Chapter 7 - Erosional Responses of Eastern and Western Coastal Regions of India, Under Global, Regional, and Local Scale Causes

Abstract

The coasts are the most dynamic zones located at the interface of land and water, and exhibit changes through time by erosion/deposition and submergence/emergence due to various natural phenomena such as waves, tides, storm surges, tsunamis, sea level, and tectonics. Superimposed on these natural phenomena, human activities at global, regional, and local scales have triggered large-scale coastal erosion in recent decades. We have analyzed the coastal changes that occurred during the past three decades (1990–2017) in the Indian states of Andhra Pradesh (AP) along the east coast, and Kerala along the west coast, as case studies for assessing the impacts of human activities at the global scale; the Krishna Delta front coast in AP as an example of the impact of regional scale, and the Visakhapatnam city coast in AP as an example of local-scale human activities. Results of the study showed that during the 27-year period (1990–2017), 65% of the 1080km-long AP Coast and 69% of the 590km-long Kerala Coast witnessed erosion leading to a net loss of 102 and 13km2 of land, respectively. Similarly, a net loss of 27-km2 in the Krishna Delta is construed as the result of diminished sediment supply due to the burgeoning upstream river dams, and the land subsidence by sediment compaction in the coastal sectors. We determined that the pattern of perpetual beach erosion leading to the loss of 0.54km2 of beach area in the coastal city of Visakhapatnam is due to the construction of harbor breakwaters and seawalls that interfered with local sediment transport.