Arientha Primanita – The recent localized street flooding caused by unseasonal rains across Jakarta highlights the need to seriously improve the city's poor drainage system, an academic and council officials said on Wednesday.

"The administration should repair and expand the existing roads and add more drains," Trisakti University urban planning expert Yayat Supriyatna said.

He said the cityscape had changed drastically over the decades while the drainage system had been relatively untouched during the same period. Most drains were now either broken, clogged with garbage or closed off due to buildings being constructed above them.

Yayat called on the administration to remap the city's drainage network, pointing out that it was easy to spot the non-functioning drains by looking for flooded streets.

"Jakarta's drainage system is in bad condition, which has an adverse knock-on effect on the traffic problems," he said. "Even moderate rains can cause localized flooding that leads to heavy traffic jams."

Yayat said Jakarta had developed so rapidly that it would be difficult and costly to overhaul the drainage system.

City councilor Berlin Hutajulu said the Jakarta Public Works Office must prioritize repairs of the drains. "It's important that the drainage system is fixed and expanded, because it will help channel the rainwater more effectively, which in turn will lead to smoother-flowing traffic."

In some parts of the city, roadside gutters often overflow onto the streets, Berlin said. "This is something the city administration should ideally be prepared for, because it has the budget and the program in place."

Tarjuki, head of water resources maintenance at the public works office, said it had allocated Rp 30 billion ($3.2 million) this year for the repair and construction of drains in 33 flood-prone locations, with priority points along Jalan Jendral Sudirman and Jalan MH Thamrin.

He said one short-term solution for the problem of flooding would be to widen roadside drain inlets to allow for faster runoff.

Fakhrurozi, the office's head of water resources, said Jakarta's drainage system had been laid out in the 1960s and had not been overhauled since, receiving only routine maintenance.

"The age is just one problem," he said. "Another is that the drains also carry utility cables for telephones, electricity and fiber optics. The biggest culprit, though, is all the garbage that gets tossed in there."

Wiriatmoko, head of the Jakarta Spatial Planning Agency, said the drainage system and the utilities should ideally be separated. "Building a ducting system is probably the best option to get around this problem," he said.

A ducting system to carry utility connections underground would free up the drains, Wiriatmoko said, but would require a thorough study of the existing drainage network before it could be drawn up.