International aid agency Oxfam says poorly built flood defenses in South Asia may have aggravated the intensity of the recent flooding in the region. It calls for a reassessment of flood policies in the region, where nearly 20 million people have been affected by flooding. Anjana Pasricha has a report from New Delhi.

A Pakistani family make their way through a flooded street after a heavy rain on 10 Aug. 2007 in Karachi, Pakistan

In a recent report, aid agency Oxfam said that defenses such as river embankments built to prevent flooding in countries such as India, Nepal, and Bangladesh can make matters worse.

Ian Bray of Oxfam has traveled through flood-hit areas in the Indian state of Bihar. He says many embankments are 50 years old, and are easily breached.

"We witness huge breaks in the embankments. What happens is about a 12-foot wall of water probably 300 meters wide that breaks through the embankments and inundates anything in its way," he said.

The report estimates that in Bihar, embankments may have tripled the area prone to floods to about seven million hectares from two and a half million hectares. It says in Bangladesh, 75 embankments were breached in one month during this year's floods. And in Nepal culverts and embankments triggered major floods by obstructing the flow of water.

Experts say breached embankments not only contribute to massive flooding, they can be more destructive because they prevent water from draining away from flooded land.  

Oxfam says governments must build good drainage systems to reduce the risk of floods.

Oxfam also urges South Asian governments to build more flood-proof infrastructure such as shelters on higher ground, and homes and wells on raised land to ease the miseries that flooding inflicts on communities.

Other aid agencies agree that flood preparedness needs to improve.

ActionAid India's emergency adviser, P.V. Unnikrishnan, says governments need to spend more to prepare for floods, which have become an annual occurrence.

"If you make an investment of $1 in disaster preparedness and disaster risk reduction, it is thousand times more cost effective than reactionary responses which happen after the disaster," he noted.  "Invest in early warning systems and early response mechanisms and most importantly, develop plans by engaging the local communities."

This year's floods were the most intense in recent times. Tens of thousands have lost their homes and livelihoods, and thousands of acres of farmland have been destroyed in some of the poorest regions of South Asia.