and fixed sensors at both sites reveal a consistent fresh-to-saline transition in the phreatic aquifers and a secondary freshwater lens capping the confined systems. At Gorzone, the confining layer hydraulically isolates the deeper aquifer, preserving low salinity beneath a saline, tidally constrained phreatic zone. Groundwater heads oscillate by about 0.2 m, and rainfall events do not dilute salinity; instead, pressure transients—amplified by drainage regulation and inland-propagating tides—induce short-lived EC increases via upconing. Buoro shows smaller water-level variations, not always linked to rainfall, and, in contrast, exhibits partial vertical connectivity and faster dynamics: phreatic heads respond chiefly to internal drainage and local recharge, with rises rapidly damped by pumping, while salinity remains steady without episodic peaks. The confined aquifer shows buffered, delayed responses to surface forcings. Although the monitoring window is currently limited to 2025 through the summer season, these results offer compelling evidence that coastal supersites are reliable, scalable, and management-critical relevance platforms for groundwater calibration, forecasting, and long-term assessment. Full article

Soybean seed production in low-altitude subtropical environments in Paraguay is constrained by the antagonism between achieving high grain yields and high physiological seed quality, a relationship governed by the Genotype x Environment x Management (GxExM) interaction. This study aimed to elucidate this trade-off by evaluating three sowing dates (early, normal, late) across genotypes from three relative maturity groups over four growing seasons. Our results demonstrate that sowing date is the primary factor modulating this antagonism. Early and normal sowings maximized yield (up to 62.8% higher than late sowing) by synchronizing the reproductive period with maximum solar radiation but exposed the maturation phase to severe thermal and water stress. This consistently resulted in a high incidence of green seeds (>95% higher than late sowing) and a drastic reduction in seed vigor, with longevity potential reduced by up to 63.6%. In contrast, late sowing functioned as a stress-escape strategy, shifting maturation to milder autumn conditions and consistently producing seeds of high vigor, viability, and greater longevity. Critically, during a season of extreme drought and heat, the late sowing not only preserved quality but also produced the highest grain yield, highlighting its decisive role in risk mitigation. Thus, sowing date is a key management tool for targeted production in these environments. Full article

Evapotranspiration (ET) plays a vital role in understanding water and energy cycles in forest ecosystems, particularly in tropical regions where rubber plantations are widespread. In this study, a rubber plantation system was used. By combining meteorological data from flux towers and 30 periods of Landsat-8 image data, we estimated the daily ET of a rubber plantation from 2022 to 2024 using the Surface Energy Balance System (SEBS) model. Additionally, the study employed the eddy covariance method to validate the accuracy of the daily average ET estimated by the SEBS model in different source areas, in order to explore the model’s applicability. Simultaneously, we examined the key drivers influencing ET in rubber plantations by analyzing meteorological factors and physiological growth indicators. The results indicated that the SEBS model exhibited the highest estimation accuracy (R² = 0.90, RMSE = 0.43 mm, RE = 15.23%) for the rubber plantation ET in the region 1.5 km away from the flux tower, and the retrieval accuracy of 30 periods of ET was higher (RMSE ≤ 1 mm, RE ≤ 46.84%), indicating that the SEBS model was well-suited for estimating ET in rubber plantations. From 2022 to 2024, the daily average and monthly cumulative ET showed a unimodal distribution, with high summer and low winter values; the average monthly accumulated ET during the wet season (102.75 mm) was found to be significantly greater than that during the dry season (50.61 mm). On the daily and monthly scales, the correlation between atmospheric pressure, temperature, and ET was the most significant. These findings enhance our understanding of rubber plantation water use patterns and support the application of remote sensing models for regional water resource management, offering valuable insights for optimizing irrigation strategies and ensuring sustainable rubber production in tropical regions. Full article

This work assesses the viability of ultrafiltration (UF) membranes as a substitution for classic tertiary technologies for municipal wastewater (MWW) treatment. UF membranes can offer efficient MWW filtration, meeting quality standards regarding solids, bacteria, viruses and emerging pollutants, such as microplastics. All of these make UF not only an attractive competitor regarding tertiary treatments but also a potential quaternary treatment according to the latest legislation. Indeed, the achieved permeate quality meets the more stringent parameters for water reuse in agriculture according to the European standard (A-type water). The UF membrane’s feasibility when used as an MWW tertiary/quaternary treatment was assessed in a semi-industrial plant with commercially available industrial membrane modules under different operating conditions: (1) transmembrane flux, (2) air sparging intensity and filtration/relaxation periodicities, (3) the concentration of solids reached in the membrane tank and (4) the efficacy of chemically enhanced backwashing (CEB) to mitigate fouling. Increasing the air intensity (around 0.25 m³ m⁻² h⁻¹), increasing the solids concentration (3–4 g L⁻¹) and using acid chemicals for backwashing at low concentrations but high periodicities (about 25–50 ppm of HCl/citric acid at a pH of 2.5 once or twice every 15 days) displayed great effectiveness in minimizing fouling, which was found to be mainly reversible. Thanks to the stablished conditions, semi-industrial UF membrane filtration was possible for more than 30 days when operating at relatively high transmembrane fluxes (21.5 LMH), achieving an average transmembrane pressure of around 120 mbar with an extremely low fouling growth rate of 0.024 mbar d⁻¹. Full article

Urban Flooding is one of the most prevalent natural hazards worldwide, leading to substantial human and economic losses. Therefore, the assessment and mapping of flood hazard levels are essential for reducing the impact of future flood disasters. This study develops and integrates a methodology to evaluate urban flood susceptibility in Nangarhar Province, Afghanistan, a semi-arid region with limited prior research. Landsat imagery from 2004 to 2024 was used to analyze land use land cover change (LULCC), indicating that built-up areas increased from 124 to 180 km² in 2004 to 2024, respectively, while agricultural land decreased from 1978 km² to 1883 km² during the same period. Climate data exhibit increases in temperatures and intensifying rainfall, exacerbating flood hazards. Geospatial analysis of elevation, slope, drainage density, and proximity to water bodies highlights the high susceptibility of low-lying areas. The Analytical Hierarchy Process (AHP) was employed to integrate diverse flood risk factors and produce accurate flood hazard maps. The findings show that very-high flood susceptibility zones expanded from 1537 to 1699 km² in 2004 to 2024, whereas low-susceptibility zones declined from 131 km² to 110 km². Socioeconomic indicators such as population density, built-up density, and education accessibility were also incorporated into the assessment. This study underscores the need for adaptive land use planning, resilient drainage systems, and community-based flood risk reduction strategies. The findings provide actionable insights for sustainable flood management and demonstrate the value of combining GIS, remote sensing, and multi-criteria analysis in data-scarce, conflict-affected regions. Full article

The COVID-19 pandemic presented an unprecedented opportunity to assess the environmental effects of reduced anthropogenic activity on urban climates. This study investigates the impact of COVID-19-induced lockdowns on land surface temperature (LST) and the intensity of the surface urban heat island (SUHI) in Nowshera District, Khyber Pakhtunkhwa Province, Pakistan, which is experiencing rapid urbanization. Using Landsat 8/9 imagery, we assessed thermal changes across three periods: pre-lockdown (April 2019), during lockdown (April 2020), and post-lockdown (April 2021). Remote sensing indices, including NDVI and NDBI, were applied to evaluate the relationship between land cover and LST. Our results show a significant reduction in average LST during lockdown, from 31.38 °C in 2019 to 25.34 °C in 2020, a 6 °C decrease. Urban–rural LST differences narrowed from 9 °C to 6 °C. A one-way ANOVA confirmed significant differences in LST across the three periods (F (2, 3) = 3691.46, p < 0.001), with Tukey HSD tests indicating that the lockdown period differed significantly from both the pre- and post-lockdown periods (p < 0.001). SUHI intensity fell from 35.10 °C to 28.89 °C during lockdown, then rebounded to 35.37 °C post-lockdown. The indices analysis shows that built-up and rangeland areas consistently recorded the highest LST (e.g., 35.36 °C and 37.09 °C in 2021, respectively), while vegetation and water bodies maintained lower temperatures (34.68 °C and 32.69 °C in 2021). NDVI confirmed the cooling effect of green areas, while high NDBI values correlated with increased LST in urban areas. These findings underscore the impact of human activity on urban heat dynamics and highlight the role of sustainable urban planning and green infrastructure in enhancing climate resilience. By exploring the relationships among land cover, anthropogenic activity, and urban climate resilience, this research offers policymakers and urban planners’ valuable insights for developing adaptive, low-emission cities amid rapid urbanization and climate change. Full article

SWMM (Stormwater Management Model) is one of the most widely used computation tools in urban water resources management. Traditionally, the choice of rainfall data for calibrating the SWMM model has been arbitrary, lacking clarity on the most suitable rainfall types. In addition, the simplification in the SWMM hydrological module of the rainfall–runoff process, coupled with measurement errors, introduces a high level of uncertainty in the calibration. This study investigates the influences of rainfall types on the highly uncertain SWMM model calibration by implementing the Bayesian inference theory. A Bayesian SWMM calibration framework was established, in which an advanced DREAM(zs) (Differential Evolution Adaptive Metropolis, Version ZS) sampling method was used. The investigation focused on eight key hydrological parameters of SWMM. The impact of rainfall types was analyzed using nine rainfall intensities and three rainfall patterns. Results show that rainfall events equivalent to a one-year return period (R5, 42.70 mm total depth) or higher generally yield the most accurate parameters, with posterior distribution standard deviations reduced by 40–60% compared to low-intensity rainfalls. Notably, three parameters (impervious area percentage [Imperv], storage depth of impervious area [S-imperv], and Manning’s coefficient of impervious area [N-imperv]) demonstrated consistent accuracy irrespective of rainfall intensity, with a coefficient of variation below 0.05 for Imperv and S-imperv across all rainfall intensities. Furthermore, it was found that rainfall events with double peaks resulted in more satisfactory calibration compared to single or triple peaks, reducing the standard deviation of the Width parameter from 168.647 (single-peak) to 110.789 (double-peak). The findings from this study could offer valuable insights for selecting appropriate rainfall events before SWMM model calibration for more accurate predictions when it comes to urban non-point pollution control strategies and watershed management. Full article

Coral life cycle dynamics are poorly understood in most reefs, especially at the large geographic scales commensurate with ocean transport, genetic flow, and other synoptic scale processes. We present a spatially explicit, large-scale, and multi-temporal study of coral settlement along a 30 km long reef system in the Southwest portion of Hawaiʻi Island. Here, we focused on interannual variability in coral recruitment from 2021 to 2024, a period without a major marine heatwave. We used stratified random site selection to place 320 coral settlement tiles at 32 sites (10 tiles per site) at 10 ± 3 m water depth annually to monitor recruitment of the three most common coral genera found in the region (Montipora, Pocillopora, Porites). Site-level interannual variability in coral recruitment was high yet the overall geographic distribution of recruits was consistent through time. This occurred despite a decrease in benthic temperature and recruitment rates during the study period. Persistent geographic patterns in coral recruitment strengthen our understanding of mechanisms and conditions that drive reef resilience. They also strongly suggest a need to protect areas of high recruitment while studying drivers of low recruitment in contrasting habitats. This approach will further increase support of coral production in an era of climate- and coastal pollution-driven declines in coral reefs. Full article

Water environmental carrying capacity (WECC) is an important support for social and economic development and is closely related to regional production and consumption patterns. Exploring the level of WECC and its evolution trend is very urgent for the scientific formulation of targeted early warning control strategies. Therefore, this study first constructs the index system of WECC with a DPSIR model, and conducts the quantitative evaluation by combining the Kantiray Weighting method and the TOPSIS method. Then, the Kernel Density Estimation method and the Markov Chain model are applied to explore the spatiotemporal variation characteristics of WECC and predict its evolution trend. Finally, a case study of 17 municipal administrative regions in Hubei Province is carried out. The main findings are as follows: (1) The WECC status in Hubei Province during 2013–2022 was generally satisfactory and showed a trend of fluctuating improvement. (2) The spatial agglomeration effect of WECC in Hubei Province was significant, showing a distribution pattern of “high-high” agglomeration and “low-low” agglomeration. The improvement of the WECC in eastern Hubei was obvious, while that in central Hubei was slower, and the cities with a lower level of WECC had a more significant improvement effect. (3) Overall, the WECC of cities in Hubei Province tends to shift to a higher level. In a short period of time, the grade improvement of urban WECC in Hubei Province is more likely to occur between adjacent grades. With the increase in time span, the probability of this transition rises gradually. This study has proposed a set of methods for the evaluation and prediction of WECC status, which can provide important decision-making guidance for the early warning and regulation of regional differentiated WECC. Full article

The worldwide issue of surface water contamination by heavy metals is a matter of great concern, as it has the potential to affect human health. This study intended to compute heavy metal contamination and human health risks in surface water using the following pollution indices: heavy metal pollution index (HPI), contamination index (CI), metal index (MI), ecological risk index (ERI), human health risk and statistical analysis. For this purpose, eleven water samples were gathered and analyzed by ICP-AES for trace metals such as Pb, As, Zn, Cd, Cu, and Ni. The results showed that heavy metal concentrations varied significantly throughout the study area, with Pb, As, and Cd levels exceeding the WHO limits for drinking purposes. Pollution indices indicated low to high water contamination, with HPI results ranging from 16.41 to 862.18 and from 12.76 to 774.03, above the critical value of 100, requiring serious interventions to reduce heavy metal pollution. MI results range from 0.90 to 20.92 and from 0.70 to 18.41 and CI values range from 0.34 to 20.38 and from 0.15 to 17.86 in the dry and wet periods, respectively, with different contamination levels observed throughout the study area; ERI showed low to considerable ecological risk. Nonetheless, the non-carcinogenic risk, THI < 1, indicates low health risks, while the carcinogenic risk for As and Cd was significantly higher than the negligible threshold of 10⁻⁶, suggesting tolerable health risks. However, managing the contaminated area and minimizing the metal concentrations and predominant routes through which metals impact human health should be priorities for long-term development and to establish a favorable environment. Full article

Chile, the leading exporter of cherries (Prunus avium L.) in the southern hemisphere, faces sustained variations in precipitation patterns and high evaporative demand in its productive areas. The low availability of water during the period of highest environmental demand makes it essential to reduce or suspend irrigation applications. In this scenario, regulated deficit irrigation (RDI) after harvest is an efficient strategy for optimizing water use without compromising orchard yields. This study was conducted over three consecutive seasons in a traditional commercial orchard of ‘Santina’ cherry trees grafted onto Colt rootstock, evaluating the effect of two levels of RDI, moderate (MDI) and severe (SDI), on productive and ecophysiological parameters. Both treatments resulted in water savings of between 10% and 28%, without negatively affecting yield or fruit quality. The SDI treatment, despite reaching higher levels of cumulative water stress, improved intrinsic water use efficiency while maintaining stable photosynthetic efficiency. In addition, an increase in the abundance of fine roots and beneficial rhizosphere bacteria populations, such as Azospirillum and Bacillus, was observed, suggesting the activation of water resilience mechanisms mediated by plant–microbiota interaction, possibly associated with stress-induced ecological memory and microbial legacy effects. These results position after-harvest RDI as a sustainable tool for coping with climate variability and water scarcity in commercial cherry orchards. Full article

The stage-discharge relationship in the Jingjiang Reach of the Yangtze River has undergone significant alterations due to post-Three Gorges Reservoir (TGR) operation effects, notably bed erosion and roughness variation. This study employs a calibrated 1D hydrodynamic model based on Saint-Venant equations. The model was validated with high accuracy (Nash-Sutcliffe efficiency >0.94 at key stations) using long-term hydrological data (1996–2022). Four scenarios were simulated: pre-dam conditions, post-dam topography with pre-dam roughness, pre-dam topography with increased roughness, and coupled post-dam changes. A novel scenario-based decomposition framework was developed to isolate individual and coupled factor contributions, advancing beyond traditional descriptive approaches. The results indicate that upstream water level changes are mainly controlled by riverbed erosion (e.g., at the Zhicheng Station: the topographic contribution rate exceeds 80% at a flow rate of 5000 m³/s, resulting in a water level drop of approximately 1.7 m), while downstream, an increase in roughness becomes the dominant factor (e.g., at the Jianli Station: causing a water level rise of about 1.0 m at a flow rate of 13,000 m³/s, with such changes being particularly pronounced under low-flow conditions). Spatially, topographic influence attenuates downstream, whereas roughness sensitivity amplifies in high-sinuosity reaches (bend coefficient: 3.0). Seasonally, the topographic contribution rate remains stable overall during the low-flow period, e.g., within a narrow range of 0.88–0.98 at Zhicheng Station, while roughness effects exhibit negative values in dry periods (November) due to fine sediment deposition. The coupling effect in mid-discharge ranges (15,000–20,000 m³/s) at Jianli partially offsets stage reductions. These findings not only provide critical insights for flood forecasting and navigation management in the Jingjiang Reach but also offer a transferable methodology for quantifying hydro-morphodynamic interactions in global regulated rivers, highlighting the model’s utility in predictive water resource management. Full article