Hydraulic Regime Research Articles

Оперативное диспетчерское управление водораспределением в оросительных системах по расчетному приращению объемов

Goal: to improve the methodological approach to developing an algorithm for operational dis-patch control of water distribution based on the calculated increment of water volumes in irri-gation canals. Materials and methods: the dispatch control methodology is described, which is based on the typification of flow conditions between two partitioning structures in technical and functional directions, as well as on the development of systems for unifying channels and their modes using similarity theory methods, which are widely used in hydromechanics and hydraulics. The basis for the implementation of the similarity theory is the principle of using similarity numbers, that is, combinations of dimensionless parameters that determine the char-acteristics of the unsteady motion of a heavy, incompressible, viscous fluid in channels. Re-sults: the general tasks of the dispatcher were determined to re-regulate the hydraulic regime of sections of the irrigation system, without tying them to specific types of hydraulic struc-tures. The main provisions of the method of dispatch control of water distribution based on the calculated increment of volumes, determination of the time of re-regulation between the main and compensating processes of re-regulation are substantiated. Four types of situations are identified when solving dispatch problems of water distribution, which are determined by comparing the volumes and flow rates installed on the site, for each of which the inherent re-regulation order is determined. Conclusion: the article outlines a new methodological ap-proach that ensures the joint use of the method of similarity theory and a simulation experi-ment with the Saint-Venant equations for steady and unsteady water flow in the canals of ir-rigation systems, to solve problems of operational dispatch control of water distribution ac-cording to the calculated increment of volumes.

Дослідження міграції сучасних пестицидів амікарбазону, біциклопірону та підіфлуметофену з ґрунту до ґрунтових вод (результати експериментальних досліджень)

ABSTRACT. The expansion of the range and volume of application of plant protection products in agriculture increases the risk of contamination of soil, and subsequently of underground and surface water sources, especially with highly persistent pesticides in the soil. Аim. Establishing and comparative assessment of migration characteristics of new pesticides — representatives of different chemical classes, from soil to groundwater when modelling different initial concentrations and irrigation regimes. Materials and Мethods. In a laboratory experiment, the migration of the investigated substances in the soil – ground water system was studied with the help of filtration columns designed by the Academician E.H. Honcharuk. Soil Standard Model no 1 (SSM no 1) and leached chernozem were used as arable soil layers. Three hydraulic regimes were simulated: annual, three-month, or monthly precipitation rates were supplied to the column for 30 days. The initial concentrations of amicarbazone, bicyclopyrone, and pydiflumetofen corresponded to both one maximum consumption rate (m.c.r.) and 0.5, 0.2 and 5 m.c.r. respectively. Quantitative determination of the studied substances in the filtrate was carried out by the method of high-performance liquid chromatography. The results. It was established that with higher initial concentrations of all three substances in the topsoil and greater hydraulic load on the filtration column in the case of both herbicides, the concentrations of compounds in the filtrate were higher. At the same time, with the same arable soil layer (SSM no 1) and hydraulic load (maximum) and almost the same initial concentration in the soil (0.05 and 0.06 mg/kg), bicyclopyrone appeared in the filtrate much earlier and in in larger quantities, its maximum concentration in the filtrate was reached much faster, it was 17 times higher. It took much more time to detect pydiflumetofen than bicyclopyrone. The migration levels of bicyclopyrone were almost independent of the type of arable soil layer, while pydiflumetofen in leached chernozem retained longer and migrated more slowly than in SSM no 1. Conclusions. Both general regularities and significant differences in the migration of the studied substances to the ground water depending on the soil profile were revealed. It has been proven that, compared to bicyclopyrone, pydiflumetofen is less mobile, appears in the filtrate much later and migrates from SSM no 1 more slowly. Compared to bicyclopyrone, amicarbazone is more mobile, migrates from leached chernozem longer and more intensively. The highest potential danger of groundwater contamination due to vertical migration from chernozem, the most common soil type in Ukraine, is inherent to amicarbazone, the lowest — to pydiflumetofen. Keywords: plant protection products, herbicide, fungicide, soil, groundwater, migration, pollution, threshold limit value.

Environmental effects of river ice, The Saint John (Wolastoq) River, New Brunswick, Canada

ABSTRACT The Saint John (Wolastoq) River (SJR) is a major international river flowing through the State of Maine, USA, and the Province of New Brunswick, Canada. In terms of river length and basin area, it is one of the largest rivers on the eastern seaboard of North America south of the St. Lawrence River system. Subject to seasonal ice cover, ice conditions vary along the SJR due to natural differences in climate and terrain, and due to anthropogenetic changes, such as the construction of dams. Ice formation, growth, and breakup along the SJR affects its hydraulic and ecological regimes and leads to the potential for ice jamming that has caused severe flooding and ice runs. Ice affects river erosion, flooding, ecology, water quality, and recreational uses of the SJR. An overview of typical winter climate and ice season characteristics along the SJR from Dickey, Maine, USA to Saint John, New Brunswick, and some of its environmental consequences are summarized in this review paper. Ice processes and phenomena that occur along the SJR occur along other northern rivers, and can cause similar environmental concerns and consequences that should not be ignored in river engineering and basin management.

Modelling the effect of cascade reservoir regulation on ice-jam flooding

In regulated rivers, dams and their reservoirs are the main means to change the flow conditions, and strategic reservoir operations can be an important measure for mitigating ice-jam flooding (IJF). Previous studies have shown the effect of single reservoir operation on IJF probabilities, but little is known about the effect of cascade reservoir operation on IJF occurrences and severity. This study presents a probabilistic modelling framework that couples machine learning (LSTM, Long Short-Term Memory) and river ice (RIVICE) models to assess the effects of regulated and naturalized flows on IJF backwater levels. The trained LTSM shows good performance in both validation (RMSE = 398.88, R = 0.86 and NSE = 0.67) and testing (RMSE = 366.57, R = 0.84 and NSE = 0.71) periods and the calibrated RIVICE can well simulate backwater levels caused by three IJFs from 2008 to 2010 with total volumes of incoming ice for 0.4 million m3, 0.55 million m3 and 0.32 million m3. The completed framework was used to assess IJF hazard along the Sanhuhekou bend, a reach of the upper Yellow River, whose hydraulic regime is impacted by eight upstream reservoirs. The effect of naturalized and regulated flows on IJF are compared from two aspects. Firstly, comparing the median of naturalized and regulated IJF backwater level ensembles, the results show that regulation increases the IJF backwater levels. Secondly, comparing the extreme values of naturalized and regulated IJF backwater level ensembles, results show that regulation can increase the hazard of IJF inundation when annual exceedance probability (AEP) is less severe than 1:100 and regulation can decrease the hazard of IJF when AEP is more severe than 1:125.

Impact of modelling assumptions in cavitating flow of simplified injector

Here, three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulations are employed for in-nozzle flow modelling. The aim is to evaluate the capabilities and sensitivities of simulating in-nozzle flow phenomena by using homogeneous phase change models. Two commonly used homogeneous models are employed – (i) Homogeneous Equilibrium Model (HEM) and (ii) Homogeneous Relaxation Model (HRM) A simplified nozzle with reference experimental data is modelled in the developing, super cavitation, and hydraulic flip regimes using OpenFOAM. The influence of the inlet boundary condition and turbulence models are investigated. With HEM, three barotropic compressibility models are tested. The research seeks to understand the strengths and limitations of each approach by comparing different sub-models and their interactions with the flow fields and phase change phenomena. Ultimately, this study contributes to a better understanding of how different modelling choices can influence the accuracy and reliability of cavitation simulations using homogeneous phase change models. While the simulations demonstrated reliable predictions for low-order velocity statistics, substantial discrepancies were identified in the prediction of the cavitating region by both homogeneous models. Additionally, the relaxation model predicted only minor cavitation. In contrast, acceptable flow predictions were achieved using different barotropic compressibility models and inlet boundary condition types, as well as most RANS turbulence models, where the RNG k-ɛ model deviated more from the other turbulence models. Therefore, the added value of the present study is summarised as: (a) Four different cavitation regimes are simulated with HEM and HRM in a single study. (b) The more comprehensive HRM approach does not produce better velocity or cavitation predictions for a low-speed flow using the default relaxation time. (c) The choice of turbulence model can radically affect the cavitation prediction, in addition to velocity fields. (d) The HEM flow simulation has little sensitivity to the barotropic compressibility model.

Influence of the last (de)glaciation on a complex cave system: Grønli-Seter cave system, Northern Norway

Cave studies enable us to unravel valuable information on landscape evolution. In glacial settings, the glacial cycles induced fluctuations in the underground hydraulic regime, sediment availability and base level in adjacent caves. Here, we present our work on the Grønli-Seter cave system in Northern Norway, which comprises >8 km of passage length at an elevation between 250 m and present sea level. By linking cave morphology and deposits to shifting glacier configurations and external base level changes during the last deglaciation and the Early Holocene, we establish how the hydraulic conditions in the cave system shifted in pace with glacier fluctuations. Maze sections and phreatic loops appear in a hydraulic confined setting close to the interface between the calcite marble and the overlying mica schist. Scallops in the cave walls demonstrate slow, ascending water flow, evidence of subglacial speleogenesis under wet-based, topographically constrained glaciers with a gentle surface slope. Moreover, cave morphology and clastic deposits indicate various hydrological phases of descending water flow, stagnant conditions, and excessive flow rates. Our work establishes that the last glaciation and deglaciation had an insignificant effect on the cave system's solutional development. In contrast, the cave sediments reveal diverse hydraulic conditions that may be related to shifting glacier configurations. This research offers valuable insights into glacier ice-contact speleogenesis and landscape development in glacial terrains.

THERMODYNAMIC IMPERATIVES THE MODERNIZATION OF THE ELECTRIC DRIVE OF PUMP UNITS OF THE CENTRALIZED HEAT SUPPLY NETWORK IN THE CONTEXT OF INCREASEING ENERGY EFFICIENCY

The relationship between thermodynamic and hydraulic parameters of the heat supply network has been established. The dependence of the electric power consumed by the electric drive of the pump unit on the pressure and supply of the coolant was determined. It is proved that the regulated electric drive system has advantages over the non-regulated electric drive system in the context of energy efficiency of the pumping unit and the district heating network in general. Approaches and criteria for the synthesis of a regulated electric drive system, including its automatic control system, were determined, regulation methods were analyzed, and the most acceptable version of the electric drive was chosen: a controlled frequency converter - an asynchronous motor with a short-circuited rotor, taking into account the above, an energy-saving mechanical system of a centralized heat supply network was synthesized. The peculiarity of this system is that the protection of parameters of hydraulic and temperature regimes in the network of centralized heat supply is ensured with the help of extreme automatic control systems. At the same time, the assignment of mode parameters is provided by the temperature controller of the heat exchange point of the network. Regulation of the pressure and productivity of the pumping unit is carried out by changing, according to a certain law, the frequency and power supply of the asynchronous motor.

“Turbulence effect on total mechanical energy budget and energy loss of turbulent flows with different hydraulic regimes in open-channel transitions”

ABSTRACT Transitions are needed in hydraulic structures which are flumed. In expanding transitions, flow separates from the boundary if the angle of divergence exceeds about 5 degrees. The present paper gives an insight into the turbulence effect and energy loss in expanding transition with small angle of divergence. In wide angle expansion, flow separates from the boundary resulting in highly non-uniform velocity distribution at the exit of expansion resulting in erosion of down stream channel. Author performed experiments to control separation of flow in wide angle expansion. The paper discusses about the devices used by the author to control separation in wide angle expanding transition.

Biomonitoring of the surface waters of the Volyntsevo reservoir using the fluorimetry method

The article examines the state of the drinking Volyntsevo reservoir and its tributaries in conditions of significant changes in the hydraulic regime and pollution by waste mine waters. The state of algoflora of a water body is considered, the results of studying the species composition of phytoplankton, the content of basic photopigments and photosynthetic activity of microalgae are presented. The study presents the results of the application of the method of fluorimetric assessment of the state of phytoplankton cells as the main bioindicator of the state of the aquatic environment. The research was conducted in the vicinity of Yenakievo for the Volyntsevo reservoir and the Bulavin river. These water bodies are subject to significant man-made impacts: as a result of intensive water use of reservoir resources, there has been a significant decrease in water levels and, as a result, a deterioration in water quality. The conducted studies have shown a significant excess of the permissible standards for the content of magnesium ions, sulfates, total hardness and alkalinity in water samples. The negative impact of surface water pollution on the species composition of algoflora, as well as the photosynthetic activity of phytoplankton cells, has been shown. The obtained materials can serve as a basis for further monitoring of drinking reservoirs in the region. The current situation requires constant monitoring observations aimed at identifying and eliminating all sources of pollution of the studied water bodies.

Prediction of water temperature of Sebou estuary (Morocco) using ANN and LR

Water temperature is an important component for river water quality. Good knowledge of river thermal regime is critical for aquatic resources management and environmental impact studies. This study aims to predicting surface water temperature at a given site of Sebou estuary (Morocco) from air temperature, using artificial intelligence applied to neural networks (NN) and linear regression (LR). The models used were applied to an hourly temperature database obtained by simulating hydraulic and thermal regime of the estuary using HEC-RAS model. Temperature data (1560) was divided into training and validation series. The results showed that coefficient of determination for training was 86.26%(NN) and 79.94%(LR). For validation it was 91.23%(NN) and 80.3%(LR). Moreover the residuals generally vary between −1.5°C and +1.5°C, no trend was noted as function of estimated temperature. Hence, it is possible to predict water temperature of estuary using air temperature. Additionally, NN model gave slightly results compared to LR.

Quantifying the consequences of unsustainable sand mining and cascade dams on aspects in a tropical river basin

Human interventions at the river basin scale, such as sand mining and hydropower dam construction, have profoundly affected hydrological and hydraulic alteration regimes, sediment budgets, and morphological changes worldwide. Quantifying the consequences of unsustainable ongoing sand mining and hydropower is crucial for obtaining sediment load data and managing hydrogeomorphology. In this study, comprehensive long-term consecutive four-field monitoring, statistical methods, and hydrological models (SWAT) were applied to quantify the spatiotemporal changes in long-term discharge and sediment load from 1996 to 2020 for the tropical river of the Vu Gia Thu Bon (VGTB) in the central region of Vietnam. The SWAT model was calibrated from 1996 to 2010, validated from 2011 to 2020 and showed good performance for daily discharge and monthly sediment. The evolution of river bathymetric data (2010, 2015, 2018, and 2021) was analysed to clarify the upstream sediment supply trapped in the riverbed and how the sand mining volume was removed. The results showed that the mean annual sediment in the Vu Gia and Thu Bon Rivers decreased by 57.3% and 23.8%, respectively, in the postdam period compared with the predam period. The thalweg elevation decreased at the Ai Nghia and Giao Thuy stations from 2010 to 2021 by 1.8 m and 3.9 m, respectively. The water level decreased by 21.1% at Ai Nghia and 44.3% at Giao Thuy. Dam development, sand mining, and changes in land use are the main factors responsible for flow discharge and sediment morphodynamic alterations. Morphological change have increased the water transfer rate from the Vu Gia River to the Thu Bon River through the Quang Hue channel. Downstream of the Vu Gia River, water transfer and riverbed incision have decreased flow discharge and water level and increased saltwater intrusion in recent years. As a result, water shortages induced by saltwater intrusion during drought periods have emerged as a significant constraint in hindering the domestic water supply and agricultural production.

Integrated geomorphological analysis of a Mediterranean temporary pond priority habitat: the Lago del Capraro doline (Salento peninsula, Italy)

The Lago del Capraro doline (Salento peninsula, southern Italy), a valuable Mediterranean Temporary Pond (MTP), has been investigated aiming to define its geomorphological features and to collect data about the local hydraulic regime. At the bottom of the Lago del Capraro doline, in fact, a small temporary pond appears soon after major precipitation events as that one of autumn 2013. The morphological survey shows that this solution doline is placed on a karst plain surface stretching at about 70 m of altitude; the doline has an elliptical shape with the major axis 130 m long whereas the length of the minor axis is about 100 m. It shows a flat bottom, placed at about 65 m above m.s.l., due to the presence of a colluvial sandy clays filling, bordered by steep limestone slopes about 5 m high. Geophysical surveys and a cone dynamic penetrometer test allowed a detailed geological model to be realized. In particular, ERT and seismic refraction models revealed the geometry and the thickness of doline filling deposits as well as the preferential infiltration zones of surface waters. Interestingly, the cone penetrometer test reveals that resistance decreases downward in the filling lower part, most likely because of the active solution process at the doline bottom. The results of this study suggest an increase of surface water infiltration at doline bottom in the next future so that the development of a pond will be an increasingly rare event, partly compensated by the clustering of rainy periods during autumn months as expected in the future by climate models.

Direct assessment of the hydraulic structure of the plate boundary at the toe of the Nankai accretionary prism

SUMMARY The Nankai Trough is a locus of slow slip, low-frequency earthquakes, and large magnitude (Mw > 8) earthquakes. It is usually assumed that high pore pressure contributes substantially to earthquake dynamics. Hence, a thorough understanding of the hydraulic regime of the Nankai accretionary prism is needed to understand this diversity of behaviours. We focus on the toe of the accretionary prism by studying data from Hole C0024A, part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project, that intersected the décollement at 813 m below seafloor (mbsf) about 3 km away from the trench. We contribute to this understanding by innovatively integrating drilling and logging data to derive high-resolution hydraulic profiles along the borehole. A quantitative re-analysis of the variation in the downhole annular pressure monitored during drilling show localized fluid flow from the formation to the borehole in excess of 0.05 m3 s−1, especially in the damage zones at the footwall of the décollement. To validate the fluid flow profile, pore pressure was estimated independently from empirical relationships between pore pressure, porosity and P-wave velocity, obtained from consolidation experiments and Eaton-type methods based on drilling or sonic velocity data. The formation fluids are becoming significantly overpressurized with depth in the few hundred metres above décollement. The hydraulic profile suggests that the core of the décollement acts as a barrier inhibiting upward fluid convection, whereas the damage zone acts as an efficient longitudinal channel able to diffuse high pressure from the deeper part of the subduction.

NUMERICAL MODELLING TOXIC SUBSTANCE TRANSPORT IN MINE WATER FLOWS

The purpose of this work is to develop and test a methodology for modelling the migration of toxic substances left after mining in mine water flows in a system of hydraulically connected mine workings of various sizes and elevations depending on the drainage parameters. Methods of research include the analysis of factors that influence the formation of the hydraulic regime in flooded mines, the accumulation and transport of toxic substances. Parameters of moving toxic substances in mine waters are calculated using hydraulic flow equations written for mining workings, with flooded workings being considered as pipelines with distributed recharge. Modelling of non-stationary 1D transport in water from local sources of toxic substances was performed using the finite difference method. Results. Flow rates and velocities in flooded mine workings on two hydraulically connected horizons of different elevations were calculated. For different locations of sources of toxic substances on the example of polychlorinated biphenyls, their concentrations in mine waters along the migration path and at the water hoisting at different flow rates were calculated. The influence of increased water withdrawal, dilution with additional recharge along the migration path and the position of potential sources of substances in the flooded mine were investigated. It wasshown that for the considered example, increasing the water outflow rate by two times accelerates the stabilisation of mass transport with an increase in the daily removal of substances by 3.4–6.4 times, which is more active from the upper horizon. Scientific novelty. For the first time, the transport of substances in flooded workings was simulated by combining a hydraulic flow model with a numerical transport model. Unlike 2D and 3D numerical transport models based on solid mechanics, which average the concentration in the grid blocks, the proposed approach allows the reproduction of the geometry of the mined-out space more accurately. It provides a more realistic distribution of flow velocities and concentrations depending on the parameters of the mine water withdrawal, depth of mine workings, and the mine water level. Practical significance. Using the tested methodology will make it possible to perform engineering predictions of the quality of groundwater and surface water near closed mines for different periods at different levels of flooding, water withdrawal rates and depths of the pumps for mine water drainage. In addition, the proposed technique can be used to justify the conceptual scheme of the numerical hydrogeochemical model of the post-mining areas. Keywords. Close mines, toxic substances, flooded workings, hydraulic flow, water hoisting, transport model.

Deriving synthetic rating curves from a digital elevation model to delineate the inundated areas of small watersheds

Study regionTwo southern Quebec (Canada) watersheds were used to validate the proposed method for delineating inundated areas of small watersheds: the 554-km2 St.Charles and the 133 km2 À la Raquette watersheds. Observed data from six-gauge stations were used to validate the Synthetic Rating Curves (SRC) developed in the study. Study focusThis research focuses on the application of the Height Above the Nearest Drainage (HAND) method to derive SRCs and support floodplain mapping in small watersheds.Accurate floodplain delineation is crucial of flood management, particularly in datascarce regions. This study presents a novel approach using (HAND) approach to precisely identify flood-prone areas. It involves generating (SRCs) connecting discharge and terrain derived hydraulic characteristics, integrated into PHYSITEL; a Geographic Information System (GIS) for distributed hydrological modeling. The Froude number established a consistent relationship between mean discharge and water depth across various discharge levels, defining unique hydraulic regimes. A Global Sensitivity Analysis quantified the uncertainty associated with SRC parameters, guiding calibration efforts to achieve biases below 20%. For both watersheds, postcalibration results showed SRCs with NRMSE values between 0.03 and 0.62. HANDSRC-based inundated areas corroborated the Quebec City flood risk zones well, with over 70% recall and 90% precision, validating its efficacy. These results contribute significantly to the region by providing SRCs for ungauged river sections and delineating first-hand floodplain maps.

Short and medium chain organic acids production from hydrolyzed food waste: technical–economic evaluation and insight into the product’s quality

Food waste (FW) was subjected to thermal-alkaline hydrolysis before to be used as source for organic acids (OAs) production under different temperatures and hydraulic regime in long-term acidification process. Mesophilic environment led to the highest acidification yield (0.87 g CODOAs/g VS) with chain-elongation process to caproic acid production (>9.0 g CODcap/L) occurring at lower HRT (2 days). The product’s quality, in terms of OAs production and composition, was evaluated through a multivariate approach, which indicated that the mesophilic condition was also appropriate to steadily maintain the requested product’s features.The specific gas production (SGP) from the solid-rich acidified residue was 0.47 Nm3/kg VS and, in a full-scale scenario of 150,000 kg FW/d, it can be potentially converted into 24.9 MWh/d as electrical energy. Also, according to the acidification performances, an overall OAs production of 7.2 ton/y has been estimated, generating a yearly economic outcome higher than 4,800,000 €.

Turbulence effect on total mechanical energy budget and energy loss of turbulent flows with different hydraulic regimes in open-channel transitions

ABSTRACT In this study, a modified form of the total mechanical energy budget equation is developed for 3-D turbulent flows with different hydraulic regimes in open-channel transitions, from which the effect of all turbulence parameters can be evaluated by applying some equalizations and RANS numerical simulations. The total energy equation is also used to extract an explicit relationship for energy loss based on turbulence parameters. The findings are presented in the form of the application of the relationship to calculate the energy loss based on simulation results for subcritical turbulent flow and hydraulic jump in open-channel transitions, which leads to identifying the effect of non-homogeneity and anisotropy of turbulence on flow energy balance. The results show that the work done by viscous shear stresses, the viscous diffusion of turbulence, and the turbulent diffusion have little to no effect on the total mechanical energy budget of open-channel turbulent flows; instead, the effect of the variations of turbulent kinetic energy and the work done by turbulence stresses is more significant. The benefit of using the modified energy equation is demonstrated by the potential for evaluating the details that were not previously considered.

The influence of the static component of the water supply network on the change in the power consumption of the pumping unit with frequency control

RELEVANCE. The effective functioning of urban water supply systems plays an important role in maintaining the normal life of cities and towns. Of particular importance is the management of pressure and the optimization of hydraulic regimes in water-wired networks, since they directly affect the reliability of water supply and the efficient use of resources. However, the determination of the optimal parameters and methods of regulation in each specific case requires careful research and analysis. In the context of a constant increase in requirements for automation of water supply and growing investments in its infrastructure, the problem of a correct feasibility study for such investments is of particular relevance.PURPOSE. For smooth regulation of the pressure characteristic of the pump in the conditions of the need to maintain a given pressure of the water supply network, frequency converters are widely used. In the context of the significance of an accurate assessment of investment costs for the automation of pumping units, it becomes necessary to obtain equations that take into account the features of the operation of the water supply network at the pre-design stage. In this regard, the authors of the article set themselves the goal of studying the degree of influence of the static component of the water supply network on the change in the power consumption of the pumping unit with frequency regulation and testing the obtained dependencies on real statistics of the water and energy consumption modes of the Sozh water intake of the Gomel water utility.METHODS. To solve the tasks, classical formulas of similarity of the pumping unit were used, reflecting the relationship between flow, pressure and power consumption. The mean squared error, the mean absolute error and the average absolute error in percentages were used as the evaluation metric for verifying the electric power supply model of the pumping unit.RESULTS. The study demonstrates a significant improvement in the accuracy of power consumption modeling when using a modified coefficient reflecting the degree of power change when the frequency of the supply network changes. When using this approach, the standard error is reduced more than twice, from 0.35 to 0.167, the average absolute error is reduced from 0.347 to 0.165, and the average absolute percentage error is reduced from 0.20% to 0.08%.CONCLUSION The conducted research confirms the effectiveness of the use of frequency control of pumping units, which provides a nonlinear change in electrical power, and demonstrates the possibility of more accurate forecasting of electricity consumption, taking into account the specifics of the water supply network. The results of this work can be useful for projects to optimize urban water supply systems, providing more accurate planning and use of resources.

Numerical simulation of flow over spillway: A case study of Tahoet reservoir

The spillway is one of the most important construction components in the irrigation system; it is the key to ensuring the safety of the reservoir. In this study, the 3D-Fluent numerical model is used to simulate the hydraulic regime in the Ta Hoet spillway. The 8 simulation cases include different gate opening modes and variable flood flows. The change in velocity, water surface, and other hydraulic factors on the spillway have been studied in detail. The results also show that the direction of flow into the spillway is not straight but curved, resulting in different hydraulic regimes at the valve gates. The model results have been calibrated and show excellent accuracy when compared to the experimental data

Effect of hydraulic regime on sulfur-packed bed performance: Denitrification and disproportionation

Sulfur-packed beds (SPBs) have been increasingly incorporated into constructed wetland systems to overcome limitations in achieving satisfactory nitrate removal efficiency. However, the underlying impact of hydraulic regimes on SPB performance remains understudied. This study investigated the performance of a pilot-scale SPB, encompassing sulfur autotrophic denitrification (SAD) and sulfur disproportionation (SDP) processes, under various horizontal flow (HF) and vertical flow (VF) regimes. The HF regime exhibited superior SAD efficiency, achieving 3.1–4.4 mg-N/L of nitrate removal compared to 0.9–2.8 mg-N/L under VF regimes. However, greater sulfide production of 3.8–5.6 mg/L was observed, in contrast to only 1.5–2.3 mg/L under VF regimes when SDP occurred. Employing current computational fluid dynamics simulations could predict general regimes but lacked precision in detailing sulfur layer dynamics. In contrast, determining the spatial distribution of SAD substrates and SDP products offered a viable solution, revealing stagnate, short-circuit, and back flows. Moreover, the feasibility of an aeration approach to reduce sulfide emissions below 0.5 mg/L in case of accidental SDP occurrence was confirmed. This study offers a method for assessing detailed hydraulic regimes within SPBs. Additionally, it provides guidance on optimizing the packing of sulfur-based materials when implementing SPBs in constructed wetland systems and presents a strategy for mitigating excessive sulfide emissions.