Indonesia's coastlines shrink as sea levels rise

Unsustainable economic activities also contributing to loss of land

JAKARTA • Indonesia, the world's largest archipelagic nation, is fast losing its coastal areas due to rising sea levels and unsustainable economic activities.

According to a study by the Maritime Affairs and Fisheries Ministry, the country loses around 1,950ha of coastal area - an area equivalent to Padang Panjang, a city in West Sumatra - annually to erosion. Only 895ha of new beach land is formed every year from natural sedimentation.

In the last 15 years, the country has lost 29,261ha of coastal area, which is about the size of Jakarta.

In the island of Flores in the southern-most province of East Nusa Tenggara, officials and residents say waves from the Flores Sea have eroded the coast of Aeramo, the area's most populous village with 6,000 people, by 3m to 4m yearly.

The village chief of Aeramo, Mr Dominggus Biu Dore, said erosion has worsened in the past several years as more people have been clearing coastal mangrove forests to make space for milkfish ponds.

The northern coast of Java Island, meanwhile, is one of the areas most affected by erosion. In terms of provinces, the three most affected regions are Central Java, East Java and South-east Sulawesi.

Coastal erosion is a natural phenomenon that occurs in areas where land along the coastline is displaced due to the effects of waves, tides, currents and wind, among other factors.

In ideal conditions, such land is replaced by the same amount of sediment eroded from other areas in what is called accretion. However, this natural balance is not occurring in Flores, Java, Sulawesi and other regions in Indonesia.

  • 1,950ha Coastal area - an area equivalent to Padang Panjang, a city in West Sumatra - that Indonesia loses annually to erosion, according to a study by the Maritime Affairs and Fisheries Ministry.

    895ha New beach land formed every year from natural sedimentation, not enough to make up for loss.

    29,261ha Coastal area that Indonesia has lost in the last 15 years, which is about the size of Jakarta.

    150million Number of people (or around 60 per cent of Indonesia's total population) living in coastal areas, according to a government estimate.

"In Java, a small number of beaches have experienced massive abrasion. The erosion in Sulawesi hit more places compared to Java," Mr Abdul Muhari, the ministry's head of coastal disaster mitigation, told The Jakarta Post. As a result, Sulawesi has lost more of its coast compared to Java, he said.

While rising sea levels due to climate change have become a factor in land loss, environmental damage has also made the coastal areas more vulnerable.

Mr Wahyu Budi Setiawan, a researcher with the Centre of Oceanography Research at the government-sanctioned Indonesian Institute of Sciences, said local factors may play more of a role in erosion than global factors.

"While the rise of sea levels due to global warming might have contributed to erosion in some regions, a disruption in the local coastal landscape will have a bigger role in worsening the phenomenon," he said.

Erosion along the western coast of Demak, Central Java, over the last 20 years has caused three villages to sink into the sea. Experts said the abrasion in the area, considered among the worst in the country, was due to the construction of ports and industrial projects.

In South-east Sulawesi, rampant mining has been blamed for environmental destruction on the islands in the northern part of the province. At Siontapina Beach on Buton Island, there have been reports of abrasion due to rampant illegal sand mining.

According to a government estimate, 60 per cent of Indonesia's total population - or about 150 million people - live in coastal areas. The country is also at risk of suffering economically as more than 80 per cent of industrial locations are located in coastal areas.

The government has been taking various measures to protect the coastal regions from erosion. The Public Works and Housing Ministry, for example, has been putting up concrete-based structures such as seawalls.

And the Maritime Affairs and Fisheries Ministry, on its part, has been installing green structures at beaches in 14 regencies since 2015 to help in the erosion recovery process.

Green structures are expected to act as a substitute for mangrove forests, helping in the sedimentation process and formation of new land. Mangrove seeds are expected to be spread by sea waves onto sedimented land in this process.

The ministry has estimated that 1,025ha of coastal areas would be restored through this approach by the end of the year.


A version of this article appeared in the print edition of The Straits Times on July 09, 2019, with the headline 'Indonesia's coastlines shrink as sea levels rise'. Subscribe