KONTAN.CO.ID - KUALA LUMPUR. Indonesia's flood-hit capital Jakarta must protect and plant trees, stop extracting so much groundwater, and develop long-term plans together with surrounding towns if it is to keep pace with the growing threats from climate change, green groups said.

Since Dec. 31, some of the heaviest rain since records began has caused chaos in the mega-city, killing at least 60 people and displacing nearly 175,000 - and more rain is forecast for this month.

"Indonesia has got enough resources to deal with these problems," said Leonard Simanjuntak, country director for Greenpeace Indonesia in Jakarta.

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"However, for decades, political leaders never really had any consistency in implementing long-term plans for flood management," he told the Thomson Reuters Foundation.

Southeast Asia's biggest city is located by the coast and built on a swampy plain, with 40% lying below sea level.

More than 10 rivers flow through the capital, but the water catchment areas and forests around it have been largely converted over decades for residential and agricultural use, falling victim to rapid urbanisation.

The capacity of Jakarta's rivers has also shrunk because of sedimentation, poor waste management and illegal settlements, meaning remaining waterways tend to clog up during heavy rains.

Making matters worse, most residents and businesses rely on wells that drain underground aquifers for their water supplies, causing the city to sink by 5-10 cm (2-4 inches) each year.

Rising sea levels and the inability of infrastructure to cope with excess water during the monsoon season have resulted in regular flooding in the city, which is home to more than 10 million people.

Jakarta's authorities must dredge and clean up its rivers and waterways, and help communities access water without huge, uncontrolled groundwater extraction, said Milag San Jose-Ballesteros, director of East, Southeast Asia and Oceania for the C40 Cities network.

Many cities, meanwhile, are now looking at nature-based solutions, such as turning concrete drainage and grey infrastructure back into flood-plains, she added.