Coastal Hazards along West Coast of India in Gujarat State and Mitigation Measures

Storm surges, where ocean water is pushed and thrown onto the coast generating 5 to 10 meters high waves that causes severe damages. Different factors affecting the coastal areas are coastal erosion caused by storm waves and coastal inundation by storms, sea level rise and tsunami. A review of coastal hazards has been made from the west coast in the state of Gujarat, India (Fig. 1). The Gujarat coast has experienced in recent times high industrial growth rates, but also over a period of time was an epicenter for a number of moderate to high magnitude earthquakes. The 1819 Kachchh earthquake of 7.5 magnitude occurred in the Rann of Kachchh near the India-Pakistan border and caused an area of subsidence forming the Sindri Lake and upliftment of about 6m towards north of the Lake which is about 80 km long and 6 km wide land area making a natural dam, known as the Allah Bund (Dam of God), The Makran tsunami (due to earthquake of magnitude 8.1) that happened on 28 November 1945 was the most devastating one in the Arabian Sea which affected the western coast of Gujarat and modified the coastal geomorphology due to heavy flooding of coastal land. Recent studies have presented coastal geomorphological map of Gujarat showing 5 to 10 m inundation due to successive tsunami events. The massive Gujarat earthquake of magnitude 7.8 which took place on 26 January 2001 at 8 h 46 min affected the whole of Gujarat and adjoining areas. It resulted in significant increase in chlorophyll and suspended sediment concentrations all along the coast, due to the upwelling of subsurface water and vertical mixing. The eutrophic condition, induced by algal blooms, depletes oxygen levels and produces toxins; thus inhibits growth of life. The spectral bands of hyperspectral sensors can be fine-tuned for specific pigment detection and thus act as a useful tool for coastal hazard detection and monitoring. The coast of Gujarat is emerging as major economic hub in western India. For mitigation of coastal hazards, the susceptible structures such as roof straps, storm shutters, groins, jetties and other reinforcements are required to be made to resistant cyclones, prevent beaches from erosion and to protect sand movement into the inlets where boats for fishing and recreation move through. Loss of life can be prevented through cyclone tracking, early warning alerts by monitoring through satellite followed by planned evacuation.