Jakarta, CNBC Indonesia – Several cities on the coast of Central Java were flooded. For example in Demak, Pati and Kudus. This raises suspicions that the Muria Strait will be re-formed.
The Muria Strait is long gone. Previously, the strait separated Java Island and Mount Muria. Then, the strait became land around 300 years ago.
Geology expert at the National Research and Innovation Agency (BRIN) Eko Soebowo said land subsidence in the area could easily occur. It is possible that the Muria Strait could reappear, but the cause is not the current flood.
“If there is a load on the material, it will easily experience subsidence. It is still vulnerable. Cities like Semarang and the northern coast region are experiencing subsidence because the underground material has not yet experienced perfect compaction,” said Eko, quoted from CNN Indonesia, Thursday (21/3/2024 ).
Eko explained that land subsidence in the Semarang, Demak and surrounding areas varied with the highest intensity reaching 10 centimeters per year, as happened in the east Semarang area.
This difference depends on the typical soil in each area and the supporting factors for land subsidence in that area.
Land subsidence factors are divided into two, namely natural factors and anthropogenic factors or the impact of human activities.
Natural factors include the characteristics of young sedimentary soil which makes it certain to experience land subsidence. This factor usually creates a decrease of about 1 centimeter per year.
Apart from that, the second natural factor is tectonic activity. This factor does not have too big an impact, because it only causes a decrease of about a few millimeters.
Meanwhile, anthropogenic or human-made factors are the biggest contributor. The burden of soft soil infrastructure can cause a subsidence of 1 centimeter per year.
Then, groundwater exploitation is the dominant factor which can cause a decline of up to 7-8 centimeters per year.
Apart from decreasing land levels, Eko said that rising sea levels due to climate change could also cause the Muria Strait to potentially reappear.
The Muria Strait is not caused by flooding
Eko said flooding was not a factor in the return of the Muria Strait. He said the flood would actually make the land higher.
“When it comes to floods, the floods actually fill sedimentation in the strait area. From Muria, from the south of Demak, south of Semarang, all the rivers empty into the Pantura area,” said Eko.
“It carries material, creates shallowing. But flooding does not cause another strait to occur,” he continued.
In addition, flooding will bring sediment to the affected area and as a result increase the height of the land.
[Gambas:Video CNBC]
(fab/fab)