Abstract This paper deals with the wave-induced cyclic response of a poro-elastic seabed (by means of oscillations of the pore-fluid pressure, soil displacement, effective normal stress and shear stress in a soil skeleton) due to a surface sinusoidal water-wave propagating over a seabed of finite thickness. The main existing analytical solutions to the governing problem, assuming a dual-elastic system of the two-phase (pore-fluid and soil skeleton) seabed medium, are critically discussed, pointing out their limitations, doubtful items, and meaningful errors. The amplitude phenomena is particularly studied as an immanent part of any complex-valued analytical solution of a cyclic nature. A series of calculation analyses, performed for the North Sea wave and soil conditions, has indicated problematic results as far as high values of the shear modulus of soil are concerned. An application of meaningfully different values of the degree of saturation, obtained for one and the same calculation example, has caused many additional doubts as to the quality of the tested analytical solutions.
Abstract Precise long-term rainfall prediction is important for agricultural planning, climate resilience, and reducing disaster risk, particularly for countries like Nigeria with diverse regimes of rainfall. In this research, the potential of machine learning (ML) and statistical models to predict monthly univariate rainfall in 24 Nigerian stationswas evaluated. Model training employed historical rainfall data (1960–1999), while validation was carried out for 11 years (2000–2010). SARIMA ( p; d; q ) ( P; D; Q ) s models were used in Minitab ® , R, and Python, and the most important parameters ( p; d; q; P; D; Q ) were tuned manually and by using auto.arima(). ML models such as feedforward neural networks, adaptive neuro-fuzzy inference systems, support vector regression and random forest were utilized in MATLAB ® and R with hyperparameter-tuned models. Model performancewas evaluated in using statistics such as root mean square error ( RMSE ) and coefficient of determination ( r 2 ). SARIMA performed best in areas where rainfall variability was minimal. Nguru (12.03°N), the area with the lowest average monthly rainfall (35.71 mm), showed the highest SARIMA estimation with RMSE of as low as 7.84mm and r 2 of as high as 0.85. ML models underperformed in capturing seasonal dynamics. For instance, SVR failed to model temporal trends effectively, while random forest produced nearly constant outputs across all years. Adjustments to SARIMA parameters (e.g., setting seasonal differencing D = 0 or Q = 1) were essential in reducing unrealistic forecasts. The findings demonstrate that SARIMA, with proper tuning, is better suited for univariate rainfall forecasting in Nigeria than non-customized ML models. Forecast reliability strongly correlates with regional rainfall characteristics and model sensitivity to seasonality.
For flood protection infrastructure to be designed effectively, it is essential to accurately assess the maximum discharge ( Q max ) in Algerian wadis and watercourses. In the absence of direct field measurements, reliance on foreign methodologies is common. However, these methods often overlook the specific characteristics of hydrological systems in Algeria leading to significant inconsistencies and complicating methods choice. Accordingly, the crucial question that arises is: which methodology provides the most reliable ( Q max ) estimates for the purpose of designing effective flood defenses? Therefore, this paper explores the estimation of maximum discharge in Wadis when direct flow rate data is unavailable. The proposed model, outlined in equation (3), is developed through statistical modeling and incorporates key factors such as watershed area (A) and rainfall intensity ( P tc ). The model correlates with observed discharge values by utilizing data from Algeria’s National Water Resources Agency, covering 60 Wadis across diverse regions. This approach outperforms existing models, achieving a notably low mean normalized error of 10%, signifying substantial improvements in accuracy.
Abstract Irrigation development focused on implementing ecologically sound and nature-based solutions was explored. This approach is crucial in addressing the pressing need to conserve water and electricity resources, aligning irrigated farming practices with current global challenges and sustainable development goals. Unlike traditional methods, it is essential to view water and electricity resources as integral components of irrigation efficiency from a resource-ecological perspective. A computer experiment involving predictive and simulation modeling was conducted to assess the feasibility and potential cost savings of adopting resource-ecological principles in irrigation practices. The study evaluated the resource-ecological efficiency of different sprinkler irrigation regimes based on irrigation reliability, which measures deviations from projected irrigation and watering rates. Multicriteria regression analysis revealed a strong correlation ( R 2 = 0:874) among various factors influencing irrigation efficiency. Results indicated that implementing different levels of irrigation reliability could significantly improve technological efficiency, with crop productivity reductions ranging from 10.80% to 18.06% and water and electricity cost savings of 27% to 48%. These findings support the integration of nature-based and ecologically effective irrigation solutions to promote sustainable agriculture in the face of global challenges such as climate change, water scarcity, food insecurity, and energy shortages.
Abstract In the modern global field of underground water treatment, the technology of biological iron removal is gaining more and more recognition, as it has a number of significant advantages compared to traditional ones, namely: increased rates of Fe(II) oxidation, filtration, as well as a large dirt capacity of the filter filling. Therefore, the search for methods to activate cellular metabolic processes has practical implications. One of the possible ways of such activation is by using the effect of a constant magnetic field (CMF) on communities of ferrobacteria attached to the contact loading of bioabsorbents made of synthetic material. Based on the results of the research, it has been established that the CMF with an induction value of 5–10 mT is the most favorable for the development of ferrobacteria colonies, while the induction of 130–150 mT, on the contrary, inhibits their development. There has been studied the effect of CMF with the power of 10–15 mT on the e ciency of combined processes of treatment from dissolved organic compounds and Fe(II). The results of comparative studies on the effectiveness of various technological schemes are presented. It was found that with the use of CMF with a magnetic induction of 5–10 mT, the effect of iron removal increases by 20%. There has been developed biotechnology for treating weak acid (pH 6.3–6.5), iron-containing (Fe2+ 6–8 mg/dm3) underground waters which is based on the combinatorics of physical (aeration, influence of constant magnetic field) and biochemical (use of ferrobacteria consortia) methods. The main technological parameters of the process: filtration rate for the bioreactor 7–10 m/h, for filters 6–8 m/h; duration of filter cycles for the bioreactor is 2–3 weeks; for filters 44–48 hours have been determined. The theoretical aspects of the impact of CMF on the processes of biochemical treatment of underground water have been substantiated.
Abstract A tunnel at a shallow depth, lying between several and 55 meters, was excavated in a jointed rock mass. Models of the rock mass and tunnel were elaborated basing on the data from an object in Carpathian flysch (Poland). The tunnel behaviour was analysed by using FLAC3D program and Coulomb-Mohr criterion and ubiquitous model of the rock mass with 10 combinations of the joint systems orientation (with respect to the tunnel axis). The tunnel shape is horse-shoe and its height equals 4.5 m. In each tunnel cross-section, 16 rock bolts and 20 cm shotcrete layer (with the strength increasing with time) were mounted. In cases of unfavourable orientation of joint system and unstable conditions, rock bolting of the tunnel heading face was installed and modelled. The numerical analysis was carried out for each excavation step, equal to 1.5 m. The entire deformation process and stress redistribution were registered starting with the cross-section in originally intact rock mass (i.e. before the tunnel heading face reached it), to the section located far from the face, in already supported and stabilized tunnel. The results obtained show the effect of discontinuities orientation on the stress distribution and displacement magnitude. The first signs of tunnel approaching heading face appear in a cross-section situated in a distance of 7 to 9 m from it. The processes of stress and displacement redistribution are long-range and occur in a distance of many meters from the already excavated tunnel face. The important result of the analysis was the determination of the ground response curves representing decompression and support loading as a function of the excavation advance. These results allow for better design of a proper support system of the tunnel.
Abstract The air-water flow properties of skimming flow over a moderately sloping stepped spillway with beveled-face steps were investigated using a non-hydrostatic depth-averaged mixture flow model. The proposed model couples the Boussinesq-type equations with the depth-averaged air transport equations. Additionally, it incorporates a depth-averaged k − ε turbulence model to deal with the turbulent issue of the self-aerated flow. The numerical solutions of these higher-order equations were obtained by means of a hybrid finite-volume and finite-difference scheme and were validated with a set of data from large-scale experiments. For the flow condition considered, the simulation results closely correlated with the experimental data, thereby demonstrating the model’s capacity for capturing the effects of air entrainment on the dynamic characteristics of the flow. Furthermore, the energy dissipation performance of the stepped spillway was examined. The results attested that the total energy loss decreases as the drop number increases, highlighting the link between the loss of the flow’s kinetic energy and the variation of the spillway discharge. With the established acceptable accuracy, the proposed model is well suited to analyzing the mean flow characteristics of aerated flow in such a type of stepped chute.
Abstract This study presents the use, and its advantages, of artificial intelligence methods to predict the discharge coefficient (Cw ), considering the approach conditions of the labyrinth weir type D. The study suggests modifying the training and validation rates in AI tools, which are often fixed without proper justification in previous studies. Unlike most studies that use geometric dimensions as inputs, this work focuses on the approach conditions (the emplacement of the labyrinth weir and filling the alveoli upstream and downstream) of the labyrinth weir type D. The results, based on laboratory experiments, show that these modified inputs significantly impact the e ciency and cost of constructing the weir. Moreover, the C w predictions based on these inputs are highly satisfactory compared to laboratory test results. In terms of training and validation ratios, the study confirms that the optimal ratio is 70/30 for accurate and highly satisfactory predictions.
Abstract Desirable conditions of airflow should be provided for spillway chute aerators in two-phase air-water flow, especially in large-width chutes. There is no general approach to determine air entrainment, concentration distribution, and submergence along a chute introduced by an aerator shaft. The two-phase air-water modeling of Gavoshan dam in Iran as a case study of chute flow, its aerator, and the characteristics of flow into the cavity formed below the jet have been numerically investigated, and the results obtained have been validated against the laboratory experiments. The hydraulic parameters of the cavity and aerator shaft were determined to evaluate their performance and emphasize the importance of a proper aerator design. Sections with a greater distance from the bottom of the chute exhibit higher pressure magnitudes, while the mean air concentration values in the cavity are smaller in sections close to a ramp. Higher water discharge, lower pressure head in sections near the bottom of the cavity, and lower air concentration in sections near the ramp into the cavity increase the probability of cavitation occurrence.
Abstract The determination of resistance coefficients, such as Chezy’s or Manning’s coefficients, requires a great deal of sensible thought in order to express these coefficients better and more extensively in free-surface channels and aqueducts. This can be achieved if the expression of the resistance coefficient is well stated and takes into account the maximum number of parameters for governing flows in channels. However, in most practical cases, if these coefficients are not expressed by implicit models, they are generally taken as constant and arbitrary. To this end and in a rational manner, the dimensioning and design of channels requires the expression of the resistance coefficient in an easily and explicit form by adopting numerous flow parameters, namely the roughness of the walls, the aspect ratio, the slope of the channels and essentially the viscosity of the liquid. To achieve this aim, the Chezy’s resistance coefficient C is identified using the rough model method (RMM), which gives the discharge under uniform flow conditions appropriate to a round-cornered rectangle channel.
Abstract The shallow-water and multilayer hydrostatic models have been commonly used to analyze the problems of a sediment-laden, plane open-channel flow. The models are adequate to solve a quasi-hydrostatic flow problem, but their accuracy deteriorates as the e ects of the vertical acceleration gain in significance. Herein, a higher-order numerical model for treating the problems of unsteady, plane open-channel flow over a movable bed is proposed. In this model, the flow hydrodynamics is governed by the depth-averaged Boussinesq-type equations, and the bed morphodynamics is determined by an Exner-type equation and additional equations describing the non-equilibrium transports of suspended load and bed load. A hybrid finite-volume and finite-di erence scheme was used to discretize and solve the governing equations, yielding solutions that are in satisfactory agreement with the experimental data. Overall, the results of the proposed model for the temporal free-surface profile and bed evolution were fairly adequate. For the two particular cases considered, however, the quality of its results was moderately a ected by the e ects of the three-dimensional characteristics of the dam-break flow and the sliding of the dike body due to sub-surface flow. The results of this investigation highlight the importance of including a higher-order Boussinesq-type correction for refining sediment transport computations.
Abstract The paper is devoted to the long-term project concerning monitoring and stability analysis of a 40 m high phosphogypsum heap located at Wiślinka, Poland. The research presented in the paper focused on collecting and processing rainfall data, which subsequently allows us to perform numerical simulation of rainfall impact on heap’s behaviour. Such analysis requires time history of rainfall intensity, that is recorded by an automatic precipitation station. Since this is not common monitoring equipment, the characteristics of the station installed in the immediate vicinity of the heap are presented, and the data obtained in two experiments conducted in the laboratory are discussed. The analysis revealed that di erences between introduced and measured total rain are as large as 10% for very heavy rains. Moreover, the recorded maximum rainfall intensity often includes errors. The data processing procedure to obtain time history of rainfall intensity is presented on the basis of data collected in the first half of the hydrological year 2023 (the first period of the station’s operation). The total precipitation registered was 107 mm, and the maximum daily rain was only 26 mm. However, first single and multi-stage rainfall models for the Wiślinka region that would be applied into numerical simulations are presented.
Abstract A system optimization method was used, which consists in the consistent justification of optimal technological and constructive solutions and parameters of drainage polder systems during the development of their projects. This is done in compliance with modern economic and environmental requirements according to criteria and models for di erent levels of management decision-making over time (project, planned operation). Based on the performed relevant predictive and optimization calculations for the conditions of the real object, the following three tasks have been accomplished. (1) The optimal pump module at the stage of operation for the existing polder drainage system has been substantiated. (2) The design of the pumping unit and the parameters of its components during the reconstruction of the polder drainage system have been improved. This made it possible to reduce the load on the pumping equipment, the duration of its operation, and the cost of electricity by 20–40%, depending on the water level of the year. The improvement was carried out by the diversion of the corresponding part of the surface runo with additionally introduced gravity elements in the form of a puncture in the body of the protective dam and a siphon intake. (3) We have substantiated the optimal water regulation technology for the existing polder drainage system in modern and forecast weather and climate conditions, which will ensure the maintenance of the necessary water-air regime of the drained soils in di erent phases of the growing season of agricultural crops. This will make it possible, on demand, to increase the energy and general environmental and economic e ciency during their creation and functioning of the polder drainage system in accordance with modern changing conditions.
Abstract The environmental state of rice irrigation systems (RIS) is determined by many factors, including natural ones (soil, topographical, hydrogeological, and climatic factors) and technological ones (irrigation norm, design, and parameters of irrigation and drainage networks, etc). The most significant influence on the ecological reclamation state of the RIS carries is effected by its drainage network (DN). The need to maintain a flushing water regime with specific filtration rates to prevent secondary salinization in the Danube Delta’s rice systems is a crucial aspect of managing these agricultural areas. In the saline areas of rice systems located in the Danube Delta, the DN must ensure the maintenance of the flushing water regime with the rates of filtration ranging between 10 to 12 mm/day. This is a prerequisite for preventing secondary salinization of irrigated lands of these rice systems. According to the results of studies, the filtration from the surface of the irrigation checks of the Danube Delta RIS has been established, and its values in the area of the rice check vary significantly. Different intensity of filtration in the area of rice checks causes the difference in mineralization of groundwater and in the content of salts in the soil. This leads to the fact that the same rice check created various natural reclamation conditions and different productivity of cultivated crops.
Abstract The paper presents the results of theoretical studies on turbulent water motion in pipelines, obtained by the analysis of experimental data regarding hydraulic patterns of turbulent flows. The authors suggest to evaluate the relevant parameters on the basis of the molecular and turbulent viscosity indicators, with the introduction of the conditional relative thickness of the boundary layer on the pipeline walls into the calculations. On this basis, the authors specified semi-empirical relationships for the distribution of averaged velocities in the pipe cross-sections, and revealed new theoretical relationships between the main parameters of turbulent pipe flows. The research confirmed the adequacy of these relationships given the good agreement of the calculated averaged velocity values with the experimental data which formed a basis for the current standards for hydraulic calculations of water supply pipes. For hydraulically smooth pipes, the authors derived an explicit dependence of the hydraulic friction coe cient on the Reynolds number, which almost completely corresponds to the well-known Prandtl-Colebrook equation that has an implicit form. The presented research allowed to determine numerical values and analytical relationships between parameters, which enabled evaluating turbulent flows in hydraulically smooth pipes in a new way.
Abstract Subcritical flows over highway and railway embankments, commonly encountered during flood events, can be treated like submerged flows over trapezoidal-shaped weirs. In earlier studies, the equation of the submerged-flow discharge for such types of weirs was developed as a function of the degree of submergence and free-flow discharge. However, the application of this equation in practice requires a pre-determined discharge from experiments performed under free-flowconditions. In this study, a discharge equation was deduced from the streamwise momentum balance equation, which overcomes the drawback of the previous approaches. The results of the validation demonstrated that the proposed equation is capable of predicting the submerged-flow discharge of a trapezoidal-shaped weir within ±6.0% of the measured value. Furthermore, the most prominent features of the submerged overflows were examined by systematically analyzing the experimental data. For such flows, the free-surface and bed-pressure profiles are self-similar only over the upstream face of the weir. Results of this investigation confirmed that the degree of submergence and the slope of the downstream weir face significantly affect the characteristics of the submerged flow, but the effect of the latter on the non-modular discharge is marginal.
In this study, the effect of mineral pumice was investigated in sewage treatment of the dairy industries with various factors such as adsorbent dose, mixing speed, pH and contact time were also studied. Results showed that granular mineral, with a contact time of 20 hours and a volume percentage of one third and pH of 8 has the ability to COD (Chemical Oxygen Demand) decreasing up to 56.9%. However, by using mineral pumice in powder form, in 3 cases, higher efficiency than granules has been obtained. It seems that acidity conditions will not have a positive effect on this efficiency. As the contact time increased, the adsorption rate increased due to the increased probability of collision with the adsorbent surface mostly. With increasing the adsorbent dose, the absorption rate also increased especially in the range of 15 g/l. About mixing speed, no definite conclusion can be made, because in some cases, with increasing the mixing speed COD reduction efficiency decreased. Regarding the use of mineral pumice in reducing COD, according to the obtained results, it is better to use mineral pumice in granular form.
Abstract Computational examinations of the flow field in an open channel having a single Backward--Facing Step (BFS) with a constant water depth of 1.5 m were performed. The e ects of the expansion ratio, and the flow velocity along the reattachment length, were investigated by employing two di erent expansion ratios of 1.5 and 2, and eight various flow velocities of 0.5, 1, 2, 3, 4, 5, 7.5 and 10 m/sec in the Computational Fluid Dynamic (CFD) simulations. Commercially available CFD software, ANSYS FLUENT, was used for calculations. The simulation outcomes were verified using experimental results. Moreover, analyses were performed by using two equation turbulence closure models, K-ɛ family (standard, RNG and realizable), and K-ω family (Wilcox’s and SST K-ω). The analyses have revealed that the reattachment length increases with an increase in the expansion ratio, the flow velocity and the Reynolds number. The results obtained for two expansion rates and eight di erent flow velocities have shown insignificant di erences between one turbulence closure model and the others. Furthermore, it was observed that both velocity and expansion ratios have an e ect on the reattachment zone size.
Abstract Intensification of extreme rainfall-runo events in arid and semi-arid regions because of climate change induce the water erosion that contributes considerably to the loss of vegetal layers of soils and reduce the storage capacity of dams by silting of transported sediments from the watershed to the impoundment. This paper aims at proposing means for protecting the Mghila dam against silting by identification and delimitation of vulnerable areas to water erosion. This dam, built in the North-West of Algeria, ensures irrigated cultivation. Topographical, geological, and land use characteristics of the watershed were analyzed using the geographic information system (GIS). Analysis of results has allowed the identification by area percentage four-vulnerability classes with sensitivity to the water erosion: low(18.89%), medium (13.08%), high (65.05%) and very high (8.38%). The spatial distribution of the lithological substratum friability, the vegetation cover and slope degrees have led to the development of an e cient strategy for the watershed management in order to reduce the e ect of water erosion on soil degradation and silting of the Mghila dam.
Abstract The provision of a reliable water-supply system is essential for the development and well-being of urban communities. Samdrupjongkhar Thromde, located in Bhutan, has been facing water supply challenges despite the presence of a water treatment plant. The non-perennial nature of the current water source coupled with malfunctions in water pumps has led to acute water shortages in the municipality. To address this issue, this study carried out a feasibility investigation and designed a gravity water supply system by conducting an EPANET (Environment Protection Agency Network Evaluation Tool) analysis. The study involved field visits to identify potential water sources, and a topo-graphic survey using RTK (Real Time Kinematics) technology to determine the optimal pipeline route. The EPANET analysis was then conducted to evaluate the hydraulic performance of the initial route. Based on these findings, a final water pipeline route was selected considering factors such as terrain characteristics, construction feasibility, avoidance of negative water pressure, and minimum encroachment of private land. The results showed that the maximum pressure head within the pipeline system reached 296 m with a maximum water flow velocity of 5 m/s. However, at the outlet, the pressure head decreased to 70 m and the velocity decreased to 2 m/s. Two Break Pressure Tanks (BPT) were strategically placed to achieve this pressure reduction. The chosen pipe materials and their placement ensure the long-term reliability and functionality of the water supply system, while considering maintenance convenience and terrain characteristics.
