India lost One-Third of its Coastline Due to Soil Erosion

• 16 Aug 2018

A staggering one-third of almost the entire Indian coastline was lost due to soil erosion in the last 26 years as per the report of the National Centre for Coastal Research(Ministry of Earth Sciences) titled National Assessment of Shoreline Changes along the Indian coast.

• India has a total coastline of 7,517 kilometres. Of this, 6,031 kilometres were surveyed (excluding creeks) and 33 percent of it was found to be eroded.
• The erosion was more on the eastern coast beside the Bay of Bengal rather than on the Western coast beside the calmer Arabian Sea.
• According to the report, West Bengal (63%) and Puducherry (57%) are most vulnerable to erosion, followed by Kerala and Tamil Nadu at 45% and 41%, respectively.
• Odisha on the eastern coast is the only state where the coast witnessed an expansion of more than 50%.
• Moreover, 29 percent of the coastline also saw a gain in soil or land accretion.
• The survey used data from five satellites - Landsat 5 and 7 (operated by NASA), ISRO's Resourcesat 1 and 2 and Cartosat-1.

Factors and Causes of Soil Erosion due to Water

• Human Induced factors: Faulty farming systems, deforestation caused by overgrazing, clearance of land for agricultural purpose and construction, dam construction and diversion of the natural course of rivers, and mining activities weaken the topmost layer of the crust directly or indirectly, thus making it vulnerable to excessive wearing away by various agents of erosion.
• Rainfall Intensity and Runoff: The impact of raindrops will break up the soil and water build-up will create runoff, taking sediment with it.
• Soil Erodability: Based on the characteristics of each unique soil, it is more or less susceptible to erosion. Recurring erosion is more typical for soil in areas that have experienced erosion in the past.
• Slope Gradient and Length: The steeper the slope, the greater amount of soil can be lost. As the soil erodes downward, it increases the slope degree, which in turn, creates further erosion.
• Vegetation: Vegetative cover of plants or crop residues protect the soil from raindrop impact and splash. The less vegetation cover, the more erosion can occur.

Coastline of India

• Length of the coastline of India including the coastlines of Andaman and Nicobar Islands in the Bay of Bengal and Lakshadweep Islands in the Arabian Sea is 7517 km.
• Length of Coastline of Indian mainland is 6100 km which is surrounded by the Arabian Sea in the west, Bay of Bengal in the east, and the Indian Ocean in the south.
• The long coastline of India is dotted with several major ports such as Kandla, Mumbai, Navasheva, Mangalore, Cochin, Chennai, Tuticorin, Vishakapatnam, and Paradip.

Why did the Eastern coast see more erosion than the Western coast?

• The eastern coast of India saw more soil erosion than the western coast as the Bay of Bengal sees rougher waters than the Arabian Sea.
• The eastern coast sees a lot of rain which keeps the seas rough through most of the year.
• Besides the Southwest Monsoon (June to September), the eastern coast also witnesses the Northeast Monsoon from October to December and brings rain to coastal Andhra Pradesh and Tamil Nadu.
• The eastern coast underwent more erosion due to frequent cyclonic activities from Bay of Bengal in past three decades, compared to the western coast, which remained largely stable.

Difference between Soil Erosion and Land Accretion

• “Erosion and accretion are complementary to each other. If the sand and sediments have drifted from one side, it must accumulate somewhere else”.
• Soil erosion is the loss of land and human habitation as sea water washes off regions of soil along the coastline.
• Soil accretion, on the other hand, results in an increase in the land area.
• However, if accretion happens in deltas, estuaries, and creeks, the soil will block the inflow of seawater into these areas which are breeding ground for several species of aquatic flora and fauna.