Showing papers in "Journal of Hydraulic Engineering in 1973"
TL;DR: In this article, the relationship of sediment transport to fluid flow is considered and predictive equations are derived which relate total sediment flux to measurable properties of flow, and a preliminary comparison is made with observations from other sources, including natural rivers.
Abstract: The relationship of sediment transport to fluid flow is considered. Physical reasoning leads to dimensionless groupings of the variables which are different for coarse sediment and for fine sediment, because of dissimilar modes of transport. This concept provides a basis for a new analysis of data from flume experiments, and a method for dealing with transitional sizes of sediment is suggested. The analysis of experimental data supports the theory put forward and predictive equations are derived which relate total sediment flux to measurable properties of flow. A preliminary comparison is made with observations from other sources, including natural rivers.
932 citations
TL;DR: In this paper, a new criterion based on average flow velocity, fall velocity, and shear velocity Reynolds number is proposed to calculate the dimensionless critical unit stream power in a dimensionless stream power equation for sediment transport, which is the ratio of the time rate of potential energy expenditure per unit weight of water and the terminal fall velocity of sediment.
Abstract: A review of existing literature reveals some disadvantages of using Shields diagram as the criterion for incipient motion of sediment particles on an alluvial bed. A new criterion based on average flow velocity, fall velocity, and shear velocity Reynolds number is proposed herein with the supporting data collected by different investigators. This new criterion is used to calculate the dimensionless critical unit stream power in a dimensionless unit stream power equation for sediment transport. The dimensionless unit stream power is the ratio of the time rate of potential energy expenditure per unit weight of water and the terminal fall velocity of the sediment. More than 1,000 sets of data from both laboratory flumes and natural streams published by different authors are used to support this dimensionless equation for sediment transport.
580 citations
TL;DR: In this paper, a Galerkin-type finite element method is employed to solve the quasilinear partial differential equations of transient seepage in saturated-unsaturated porous media.
Abstract: A Galerkin-type finite element method is employed to solve the quasilinear partial differential equations of transient seepage in saturated-unsaturated porous media. The resulting computer program is capable of handling nonuniform flow regions having complex boundaries and arbitrary degrees of local anisotropy. Flow can take place in a vertical plane, in a horizontal plane, or in a three-dimensional system with radial symmetry. An arbitrary number of seepage faces can be considered simultaneously, and the positions of the exit points on these boundaries are adjusted automatically during each time step. Two examples, one of seepage through an earth dam with a sloping core and horizontal drainage blanket, and the other of seepage through a layered medium cut by a complex topography, are included. These examples indicate that the classical concept of a free surface is not always applicable when dealing with transient seepage through soils.
429 citations
TL;DR: In this article, a logarithmic flow formula for open channels is valid for flow over a roughness cover made up of flexible plastic strips, and three regimes of boundary behavior are observed for flexible plastic roughness, leading to two resistance functions.
Abstract: The logarithmic flow formula for open channels is valid for flow over a roughness cover made up of flexible plastic strips. The deflection of such roughness is an important parameter as the deflection directly influences the relative roughness. Dimensionless parameters which relate the amount of bending to the stiffness of the roughness and the boundary shear are defined. Three regimes of boundary behavior are observed for flexible plastic roughness, leading to two resistance functions. The flexible plastic roughness is produced by affixing thin plastic strips of various thickness to the bed of a flume. The flow of water over flexible plastic strips simulates flow over a vegetative channel lining.
301 citations
TL;DR: In this paper, a mathematical model to estimate the resistance of flow due to various groupings of tall vegetations (such as trees on flood plains) on the order of flow depth is given.
Abstract: A mathematical model to estimate the resistance of flow due to various groupings of tall vegetations (such as trees on flood plains) on the order of flow depth is given. The relative effect of various groupings of tall vegetation on the reduction of sediment yields based on reduction of flow rates is studied. This should be rather useful in determining the relative effect on flow rates and sediment yields by clear cutting and other selective cutting of forest timber.
216 citations
TL;DR: The behavior of turbulent buoyant jets in uniform density environments is found to be governed by an entrainment function and buoyancy function, both of which are functions of the local jet densimetric Froude number as mentioned in this paper.
Abstract: The behavior of turbulent buoyant jets in uniform density environments is found to be governed by an entrainment function and buoyancy function, both of which are functions of the local jet densimetric Froude number and the local jet spreading angle. For plumes, Batchelor's analysis is used to show that the local Froude number and jet angle are constant. These two facts are then used to show that the buoyancy and entrainment functions in plumes are also constant and that their values can be deduced from an experimental velocity profile alone. Experimental results are also used to show that the axisymmetric buoyant jet is virtually independent of elevation and this result leads to the conclusion that the entrainment function is linearly dependent on the inverse of the local jet Froude number, thus confirming the result obtained by Priestly and Ball (1955). The buoyancy function is found to be constant with the value 1.16 for axisymmetric buoyant jets.
125 citations
TL;DR: Based on linearized Navier-Stokes equations and Darcy's equations, the viscous damping of small amplitude surface waves over a permeable bed is reexamined in this paper.
Abstract: Based on linearized Navier-Stokes equations and Darcy’s equations, the viscous damping of small amplitude surface waves over a permeable bed is reexamined. Boundary layer approximation is employed in order to solve the velocity field and pressure field. Demanding that the net dissipation per period must be balanced by the slow decay of wave energy, the damping rate is found. The shortcomings of previous works are examined and are improved. Theory agrees fairly well with the experimental results.
106 citations
TL;DR: In this article, the authors established the variation of friction factor for different flows and rainfall conditions by statistical analysis and found that the friction factor is a function of both the flow Reynolds number, R, and the rainfall intensity.
Abstract: The variation of friction factor for different flows and rainfall conditions is established by statistical analysis. Boundary shear stress was directly measured by hot-film anemometry. The friction factor is found to be a function of both the flow Reynolds number, R , and the rainfall intensity, I , for a flow Reynolds number of less than 900. For a flow Reynolds number greater than 2,000, the friction factor is only a function of Reynolds number. A numerical model and a simplified procedure to predict the water surface profiles and boundary shear stresses for sheet flow with rainfall are presented. The computations of flow depths and boundary shear stresses are not too sensitive to the effect of uncertainties in selecting friction factor.
94 citations
TL;DR: In this article, a least-cost method for designing water distribution systems is presented, in which the cost of the system is to be minimized subject to equality and inequality constraints, and the inequality constraints are eliminated by a transformation of Box, from which Haarhoff and Buys' method for equality constraints is used to solve the remaining part of the problem.
Abstract: A least-cost method for designing water distribution systems is presented. Basically, the behavior of a network obeys two physical laws: (1) the conservation of headloss around any loop; and (2) the continuity of fluid flow at any pipe junction. From these physical laws and from the performance criteria that the pressures at the delivery points of the network must be above a specified level, a nonlinear programming problem is formulated, in which the cost of the system is to be minimized subject to equality and inequality constraints. Because of their simplicity, the inequality constraints are eliminated by a transformation of Box, from which Haarhoff and Buys' method for equality constraints is used to solve the remaining part of the problem. The method of solution is so coded that it is capable of handling existing or predetermined design components. Various sensitivity analyses are made on a model network, yielding results which can be useful to complex systems.
70 citations
TL;DR: In this paper, a mathematical model is presented for the prediction of the flood wave resulting from the instantaneous break of a dam in a prismatic, dry channel of general parabolic cross section.
Abstract: A mathematical model is presented for the prediction of the flood wave resulting from the instantaneous break of a dam in a prismatic, dry channel of general parabolic cross section. It consists of the numerical integration of the characteristic equations over the irregular grid formed by the characteristic lines using a predictor-corrector scheme. The solution is advanced towards the wave front by a gradual refinement of the characteristics net for reasons of accuracy and economy. Finally, the solution is extended over a short region to the wave tip, which is characterized by zero depth, using a simplified form of the momentum equation resulting from physical considerations in the wave-tip region. Computed results are compared with experimental and theoretical results obtained by others. Corroboration with experimental results is generally good. The solution can be advanced in time until the negative wave propagating into the still water reaches the upstream end of the reservoir.
68 citations
TL;DR: In this paper, a method is developed to determine the optimal design of any system of reservoirs with series and parallel connections, where the original problem is decomposed by successive approximations into a series of subproblems in such a way that the sequence of optimizations over the sub-problems converges back to the original one.
Abstract: A method is developed to determine the optimal design of any system of reservoirs with series and parallel connections. The original problem is decomposed by successive approximations into a series of subproblems in such a way that the sequence of optimizations over the subproblems converges back to the original one. The optimal design is obtained by maximizing the net benefits. Incremental dynamic programming is used to find the optimal operating policy. The theories developed are applied to a real system, i.e., the Eel River Ultimate Project in northern California.
TL;DR: In this article, the loss coefficients and the power-loss coefficients for four smooth tees with diameter ratio of unity were determined experimentally for each configuration of flow through tees, and the results showed that the proposed formulas can be used to reliably estimate the energy losses at tees.
Abstract: The loss coefficients and the power-loss coefficients for four smooth tees with diameter ratio of unity were determined experimentally for each of all configurations of flow through tees. Throughout the test the Reynolds number before the division or after the combination of flow was within the range of 10\u5–2x10\u5. The radius of curvature of the wall at the joining edge ranged from zero up to half the diameter of the straight pipe. Empirical formulas for loss coefficients and those for power-loss coefficients which are in good agreement with experiments were presented for each configuration of flow. Empirical formulas for loss coefficients for dead end tees were also given. The comparison of the proposed formulas with the experimental results of the previous investigations showed that the proposed formulas can be used to reliably estimate the energy losses at tees.
TL;DR: The concept of hydraulic radius of pore space is used to substantiate that the square root of the permeability is the important length parameter in defining the friction factor and Reynolds number in flow through porous media as discussed by the authors.
Abstract: The concept of hydraulic radius of pore space is used to substantiate that the square root of the permeability is the important length parameter in defining the friction factor and Reynolds number in flow through porous media. Hydraulic radius was defined by applying the Kozeny-Carman theory of hydraulic radius of pore space. It was found that various porous media had different relationships between friction factor and Reynolds number. Experimental results showed a similarity to the Moody diagram used for pipe flow, with a ratio of particle mean diameter to the mean hydraulic radius of pore spaces as the third parameter.
TL;DR: In this paper, the longitudinal spreading of tracer solution and the distribution of velocity were investigated experimentally in a laboratory flume having a series of 13 uniform bends in alternating directions.
Abstract: The longitudinal spreading of tracer solution and the distribution of velocity are investigated experimentally in a laboratory flume having a series of 13 uniform bends in alternating directions. Viewing the tracer cloud as a whole, the dispersion process behaves like a one-dimensional diffusion process, as in a straight channel. The dispersion coefficient is larger, and the initial convective period is shorter than in an equivalent straight channel. From the perspective of a single cross section, however, the process is periodic. The convective dispersion coefficient attains a maximum at about the middle of each bend, a minimum between bends, and lags the mean square velocity deviation by about a quarter of a bend. Analysis of the flume data together with available river data indicates that the dispersion coefficient tends to increase with increasing radius of curvature, and decrease with increasing bend length and depth.
TL;DR: In this article, the Lax-Wendroff scheme with Burstein-Lapidus modifications is combined with a quasilinear partial differential equation for two velocity components and a flow depth at any point on the watershed.
Abstract: Unsteady surface flow over watersheds is modeled hydrodynamically by a system of quasilinear partial differential equations for two velocity components and a flow depth at any point on the watershed. Computer solution is made possible by a new difference scheme based on the combination of the Lax-Wendroff scheme with Burstein-Lapidus modifications. A numerical example is given for the solution of watershed flow resulting from a uniform rainfall intensity and finite duration and its result is tested experimentally in the University of Illinois Watershed Experimentation System Laboratory. Preliminary results indicate that the proposed two-dimensional hydrodynamic model is suitable for the study of the watershed flow under consideration.
TL;DR: In this article, Wang et al. determined division lines having zero shear stress so that they need not be included in the wetted perimeter for flow computation in flood plain channels.
Abstract: For flow computation in flood plain channels, the flow cross section is usually divided into subsections to ensure hydraulic homogeneity. However, the question of whether or not to include the division lines as part of the wetted perimeter still remains unanswered. In this study, efforts have been made to determine division lines having zero shear stress so that they need not be included in the wetted perimeter. Laminar flow cases were solved to gain qualitative insight into the shape effects on resistance and location of division lines. For turbulent flows, division lines were determined from velocity distribution patterns; and resistance coefficients for both laminar and turbulent flows are lower than those in wide rectangular channels having the same boundary materials. New formulas are proposed for computation of discharge in both main-channel and flood-plain portions.
TL;DR: In this article, the authors considered physical limits for thunderstorm rainfall and runoff in the southwest and suggested some upper limits for peak discharges for different sized Walnut Gulch watersheds, and the variances of the individual predictions were estimated through least squares fitting of the sample data.
Abstract: Air-mass thunderstorm rainfall produces the major floods on small [100 sq mile (259 km² or less)] rangeland watersheds in the southwest. The intense central volume of thunderstorm rainfall, referred to as the core of runoff-producing rainfall, is correlated to peak discharge. The core was represented by the maximum 30-min. depth of rainfall at each gage as estimated from a dense rain gage network on the ARS Walnut Gulch Experimental Watershed. Physical limits are considered for thunderstorm rainfall and runoff in the southwest. These limits are important because of the scarcity of records and the uncertainties involved in extrapolating short records to longer recurrence intervals. Some upper limits for peak discharges are suggested for different sized Walnut Gulch watersheds, and the variances of the individual predictions are estimated through least squares fitting of the sample data.
TL;DR: In this article, the correlation between the minimum length of salt intrusion and tidal quantities was found. But the correlation was not analyzed in terms of the density difference between seawater and freshwater.
Abstract: Experiments on salt intrusion from a sea basin into a rectangular flume are described. Boundary conditions such as seawater density, tidal amplitude, and hydraulic resistance, have been varied. Minimum and maximum lengths of salt intrusion during a tidal cycle as functions of the varied quantities are presented. Dimensional analysis is applied to find correlations between the minimum length of salt intrusion and tidal quantities. Results indicate a relation between a nondimensional parameter containing the minimum length of salt intrusion, the depth and resistance coefficient, and three nondimensional parameters characterizing the tidal movement and containing the density difference between seawater and freshwater.
TL;DR: In this article, a practical procedure for determining wind-induced drift currents near the free surface, at all fetches, from a single wind-velocity measurement is outlined, where the wind stress is scaled according to the Froude number and the momentum flux of the wind is considered to be partitioned between the wave drag and the current.
Abstract: A practical procedure is outlined for determining wind-induced drift currents near the free surface, at all fetches, from a single wind-velocity measurement. The wind stress is scaled according to the Froude number and the momentum flux of the wind is considered to be partitioned between the wave drag and the momentum flux of the current. Some coefficients involved in the procedure are derived from the available data; further studies are suggested to refine the present estimation.
TL;DR: UNIT-RESPONSE FLOW ROUTING is a TECHNIQUE of open-channel FLOW-Routing Base on the UNIT HYDROGRAPH PRINCIPLE OF LAGGING and SUPERPOSITION as mentioned in this paper.
Abstract: UNIT-RESPONSE FLOW ROUTING IS A TECHNIQUE OF OPEN- CHANNEL FLOW ROUTING BASE ON THE UNIT HYDROGRAPH PRINCIPLE OF LAGGING AND SUPERPOSITION. THE UNIT RESPONSE IS DEFININED AS THE FLOW HYDROGRAPH AT A DOWNSTREAM LOCATION RESULTING FROM A CONSTANT INFLOW OF 1 CFS DURING A SELECTED DURATION PERIOD, D, AT AN UPSTREAM LOCATION. IT CAN BE DERIVED FROM ACTUAL RECORDS, BUT FOR GENERAL APPLICATION IT IS DERIVED SYNTHETICALLY BY ROUTING A TRANSLATION HYDROGRAPH THROUGH RESERVOIR STORAGE TO OBTAIN AN INSTANTANEOUS UNIT RESPONSE, AND TRANSFORMING THIS RESPONSE TO THE SELECTED D-HOUR UNIT RESPONSE. LAG, OR TRANSLATION TIME, IS USED TO ACCOUNT FOR FLOOD-WAVE TRAVEL TIME IN THE CHANNEL. THIS CAN BE VARIED WITH DEPTH. ROUTING INTERVALS OF FROM 1 HR TO 24 HR AND ROUTING REACHES FROM 10 MILES TO 150 MILES HAVE BEEN USED SUCCESSFULLY.
TL;DR: In this paper, cavitation data are presented for circular sharp-edged orifices which identify incipient, critical, moderate, heavy, and choking cavitation, and an accelerometer is used to evaluate incipient and critical limits.
Abstract: Cavitation data are presented for circular sharp-edged orifices which identify incipient, critical, moderate, heavy, and choking cavitation. The experimental program included pipe sizes from 1 to 23.5 in. (25 to 597 mm), pressures from 20 to 200 psi (140 to 1,400 kn/m²), and orifice size ratios from β = 0.332 to 0.884. Incipient and critical cavitation are affected by pipe size but are independent of pressure and velocity. Choking cavitation is independent of pressure, velocity, and size. An accelerometer was used to evaluate incipient and critical limits. Moderate and heavy cavitation regions were selected by aural observations. Choking flow was identified as the flow condition where the discharge coefficient began to rapidly decrease.
TL;DR: In this paper, a procedure for computing water surface profiles and discharge in an open channel with flow over side weirs is presented, with little restriction about the channel shape, variation of invert slope, convergence of the channel along the length of weir, etc.
Abstract: A procedure is presented for computing water surface profiles and discharge in an open channel with flow over side weirs. There is little restriction about the channel shape, variation of invert slope, convergence of the channel along the length of weir, etc. A criterion for determining whether flow will be subcritical or supercritical on a mild slope is also developed. The procedure is illustrated by some examples. Some deficiencies in available knowledge are noted.
TL;DR: In this paper, five field tests were made on transverse mixing in rivers and the transverse turbulent diffusion coefficient, averaged over long flow distances, was as much as three times larger than the value for an equivalent straight rectangular flume.
Abstract: Five tests were made on transverse mixing in rivers. The transverse turbulent diffusion coefficient, averaged over long flow distances, was as much as three times larger than the value for an equivalent straight rectangular flume. This increase is due to the additional mixing associated with the protective groins which were present and with the helical motion resulting from channel bends. Net transverse velocities exist in rivers and can cause the local rates of transverse spreading to be significantly different from the rate associated with the average diffusion coefficient. Recommendations are given for conditions to be met in order to obtain meaningful data from field tests on rates of transverse diffusion in rivers.
TL;DR: In this article, a finite element analysis of the two dimensional flow of an ideal fluid which emerges as a free surface jet from a containing vessel of arbitrary shape is studied, and a rational analytical algorithm for adjusting free surface coordinates is provided.
Abstract: The two dimensional flow of an ideal fluid which emerges as a free surface jet from a containing vessel of arbitrary shape is studied. The finite element analysis of this problem seeks an approximate solution for the minimization of a functional which describes this problem. Gravity effects and curvilinear, solid boundary walls are easily taken into account. The method provides a rational analytical algorithm for adjusting free surface coordinates. The iterative technique used in conjunction with the algorithm requires the solution of a linear, symmetric, banded equation system during each iteration, which is quickly done by Gaussian elimination. Results include not only free surface profiles but also velocity and pressure distributions throughout the flow domain. Computational examples are given which required 10-20 iterations and used 3 to 8 min of execution time on the IBM 7044 computer.
TL;DR: In this paper, a new model for the prediction of the wall shear stress as a function of velocity and acceleration changes is introduced for one-dimensional flow analysis under nonsteady conditions.
Abstract: Measured data of velocity changes in oscillatory flows (0.16Hz-0.36Hz) are presented. The actual wall shear stresses obtained from the measurements are compared to calculated values based on steady flow relations and Zielke's model. A new model for the prediction of the wall shear stress as function of velocity and acceleration changes is introduced. The proposed model may be a suitable basis for the prediction of friction data for one-dimensional flow analysis under nonsteady conditions.
TL;DR: The solution of multidimensional sequencing problems encountered in the planning of capacity expansion in large-scale water resources systems by an especially efficient dynamic programming algorithm is presented.
Abstract: The solution of multidimensional sequencing problems encountered in the planning of capacity expansion in large-scale water resources systems by an especially efficient dynamic programming algorithm is presented. The dynamic programming algorithm results couples on the optimality of permutation schedules with the imbedded state space concept in order to effect a drastic reduction of dimensionality making it possible to efficiently solve problems of the dimension encountered in real-world water resource systems. Computational experience with the imbedded state space dynamic programming algorithm on the solution of a number of two- and three-dimensional sequencing problems from several real-world water resources systems is reported. Furthermore, the results of a sensitivity analysis on these data are also presented.
TL;DR: In this paper, the authors show that cold region rivers and canals covered with ice have ripple-like reliefs on the ice underside causing head losses considerably in excess of those of smooth boundaries.
Abstract: Cold region rivers and canals covered with ice have been found to develop ripple-like reliefs on the ice underside causing head losses considerably in excess of those of smooth boundaries. Observations showed that ice thickness near the banks was several times that of the conveying part of the waterway. It is postulated that these features are caused by heat transferred from the bottom of the waterway. Note that observed ratios of wave height to wave length of the ripples do not exceed approximately 0.12. This is the approximate upper limit of wave index number of separation free flow over sinusoidal waviness. Some measured values of ice roughness coefficient (Mannings n) are given. A graph presenting a dimensionless solution for composite roughness coefficient as a function of ice underside and channel bed coefficients is included.
TL;DR: In this paper, a transient mathematical model which couples the conservation of heat and mass equations is developed and solved numerically, and the results of the predictive model are compared to laboratory measurements of a conservative dye tracer and to field measurements of dissolved oxygen in the Fontana Reservoir during 1 yr of operation.
Abstract: A transient mathematical model which couples the conservation of heat and mass equations is developed and solved numerically. Vertical temperature and concentration profiles within the reservoir and outlet temperature and concentrations for conservative and nonconservative substances are obtained. The results of the predictive model are compared to laboratory measurements of a conservative dye tracer and to field measurements of dissolved oxygen in the Fontana Reservoir during 1 yr of operation. Good results for the laboratory conditions are obtained. Direct comparison with field measurements is limited by the lack of field data on biochemical oxygen demand. However, the trends shown for dissolved oxygen as a function of time are satisfactorily reproduced.
TL;DR: A quantitative methodology, utilizing Kalman filtering techniques, is developed for designing water quality monitoring systems, and a best sampling program is selected from a set of feasible sampling programs by sequentially minimizing a specified measurement system cost function.
Abstract: A quantitative methodology, utilizing Kalman filtering techniques, is developed for designing water quality monitoring systems. The basis is established for: (1) improvement of current practices of specification and enforcement of water quality standards; and (2) evaluating the economic trade-off between temporal and spatial frequency of sampling. Monitoring systems are characterized by spatial and temporal frequency of sampling and the variables to be measured. Utilizing a dynamic model of the aquatic environment and estimates of the uncertainty in model error and measurement error, a best sampling program is selected from a set of feasible sampling programs by sequentially minimizing a specified measurement system cost function. An optimal solution is not guaranteed. The power of the technique is based on the unique combination of model and data obtained from filtering techniques. The major shortcomings are: (1) the need for a model of the systems and (2) high computer costs.
TL;DR: In this article, a mathematical model is presented to simulate the BED MATERIAL SORTING in a alluvial network, and it is shown that the SORTing COEFFICIENT DEPENDS on the CHANNEL SLOPE, REGIME OF FLOW, and total BEDMATERIAL TRANSPORT.
Abstract: THE BED MATERIAL SIZE IN ALLUVIAL CHANNELS REDUCES WITH DISTANCE. THIS SIZE REDUCTION IS CAUSED BY THE PHYSICAL SIZE ATTRITION OF PARTICLES, CALLED ABRASION, ANY BY THE DIFFERENTIAL TRANSPORT OF SIZES, CALLED SORTING. A MATHEMATICAL MODEL IS PRESENTED TO SIMULATE THE BED MATERIAL SORTING IN A ALLUVIAL CHANNELS. APPLICATION OF THIS MODEL TO HYPOTHETICAL CHANNELS SHOWS THAT THE SORTING COEFFICIENT DEPENDS ON THE CHANNEL SLOPE, REGIME OF FLOW, AND TOTAL BED MATERIAL TRANSPORT. ALSO, IT IS SHOWN THAT IN CHANNELS FORMED BY AGGRADATION OF MATERIAL TRANSPORTED FROM UPSTREAM, STRICT EQUILIBRIUM IS NOT POSSIBLE IN THE ABSENCE OF ABRASION. /ASCE/