India has lost shore land of Nagpur city size to coastal erosion

Between 1990 and 2016, the country lost 235 square kilometre (sq km) of land to coastal erosion, which is slightly more than the area of Nagpur city (227. 4 sq km). In Andhra Pradesh alone, the state is losing 2.67 sq km of shoreline every year. Visakhapatnam city, the state capital, has lost 54 hectare of beach along a 10 km-long stretch at an average loss of one hectare per year.

These startling facts about shoreline changes were shared by K Nageswara Rao, professor emeritus, department of geo-engineering at Andhra University during a recent media workshop on ‘Climate change, climate justice and resilience in the Bay of Bengal region’ organised by the Earth Journalism Network. Rao has been researching and documenting changes in Indian coastline both due to natural and human-made factors.

And, these coastline changes are not limited to India alone. A study published last year — ‘Global long-term observations of coastal erosion and accretion’ — has reported that on a global scale, between 1985 and 2015, there has been a net loss of about 14,000 sq km of surface for human settlements and terrestrial ecosystems.

Coastal environments form the interface between the land and sea/ocean, and host about 40 per cent of the world’s global population. In India alone, nearly 250 million people live within 50 km of the coastline. And, over seven million coastal families of fishers and farmers directly depend on the coastal zone.

Coasts are not static and undergo constant changes due to natural factors, such as rivers flowing into the sea, sediment deposition, tides, storms, tsunamis, and so on. These natural factors lead to both accretion (land gain) and erosion (land loss) of coastline. For instance, as reported by Rao, between 1990 and 2008, Andhra Pradesh has lost 88 sq km of coastline due to erosion and gained 40 sq km by accretion. Hence, net coastal area lost in the state is 48 sq km in 18 years.

Apart from these natural factors, human presence also leaves a lasting impact on the coastline because of construction of coastal infrastructure, dams (that alter water and sediment flow), and chopping of mangroves. The study published in 2018 notes that “dams are among the most prominent erosion factors, as they retain sediment that would normally feed the downdrift beaches”. It goes on to name some threatened deltas in the world including the delta of the Indus river, at the border between India and Pakistan, and the Brahmaputra delta. Authors of the study note, in relation to Indus and Brahmaputra deltas, “the effect of the upstream dams is combined with human degradation of the coastal mangrove forests, resulting in enhanced erosion due to the decreased capacity of the estuaries to retain sediments”.

Coupled with these natural and human-made factors, climate change induced sea-level rise emerges as a serious threat multiplier for coastal erosion. As R Ramasubramanian, principal co-ordinator with Chennai-based MS Swaminathan Research Foundation points out, sea-level rise, shoreline erosion, changes in tides and currents, saltwater intrusion are some of the impacts of climate change already being witnessed by the coastal communities in India.

A study conducted by A Ramachandran, emeritus professor, Centre for Climate Change and Adaptation Research at Anna University in Chennai has projected sea-level rise of 4.51 cm to 4.94 cm along the coastline of Tamil Nadu by 2025. Highest risk is to Chennai and Kanyakumari districts.

On March 7, the Union Cabinet chaired by Prime Minister Narendra Modi approved the ‘Flood Management and Border Areas Programme’ for the period 2017-18 to 2019-20 with a total outlay of Rs 3,342 crore. Coastal erosion also finds a mention in this programme. It is important to note that protecting our coastline doesn’t need engineering solutions alone. A large number of coastal states, such as Kerala, Gujarat, Puducherry, etc have built seawalls to keep the sea at bay. But, the results aren’t encouraging, as seawall shifts the problem of sea ingress to other areas. It blocks sand movement (remember that a beach is a ‘moving’ river of sand) and destroys the beaches. Rao recommends other eco-friendly and cost-effective coastal protection measures, such as dune stabilisation by vegetation, timber fencing, planting mangroves/vegetation, etc. Coastal communities can be involved in these activities of beach protection and rejuvenation as an additional option of livelihood.

Author is environment editor with Gaon Connection