Hydrodynamic studies on vertical wall, low-crested rubble mound and semi-circular barrier system

Abstract

Coastal problems related to erosion and flooding are the outcome of the dominant wave climate in the area, in combination with currents, tides and storm surges. Further, an increasing hazard to the coastline is the development which alters the coast through the construction of buildings and infrastructures, and in so doing, interrupts the natural sediment deposition processes and wave regime. Additionally, the global climate change is causing a rise in sea-level and intensified storminess, which is yet another factor in beach erosion and flooding. Aftermath effects of recent devastating Tsunami on Indian coast alarmed the coastal engineers renew their designs for coastal management and protection systems. The creation of various coastal defence structures which protect coastlines through the reduction of the afore-mentioned problems is thus extremely important; an importance which has significantly increased during the last few decades along with amplified pressure on the coastal zone. The most commonly used coastal engineering tool is the seawall. Today, vertical walls (seawalls) armor much of the developed shoreline. Many have done their job admirably, protecting important establishments such as heavy industries, power plants, national highways, habitations etc., that otherwise could have probably tumbled in to the sea. More importantly, the beaches would become narrow and eventually be eliminated. Essentially, a seawall acts as a layer between the vulnerable coastline and the ocean. Extreme wave action is supported by the seawall without eroding the coast, although the seawall itself will eventually break down and requires repair or replacement. These walls also help to insulate communities from flooding, although high waves can still breach most seawalls. Low-crested structures such as submerged breakwaters or artificial reefs present advantages compared to other types of coastal structures due to their low height and permeable nature. Firstly, due to the low freeboard.