Search Results (2,262)

Sustainable management of hydrogeological systems that supply water and exhibit high hydrologic complexity can be studied through pragmatic numerical modeling supported by field-constrained conceptualization. This study develops a local-scale three-dimensional groundwater flow numerical model using FEFLOW for the Barranca Lebrija settlement in Aguachica town, where the Lebrija River, the Musanda floodplain lake, and groundwater system converge. The numerical model incorporates: (i) the three-dimensional distribution of geological units and lithology; (ii) water level observations from the Musanda floodplain lake; (iii) stage records from the Lebrija River; (iv) boundary conditions and flux estimates inherited from a previous regional groundwater model; and (v) hydraulic heads from two monitoring wells and five community wells. Steady-state and transient conditions were calibrated, and a sensitivity analysis was performed to identify the parameters that most strongly control surface water–groundwater exchange. The simulations reproduce seasonal groundwater level trends and demonstrate the exchange pathways among the river, floodplain lake, and groundwater system. Results indicate dual behavior: during wet periods, flooding of the Musanda floodplain lake driven by high river levels seeps into the underlying aquifer, whereas in dry periods the floodplain lake reverses its role and becomes a principal discharge boundary. This local-scale, boundary-driven approach provides a computationally tractable framework to quantify SW–GW exchange in data-scarce tropical floodplains and supports monitoring design and water-supply management. Full article

Cemented sand and gravel (CSG) dams have been widely applied due to their simple construction and use of local materials. With the increasing occurrence of extreme weather events, temperature has become an important factor affecting the safe operation of dams. To investigate the temperature stress response of CSG dams under low-temperature conditions and achieve cross-scale analysis, an adaptive macro–meso finite element method is proposed. Through an iterative “solution–evaluation–mesh adjustment” procedure, meso-scale modeling is performed in high-stress regions, and the results are compared with those obtained using the conventional submodeling method. The results show that, under low-temperature conditions, temperature gradients and thermal stresses are mainly concentrated near the dam surface, with limited influence on the interior, while hydraulic load remains the dominant controlling factor. The local stress distribution patterns obtained by the two methods are generally consistent, and both can reflect stress concentration near the aggregate–mortar interfaces. The proposed method can characterize local meso-scale responses within a global computational framework, providing a reference for cross-scale analysis of the temperature response and the identification of local unfavorable stress regions in CSG dams. Full article

This study investigated density-driven mixing and stratified flow dynamics in Paldang Reservoir, a river-type reservoir formed at the confluence of the South Han River, North Han River, and Gyeongan Stream in South Korea. High-resolution field observations were conducted under varying hydrologic and hydraulic conditions using an Acoustic Doppler Current Profiler (ADCP) and multi-parameter water quality sensors (EXO2). Spatial distributions of flow velocity, water temperature, and electrical conductivity (EC) were analyzed to evaluate tributary interaction and mixing behavior within the reservoir. Distinct spatial mixing structures associated with tributary inflow heterogeneity and hydraulic operation conditions were identified. During flood-season conditions, highly turbid and high-conductivity inflow from the South Han River propagated beneath the North Han River inflow, generating density-driven lower-layer intrusion near the confluence region. Under intermittent discharge conditions at the Cheongpyeong Dam, unstable upper- and lower-layer separation structures and localized reverse-flow behavior developed. In contrast, continuous discharge conditions promoted stable tributary propagation and persistent stratified mixing structures. Case-based Richardson number (Ri) estimates further indicated localized shear-driven mixing at low-Ri inflow sections and relatively stable stratification at high-Ri sections, providing quantitative support for the observed spatial heterogeneity in density-driven mixing. Overall, spatial mixing in Paldang Reservoir was governed by tributary density contrasts and further shaped by hydraulic operation conditions. These findings improve understanding of density-driven mixing processes in river-type reservoirs under varying hydraulic conditions. Full article

Submarine pockmarks are typical seafloor micro-geomorphic landforms formed by deep fluid seepage and sediment erosional processes. Based on high-resolution multibeam bathymetric data, multi-channel seismic sections and sediment core data, the present study systematically investigates 64 pockmarks in the northwestern Xisha Uplift, focusing on their distribution, morphology and genetic mechanisms. These pockmarks exhibit a NE–SW zonal distribution, concentrated in the 1200–1600 m central slope transition zone, and are classified into circular–elliptical, crescentic and elongated types with distinct morphometric variability. Vertically, the T40 unconformity defines the stratified geological architecture: underlying carbonate uplifts and karst-fracture systems act as fluid reservoirs and migration conduits, while overlying Late Miocene–Quaternary fine-grained hemipelagic sediments form a low-permeability caprock. Fluid overpressure accumulation and hydraulic fracturing of the caprock trigger initial pockmark formation, while spatial heterogeneity of surficial sediments and bottom-current reworking control morphological differentiation. The present study clarifies the coupled controls of deep tectono-fluid activities and shallow sedimentary and hydrodynamic processes on pockmark evolution, establishing a refined dynamic model to address the research gap regarding pockmark group genesis in the study area. Full article

The capability of recovering a portion of braking energy during vehicle deceleration is one of the distinctive advantages of new energy vehicles (EVs) over Conventional Internal Combustion Engine Vehicles (ICEVs). In existing production vehicles, regenerative braking control is commonly implemented using rule-based lookup table methods. Although such approaches are simple, reliable, and easy to implement, they lack the ability to adaptively adjust the braking force allocation according to varying driving conditions, thereby limiting the potential for high efficiency energy recovery. To improve regenerative energy recovery while simultaneously maintaining braking stability, this study introduces an ANFIS-optimized Sliding Mode–Fuzzy Joint Hierarchical Control Strategy (S-FJHCS) for regenerative braking systems. In the upper control layer, an improved tire road friction coefficient estimation algorithm is integrated with a sliding mode controller to ensure consistent slip ratio regulation between the front and rear wheels. In the lower control layer, a fuzzy control algorithm is employed to coordinate the distribution of braking torque between the hydraulic braking system and the hub motors. Furthermore, an Adaptive Neuro-Fuzzy Inference System (ANFIS) is utilized to perform offline optimization of the fuzzy controller, enabling the adaptive adjustment of fuzzy rules and membership functions based on historical operating conditions. Simulation and experimental results demonstrate that the proposed regenerative braking control strategy can improve regenerative energy recovery efficiency by approximately 5–10% compared with a conventional rule based regenerative braking strategy, while maintaining satisfactory braking performance and vehicle stability under various driving conditions. Full article

The Curve Number (CN) remains one of the most widely applied parameters for estimating direct surface runoff. However, its conventional application based on watershed-aggregated tabulated values conceals hydrological variability in regions with contrasting soils and steep topographic gradients. A recurring limitation of distributed CN approaches is the absence of independent hydrological validation; most machine learning models are trained and evaluated against the same SCS-USDA lookup values used to construct the training target, a circular scheme that measures statistical agreement rather than physical credibility. This study develops a reproducible geospatial workflow for distributed CN estimation across continental Ecuador, combining official MAG land use, soil surface texture natural drainage, and topographic slope layers at 1:25,000 scale with a Random Forest regression model at 10 m spatial resolution. The CN reference raster was derived from official geo-pedological layers and independently validated, not against tabulated assumptions, but against observed hydrological behaviour. Field hydraulic characterization across four dominant land cover classes in the Guamote microwatershed (Chimborazo Province), combined with HEC-HMS (US Army Corps of Engineers, Davis, CA, USA) rainfall-runoff modelling over 41 years (1981–2021), confirmed a mean annual discharge of 0.1568 m³ s⁻¹ consistent with the tabulated CN assignments. To our knowledge, this is the first nationally distributed CN map with field-anchored hydrological benchmarking for an Andean country. The Random Forest model achieved an RMSE = 10.4, an R² = 0.42, and an NSE = 0.41, a performance consistent with published field-based CN estimation studies and expected given the inherent scatter of the SCS-USDA method under real-world conditions. Zonal CN comparisons confirmed a mean absolute error below 5 CN units across the Andean highland and Amazon watersheds; the Guamote watershed showed a mean ∆CN below 4 units against the field-calibrated model. Land use and surface texture emerged as the dominant CN predictors, with natural drainage providing critical discrimination in volcanic and poorly drained soil environments. The resulting 10 m national CN map offers a physically grounded, spatially explicit parameterization layer for distributed hydrological modeling and water resources planning across data-scarce Andean and tropical territories, with direct relevance for flood risk screening, irrigation planning, watershed conservation, and climate adaptation under SDG 6, SDG 11, SDG 13 and SDG 15. Full article

The development of tight sandstone gas reservoirs in the Ordos Basin is increasingly challenged by complex geological conditions and declining resource quality. Accurate identification of productivity-controlling factors and reliable prediction of fracturing sweet spots are therefore essential for improving reservoir development efficiency. In this study, geological, engineering, and production data from 56 wells in the target area were collected and preprocessed using forward and reverse normalization. Grey Relational Analysis was first used to identify the dominant factors controlling absolute open flow, and the selected variables were then incorporated into Light Gradient Boosting Machine to establish an integrated GRA-LightGBM prediction framework. The results indicate that permeability, average total hydrocarbon content, porosity, brittleness index, fracture toughness, and clay content are the primary productivity-controlling factors in the study area. The proposed GRA-LightGBM model achieved an R² value of 0.9233, indicating strong agreement between predicted and measured AOF values. Comparative experiments with traditional machine learning models and tree-based ensemble models further demonstrated that GRA-LightGBM provides more accurate and stable predictions, with smaller residual fluctuations and better overall performance. Based on the prediction results, the spatial distribution of fracturing sweet spots was visualized using the Petrel platform. This study provides an effective data-driven workflow for dominant factor identification, AOF prediction, and sweet spot delineation, offering technical support for the optimization of hydraulic fracturing and well deployment in tight sandstone gas reservoirs. Full article

The optimal deployment of pressure monitoring sensors in water distribution networks is crucial for leak detection, network calibration, and system diagnostics. Water utilities face increasing pressure to reduce non-revenue water losses while continuing to improve service quality under budget constraints, thus making the strategic deployment of sensors a critical priority. However, traditional optimization approaches come with various disadvantages including high computational complexity, limited scalability, or dependence on uncertain preliminary parameter estimates. This paper addresses these shortcomings by proposing an innovative integrated framework that balances topological and hydraulic considerations, and applying a flexible metric blending approach to enable robust sensor positioning across networks that differ in scales and topologies. The methodology has been validated through three case studies: a theoretical reference grid, an urban district network, and a large-scale multisource irrigation system. The results prove the methodology to be consistently effective in identifying optimal sensor configurations across all test cases. Full article

Groundwater levels are usually mapped as water table contours produced from point data, that is, hydraulic heads measured in modest numbers of observation wells distributed across a given region. The typically sparse distributions of wells, especially in remote areas, severely limit the number of observations that can be made and may lead to ambiguous groundwater-level estimates at unsampled locations. Satellite altimetry provides reliable estimates of hydraulic heads wherever surface water and groundwater intersect, regardless of how remote the location is. Therefore, we tested the use of Ice, Cloud, and Land Elevation Satellite 2 (ICESat-2) and Surface Water and Ocean Topography (SWOT) measurements of water levels in interdune water table lakes to characterize groundwater levels in the Nebraska Sandhills (central USA), the largest dune field in the Western Hemisphere. Our satellite altimetry estimates of groundwater levels in the Nebraska Sandhills closely approximate the measurements made in nearby observation wells. ICESat-2 showed a root-mean squared error (RMSE) of 0.68 m with ± 0.45 m standard deviation (SD). SWOT estimated an RMSE of 0.75 m with ± 0.76 m SD. Monthly groundwater levels were estimated using kriging with an external drift and generalized additive models, with RMSEs ranging from 1.9 m to 3.3 m and with unbiased errors (mean error of −0.003 m to 0.153 m). We conclude that satellite altimetry has potential for the remote measurements of groundwater levels under certain geographic conditions, especially where groundwater-dominated lakes are prevalent. Full article

This study addresses the impact of the location of transverse barriers on debris flow in the Libertad sub-basin, in Chosica, Peru. Intense seasonal rainfall in this region causes destructive flows that threaten infrastructure and human lives. Using geographic information system tools, hydrological models and hydraulic simulations, scenarios with barriers installed at different distances from the debris source were evaluated. The results indicate that the barrier located closest to the source (0.3L) is the most effective, achieving a reduction in velocity of 12.9% at the most critical urban monitoring point, the greatest volume retention capacity (790.02 m³), and the greatest decrease in flow escaping from the study area (65.7%). In contrast, barriers at 0.5L, 0.7L, and 0.9L show progressively lower effectiveness. This finding highlights the importance of a strategic design that optimises the position of the barriers according to the geomorphological and hydrological characteristics of the area. It is concluded that an adequate distribution of barriers, complemented with integrated watershed management strategies, can considerably mitigate the risks associated with debris flows in vulnerable urban areas. Full article

Natural gas hydrates are characterized by abundant reserves, wide distribution, and high energy density, while geothermal energy also holds significant development potential. Conventional hydrate dissociation methods face challenges in the later stages of production, such as insufficient driving force for dissociation and secondary hydrate formation. This study explores the approach of utilizing deep-sea geothermal energy to assist in the extraction of hydrate. The aim is to achieve efficient exploitation of hydrate while expanding the applications of geothermal energy. A field-scale coupled thermo–hydro–mechanical–chemical (THMC) injection-production numerical model is established, taking a typical hydrate reservoir in the South China Sea as the study area. The engineering feasibility of geothermal-assisted hydrate extraction is evaluated through numerical simulations. Injection temperature, extraction rate, and well layout are systematically analyzed to optimize production performance, with particular focus on the evolution of physical fields, hydrate dissociation, and geothermal formation temperature stability. The novelty of this study lies in the proposal of a closed-loop ‘in-situ geothermal extraction and reinjection’ system, and the systematic optimization of its coupled THMC responses, which has received limited quantitative investigation. The results indicate that an injection temperature of 50 °C and an injection rate of 500 m³/d provide the most favorable production performance under the investigated conditions. Compared with conventional depressurization, the optimized geothermal-assisted scheme increases cumulative gas production by approximately 40% after 600 days. Horizontal well configurations outperform vertical wells, whereas excessively close well spacing reduces thermal stimulation efficiency because of hydraulic interference. Temperature variations in the geothermal layer during the simulated extraction period are minimal, indicating favorable operational stability under the investigated conditions. In summary, geothermal-assisted depressurization enhances hydrate extraction efficiency and expands geothermal applications, offering a promising approach for future development. Full article

This study investigates the optimal placement of a surge tank to mitigate pressure fluctuations induced by water hammer in a complex, real-world water distribution network (WDN). A transient-flow numerical model was developed using the Method of Characteristics (MOC) integrated with surge tank theory, applied to a simplified and skeletonized representation of the target network. To determine the most effective installation site, Particle Swarm Optimization (PSO) was employed across 32 candidate nodes. Transient events were simulated through valve closure and reopening operations at the terminal nodes of the network. The results indicate that Node 41 is the optimal location for minimizing head fluctuations. Specifically, the maximum head fluctuation was reduced from 64.32 m in the unprotected system to 51.79 m with the surge tank at Node 41, representing a 19.48% improvement in hydraulic stability. These findings emphasize the critical role of strategic surge tank positioning and provide a robust technical framework for the design and operation of surge protection systems in complex WDNs. Full article

The eco-revetment structure serves as a link for material, information, and energy exchange between rivers, bank slopes, and organisms, providing a guarantee for the stability of river ecosystems. This study designed a new type of eco-revetment structure based on its characteristics. The internal structure is designed as a cavity, with openings on the top and side walls and curved surfaces connecting the upper and lower components to ensure smooth water flow and stable bank slopes, providing living space for aquatic organisms. By establishing a three-dimensional numerical model and using large-eddy simulation as the main research method, the distribution law of hydraulic characteristics near the revetment structure is observed, and the mechanism of water flow movement is studied. This study indicates that the internal and external water flow conditions of the new ecological revetment structure are complex and exhibit significant spatial heterogeneity. When there are no plants, the flow directions inside and outside the structure are opposite, with hairpin vortices dominating the interior. The presence of plants significantly enhances turbulence intensity and Reynolds stress, resulting in smaller and more diverse vortex structures, and the formation of Karman vortex streets on the leeward side of plants. The movement characteristics of the revetment structure vary in different regions: in region C, when there are no plants, the value of (|Q2| + |Q4|)/(|Q1| + |Q3|) is greater than 1.5, and it increases to 3 when plants are present. The ratio for region B is 0.83 and 0.8, while for region A it is 1.02 and 1.17. When there are no plants, the Reynolds stress contribution in region A is uniform, region B shows a “hyperbolic” distribution, and the proportion of S2 and S4 at the top of region C increases sharply. Plants increase the contribution of the top of the region C to three to five times that of no plants. The complex water flow environment significantly changes the mechanism of water flow movement. The Reynolds stress contribution and turbulent kinetic energy fit well. The presence of plants leads to a Reynolds stress contribution and turbulent kinetic energy value that are about three times higher than without plants. When there are no plants, the turbulent structure within the structure is mainly influenced by S1 and S3, while when there are plants, S2 and S4 dominate the turbulence. This article provides a solid theoretical foundation and quantitative experimental basis for the study of nearshore water flow mechanisms in ecological revetment structures. Full article

This study focuses on the 130QJ25–33 multi-stage submersible well pump to resolve low efficiency and flow instability under low-flow conditions by redesigning tandem space guide vanes. CFD simulations and physical experiments are carried out for validation. A grid independence analysis is completed to determine the optimal grid scheme with 9.413 million cells. The relative error of hydraulic performance between numerical simulation and the experiment is less than 10%, which verifies the accuracy of the numerical model. An orthogonal experiment is adopted to optimize three key geometric parameters: wrap angle, installation angle and axial position. Under the operating range of 0.6 Qd–1.1 Qd, the optimized tandem guide vane structure raises the pump head by 12.4% and improves efficiency by up to 8.7%. These data are derived from the comparative external characteristic tests of the original model and the optimized model. The optimized structure effectively suppresses flow separation and vortices, homogenizes flow and pressure distribution, reduces hydraulic loss, balances blade loading, and improves operational stability. The results provide theoretical and engineering guidance for high-efficiency guide vane design of well submersible pumps. The structure can effectively reduce the hydraulic loss in the pump, improve the flow efficiency, and significantly improve the hydraulic matching performance of the guide vane. Full article

An air-assisted sprayer is a primary tool for pest and disease control in orchards. However, conventional systems often suffer from insufficient deposition at the canopy top and poor coverage on the abaxial leaf surfaces, which are highly susceptible to pests and diseases. To address this limitation, a centrifugal air-assisted spraying system was developed to generate finer droplets and improve deposition distribution within tree canopies, particularly on the abaxial surfaces. Vertical deposition tests were conducted to characterize the droplet distribution pattern of the system. Single-unit spray tests were then performed under Foliage Area Volume Density (FAVD, the foliage area per unit canopy volume) of 3.3 and 1.4 m²·m⁻³, and three outlet air velocities (4, 8, and 11 m·s⁻¹) to evaluate the effects of these variables on coverage and droplet density. Comparative experiments between the centrifugal and a conventional hydraulic system were also carried out at the same flow rate (3.6 L·min⁻¹), as well as at a 30% reduced application rate for the centrifugal system. The results showed that the droplet distribution pattern followed a normal distribution and correlated well with the spindle-shaped pear tree canopy. At both FAVD levels, an air velocity of 8 m·s⁻¹ produced superior leaf coverage compared with 4 and 11 m·s⁻¹. At the same flow rate, the centrifugal system achieved significantly higher coverage on the abaxial surfaces of outer canopy leaves than the hydraulic system. Remarkably, even with a 30% reduction in application volume, the centrifugal system maintained coverage and droplet density comparable to those of the hydraulic system at its full rate. We conclude that the centrifugal air-assisted orchard spraying system effectively improves pesticide deposition distribution within pear tree canopies, with particular advantages in depositing droplets on the abaxial leaf surfaces. Future work will include a systematic assessment of spray drift potential to further evaluate its field applicability and environmental compatibility. Full article