TEMPO.CO, Jakarta - The Space Research Center at the National Research and Innovation Agency (BRIN) revealed its study result based on Synthetic Aperture Radar data that land subsidence occurred in Java’s northern coastal area or pantura.

“The results show that land subsidence occurs in Java pantura, such as Semarang and its surroundings,” said a researcher at the BRIN Space Research Center, Thomas Djamaluddin, in a webinar concerning tidal floods in the dry season, Thursday, June 2, 2022.

The professor, who is also the former Head of the Institute for Aeronautics and Space, explained that the highest land erosion occurred on the coast of Pekalongan at 2.1-11.0 centimeters per year, based on the results of the measurements throughout 2015-2020.

Meanwhile, Jakarta recorded subsidence between 0.1–8.0 centimeters per year, Semarang City at between 0.9–6.0 cm/year, Surabaya City at 0.3–4.3 cm/year, and Cirebon City at 0.28-4.0 cm/year. “This needs to be watched out for,” Djamaluddin underlined.

The satellite data strengthened the previous studies such as one conducted by the Bandung Institute of Technology (ITB) research team. Head of the ITB’s Geodetic Laboratory Heri Andreas said that the current rate of land subsidence in Semarang, Pekalongan, and Demak has reached 20 centimeters per year.

“This is the fastest land subsidence rate recorded in the world,” Heri said on May 29, 2022.

He questioned why the local government did not mention land subsidence as one of the factors of the extreme tidal flood on May 23. “Because the basis of reducing the risk of a disaster through mitigation, prevention, and adaptation efforts must be based on the investigation of the right causal factors,” Heri asserted.

Thomas also added that BRIN could involve several research centers to collaborate in researching many factors that cause tidal flooding on the north coast. The BMKG, he said, could issue an early warning of tidal flooding. “The local government can, of course, prepare for the infrastructure."

ANWAR SISWADI (CONTRIBUTOR)

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