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The progressing development of civilisation and climate change require access to an appropriate quantity of environmental resources. One of the key resources is water. Both its deficit and excess evidently affect human life. Contr...
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The progressing development of civilisation and climate change require access to an appropriate quantity of environmental resources. One of the key resources is water. Both its deficit and excess evidently affect human life. Control over water circulation is possible owing to water management, largely involving introduction of hydraulic structures. The paper analyses the effect of the Jeziorsko dam reservoir on the flows of the Warta River, the third largest river in Poland. It analyses water flows in the Warta River in the years 1993–2020 for hydrological stations above and below the reservoir. The conducted research showed that the construction of the Jeziorsko reservoir also substantially contributed to an increase in minimum flows and a decrease in maximum flows. Moreover, the simulation showed that in the case of abscence of the reservoir, the flows of the Warta River would be higher in the period from January to June, and in the period from July to October the opposite situation would occur. In November and December, the flows would be at a similar level. Results obtained in the study, show that hydraulic structures are an effective solution in the context of stabilisation of the hydrological situation in a given region, particularly in terms of hydrological lows occurring with increasing intensity mitigated on sections of rivers below the reservoirs.
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Piano Key Weirs are an effective solution for dam rehabilitation as well as new dam projects with a high level of hydraulic constraints. In order to improve the efficiency of their design, an experimental study of the influence of...
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Piano Key Weirs are an effective solution for dam rehabilitation as well as new dam projects with a high level of hydraulic constraints. In order to improve the efficiency of their design, an experimental study of the influence of the main geometric parameters has been performed. Thirty one configurations were tested for a wide range of discharges. The results of the study show the influence of the weir height, the keys widths and the overhangs lengths on the discharge capacity and flow characteristics. Based on hydraulic considerations, optimum values of the main geometric ratios are provided. An analytical formulation is developed to predict the discharge capacity of the weir as a function of its geometry. It shows an accuracy of 10% compared to the experimental results of this study and from other sources.
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Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in...
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Forum papers are thought-provoking opinion pieces or essays founded in fact, sometimes containing speculation, on a civil engineering topic of general interest and relevance to the readership of the journal. The views expressed in this Forum article do not necessarily reflect the views of ASCE or the Editorial Board of the journal.
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The objective of this study was to upgrade the form of the flow part of the injection regulator to increase the percentage of circulating flow, representing a surplus water supply. The optimization was based on the recommendations...
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The objective of this study was to upgrade the form of the flow part of the injection regulator to increase the percentage of circulating flow, representing a surplus water supply. The optimization was based on the recommendations adopted in the theory of injection pumps related to the shape and area of the nozzle located in the outlet section of the tubular part; length and diameter of the mixing chamber; and presence or absence of a diffuser outlet section. The operation of two models of injection regulators was successively studied using a mirror hydraulic flume. The models had the same water outlet pipes, but different forms of the outlet sections. The experimental data confirmed the validity of the previously obtained theoretical dependences, as well as the possibility of using regulators with nozzles without diffusers, and the significance of the nozzle and mixing chamber design in terms of increasing the injected flow rate.
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Re-packed soil columns of the Crediton series were sown with white clover or perennial ryegrass, with nitrate managed according to organic and conventional farming regimes respectively. Visual observations revealed a rapid enhance...
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Re-packed soil columns of the Crediton series were sown with white clover or perennial ryegrass, with nitrate managed according to organic and conventional farming regimes respectively. Visual observations revealed a rapid enhancement in soil structure beneath white clover compared to ryegrass and unplanted soil. Enhanced structural differentiation beneath white clover was supported by greater permeability to air and freer drainage to water. Differences in soil structure were verified by water retention measurements over a range of tensions between the witting and gravity drainage points. The void structure was simulated with the Pore-Cor network model, which verified larger pores beneath clover, a difference in local structuring and a saturated hydraulic conductivity which was four times greater than ryegrass. The study highlighted inadequacies in current approaches to the measurement and interpretation of water retention. (C) 2007 Elsevier B.V. All rights reserved.
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Abstract This study compares four data-driven methods, Gaussian process regression (GPR), multivariate adaptive regression spline (MARS), M5 model tree (M5Tree), and multilinear regression (MLR), in estimating mean velocity upstre...
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Abstract This study compares four data-driven methods, Gaussian process regression (GPR), multivariate adaptive regression spline (MARS), M5 model tree (M5Tree), and multilinear regression (MLR), in estimating mean velocity upstream and downstream of bridges. Data were obtained through multiple experiments in a rectangular laboratory flume with glass walls 9.5 m long, 0.6 m wide, and 0.6 m deep. Four different bridge models were placed at the 6th meter of the channel to determine the average velocities upstream and downstream. Different data-driven models were implemented with different combinations of effective parameters as input. They were evaluated and compared using root mean square error (RMSE), mean absolute relative error (MARE), and Nash–Sutcliffe efficiency (NSE). The results showed that the MARS had the best efficiency in estimating the mean velocity upstream of the bridge model. At the same time, the M5Tree provided the highest performance in estimating the mean velocity downstream. The MARS method improved the estimation accuracy of GPR, M5Tree, and MLR in the test phase by 23.8%, 45.1%, and 47.4% concerning the RMSE at the upstream. The M5Tree provided better RMSE accuracy of 31.8%, 70.4%, and 75.5% at the downstream compared to MARS, GPR, and MLR, respectively. The study recommends the MARS and M5Tree for estimating mean velocities upstream and downstream of the bridge.
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Block ramps are structures often used in river restoration projects. They generally ensure a stable streambed and produce high energy dissipation. This paper shows the results of an experimental investigation conducted at the Hydr...
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Block ramps are structures often used in river restoration projects. They generally ensure a stable streambed and produce high energy dissipation. This paper shows the results of an experimental investigation conducted at the Hydraulic Laboratory of the Univ. of Pisa, Pisa, Italy on ramps of different slopes characterized by different bed materials. Experiments have been carried out in three different rectangular channels, where block ramps with a slope varying between 1V: 4H and 1V: 12H have been tested. The results have been compared with the ones obtained for a smooth ramp, which can be considered as a limit case in which the diameter of the bed material tends to zero. The amount of energy loss of such structures is essentially a function of the relative submergence, the slope, and the ratio between the critical water depth and the length of the ramp. Viscous effects and air entertainment can be considered negligible in the experimental range. Tests were carried out to find the case of nonsubmerged ramp conditions.
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The content of dissolved oxygen (DO) in water helps to assess the quality of water. Enhancing the DO level in water course helps in the survival offish and other aquatic organisms. More over, Oxygen is needed for all algae, macrop...
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The content of dissolved oxygen (DO) in water helps to assess the quality of water. Enhancing the DO level in water course helps in the survival offish and other aquatic organisms. More over, Oxygen is needed for all algae, macrophytes, and also for many chemical reactions that are important to stream and lake functioning. Air-Water transfer process can be administrated in the natural flowing channel by providing suitable hydraulic structures. Construction of specific hydraulic structure across river or stream results turbulence in the flow and in some cases hydraulic jump will be formed. This phenomenon at the structure accelerates the entrainment of air to water. This paper describes the experimental investigation on the water aeration process of various hydraulic structures like sloping channel, venturi-flume, broad crested rectangular weir, rectangular grooved weir, triangular grooved weir, trapezoidal grooved weir and spillway type weir. Aeration at various hydraulic structures has been experimented in a 0.15 m wide laboratory tilting flume. Experimental observation confirms that there is positive linear relationship between aeration efficiency and energy loss along the jump.
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A method for modeling flow regime changes at gate structures in canal reaches is presented. The methodology consists of using an approximate Riemann solver at the internal computational nodes, along with the simultaneous solution ...
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A method for modeling flow regime changes at gate structures in canal reaches is presented. The methodology consists of using an approximate Riemann solver at the internal computational nodes, along with the simultaneous solution of the characteristic equations with a gate structure equation at the upstream and downstream boundaries of each reach. The conservative form of the unsteady shallow-water equations is solved in the one-dimensional form using an explicit second-order weighted-average-flux upwind total variation diminishing (TVD) method and a Preissmann implicit scheme method. Four types of TVD limiters are integrated into the explicit solution of the governing hydraulic equations, and the results of the different schemes were compared. Twelve possible cases of flow regime change in a two-reach canal with a gate downstream of the first reach and a weir downstream of the second reach, were considered. While the implicit method gave smoother results, the high-resolution scheme-characteristic method coupling approach at the gate structure was found to be robust in terms of minimizing oscillations generated during changing flow regimes. The complete method developed in this study was able to successfully resolve numerical instabilities due to intersecting shock waves.
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Hydraulic structures are, and will remain, relevant in the future, given the enormous problems in water engineering to come. After having been a key topic up to the Second World War, they have lost attractiveness until recent year...
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Hydraulic structures are, and will remain, relevant in the future, given the enormous problems in water engineering to come. After having been a key topic up to the Second World War, they have lost attractiveness until recent years, given the advance of mainly river and environmental engineering. Following the recent developments in laboratory instrumentation, a number of problems in hydraulic structures can be solved mainly using experimentation, thereby accounting for the flow complexities given by the often spatial and highly turbulent flow structures, combined with multi-phase flow. An outlook into the future of hydraulic structures further reveals the importance of updated hydraulic book series, from which students and practicing engineers profit from the knowledge available among the International Association for Hydro-environment Engineering and Research Committees. As a conclusion, hydraulic structures will play a dominant role in the future, given the enormous but fascinating problems posed by the scarcity and abundance of water on our planet.
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