Head of Geological Agency: Groundwater Depletion Rate can be Slowed down

Friday, 1 November 2019 - Dibaca 682 kali



NUMBER: 635.Pers/04/SJI/2019

Dated: 1st November 2019

Head of Geological Agency: Groundwater Depletion Rate can be Slowed down

The decrease in groundwater level in Jakarta is one of the studies made by the Geological Agency of the Ministry of EMR, especially at North Jakarta area. Inter-sectoral coordination has been carried out to monitor and supervise rate of groundwater depletion in order to slow it down, because the human factor can still be controlled.

Head of Geological Agency, Rudy Suhendar, says that groundwater depletion is caused by natural factors and human interference. "The natural factors include natural consolidation, because underground layers are naturally compacted and the effects of tectonic movements. However, tectonic movements do not occur in years or decades but instead in hundreds of years," Rudy said in Jakarta, Thursday (31/10).

He moreover reveals that land subsidence in Northern parts of Jakarta is not a new phenomenon but has occurred for a long time because geologically the areas of North Jakarta are made up of alluvium rocks with relatively young age that have not perfectly consolidated. "That is the geological reason, there is nothing we can do about it," said Rudy.

For the human interference factor, Rudy mentions weight of buildings and groundwater extraction (taking out) are the causes of faster groundwater depletion. "For example, we know that the airport toll road has drooped, as well as buildings located to the front of Jakarta Kota Station. In terms of groundwater extraction, this is because groundwater is positioned between soil pores. When the pores are empty, the soil is compacted, resulting in land subsidence. This human interference can still be controlled. This is something that we can monitor and supervise to slow down the subsidence," Rudy explained.

Rudy presented the measures taken by his agency in cooperation with various elements of the Government. "Heavy construction, be it building, road, bridge or any other construction, must be built on hard rocks. Proposal for groundwater extraction must be monitored and issuance of permit must be tightened. Construction of infiltration wells and reservoirs are massively underway," Rudy said.

The Geological Agency has carried out groundwater monitoring and conservation at a number of spots in Jakarta. "What we inform the public yesterday should act as a trigger for the authority to know the real condition. The policy is executed by the Provincial Government. Utilization of land and space, for decision making," Rudy ended.

As publicly known, based on the measurement by the Geological Agency, land subsidence in Jakarta is 12 centimeter per year. The highest rate of subsidence occurs in Ancol area, North Jakarta.

The over extraction of groundwater contributes to 30% of land subsidence in Jakarta, followed by soil compaction (natural), construction weight, and geotectonic. (IY)

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