Predicted to Sink. How?

KOMPAS/AGUS SUSANTO

Aerial photo of buildings submerged in seawater around a coastal safety embankment in Muara Baru, North Jakarta, Thursday (19/8/2021).

This newspaper’s report about cities in Indonesia that are predicted to sink in the future only reinforces what we have heard earlier.

We still freshly remember the speech by United States President Joe Biden at the office of the Director of National Intelligence on July 27, which signaled the sinking of Jakarta in the next 10 years. Other predictions are more extended, saying Jakarta will sink by 2050.

In a report using data journalism techniques, Kompas, on Friday (20/8), found that 199 coastal regencies and cities in Indonesia would be affected by tidal flooding by 2050. Around 118,000 hectares of land will be submerged in seawater and 8.6 million residents will be affected. Losses are estimated to be Rp 1,576 trillion.

Also read:

> Coastal Cities Facing Threat of Inundation

> The Last Dwellers

> Preventing Rising Sea Level

The map on the front page shows that most of the northern coast of Sumatra and Java, as well as the southern coast of South Kalimantan, are areas that are predicted to be inundated by seawater by 2050. Regarding vulnerability, for Jakarta, for example, there will be 5.53 square kilometers classified as areas of high vulnerability.

With regard to the causes, global climate change is widely cited as the main trigger of the sinking of cities, not only in Indonesia, but also in a number of other countries. Global warming is causing the ice caps in the polar regions to melt and raising the world\'s sea levels. In addition, local activities also contribute to the rapid sinking of a city. For Jakarta, the high level of ground water extraction is one of the important causes of the subsidence of the surface.

The exploitation of groundwater as the main cause of land subsidence was mentioned by Heri Andreas, a geodetic expert at the Bandung Institute of Technology (ITB), in the Kompas report, noting that the impact will be more severe than the rise in sea level.

KOMPAS/P RADITYA MAHENDRA YASA

Some of the villages on the north coast that are always faced with the problem of high tides, one of which is in Tambaklorok, Semarang City, Central Java, on Saturday (24/7/2021)

In Semarang, Surabaya and Jakarta, the land is sinking 15 centimeters per year. In Pekalongan, Central Java, the land subsidence reaches up to 18 cm per year. In response to such phenomena, a number of cities have taken anticipatory steps. However, of the 21 capital cities on the Indonesian coast, only three have taken significant action, namely Semarang, Jakarta and Surabaya.

We also know that these efforts, particularly the construction of dikes and coastal embankments, require significant funding.

Steps to deal with this issue include building physical infrastructure, such as dikes, coastal embankments, polders, motion weirs and retention ponds. These efforts are expected to be useful in preventing the entry of water into the cities. Efforts to overcome the impact of the rising sea level have also been shown by other countries, such as Singapore and Italy. We also know that these efforts, particularly the construction of dikes and coastal embankments, require significant funding.

Policy mistakes have contributed to the issue, such as in Jakarta, where groundwater extraction is excessive. However, sea levels are rising on a global scale. After a number of European countries were hit by heavy floods recently, German Chancellor Angela Merkel said countries had not done enough to curb the rate of global warming. Not only Indonesia\'s coast is threatened by rising sea levels – many other countries face the threat. We are concerned by the fact that few countries have made overcoming it a priority.

(This article was translated by Hyginus Hardoyo).