As flood waters rise, is urban sprawl as much to blame as global warming? “The driving force is the built environment”

By John Vidal
2 September 2017
(The Guardian) – First came the dire warnings of Hurricane Harvey, then the terrible scenes as the skies opened, whole neighbourhoods drowned and motorways became rivers. Now, as the waters subside and the full extent of the damage is assessed, come the voices of distraught people who have lost everything and the rallying of Americans to help in the recovery.Houston may have broken the US rainfall records, but lost in the dramatic worldwide coverage of Texas has been the plight of tens of millions of people across Asia and Africa who are also counting the human cost of equally intense storms in which months of rain has fallen in just a few hours.One of the heaviest monsoons recorded in the past 30 years has swamped large parts of India and south-east Asia, affecting millions. Nepal, Bangladesh, Cambodia, and Pakistan have all been hit and major cities such as Mumbai, Bangalore, Chennai, Karachi, and Dhaka have been paralysed as roads turn to rivers and waters flood villages.The scale of the flood disasters in the US and south Asia has shocked governments worldwide and left aid agencies struggling. Around 1,200 people are known to have died so far in Asia, more than 40 million people have been affected and millions of hectares of crops have been destroyed.Since June, 21 countries – many in west and central Africa, such as Guinea, Ghana and the Democratic Republic of the Congo – have been struggling with exceptionally heavy rains, mudslides, hurricanes and floods, say aid agencies. Twenty people died in Lagos in a repeat of last year’s unprecedented flooding in Nigeria. And three months of rain in a few hours killed 40 in Niamey, the capital of neighbouring Niger. A mudslide that killed as many as 1,000 people in Freetown, Sierra Leone in July was also triggered by torrential rain.So what is to blame for these severe weather events and some of the worst flooding ever seen?Climate scientists agree that extreme rainfall will increase as the world warms. Other researchers argue that poor urban infrastructure and the rapid, unchecked sprawl of cities on to marshlands and other places that usually absorb excess rainwater have led to flooding. […][They] argue that urban development is as much to blame for the floods as climate change. “Houston, Bangalore, and many other cities share the same problem,” says T V Ramachandra, coordinator of the energy and wetlands research group at the Indian Institute of Science. “These floods are mostly manmade. They are not natural disasters. They are very similar and largely because of concretisation.”In the rush to economic development in India, China, and elsewhere, ecological sense has been ditched in favour of explosive growth across the world, he says.Cities have expanded into marshes, wetlands and flood-prone areas as populations have grown and people have moved from rural to urban areas in search of work. The result has been that the scale, intensity and duration of floods has increased. […]Sam Brody, a Texas A&M University marine researcher who specialises in natural hazards, believes the addition of more than 1 million people moving to flood-prone areas near Houston since 2000 has overwhelmed the city’s ability to drain water.“If you are going to put 4 million people in this flood-vulnerable area in a way which involves ubiquitous application of impervious surfaces, you’re going to get flooding. The driving force is the built environment,” he says. [more]

As flood waters rise, is urban sprawl as much to blame as climate change?