T

he Japan International Corporation Agency (JICA) is offering the city a solution for its long-standing flood problem by building underground reservoirs using Japanese technology.

JICA and the Public Works Ministry are currently in talks with the administrations of Jakarta and Bogor, West Java, on developing the reservoirs using the “Cross-Wave” system developed by the Sekisui Chemical Co. of Japan.

Jakarta lacks the green space to develop water rainwater catchments, which the Cross-Wave system solves by using special polypropylene sheets and channeling devices to line underground reservoirs instead of river stones, as is typically done in existing catchments. The Cross-Wave reservoirs can hold rainwater that would otherwise be discharged into rivers.

The JICA claimed the Cross-Wave system could be used to easily create underground reservoirs. The polypropylene sheets and channel devices are lightweight and easier to transport rather than stones or concrete tanks.

JICA’s chief advisor for the project, Takaya Tanaka, said almost every building in Japan uses the Cross-Wave system.

According to Tanaka, the system can be used for water storage or recharge.

Water stored in underground reservoirs using the Cross-Wave system can prevent rivers from bursting their banks or be held for later use.

On the other hand, water stored using the Cross-Wave recharge system can be transferred to a predetermined location.

The agency is working with the ministry to promote the technology under the Jakarta Comprehensive Flood Management (JCFM) program.

Ministry official Imam Santoso said that Banteng Field, the site of the Irian Jaya Monument in Central Jakarta, has been proposed as a pilot project, although the Jakarta administration has yet to agree.

The ministry wants to require building owners in the capital to use the system.

One office building owned by the ministry in East Jakarta has been using the Cross-Wave technology, under a initiative that was fully funded by JICA.

Tanaka said that the material used to make the sheets and channels was still imported from Japan, adding that there was a possibility that Indonesia could locally produce them. “The material costs Rp 3 million (about US$312) per cubic meter. If produced locally, the price may be knocked down to Rp 500,000 to Rp 1 million,” he said.