In this paper, the variation characteristics of wave propagation on a slope are studied by model experiments. The experimental data are analysed and compared with the analytical solution to generate the wave height narrow band graph. On this basis, the wave variation law and the intensity of the shallow water effect at different locations on the slope platform are studied for different periods, wave height and high incidence parameters. The results show that the experiments have good repeatability and small errors. The waves propagate and evolve on a 1:3 slope. The effect of shallow water variation is almost negligible at 1/4 length of slope. At 2/5 of the slope length, the shallow water effect gradually starts to appear. At the same time, the period of the wave rising from the trough to the crest becomes shorter and the period of the wave falling from the crest to the trough becomes larger. At slope length 3/4, the wave deformation under the effect of changing shallow water increases sharply, leading to further shortening of the period from the trough to the crest and further increase of the period from the crest to the trough.
A series of complex phenomena such as shallow, refraction, diffraction, reflection, floor friction energy dissipation and breakage occur when waves travel from deep sea to near-shore with the influence of complex terrain, obstacles on the sea bottom. Free surface flow with large wave deformation, run-up and wave breaking is a classical complex problem in ocean engineering. It becomes more complex if the interactive dynamics between the sea bottom and the free surface is required to be considered. Therefore, the physical model test method is still a main tool to investigate the mechanism underlying the wave propagation. Zhang(1989) studied the influence of water depth on wave height on slope, proposed the formation condition of maximum wave height through model test, and gave the corresponding calculation formula. HSIAO(2008) proposed a prediction model of wave height climbing and height by using nonlinear least squares regression based on the experimental study of wave propagation along a gentle slope with a slope of 1:60. Zhu(2017) conducted an experiment on wave climbing on a two-layer slope with a slope of 1:15, studied the influence of wave direction Angle and wave steepness on climbing, and revised the wave height formula with wave depth varying along the path through experimental data results. Liu(2017) obtained high-resolution wave data in time and space through wave flume wave creation experiment using image method, and revealed the mechanism effect of incident waves with different periods on the enhancement and weakening of sub-gravity waves under the effect of shallow water. Peng(2018) conducted an experimental study on the propagation and climbing of solitary waves along a slope platform with a slope of 1:20. Based on the experimental results, he proposed an empirical formula for the climbing of three solitary waves with equal amplitude on a gentle slope. Yao(2018) conducted an experimental study on wave height along a steep slope of 1:6, and proposed an empirical formula for wave height along a steep slope. Wei(2021) pointed out the defects of the standard formula, modified and fitted the calculation formula and applicable scope, and obtained the calculation method of climbing wave height of strong nonlinear regular waves through mathematical model tests and physical model tests on three slopes with different gradients. However, due to the experimental equipment and conditions (such as the length, width and push amplitude of the wave tank), there are still few experimental studies on the shallow water effect of waves on long gentle slope and related wave height measurement. In the real sea, the slope of the continental shelf adjacent to the continental slope is usually less than 7°, so the shallow sea area often presents the characteristics of very flat. The maximum slope to the sea can be more than 20°.The previous studies are mainly focused on relatively gentle slope. In order to more accurately simulate the near-shore deformation effect of waves in the ocean, it is necessary to carry out experimental studies with larger gradients. The slope adopted in this paper is a relatively steep slope with a slope ratio of 1:3.
