Journal of Hydraulic Engineering

Adsorption often dictates the fate of trace inorganic pollutants in aquatic systems. In contrast to the nonspecific sorption mechanism proposed for hydrophobic organic compounds, adsorption of inorganic solutes is viewed as a site‐specific process in which ions bind (chemically) at functional groups on particle surfaces. This conceptual model is supported by the finding that adsorption of ions on model adsorbents with relatively well‐defined surface groups (e.g., hydrous metal oxides) can be described via mass law equations, a fact which forms the basis for all of the so‐called surface complexation models. Surface complexation reactions are distinguished from reactions among monomelic solutes in that the total energy of interaction includes long‐range electrostatic effects that vary with surface charge. Electrostatic effects are accounted for by applying a coulombic correction factor (activity coefficient) to intrinsic surface complexation constants. Formulations for the coulombic correction term differ among the various surface complexation models. These models can be used to predict inorganic ion adsorption on hydrous oxides for changing solution conditions on the basis of fewer data than needed with a purely empirical approach.

A design procedure for overflow spillway crests, which is applicable to a wide range of approach depths, upstream slopes, and heads on the crest, is developed. An earlier crest design procedure is used to proportion a series of models covering a wide range of design conditions. Discharge coefficients, crest pressures, and water surface profiles are determined for each model, both with and without piers on the crest. Results are presented in graph or tabular form. Using these results a design procedure is suggested and further design aids developed.

The lateral outflow mechanism of side weirs is investigated using a one‐dimensional approach. In particular, the effects of flow depth, approaching velocity, lateral outflow direction and side weir channel shape are included, resulting in expressions for the lateral outflow angle and the lateral discharge intensity. For vanishing channel velocity, the conventional weir formula for plane flow conditions is reproduced. However, for increasing local Froude number, the lateral outflow intensity decreases under otherwise fixed flow parameters. A comparison of the theoretically determined solution with observations indicates a fair agreement. The results are then applied to open channel bifurcations by considering a side‐weir of zero weir height. Distinction between sub‐ and supercritical flow conditions is made. Again, the computed results compare well with the observations and allow a simple prediction of all pertinent flow characteristics.

Hydraulic model studies were conducted to develop a fish screening system to be used in the turbine intakes of Wanapum Development and Priest Rapids Development on the Columbia River, Washington. The system studied utilized a mechanical screen, installed through one of the gate wells, to produce a flow pattern that would deflect downstream migrating juvenile fish into the gate well for subsequent removal by a collection system.

A summary is given of the design, installation and performance of a system of submerged vanes (“Iowa Vanes”) for erosion protection in a bend of East Nishnabotna River, Iowa. The system functions by eliminating, or reducing, the centrifugally induced helical motion of the flow (the root cause of bank undermining). The system was installed during the summer of 1985. Its performance was evaluated with data obtained in surveys in the spring of 1986. The system was found to effectively reduce velocity and scour along the bank without changing the energy slope of the channel. Areas of design improvements were identified. The summary includes a brief description of the theoretical and experimental background for the design.