Robert Go, Jakarta – Stop blaming Mother Nature, say activists rejecting claims by officials that heavy rain and low ground were behind the week-long floods that paralysed Jakarta.

Instead, they fault poor city planning and corruption that led green spaces to be used up for development; poor drainage; and refuse-choked drains. "As usual, the government blames everyone else," said Ms Wardah Hafidz of the Urban Poor Consortium, a vocal advocate for the poor.

But Mr Lukman Mokoginta, head of the Institute for Society, Environment and the City, pointed out that Mother Nature and man-made factors had combined to plunge Jakarta into its worst flooding problem in years. "Flooding in Jakarta is not just caused by the rain, but is an accumulation of different factors, including poor city planning and neglect by officials," he said.

Jakarta Governor Sutiyoso was correct in pointing out that heavy rain last week contributed to the severity of the flood. Meteorology and Geophysics Agency official Budiono said that more than 500 mm of rain has fallen on Jakarta in the week since last Tuesday. "That's extremely heavy rain compared to previous years," he said, adding that normal average rainfall in the region is only between 200 mm and 300 mm per month.

Another factor is the rise of shantytowns in many parts of Jakarta, a by-product of the country's economic crisis and the failure of the government's poverty-alleviation programmes. Having nowhere else to build, hundreds of thousands of poor residents and newcomers to Jakarta have put up shacks on any vacant swathes of land they could find after clearing away the undergrowth. As a result these areas do not absorb much water. And Jakarta, where as many as 13 major rivers – including the Ciliwung and Cisadane – merge before emptying into the sea, is at sea level and therefore is vulnerable to flooding during the monsoons.

But as cleanup and relief efforts progress, it is becoming clear that the administration was caught totally unprepared, despite the fact that filthy water swamps Jakarta on a yearly basis. The suffering of millions would have been less severe if the administration was more able and efficient, critics said.

Last year, Jakarta's government spent only 40 per cent of its US$25-million flood-prevention budget, and activists are asking where the rest of the money went. A canal to help drain East Jakarta, which got hit badly by this year's flood, has been talked about since 1973, but nothing has been done.

The canals and floodgates that control water flow date back to the Dutch colonial period; many have not received substantial improvements over the last three decades.

Jakarta's 600 garbage trucks are breaking down and can't deal with the 25,000 cubic metres of trash generated daily by residents. Leftover waste gets burned, or dumped in the rivers and canals.

The problem got worse last month when Jakarta's major dump in Bekasi, West Java, decided to stop taking any more of the capital's garbage. Ms Wardah, who is leading a fight to file a class-action suit against the government over the flooding, said: "The actions of Governor Sutiyoso and the rest of the city administrators are unforgivable. Now people die and suffer because of them."