Hydrodynamic Study of Energy Dissipation Blocks on Reduction of Wave Run-up and Wave Reflection

Abstract

Coastal Hazards are physical phenomena that expose a coastal area to risk of property damage, loss of life and environmental degradation. Rapid-onset hazards last over periods of minutes to several days and examples include major cyclones accompanied by high waves and surges or tsunamis created by submarine earthquakes and landslides. Slow-onset hazards develop incrementally over longer time periods and examples include erosion and gradual inundation. A physical process such as wave run-up is very important with regard to the design of sloping coastal structures. To assess the influence of surface roughness elements on a beach for reducing the wave run-up, energy dissipation and extreme wave events. This helps in reducing the inundation by wave flooding during storms and tsunamis. Results of the monochromatic waves on energy dissipation blocks of different configurations show a considerable energy dissipation and corresponding reduction of wave run-up on the beach. Three different of dissipation blocks i.e. Rectangular, Semi Circular and trapezoidal shapes were used in the present experimental study. These dissipation blocks may be submerged or emerged during a tidal cycle. Keeping the dissipation block height constant, water depth was varied to achieve three different relative block heights to simulate the tidal fluctuations in the coastal environment. The experiments are carried out in the wave flume of 45m long, 1.2 m wide and 1.2m deep in the Department of Civil Engineering, Andhra University College of Engineering (A), Visakhapatnam, India. The dissipation blocks with three different spacings of 0.05m, 0.1m and 0.15m was fixed on a sloping flume bed of 1: 35. The water depth can be varied from 0.25 m to 0.80 m.