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This study proposes a surface velocity method for discharge estimation in lined irrigation canals. In this method, a surface velocity radar is used for surface velocity measurement. However, this radar cannot be used to obtain a point velocity on the water surface. A velocity profiler is used to measure the velocity distribution in the cross section of a canal. The measured data are used to obtain surface and mean velocities in verticals by applying a probabilistic velocity distribution equation. Subsequently, the linear relationship between the surface velocity measured by the surface velocity radar and the surface velocity estimated by the velocity distribution equation can be established. Additionally, the relationship between the estimated surface velocity and mean velocity in verticals can be obtained through linear regression; this relationship is a constant. Therefore, these two relationships can be used to derive a surface velocity coefficient for converting surface velocity to mean velocity in a vertical. The surface velocity coefficient used in lined irrigation canals is different from that used in natural streams. It is not constant and varies with the surface velocity observed by the radar. The feasibility of the proposed method is tested by conducting discharge estimation processes in five lined irrigation canals. The results show that the proposed method is reliable and accurate for estimating discharge in lined irrigation canals.

Operator choices, both in acquiring the video and data and in processing them, can be a prominent source of error in image‐based velocimetry methods applied to river discharge measurements. The Large Scale Particle Image Velocimetry (LSPIV) is known to be sensitive to the parameters and computation choices set by the user, but no systematic comparisons with discharge references or intercomparisons have been conducted yet to evaluate this operator effect in LSPIV. In this paper, an analysis of a video gauging intercomparison, the Video Globe Challenge 2020, is proposed to evaluate such operator effect. The analysis is based on the gauging reports of the 15 to 23 participants using the Fudaa‐LSPIV software and intents to identify the most sensitive parameters for the eight videos. The analysis highlighted the significant impact of the time interval, the grid points and the filters on the LSPIV discharge measurements. These parameters are often inter‐dependent and should be correctly set together to strongly reduce the discharge errors. Based on the results, several automated tools were proposed to reduce the operator effect. These tools consist of several parameter assistants to automatically set the orthorectification resolution, the grid and the time interval, and of a sequence of systematic and automatic filters to ensure reliable velocity measurements used for discharge estimation. The application of the assisted LSPIV workflow using the proposed tools leads to significant improvements of the discharge measurements with strong reductions of the inter‐participant variability. On the eight videos, the mean interquartile range of the discharge errors is reduced from 17% to 5% and the mean discharge bias is reduced from −9% to 1% with the assisted LSPIV workflow. The remaining inter‐participant variability is mainly due to the user‐defined surface velocity coefficient α. Key Points Video‐based river discharge measurements are sensitive to both measuring conditions and user‐defined parameters and options The sensitivity of Large Scale Particle Image Velocimetry discharge computations to operator choices is quantified through a video streamgauging intercomparison Proposed automatic settings and spurious velocity filters efficiently reduce discharge biases and inter‐operator variability

Sea surface temperature (SST) anomalies caused by a warm core eddy (WCE) in the Southwestern Atlantic Ocean (SWA) rendered a crucial influence on modifying the marine atmospheric boundary layer (MABL). During the first cruise to support the Antarctic Modeling and Observation System (ATMOS) project, a WCE that was shed from the Brazil Current was sampled. Apart from traditional meteorological measurements, we used the Eddy Covariance method to directly measure the ocean–atmosphere sensible heat, latent heat, momentum, and carbon dioxide (CO 2 ) fluxes. The mechanisms of pressure adjustment and vertical mixing that can make the MABL unstable were both identified. The WCE also acted to increase the surface winds and heat fluxes from the ocean to the atmosphere. Oceanic regions at middle and high latitudes are expected to absorb atmospheric CO 2 , and are thereby considered as sinks, due to their cold waters. Instead, the presence of this WCE in midlatitudes, surrounded by predominantly cold waters, caused the ocean to locally act as a CO 2 source. The contribution to the atmosphere was estimated as 0.3 ± 0.04 mmol m −2 day −1 , averaged over the sampling period. The CO 2 transfer velocity coefficient ( K ) was determined using a quadratic fit and showed an adequate representation of ocean–atmosphere fluxes. The ocean–atmosphere CO 2 , momentum, and heat fluxes were each closely correlated with the SST. The increase of SST inside the WCE clearly resulted in larger magnitudes of all of the ocean–atmosphere fluxes studied here. This study adds to our understanding of how oceanic mesoscale structures, such as this WCE, affect the overlying atmosphere.

A design framework is presented for broad-crested weirs with exponential (power-law) head–discharge behavior and three practical control-section shapes: Rectangular, parabolic, and triangular. Unlike ideal-flow sizing, the approach explicitly accounts for real-flow effects through a velocity coefficient at the control section. Starting from the energy equation and the critical-depth condition, analytical relations are obtained for the control-section depth, the critical depth, and the velocity and discharge coefficients. These relations are coupled with geometry-specific critical-flow expressions to derive a general, dimensionless design equation that links the required contraction ratio to the approach-velocity coefficient, the control-section velocity coefficient, and the head exponent n. The core innovation of the framework is a general dimensionless design equation that directly yields the required control-section area ratio A*/Ao, i.e., the geometric contraction relative to the approach section, for a specified design head and approach-velocity condition. The method provides direct design parameters for each section family: Rectangular width, parabolic parameter, and triangular head angle. A short quantitative check against representative classical experimental ratios shows very good agreement with measured values. For the applied design example based on a trapezoidal approach section and conservative lower-bound Cv values, neglecting real-flow effects underpredicts the required contraction ratio by about 28–39%, depending on the selected section shape. The developed framework provides a transparent, theoretically grounded, and practical tool for the hydraulic design of broad-crested weirs.

In this article, we have to test the Effective Velocity Coefficient (EVC), which we proposed as a criterion for assessing the tactical model of pacing a competitive distance by professional swimmers. The value of the coefficient itself, as well as the analysis of combinations of EVC within the distance parts of swimming (DV1-DV6) in a distance of 100 m with all styles in a 50 m swimming pools, allows to trace the distribution of energy within the distance and identify tactical and technical mistakes of swimming. The information obtained during the analysis of the competition distance demonstrates the level of functional training, indicates the biomechanical characteristics of the swimmer, and also gives an idea of the level of tactical skill. Using this type of analysis will help coaches make the training process more efficient.

Addressing the critical need for precise streamflow measurements in hydro-environmental research, this study evaluates large-scale particle image velocimetry (LSPIV) using cost-effective closed-circuit television (CCTV) cameras, providing a detailed sensitivity analysis in both laboratory and real-world canal settings. In laboratory conditions, a 45° camera angle notably enhanced performance, exhibiting a 12% decrease in MAE and a remarkable 40% reduction in RMSE compared to the performance of orthographic form. Tracer particles further enhanced LSPIV accuracy, decreasing both mean absolute error (MAE) and root mean square error (RMSE) by around 0.05 m/s. Optimal velocity coefficients for the lab ranged between 0.85 and 0.90. Nighttime measurements, using projection-based illumination, showed a minor 3% MAE variation and 0.02 RMSE difference versus daytime. In field experiments, a 45° upstream CCTV camera configuration notably improved LSPIV accuracy, achieving a 3% MAE and 0.055 m/s RMSE. For best results across different turbidity levels, we recommend a velocity coefficient range of 0.84 to 0.88. This study highlights the robustness and cost-efficiency of LSPIV as a transformative method for streamflow gauging, demonstrating its wide applicability in diverse hydro-environmental scenarios.

As a result of designing an energy absorber in the zone of conjugation of water outlet structures of low-pressure and mediumpressure reservoirs, the stilling basin is not only under the influence of vertical hydrodynamic pressure with a variable value but also the disappearance of stagnation of the stilling basin can also be affected by the hydrodynamic stress arising from the force of horizontal pressure in the energy absorber. The hydraulic jump in the pool junction zone is one of the simplest energy absorbers. To increase the efficiency of this process, it is necessary to improve the hydraulic regime downstream of the water outlet, reshape the interface mode in the stilling basin and on the apron surface, and eliminate flow disturbance, through the construction of special energy absorbers in the stilling basin. These structures exert reactive (accelerating implementation), dislocation (accommodating), and distributed forces on the flow.

is a promising oilseed crop for cultivation on saline marginal lands due to its abiotic stress tolerance and low input requirements. However, intraspecific variation in salinity tolerance remains poorly understood. This study, through three sequential experiments, applied a screening framework integrating time-to-event modeling, stress tolerance indices (STIs), and multivariate clustering to dissect variation in salinity tolerance across early developmental stages. In experiment 1, two commercial varieties were germinated under a gradient from 0 to 300 mM of NaCl. In experiment 2, 57 camelina accessions were evaluated at 0 and 200 mM of NaCl for six germination indices (total germination, germination index, mean germination time, velocity coefficient, synchronization index, and normality rate) expressed as STIs, to quantify relative performance under salinity. In experiment 3, 13 representative accessions were assessed for seedling STIs (shoot length, main root length, lateral root length) under 0 and 200 mM of NaCl. Time-to-event analysis revealed significant varietal differences in germination dynamics, with 200 mM identified as the optimal threshold for discriminating genotypic responses without complete germination inhibition. Most accessions retained ≥90% total germination under salinity, yet principal component analysis and hierarchical k-means clustering classified them into three phenotypic groups with distinct germination strategies. Salinity strongly reduced lateral root length (-90%), main root length (-80%), and shoot length (-30%), indicating altered biomass allocation in response to salt stress. Integration of germination clusters with seedling responses revealed three adaptive strategies: 1) high but delayed germination accompanied by strong seedling vigor, 2) low germination with intermediate seedling tolerance, and 3) high and rapid germination accompanied by poor seedling growth. These findings highlight salinity tolerance as a stage-dependent trait, underscoring the need for multistage phenotyping to guide breeding of for saline environments.

The air entrainment caused by the transportation, loading and unloading of industrial bulk materials is the main cause of dust diffusion. Local exhaust is the most effective means to control the diffusion of industrial pollutants. In order to study the flow field disturbance and control effect of the exhaust hood on the entrained air. First, a numerical model was established for the exhaust hood to control the air entrainment caused by the particle flow falling and hitting the wall. Secondly, the numerical model was verified using experimental data. Finally, the control of entrained air by the exhaust hood was analysed using a coupled CFD-DEM method, with the exhaust air velocity, the exhaust hood size and the exhaust hood position as variables. The results showed that the best effect on entrained air control was achieved when the exhaust air velocity was 7.5 m/s, the exhaust hood diameter was 125 mm, and the position of the exhaust hood was flush with the secondary wall impact point of the particles flow. The relative velocity recovery coefficient is pioneered to analyze the degree of influence of the three variables on the flow field of entrained air. It was found that the exhaust hood size has the greatest influence on the entrainment air velocity distribution, followed by the exhaust wind speed, and the least impact is the position of the exhaust hood. Graphical Abstract

This study investigates the impact of varying degrees of bubble flow on radon migration at the water–air interface. An apparatus was designed to monitor the change in the activity concentration of radon transferred from water to air at different levels of bubble flow, and high-speed cameras were used to capture the bubble flow. The optical method determined the captured images’ bubble size and average flow velocity. A mathematical model was used to estimate and experimentally measure the activity concentration of radon in air, resulting in the determination of the optimal radon transfer velocity coefficient ( K ). Based on the experimental and fitted results, empirical equations for the variation of the radon transfer velocity coefficient under different levels of bubble flow were derived. These formulas show that the radon transfer velocity coefficient does not always increase with increasing levels of bubble flow but increases to an upper limit and then stops.