Investigation of Tidal Phenomena in the Clyde Estuary, using a Scale Model†

Abstract

1. Summary:- The model was built in the James Watt Engineering Laboratories, Glasgow University. The horizontal and vertical scales were 1 in 5280 and 1 in 115 respectively, giving a vertical exaggeration of 46. The time scale was 1 in 493, which gave the period of a 12 hours and 25 minutes tide as 90.3 seconds in the model. The model was non-mobile, the bed being constructed of cement and sand mortar. In order to have conditions at the mouth of the estuary as representative as possible, the deep sea lochs were included. Details for these were obtained from the Admiralty Charts, and the Engineer of the Clyde Navigation Trust granted access to tide curves and recent cross sections of the estuary. Tides, varying in the correct spring-neap cycle, were produced by a displacer, which was given the correct motion by mechanism designed on the principle used by Lord Kelvin in his tide predicting machine. Tide curves were taken at various points on the estuary model by a gauge using reflected light, and the effects of spates and land reclamation-were-investigated. In addition, the following items were studied:- (a) Increase of range of the tide as the tidal wave travels inland. (b) The velocity of the tidal wave. (c) The hump on the front of advancing wave. (d) Some current velocities. (e) The natural period of oscillation of the estuary. (f) Harmonic analysis of the tide curves. (g) Frictional damping of the natural oscillation. (h) The mean level of water in the estuary at various points. (i) Profiles of the surface of the water in the estuary. Wherever possible, comparisons were made throughout with the full scale estuary.