Sea Erosion 13/06/2019 – Posted in: Daily News
SEA EROSION
For: Mains
Topic covers: Coastal Erosion, –
News Flash
A major portion of the beach between Someshwara Rudrapade and Uchila looked as if it had been washed away.
Hundreds of people living in the coastal Kerala at Aliyarpalli, Marakkadavu, Murinjazhi, Puthuponnani, Azhikkal, Veliyankode, Thannithura, Palappetty and Kappirikkad evacuated their houses following the threat of sea erosion.
Coastal Erosion
Coastal erosion (or shoreline retreat) is the loss of coastal lands due to the net removal of sediments or bedrock from the shoreline.
Coastal erosion can be either a:
- rapid-onset hazard (occurs very quickly, a period of days to weeks)
- slow-onset hazard (occurring over many years, or decades to centuries).
Causes
- The loss or displacement of land along the coastline due to the action of waves, currents, tides, wind-driven water, waterborne ice, or other impacts of storms.
- Other cause may be rain. Heavy rainfall can enhance the saturation of soils, with high saturation leading to a reduction in the soil’s shear strength, and a corresponding increase in the chance of slope failure (landslides).
- On non-rocky coasts, coastal erosion results in rock formations in areas where the coastline contains rock layers or fracture zones with varying resistance to erosion. Softer areas become eroded much faster than harder ones, which typically result in landforms such as tunnels, bridges, columns, and pillars. Over time the coast generally evens out.
Control Methods
- Hard-erosion controls
Hard-erosion control methods provide a more permanent solution than soft-erosion control methods. Seawalls and groynes serve as semi-permanent infrastructure. These structures are not immune from normal wear-and-tear and will have to be refurbished or rebuilt. It is estimated the average life span of a seawall is 50–100 years and the average for a groyne is 30–40 years. Because of their relative permanence, it is assumed that these structures can be a final solution to erosion.
2. Soft-erosion controls
Soft erosion strategies refer to temporary options of slowing the effects of erosion. These options, including Sandbag and beach nourishment, are not intended to be long term solutions or permanent solutions.
Another method, beach scraping or beach bulldozing allows for the creation of an artificial dune in front of a building or as means of preserving a building foundation.
3. Relocation
Relocation of infrastructure any housing farther away from the coast is also called managed retreat. The natural processes of both absolute and relative sea level rise and erosion are considered in rebuilding.
Source: The Hindu
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