Search Results (247)

Utilising highly mineralised mine water for drip irrigation of desert vegetation in mining areas represents a crucial approach to alleviating freshwater scarcity and achieving mine water resource utilisation. However, high salt inputs may pose risks of salt return to root zones and deep accumulation. To ensure the safe and effective utilisation of mine water, laboratory 45 cm soil column infiltration tests (freshwater, 8, 12, 16 g L⁻¹) were conducted in the heavily saline-affected desert vegetation zone of Dananhu, Hami, Xinjiang, alongside 2023–2024 field drip irrigation trials (8, 12, 16 g L⁻¹). This study established a ‘soil column inversion–field validation–scenario optimisation’ framework (16 g L⁻¹) and field drip irrigation trials (8, 12, 16 g L⁻¹) during 2023–2024. A multi-scale HYDRUS-1D/3D simulation framework—‘soil column inversion–field validation–scenario optimisation’—was established to quantify water–salt transport processes in the root zone and optimise emitter flow rates. HYDRUS-1D demonstrated excellent fitting for soil moisture content, wetting front, and salinity distribution (R² = 0.964–0.979, 0.995–0.998, 0.791–0.898). Following parameter migration, HYDRUS-3D achieved R² values of 0.834–0.949 for simulating field-scale stratified salinity. Overall desalination occurred in the 0–80 cm soil profile over two years. Within the 0–40 cm root zone, reduction rates decreased with increasing irrigation salinity: 45.77% (2023) and 59.64% (2024) under 8 g L⁻¹ treatment, significantly higher than the 24.24% and 30.91% reductions observed at 16 g/L (p < 0.05). During the high-temperature period of July–August, transient salt accumulation occurred in the 0–10 cm surface layer, while the 80–120 cm zone exhibited cumulative risk. Scenario simulations indicated that increased dripper flow rates expanded the wetted zone horizontally but weakened vertical leaching. The 2.0–2.4 L h⁻¹ range demonstrated superior overall performance in balancing root zone desalination rates and irrigation uniformity. The study recommends targeting root-zone salinity stability through a combination of moderate leaching, summer transpiration suppression, and seasonal flushing/natural leaching, alongside prioritising low-to-medium flow emitters. This approach synergistically reduces both surface salinity return and deep accumulation risks. Full article

Accurate estimation of soil hydraulic parameters under drip irrigation is essential for improving water flow simulations and optimizing irrigation management; however, field measurements in aeolian sandy soils are often expensive and time-consuming. This study focused on typical aeolian sandy soils in the Kubuqi Desert. Field drip irrigation experiments were conducted to obtain temporal variations in soil water content and wetting front advancement, which were used to inversely estimate and calibrate hydraulic parameters for different soil layers. Soil pore space characteristics were quantified using nitrogen adsorption, and their relationships with hydraulic parameters were analyzed through correlation and redundancy analyses. On this basis, the combined effects of particle-size distribution and pore space structure on parameter prediction were evaluated, and soil water movement under drip irrigation was simulated and validated using HYDRUS-2D/3D. The results indicated pronounced spatial variability in soil hydraulic parameters. Residual water content, saturated hydraulic conductivity, and pore-size distribution index were significantly correlated with specific surface area, total pore volume, mean pore diameter, micropore volume fraction, and pore fractal dimension. Compared with approaches based solely on particle-size distribution, incorporating pore space structure effectively reduced the prediction errors of both hydraulic parameters and wetting front migration, thereby improving simulation accuracy. These findings demonstrate that integrating particle-size distribution and pore space characteristics provides a feasible approach for the rapid estimation of hydraulic parameters and the analysis of water movement in aeolian sandy soils under drip irrigation. Full article

Soil salinization and water scarcity pose critical threats to agricultural sustainability. Therefore, investigating the impacts of tillage practices and brackish water irrigation on the dynamic changes in soil water and salt is of great significance. To investigate the effects of fenlong-ridging deep tillage (FL) on soil water and salt distribution under brackish water irrigation, indoor soil column experiments were conducted comparing FL and conventional tillage (CT) across three irrigation water salinity conditions (0, 3, and 5 g·L⁻¹). The dynamic changes in soil moisture content and electrical conductivity (EC) were measured. The HYDRUS-2D model was used to simulate transport processes under varying FL depths (40/60/80/100 cm). Results indicated that compared with CT, FL can promote water infiltration. Furthermore, FL obviously reduced EC in the 0–50 cm layer compared to CT. Simulations confirmed that increasing FL depth enhanced desalination. Notably, irrigation with 3 g·L⁻¹ brackish water yielded higher EC reduction rates (26.04–30.12%) than 5 g·L⁻¹ water. The combination of 3 g·L⁻¹ salinity and 60 cm FL depth proved most effective; the soil electrical conductivity decreased by 28.28%. This study offers a feasible technical solution for the sustainable utilization of brackish water resources and the amelioration of saline soils. Full article

Accurate quantification of groundwater evapotranspiration (ET_g) is essential for reliable water resource assessment. Existing methods for estimating ET_g from water table fluctuation largely rely on one-dimensional simplifications that neglect transient groundwater flow. However, in areas with shallow water table and topographic relief, where transient groundwater flow often occurs, the validity and accuracy of this simplification remain inadequately evaluated. In this study, we used HYDRUS-2D to construct a 50 m-long sandy hillslope with a 0.05 gradient to investigate ET_g based on the water table fluctuation (WTF) method under transient groundwater flow conditions. The results indicate that periodic evapotranspiration generates water table fluctuations along the hillslope that exhibit amplitude attenuation and temporal phase lag, features not captured by 1D models. Ignoring transient groundwater flow leads to a systematic underestimation of ET_g by up to 85% in sandy soil near the topographic lows. Furthermore, we found that both the decoupling depth and the extinction depth are significantly amplified by lateral groundwater flow, by up to 66% and 51%, respectively, compared with 1D estimates derived from the Shah method. These findings highlight the importance of incorporating transient flow processes into ET_g estimation to improve the accuracy of water balance assessments and ecohydrological predictions, particularly in areas with shallow water tables and topographic relief. Full article

Background: Minimally invasive glaucoma surgery, often performed with phacoemulsification (PHACO-MIGS), for the management of primary open angle glaucoma (POAG), has good clinical outcomes and safety profiles. However, few studies have comprehensively evaluated the impact of PHACO-MIGS on patients’ quality of life (QoL). We determined the post-operative effectiveness of PHACO-MIGS on glaucoma-specific QoL domains in mild–moderate POAG patients. Methods: In this prospective study, adults aged ≥ 21 years with mild–moderate POAG in one eye scheduled for PHACO-MIGS at the Singapore National Eye Centre were administered a digital patient-reported outcome measure (PROM) that utilizes computerized adaptive testing (CAT) to precisely estimate glaucoma-specific QoL across 12 different domains (GlauCAT^TM), pre-surgery and at 6 months post-surgery. The 12 domains included the following: Visual Symptoms (VSs), Ocular Comfort Symptoms (OSs), Emotional (EM), Activity Limitation (AL), Driving (DV), Lighting (LT), Mobility (MB), Treatment Convenience (TCV), Concerns (CNs), Social (SC), General Convenience (GCV), and Economic (EC). Clinical variables collected included intraocular pressure (IOP), better eye visual acuity (VA), visual field deficit (VFD) and number of glaucoma drops prescribed. Linear mixed models were utilized to determine the within-group changes in each domain, adjusted for relevant clinical, treatment and sociodemographic variables. Results: Of the 83 patients (mean age ± SD: 70.84 ± 6.70 years; 65.1% male; 90.4% Chinese), 61 (73.5%) underwent PHACO-MIGS with Hydrus^® Microstent, and 22 (26.5%) with iStent^® inject. Mean (SD) improvements in VA and IOP were observed post-surgery (0.11 [0.15] LogMAR units and 1.35 [4.20] mmHg, respectively), while VFD and the average number of anti-glaucoma medications prescribed decreased by 0.90 (2.97) dB and 1.30 (0.11) drops (all p < 0.05). Compared to pre-operative scores, four GlauCAT^TM domains [VSs (13.04%, p < 0.001; ES: 0.84), OSs (6.42%, p < 0.001; ES: 0.52), CNs (7.53%, p = 0.002; ES: 0.51), and GCV (6.34%, p = 0.004; ES: 0.45)] showed significant improvements post-surgery. The improvements across these four domains were driven primarily by a reduction in IOP and improvements in VA. Conclusions: Using a novel and AI-driven QoL PROM, we found significant post-operative improvements in Visual and Ocular Comfort Symptoms, Convenience, and Concerns in patients with POAG undergoing combined PHACO-MIGS, driven by improvements in IOP and VA post-surgery. Full article

Understanding the distribution of water and salt in the crop’s root zone and predicting future soil degradation requires specific monitoring to establish guidelines for irrigation management and system performance. Two field experiments were conducted in the arid region of Southern Tunisia to assess soil water and salt dynamics under surface- and drip-irrigated carrots using HYDRUS 2D/3D simulations in the 2017–2018 and 2018–2019 crop seasons. The soil water contents and bulk soil electrical conductivities were measured at three distinct soil layers: 0–20 cm, 20–40 cm, and 40–60 cm, where TDR probes were located. Statistical indicators (nRMSE, IA, and PBIAS) suggest that HYDRUS 2D/3D is reliable in simulating field hydro-saline dynamics for irrigated carrots. The results obtained for the two crop seasons exhibit a strong correlation between the simulated and measured values for both soil water contents and electrical conductivities. The study also shows that HYDRUS 2D/3D allows more accurate simulations of soil water dynamics than soil salinity under these conditions. Overall, these results provide valuable insights for understanding the hydrological processes in arid regions and can help in improving the management of water resources in these areas. Full article

This study investigates the adsorption and migration of sulfadiazine (SDZ) in soda saline–alkali soils under Cu/Zn co-pollution using equilibrium adsorption and soil column experiments. Freundlich and Langmuir isothermal models, combined with Hydrus-1D two-site modeling, revealed concentration-dependent interactions. Low Cu (10–100 mg kg⁻¹) and Zn (10–100 mg kg⁻¹) enhanced SDZ adsorption via charge regulation and complexation, while high concentrations (300 mg kg⁻¹) suppressed adsorption through competitive adsorption and hydroxide precipitation. Synergistic Cu-Zn coexistence further reduced adsorption to 3.035 mg kg⁻¹. Freundlich modeling (R² = 0.922–0.995) outperformed Langmuir, confirming adsorption site heterogeneity. Column experiments showed Cu (300 mg kg⁻¹) and Zn (300 mg kg⁻¹) accelerated SDZ migration (peaks 0.93–0.94), delaying breakthrough versus Br⁻. Hydrus-1D simulations (R² ≥ 0.915, RMSE < 0.1) effectively quantified nonlinear dynamics between instantaneous adsorption sites (f = 0.101–0.554) and metal concentrations. Results demonstrate heavy metals critically regulate antibiotic fate via concentration-dependent mechanisms in saline–alkali ecosystems. Full article

The Yellow River Diversion Irrigation District is a critical area for food security within the river basin; however, a significant contradiction exists between water supply and demand. The lag process of irrigation return flow is crucial for effective water resource management, yet this aspect has been overlooked in existing studies. This research focuses on the east-ern part of the Jingdian Irrigation District, where data related to agricultural hydrology was collected through monitoring efforts. The unit hydrograph method was introduced to construct a model, and numerical simulations were developed using Hydrus-2D to investigate the lag characteristics of irrigation return flow. The findings indicate that the lag time of return flow in response to precipitation and irrigation in the Hongbiliang Basin ranges from 0 to 2.3 months, while in the Nanshahe Basin, it spans from 0 to 5 months. The unit hydrograph model demonstrated high predictive accuracy, with a coefficient of determination (R²) exceeding 0.72 and a mean relative error (MRE) below 11.6% in both basins. The peak lag times recorded were 60 days and 110 days, respectively. The formation of return flow occurs in three stages: soil water infiltration, groundwater recharge, and channel drainage. Additionally, the unit hydrograph exhibited a strong fitting effect on silt loam and other soil types, confirming the validity of the “proportion and superposition” principle. This study contributes to the optimization of the water cycle model and the establishment of a comprehensive system within the irrigation district, thereby aiding in alleviating the pressure on water resources. Full article

Soil moisture plays a key role in the critical zone of the Earth and has extensive value in the understanding of hydrological, agricultural, and environmental processes (among others). Long-term (in situ) monitoring of soil moisture measurements is generally not practical; however, short-term measurements are often found. Limited soil moisture measurements can be employed to develop a numerical model for long-term and accurate soil moisture estimations. A key input variable to the model is precipitation, which is also not easily accessible, particularly at a finer spatial resolution; hence, publicly available remote sensing data can be used as an alternative. This study, therefore, aims to develop a numerical model HYDRUS-1D to estimate soil moisture in the data-scarce state of the Northern Territory, Australia, with a land cover of shrubland and a Tropical-Savannah type climate. The HDYRUS-1D is based on the numerical solution of Richards’ equation of variably saturated flow that relies on information about the soil water retention characteristics. This study utilized the van Genuchten model parameters, which were optimized (against measured soil moisture) through parameter optimization with initial estimates obtained from the HYDRUS catalogue. Initial estimates from different sources can differ for the same soil texture (e.g., loamy sand) and can induce uncertainties in the calibrated model. Therefore, a comprehensive uncertainty analysis was conducted to address potential uncertainties in the calibration process. The HYDRUS-1D was calibrated for a period between March 2012 and February 2013 and was independently validated against three different periods between March 2013 and October 2016. Root Mean Square Error (RMSE), Pearson’s correlation coefficient (R), and Mean Absolute Error (MAE) were used to assess the efficiency of the model in simulating the measured soil moisture. The model exhibited good performance in replicating measured soil moisture during calibration (RMSE = 0.00 m³/m³, MAE = 0.005 m³/m³, and R = 0.70), during validation period 1 (RMSE = 0.035 m³/m³ and MAE = 0.023 m³/m³, and R = 0.72), validation period 2 (RMSE = 0.054 m³/m³ and MAE = 0.039 m³/m³, and R = 0.51), and validation period 3 (RMSE = 0.046 m³/m³ and MAE = 0.032 m³/m³, and R = 0.61), respectively. Remotely sensed precipitation data were used from the CHRS-PERSIANN, CHRS-CCS, and CHRS-PDIR-Now to assess their capabilities in estimating soil moisture. Efficiency evaluation metrics and visual assessment revealed that these products underestimated the soil moisture. The CHRS-CCS outperformed other products in terms of overall efficiency (average RMSE of 0.040 m³/m³, average MAE of 0.023 m³/m³, and an average R of 0.68, respectively). An integrated approach based on numerical modelling and remote sensing employed in this study can help understand the long-term dynamics of soil moisture and soil water balance in the Northern Territory, Australia. Full article

Mining-induced subsidence has significantly altered the structure of the vadose zone in coal mining areas, where soil cracks act as preferential pathways controlling water infiltration and redistribution. In this study, a Hydrus-2D dual-domain seepage model incorporating geometric parameterization of cracks was developed to simulate water migration in the vadose zone of a typical subsidence area in the Ordos Basin. The model integrates field-measured crack geometry, soil texture, and rainfall characteristics to quantitatively analyze preferential flow formation under twelve combinations of crack width, soil type, and rainfall intensity. The results show that (i) crack width dominates preferential flow behavior, with wider cracks (≥5 cm) deepening the wetting front from approximately 107 cm to 144 cm within 120 h and sustaining high conductivity after rainfall; (ii) soil texture governs infiltration pathways, as sandy soils promote deeper wetting fronts (up to 99 cm, ~40% deeper than loam) and layered soils induce interface retention or “jump” infiltration; and (iii) rainfall intensity controls infiltration depth, with storm events producing wetting fronts more than four times deeper than those under light rain. Overall, this study demonstrates the feasibility and significance of integrating crack parameterization into vadose-zone hydrological modeling using Hydrus-2D, providing a quantitative basis for understanding rapid infiltration–migration–recharge processes and supporting ecological restoration and water resource management in arid and semi-arid mining regions. Full article

Unsymmetrical dimethylhydrazine (UDMH), a highly toxic rocket propellant, remains a significant environmental concern in Kazakhstan due to repeated rocket stage falls near the Baikonur Cosmodrome. This study integrates chemical analysis with stochastic contamination transport modeling to evaluate the persistence and migration of UDMH transformation products (TPs) in soils collected 15 years after the rocket crash. Vacuum-assisted headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (Vac-HS-SPME-GC-MS) was used to determine five major TPs. Among these, pyrazine (PAN) and 1-methyl-1H-pyrazole (MPA) were consistently detected at concentrations ranging from 0.04–2.35 ng g⁻¹ and 0.06–3.48 ng g⁻¹, respectively. Stochastic simulations performed with HYDRUS-1D indicated that the long-term persistence of these compounds is mainly controlled by physical nonequilibrium transport processes, including diffusion-limited exchange, weak sorption, and slow inter-domain mass transfer, rather than by degradation. Sensitivity analysis demonstrated that low dispersivity and diffusion coefficients enhance solute retention within immobile domains, maintaining residual levels over extended periods. The results demonstrate the efficacy of combined long-term monitoring and predictive modeling frameworks for assessing contamination dynamics in rocket impact zones. Full article

The centrifuge method serves as an efficient and rapid approach for determining the soil–water characteristic curve (SWCC). However, soil shrinkage during centrifugation remains overlooked and prior modified methods may suffer from complex operations, high costs, time consumption, and limited applicability. To address these issues, this study introduces a simple correction scheme (G3) for determining drying SWCCs using the centrifuge method based on high matric suction calibration points. The performance of the proposed G3 method was systematically evaluated against a modified method considering soil shrinkage (G1) and the conventional uncorrected method (G2). Results revealed significant soil linear shrinkage post-centrifugation, accompanied by a reduction in total soil porosity and an increase in soil bulk density. SWCCs from all methods exhibited strong consistency at low matric suction ranges but diverged markedly at high matric suction segments. High matric suction data dominated the SWCC fitting. The G1 method achieved the highest fitting accuracy, while the G3 method performed the worst yet maintained acceptable reliability. The G2 method yielded optimal SWCC for simulating saturated soil water content, field capacity, and permanent wilting point. Conversely, Hydrus-1D simulations revealed superior performance of the G3 method in simulating farmland soil moisture dynamics during the dehumidification process. Values of R² across methods followed G3 > G1 > G2, while mean absolute error, mean absolute percentage error, and root mean square error exhibited the opposite trend. These findings highlight that the previous modified approaches are more suitable for low and medium matric suction ranges. The proposed correction method enhances drying SWCC performance across the full matric suction range, offering a practical refinement for the centrifuge method. This advancement could enhance the reliability in soil hydraulic characterization and contribute to a better understanding of the hydraulic–mechanical–chemical behavior in soils. Full article

Water scarcity in semi-arid regions necessitates accurate soil water modeling to optimize irrigation management. This study compares three HYDRUS-1D parameterization approaches—based on the drying-branch soil water retention curve (SWRC), wetting-branch SWRC (using Shani’s drip method), and inverse modeling—to simulating soil water content at 15 cm and 45 cm depths under center-pivot irrigation in a semi-arid region. Field experiments in three maize fields provided daily soil water, soil hydraulic, and meteorological data. Inverse modeling achieved the highest accuracy (NRMSE: 2.29–7.40%; RMSE: 0.006–0.023 cm³ cm⁻³), particularly at 15 cm depth, by calibrating van Genuchten parameters against observed water content. The wetting-branch approach outperformed the drying branch at the same depth, capturing irrigation-induced wetting processes more effectively. Statistical validation confirmed the robustness of inverse modeling in reproducing temporal patterns, while wetting-branch data improved deep-layer accuracy. The results demonstrate that inverse modeling is a reliable approach for soil water simulation and irrigation management, whereas the wetting-branch parameterization offers a practical, field-adaptable alternative. This study provides one of the first side-by-side evaluations of these three modeling approaches under real-world semi-arid conditions. Full article

To investigate differences in water and salt transport during irrigation, freezing, and thawing periods in typical saline-affected paddy fields and saline-affected upland fields, field-based automated in situ monitoring was conducted in both types of saline-affected farmland (May 2023 to May 2024). Correlation analysis identified seasonal drivers of water–salt migration, while the HYDRUS-3D model simulated transport and equilibrium processes. The HYDRUS-3D model, equipped with a freeze–thaw module, accurately simulated complex water–salt transport in cold arid regions. Key findings include: (1) During freeze–thaw periods, soil moisture content and electrical conductivity (Ec) increased with the retreating frost front in both upland and paddy soils. During the irrigation period, maximum soil moisture content and Ec values occurred at 80 cm depth in dryland soils and 60 cm depth in paddy soils, primarily influenced by irrigation and capillary rise. (2) Groundwater salt ions significantly affected soil salinization in both farmland types. During the freeze–thaw period, Ec positively correlated with soil temperature. During the irrigation period, Ec positively correlated with evapotranspiration and negatively correlated with precipitation. (3) Salt changes during the irrigation, freezing, and thawing periods were −565.4, 326.85, and 376.55 kg/ha for upland fields, respectively; corresponding changes for paddy fields were −1217.0, 280.07, and 299.35 kg/ha. (4) Both land types exhibited reduced salinity during the irrigation period, with paddy fields showing a reduction 3.36 times greater than dryland fields. During the freezing and thawing periods, both land types experienced salinity accumulation, with dryland fields accumulating higher salinity levels than paddy fields. These results indicate that paddy field irrigation and drainage systems help mitigate salinization, while dryland fields are more prone to springtime salt accumulation. These findings provide a basis for developing targeted management strategies for saline–alkali soils. Full article

The management of groundwater depth (GWD) in alluvial soils under irrigation in arid climates is critical for soil and water conservation, given its influence on salt dynamics and water availability for crops. GWD is influenced by the interaction of irrigation water supply and drainage system design and operation. Controlling GWD is a significant issue in the Hetao Irrigation District due to continuous irrigation, arid climate, and high risks of soil salinization, which concerns farmers and water management authorities. To address this issue, a study was conducted based on open-air laboratory experimentation to rigorously assess the effects of GWD on soil salt dynamics and capillary rise contribution to maize cultivation under level basin irrigation. Data collected served as the basis for parameterizing and calibrating the HYDRUS-1D model, facilitating simulation of soil water and salt dynamics to enhance understanding of GWD effects ranging from 1.25 m to 2.25 m. It was concluded that during calibration and validation, the model demonstrated strong performance; SWC simulations achieved R² > 0.69, RMSE < 0.03 cm³ cm⁻³, and NSE approaching 1; and EC simulations yielded R² ≥ 0.74 with RMSE < 0.22 S cm⁻¹. Additionally, the simulated bottom boundary moisture flux closely matched the measured values. The most favorable GWD range should be between 1.75 m and 2.0 m, minimizing the negative impacts of irrigation-induced soil salinity while maximizing water use efficiency and crop productivity. A higher GWD causes crop water stress, while a lower value results in a greater risk of soil salinity. This study anticipates future field application in Hetao to assess drainage system effectiveness and variability in salinity and productivity effects. Full article