rss_2.0Archives of Hydro-Engineering and Environmental Mechanics FeedSciendo RSS Feed for Archives of Hydro-Engineering and Environmental Mechanics of Hydro-Engineering and Environmental Mechanics Feed Modeling of Sediment Transport and Bed Evolution in Nonuniform Open-Channel Flows<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue Aspects of Turbulent Flows in Pipeline<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue Pumice Efficiency in Wastewater Treatment in Dairy Industries<abstract> <title style='display:none'>Abstract</title> <p>In this study, the effectiveness of mineral pumice application in sewage treatment in the dairy industries was investigated, with various factors such as adsorbent dose, mixing speed, pH and contact time being studied in detail. The results obtained showed that mineral pumice in a granular form, with a contact time of 20 hours and a volume fraction 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 three cases considered, higher efficiency than for pumice granules has been observed. It seems that acidity conditions do not have a positive effect on this efficiency. As the contact time increased, the adsorption rate increased, mostly due to increased probability of collision with the adsorbent surface. With an increasing adsorbent dose, the absorption rate also increased, especially in the range of 15 g/l. Regarding the mixing speed, no definite conclusion can be drawn, because in some cases, with increasing mixing speed, the COD reduction efficiency decreased. Considering the use of mineral pumice in reducing COD, in accordance with to the obtained results, it is better to use mineral pumice in granular, rather than in powder, form.</p> </abstract>ARTICLEtrue of a Favorable Filtration Regime of Soils in Saline Areas of the Danube Delta Rice Irrigation Systems<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue Water Scarcity in Samdrupjongkhar Thromde, Bhutan: Feasibility Study and Design of a Sustainable Gravity Water Supply System<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue Determination of the Relationship between Soil Structure Parameters and Indicators of Water Saturation and Filtration<abstract> <title style='display:none'>Abstract</title> <p>Modern climatic changes, in particular, changes in the amount and intensity of soil moisture (precipitation regime), have a significant impact on the water-physical properties of mineral soils. The state of soil’s solid phase and the mutual arrangement of its structural particles can be considered as the most significant factor for soil properties. Due to the structure of the soil, it is possible to influence the uniformity of the distribution of water in the soil sample not only in the vertical direction, but, partially, also in the horizontal direction, which will allow to resolve the issue of local flooding of individual areas and the bearing capacity of mineral soils. For the analysis of changes in the water-physical properties of the soil environment, the soil was considered as a homogeneous in density and continuous environment formed by a set of separate structural aggregates connected by cohesive forces. Based on the experimental results of the physical modelling, it was determined that the presence of structural soil macroaggregates with a size of 4 to 6 mm is the most appropriate for slowing down the vertical filtration of water saturating the lower soil layers, and the formation of structural soil macroaggregates of size larger than 6 to 10 mm for the predominant types of soils is necessary to increase the vertical filtration. Due to the size of the formed macroaggregates, it is possible to predict a change in the water-physical parameters of the soil, which then can be used for the assessment of the calculated characteristics of the soil environment.</p> </abstract>ARTICLEtrue and Mapping of Water Erosion Vulnerability Using GIS for the Mghila Watershed, Northwest of Algeria<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue the Hydraulic Characteristics of Submerged Flow over Trapezoidal-Shaped Weirs<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue analysis of Fractured Koyna Concrete Gravity Dam<abstract> <title style='display:none'>Abstract</title> <p>Seismic analysis of a fractured dam is a generally complex problem. This paper presents an earthquake behavior investigation of a fractured concrete gravity dam considering dam-reservoir--foundation rock interaction. The Koyna dam profile, located in India, is adopted in this study. The nonlinear finite element analyses are conducted taking into account empty and full reservoir cases, to exhibit the hydrodynamic e ect of reservoir water on the dam earthquake response. The hydrodynamic pressure is modeled by fluid finite elements based on a Lagrangian approach. Transient analyses take into account material and connection nonlinearity. Drucker-Prager model is employed in nonlinear analyses for the dam concrete and foundation rock. The structural crack between the top and bottom blocks of the dam is presented by surface-to-surface contact elements based on Coulomb’s friction law in order to simulate the behavior of contact joints and deformation of blocks. The distribution of horizontal displacements and principal stresses along the dam height is investigated for empty and full reservoir cases.The failure processes of two potential failure modes of cracked dam, i.e, the separation and sliding of top block during an earthquake, are examined.</p> </abstract>ARTICLEtrue of Pipe Networks Using EPANET to Optimize Water Supply: A Case Study for Arjawinangun Area, Indonesia<abstract> <title style='display:none'>Abstract</title> <p>In providing clean water services to a community, a clean water supply distribution network system is very important. This study is aimed at the determination of the distribution pipe network by simulating and optimizing the water supply system in the Arjawinangun area, Cirebon, West Java, Indonesia. The data collected was analyzed by using EPANET 2.0 software for modelling water distribution systems. The results show that the total domestic and non-domestic water demand is 391.41 l/s, with a leakage rate of 20%. The pipeline installation plan for the Arjawinangun area is planned to be installed for a length of 23,045 m, with pipe diameters ranging from 400 to 90 mm. The Arjawinangun Area O take Reservoir drainage system, which is at an elevation of +25 m above sea level, requires a distribution pump with a head (H) of 6.0 bar. Also, using the gravity distribution technique, a water tower can be built (~ 55 m) as a water supply booster pump.</p> </abstract>ARTICLEtrue Analysis of Turbulent Flow over a Backward-facing Step in an Open Channel<abstract> <title style='display:none'>Abstract</title> <p>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.</p> </abstract>ARTICLEtrue Technological System for Using Waste Warm Water from Energy Facilities for Effective Agriculture<abstract> <title style='display:none'>Abstract</title> <p>The waste warm waters from power plants, owing to their temperature regime (25–38°C) and the volumes of discharge, allow for their use for heating of open ground areas in agriculture. Underground heating by such water is a new, special heat and irrigation method which enables not only purposeful regulation of temperature conditions of the crop growing environment, but also dissipates heat in the soil, thus cooling the water for its reuse. This makes it possible to reduce the thermal pollution of water sources.</p> </abstract>ARTICLEtrue Supply of the Ukrainian Polesie Ecoregion Drained Areas in Modern Anthropogenic Climate Changes<abstract> <title style='display:none'>Abstract</title> <p>The paper focuses on research on improving the water supply of drainage systems of humid areas in the context of anthropogenic climate change. The aim of the research is to elaborate on the ways for increasing the available water supply of drainage systems and restoring active water regulation on reclaimed lands in a changing climate. Reclaimed lands are the main factor of sustainable agricultural production in Ukraine and guarantors of its stability. The area of drained lands in Ukraine is about 3.2 million hectares, including 2.3 million hectares drained with the help of closed drainage; in an area of 1.3 million hectares a two-way regulation of the soil water regime is carried out. An increase in air temperature and uneven distribution of precipitation, which has a torrential, local character in the warm period, do not allow for the e ective accumulation of moisture. The recurrence of droughts in di erent justified climatic zones of Ukraine has increased by 20–40%, which prevents sustainable agricultural production in the zone of su cient atmospheric moisture, in particular the Polesie Ecoregion. In this paper, the analysis of water consumption of reclaimed lands in the Polesie Ecoregion of Ukraine is carried out, on the examples of the drainage system “Maryanivka” and the calculation of the water supply for the corn and winter wheat.</p> </abstract>ARTICLEtrue Frequency Analysis and Hydraulic Design of Bridge at Mashan on River Kunhar<abstract> <title style='display:none'>Abstract</title> <p>Kunhar River hydrology and hydraulic design of a bridge on this river are being studied using HEC-Geo-RAS and Hydrologic Engineering Centers River Analysis System (HEC-RAS). The river flows in the northern part of Pakistan and is 170 km long. On both sides of the river, there are residential settlements. The river hydraulics is studied by using 30-metre remotely sensed shuttle radar topographic mission - digital elevation model (SRTM DEM) and Arc Map. 32 cross-sections are imported from Geographic Information System (GIS) to HEC-RAS. On historical peak flow results, the extreme value frequency distribution is applied, and a flood is determined for a 100-year return period, with a discharge estimated as 2223 cubic metres. Three steady flow profiles are adopted for HEC-RAS, the first is for the maximum historical peak data, the second is for the 100-year return period, and the third profile is for the latter 100-year period with a safety factor of 1.28. With remote sensing-based assessments, the proposed location for a bridge is determined and then verified with a field survey which was physically conducted. The maximum water height estimated in the river is about 4.26 m. This bridge will facilitate about 50 thousand population of Masahan and its surroundings. It will create a shortest link between Khyber Pakhtunkhwa and Azad Kashmir and thus will enhance tourism and trade activities.</p> </abstract>ARTICLEtrue Modeling of Compound Channels for Determining Kinetic Energy and Momentum Correction Coefficients Using the OpenFOAM Software<abstract> <title style='display:none'>Abstract</title> <p>The non-uniformity of the flow velocity distribution in each section of compound channels and in the main channel-floodplain interface area causes errors in estimating water surface profile, flood routing, pollution transfer, and so on. To reduce the impacts of non-uniformity on the exact calculation of kinetic energy and momentum, <italic>α</italic> and <italic>β</italic> correction coefficients are used, respectively. However, the determination method of these coefficients is a challenging issue in river engineering. This study used the OpenFOAM Software to determine these coefficients numerically for two laboratory models of compound open channels of which the data are available, using the single-phase pimpleFoam solver to do modeling in the mentioned software and the k-<italic>ω</italic>SST turbulence model to calculate the flow characteristics. Based on the results, the highest difference (13%) between the results estimated by the software and those obtained from the lab experiments was seen in the low flow depth where the flow left the main channel and entered the floodplain of a very shallow depth, possibly due to the grid generation of this area. This difference decreased as the flow depth increased, and its average was 6.65% for <italic>α</italic> coefficient and 2.32% for <italic>β</italic> coefficient in all cases, which means the results of numerical modeling and the experimental data conformed well, and the OpenFOAM software can be successfully used in flow modeling and analyzing flow characteristics in compound channels.</p> </abstract>ARTICLEtrue Intelligence Based Flood Forecasting for River Hunza at Danyor Station in Pakistan<abstract> <title style='display:none'>Abstract</title> <p>Floods can cause significant problems for humans and can damage the economy. Implementing a reliable flood monitoring warning system in risk areas can help to reduce the negative impacts of these natural disasters. Artificial intelligence algorithms and statistical approaches are employed by researchers to enhance flood forecasting. In this study, a dataset was created using unique features measured by sensors along the Hunza River in Pakistan over the past 31 years. The dataset was used for classification and regression problems. Two types of machine learning algorithms were tested for classification: classical algorithms (Random Forest, RF and Support Vector Classifier, SVC) and deep learning algorithms (Multi-Layer Perceptron, MLP). For the regression problem, the result of MLP and Support Vector Regression (SVR) algorithms were compared based on their mean square, root mean square and mean absolute errors. The results obtained show that the accuracy of the RF classifier is 0.99, while the accuracies of the SVC and MLP methods are 0.98; moreover, in the case of flood prediction, the SVR algorithm outperforms the MLP approach.</p> </abstract>ARTICLEtrue Rainfall-Runo Events Modeling Using HEC-HMS Model for Oued El Hachem Watershed, Northern Algeria<abstract> <title style='display:none'>Abstract</title> <p>Flood forecasting has become necessary for dam management during extreme hydrological events. The lack of streamflow data in ungauged watersheds of arid and semi-arid regions makes the assessment of water resources di cult. In this paper, the Hydrologic Modeling System developed by the Hydrologic Engineering Center (HEC-HMS) was applied to the Oued El Hachem watershed. Calibration and validation of the model have been performed, taking into account the lag time and the curve number CN that is expressed as a function of soil group, land use and antecedent runo condition. The model was evaluated on the basis of the coe cient of determination, the Nash Sutcli e E ciency (NSE), and the percentage di erences between peak and volume. Performance indices of calibration showed a good agreements between observed and computed flows. The validation of the model has given satisfactory results. The calibrated model can be used to manage the dam of Boukerdane during extreme rainfall events by forecasting the induced hydrographs from which adequate procedures will be operated in order to ensure the safety of the dam against possible overtopping.</p> </abstract>ARTICLEtrue Neural Network for Estimation of Local Scour Depth Around Bridge Piers<abstract> <title style='display:none'>Abstract</title> <p>Local scour around bridge piers impairs the stability of bridges’ structures. Therefore, a delicate estimation of the local scour depth is vital in designing the bridge piers foundations. In this research, MATLAB software was used to train artificial neural network (ANN) models with four hundred laboratory datasets from different laboratory studies, including five parameters: pier diameter, flow depth flow velocity, critical sediment velocity, sediment particle size, and equilibrium local scour depth. The outcomes present that the ANN model with the Levenberg-Marquardt algorithm and 11 nodes in the single hidden layer gives an accurate estimation better than other ANN models trained with different training algorithms based on the regression results and mean squared error values. Besides, the ANN model accurately provides predicted local scour depth and is better than linear and nonlinear regression models. Furthermore, sensitivity analysis shows that removing pier diameter from training parameters diminishes the reliability of prediction.</p> </abstract>ARTICLEtrue the Regression Equations to Determine the Bankfull Discharge from the Basin Characteristics<abstract> <title style='display:none'>Abstract</title> <p>Bankfull discharge is an important criterion for flash flood warnings. In this study, the authors propose a new approach to determine the bankfull discharge for basins in Ha Giang province, Vietnam. The study combines the field survey to determine the bankfull discharge through the bankfull indicators and develop a multivariate regression equation between the bankfull discharge and the basin characteristics. The results of the study give a simple equation with 2 independent variables. They are the catchment area and the main river length. They show a strong relationship with the bankfull discharge with the R<sup>2</sup> indexes in developing and validating process equal to 95.3% and 92.7%, respectively. With this approach, the workload is significantly reduced. However, the accuracy and flexibility of the total discharge calculation are enhanced. This will be the foundation to reduce uncertainty in flash flood warnings.</p> </abstract>ARTICLEtrue Modeling of the Pipeline Uplift Mechanism in Clay<abstract> <title style='display:none'>Abstract</title> <p>Buried pipelines are a vital infrastructure and are mainly used to transport energy carriers and other essential products. The pipes are generally buried in the upper layer of soil deposits and, therefore, are highly affected by different geo-environmental conditions. The various pathological cases recorded in the world are caused by the degradation of structures in contact with swelling soils, the fact that necessitates a full understanding and investigation of such a phenomenon. This paper presents a method for the pipeline behavior modeling based on the finite element analysis by using PLAXIS 3D software, aimed at the determination of the pipe bending moment, displacement over its length, and the evaluation of vertical stresses in soil under the pipe. A parametric study has been carried out to investigate the effect of the pipe burial depth and the soil cohesion. The finite-element results have been compared with experimental data from the literature. It was found that, unlike laboratory models, the numerical analysis can account for the internal pressure in the pipe and the depth of the pipe burial. The finite-element analysis showed that the presence of fluid pressure inside the pipe results in a decrease in the maximum swelling of the soil by about 95%. The displacement of the pipe is considerably affected by the burial depth. The vertical stress at one end of the pipe can be greater than that at the other end in the case of a pipe under internal pressure, while in the case of an empty pipe, the values are very close at both ends. The numerical analysis shows that an increase in the pipe internal pressure leads to a decrease in its vertical displacement.</p> </abstract>ARTICLEtrue