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Source: https://erdc-library.erdc.dren.mil/jspui/ Prototype tests were conducted during 11-14 August 1986 at Taylorsville Dam, Kentucky, to evaluate the performance of the project's selective withdrawal system. Taylorsville Dam is located on the Salt River in north-central Kentucky 50 miles above the confluence with the Ohio River. The existing project consists of a rock-filled dam, uncontrolled spillway, and controlled outlet works. Reservoir releases are regulated by a gated intake tower consisting of two flood-control intakes at the base of the structure and two wet wells with five 6- by 6-ft water-quality intakes in each wet well. All flows pass through two separate 5.5- by 14.75-ft rectangular passages transitioning into a single 11.5- by 14.75-ft oblong conduit. The primary purpose of the prototype measurement program was to obtain prototype information on the performance of the selective withdrawal system. The data are used to determine the reservoir withdrawal zone characteristics, intake tower blending characteristics, the occurrence of density blockage, the degree of mixing of different water qualities, and the amount of dissolved oxygen uptake. Results were also used to compare prototype performance with both physical and numerical model predictions. The basic measurements included dissolved oxygen and temperature profiles in the reservoir, at locations within the outlet works, and at one station in the downstream channel. Two-directional intake velocity profiles were measured for each port and total discharge was measured in the downstream channel. The water-quality data show that the Taylorsville water-quality intake structure can function effectively for release temperature control by selective withdrawal and that the system effectively reaerates flow through the structure. The results also show that the one-dimensional-numerical model SELECT can predict release dissolved oxygen concentration and temperature for Taylorsville. Density blockage of the upper ports due to reservoir density stratification occurs during the multilevel tests at flows less than 100 cfs. The hydraulic measurements revealed basically uniform flow distributions within each intake. The prototype data for submerged orifice flow fall slightly below the physical model data. Discharge coefficients for the total water-quality-system were computed to be less than those determined in the model.

Source: https://erdc-library.erdc.dren.mil/jspui/ The US Army Engineer Waterways Experiment Station was tasked with evaluating the water temperature release capabilities of a proposed hydropower intake structure at Wynoochee Dam near Montesano, WA. The existing dam structure has passageways for juvenile fish migrating downstream and has flexible operation capabilities due to multilevel ports to meet downstream target temperatures. The hydropower developers have proposed a single wet well intake structure with two variable-opening gates. The study objective was to demonstrate the ability of the proposed structure to meet water temperature objectives at least equal to that of the existing structure. All objectives were accomplished by modifying and using the one-dimensional thermal simulation model, WESTEX. After verification of WESTEX to 2 years of historical temperature release data, prediction runs were made using an assumed range of intake loss coefficients and withdrawal angles for 3 years of data. The study concluded that the combination of the existing and proposed structures can meet downstream target temperatures as well as the existing structure alone.

Source: https://erdc-library.erdc.dren.mil/jspui/ Model investigation of the outlet works for Taylorsville Lake was concerned with verification and improvement of the hydraulic design of the intake structure, conduit, and stilling basin. The study was conducted on a 1:25-scale model of the outlet works which reproduced a portion of the approach area, the intake structure, the outlet conduit, the hydraulic-jump type stilling basin, and approximately 120 ft of exit channel. The proposed intake structure provided effective regulation of both flood-control and water-quality releases. Flow and pressure conditions were satisfactory for all expected operating schemes. However, certain extreme operational procedures must be avoided to prevent subatmospheric pressures in the throat section of the water-quality system and flow instabilities in the wet well during selective withdrawal and in the conduit during flood-control flow. Performance of the original design stilling basin was unacceptable as unstable hydraulic action in the basin resulted in poor energy dissipation. Eddy formation throughout the lower range of discharges was a difficult problem to overcome because of the relatively low elevation of the outlet portal invert with respect to the tailwater elevation. A humped trajectory with the central section raised higher than the sides (type 8 basin) diverted more flow to the sidewalls and eliminated eddying. The chute blocks and tapered training walls of the type 8 basin provided stable basin action with good energy dissipation. Single or uneven gate operation produced unbalanced flow in the stilling basin; however, the eddies were not as severe as in the original design. Since single gate operation is rarely necessary and should be avoided, the type 8 basin is considered to be acceptable for prototype construction.