Physical Model Study of the San Antonio River Lock System

Abstract

The San Antonio River Authority (SARA) initiated a project to extend tour boat navigation approximately 7,000 feet upstream on the San Antonio River. To make this section of the river navigable, a small dam and parallel lock system will be built to transfer vessels between lower pool elevation of 631.2 feet and upper pool elevation of 640.0 ft. The hydraulic locks must transfer tour boats quickly, efficiently, comfortably and safely using available river flow. A physical model study was required to verify and refine the operational suitability of the proposed side-port lock system. The model was constructed and studied at St. Anthony Falls Laboratory. The scope of the study was to build a physical model of one lock and its associated filling and emptying system and to test its operation on a scale model of the design vessel. The model was built at a scale of 1:8 and included a single lock chamber, a side-port gallery to convey water into and out of the lock chamber, and the upstream and downstream sluice gates. Two series of tests were conducted and at least one of the following parameters was modified during each test: The gate opening height, the gate opening duration, the gate opening as a function of time, the lock chamber floor level, and the loading of the vessel. For each test, headwater, tailwater, water surface level in the lock chamber and the opening rate of the sluice gate were recorded. The performance of the lock chamber was determined qualitatively by inspection of the vessel reaction and the flow patterns inside the gallery and the lock chamber. The second and more extensive series of tests were videotaped.