Journal of Hydraulic Engineering

A methodology is presented which enables estimation of the advective transport probabilities from a coastal wastewater discharge based on information that can be obtained from current measurements. From these, shoreline impact can be assessed, and the tendency for background buildup and benthic accumulation estimated. The method utilizes measured data to obtain parameter values to allow synthetic currents to be generated that can in turn be used in a Monte Carlo scheme for obtaining the advective transport probabilities. The method permits enhancement and improvement of the estimates when the amount and extent of data coverage are expanded.

Computational methods for the solution of two‐dimensional shallow‐water equations in steady, supercritical flow are presented. The limitations of these equations and criteria regarding their applicability to the solution of supercritical flows are discussed. Two explicit, shockcapturing, finite‐difference schemes—Lax and MacCormack—are investigated. The boundary conditions along walls require careful attention for a successful implementation of these schemes. Comparison of the numerical and analytical solutions indicate that, with proper treatment of the boundaries, very good agreement can be obtained. Comparison of numerical and experimental results shows that the assumption of hydrostatic pressure distribution imposes restrictions on the utility of the shallow‐water equations to represent the steady, supercritical flow. However, it appears that the basic features of many practical problems may be simulated using the procedures presented herein.

This paper describes the design, construction, and performance of a cut‐and‐cover diversion conduit, which required applying some unconventional design concepts. The reasons for selecting a cut‐and‐cover conduit instead of a tunnel are also presented. The hydrological, hydraulic, and structural criteria for design of the conduit are explained, and the construction of the conduit and the problems that occurred during river diversion are also described. Finally, performance of the structure and its conformity to the design assumptions are analyzed.

Previous analytical studies on potential flows past spillway flip buckets have almost always been done based on the essential assumption that gravity effects on the bucket flows can be neglected. This limits their applications only to flows with very large Froude numbers past very high dams. The Riemann‐Hilbert mixed‐boundary value problem technique is employed herein to solve the gravity‐affected potential flows through curvilinear and straight segmental flip buckets. Pressure distributions along the flip buckets and exit angles of the deflecting jet are computed by solving the resulting integral equations. Experimental data on pressure distributions along the bucket have been compared with this theoretical analysis, and it is shown that the agreement is satisfactory. This is a great improvement over the previous solutions in the absence of gravity.

A theoretical model for division of flow in a short branch channel set at right angles to a main channel is presented for various width ratios of the branch channel to the main channel. The model is developed using the principles of momentum, energy, and continuity and is based on the existence of free flow conditions in the branch channel. The analysis makes use of the similarity of flow configuration between the division of flow in a branch channel and in a twodimensional lateral conduit outlet fitted with a barrier. This similarity of flow is used to estimate the contraction coefficient of the converging jet entering the branch channel. The ratio of the branch channel flow to the main channel flow is related to the Froude number in the main channel section downstream of the junction. Data from present experimental studies and those from earlier investigations are presented to validate the theoretical model.

Open channels carrying supercritical flow may have changes in cross section or alignment. Where the geometric transition causes a channel wall to deflect into the tangent of the approaching streamlines, a positive standing oblique wave is generated. While such waves are not simple hydraulic jumps, their fundamental basis is the same as that of jumps and their physical aspect is similar. Under certain conditions, an oblique wave may choke discharge and the flow regime must reestablish itself in the subcritical state. From mass, velocity, and momentum balances and differentiation, an explicit expression is determined for the limiting channel-wall deflection at which choked flow must occur. It is seen that while rules of thumb for choke angle may be reasonable for many applications, the analytic value varies significantly with Froude number and criteria of wave stability.