High water risin'
Major floods have grown exponentially from just seven in the 1950s to thirty-four in the 1990s. But it’s not just floodwaters that are on the rise – the UN projects the number of people threatened by flooding will double to over two billion by 2050. Global warming is partly to blame. But a recent International Rivers report argues that human engineering is the real problem. Rivers are tamed, channelled, banked and carelessly dammed. Their flood plains are eliminated for agriculture or housing, making them rise perilously above the surrounding area. From the Mississippi to the Danube, the Indus to the Mekong, floods are becoming more frequent, more intense and more deadly.
Tim Kingston sees a soft solution to a warming world’s hard problem.
Every continent has been hit by extreme weather this past year. Week after week, headlines alerted readers to lethal floods while millions were forced from their homes. The damage can be tallied in billions of dollars. India, Pakistan and Bangladesh have all seen deadly, torrential monsoon storms. Papua New Guinea, Mexico and Mauritania were all hit this past autumn. The Arabian Sea even had its first documented cyclone. At the same time other areas baked and burned. Southern Europe and Russia broke heat records while Germany yo-yoed from its driest April since 1901 to its wettest May on record.
But it is flooding that has caught global attention. No-one could have predicted England’s green and pleasant land would become a sodden brown mess this past summer. Soaking wet townspeople and villagers trudged through murky waters, suffered mass evacuations and had to queue for drinking water. The downpours caused several deaths and at least $6 billion in damages.
But Britain was by no means the only area inundated. In India, the state of Assam suffered severe mid-July flooding. Monsoon floods affected 650,000 people from 300 villages. By August, UNICEF estimated a startling 25 million people in the region were flooded out of their homes. Wire service reports indicate that some 1,400 died.
The disasters rolled in as the year rolled on. Storms and floods hammered China. Some 700 Chinese died in floods, landslides and mudflows. Unexpectedly powerful flooding hit Australia, Canada, Colombia, Ghana, Indonesia, Kenya, Malaysia, Mozambique, Sudan, South Africa, Switzerland and Uruguay. West Africa and the Philippines both saw significant late autumn storms and typhoons.
There is little doubt that the annual toll of floods around the world is growing. There used to be seven to nine major floods a year. In the 1980s the number skyrocketed to 20 and in the 1990s it reached 34 major floods a year.
‘Global warming [modelling] predicts a greater frequency of high intensity rainfall events,’ warned Himanshu Thakkar of the South Asia Network for Dams, Rivers and People. Indeed, the amplified destructive power of floods is due, in part, to global warming causing more intense storms. But it is also due to increased floodplain development. Where there were once farmlands there are now homes and businesses. This is certainly true of California’s Central Valley. But even in China and India, where people have lived on floodplains for millennia, growing populations still mean intensive development of risky areas.
Traditional or ‘hard path’ flood control advocates argue that floods can be prevented with large infrastructure projects like dams and embankments. These technocrats have an undying faith in engineering solutions like straightening and concreting-over rivers. Among the true believers in such ‘technological fixes’ are the World Bank, many elements of the US Army Corps of Engineers, the Indian and Chinese water establishments and politicians interested in ‘pork barrel’ mega-projects.
Yet despite the billions spent on these methods in recent years the number of devastating floods continues to grow dramatically. Not only do these technological fixes often fail, they can also make floods worse.
‘The very concept of “hard” flood control is based on the idea that nature can be confronted, constrained and made to do humanity’s bidding,’ explains Patrick McCully, Executive Director of the activist group, International Rivers. In the report, ‘Before the Deluge: Coping with Floods in a Changing Climate’, McCully says that ‘experience shows that such measures both cause great harm to riverine ecosystems, and, in the long run, only tend to increase vulnerability to severe floods.’
Hard path projects share three critical weaknesses. First, no complex engineering structure is foolproof or failure-proof. Second, such systems are frequently based on an incomplete understanding of the water ecosystems they are supposed to control, thus the builders are ignorant of the unexpected consequences of their projects. Third, such structures create a false sense of security that encourages flood plain development and consequently discourages effective flood proofing as well as early warning and emergency evacuation systems.
Politicians love expensive ribbon-cutting ceremonies but frequently refuse to commit adequate funds to keep those projects in good repair. In the US, academics and economists have long warned that the nation’s infrastructure is crumbling. But it took a dramatic bridge collapse in Minneapolis to prompt a long overdue look at bridges nationwide. Will it take another Hurricane Katrina-style disaster involving embankments and dams to encourage a similar evaluation of hard path flood control structures?
Dam operators are also human and sometimes make fatal decisions. The Indian city of Surat was inundated in 2006 because of negligence and human error. The monsoon that year was early and heavy, yet operators at the Ukai dam allowed the reservoir to fill dangerously close to capacity instead of leaving room for monsoon waters. When the surge hit, worried operators opened 21 sluice gates with scant warning. Surat flooded and 120 people died. It was just one of many avoidable dam-related disasters around the world that year.
Traditional flood control systems are also not foolproof. The most notorious recent failure was in New Orleans in 2005 where the real damage was caused by embankment failure, not by Hurricane Katrina.
Dams fail too. In 2005, five dams in Pakistan breached – one over a hundred feet tall – after torrential rains. Nearly 4,000 people were made homeless and 80 died. In 1975, a typhoon triggered a series of dam failures in China; the resultant flood and subsequent epidemics killed 230,000 people. As author and journalist Jacques Leslie aptly put it, dams are ‘loaded weapons aimed down rivers.’
Hard path flood control ignores the way that dams and embankments alter water flow and sedimentation in rivers. Embankments cut rivers off from their floodplain while reducing their meanders. More sediment gets dumped in the riverbed. Increased sediment raises the level of the riverbed and in response embankments are raised. Higher embankments make floodwaters run faster. Floods then become more destructive when embankments are breached or floodwaters reach an area without embankments.
Eventually some embanked rivers become ‘perched’, with their beds above the level of the surrounding land. When their embankments are breached, floodwaters cannot drain back into the elevated river.
Hard path policies also impose massive ecological damage on wetlands and other river ecosystems. For example, sediment that is dumped in riverbeds but does not make it to river deltas helps contribute to delta subsidence and coastal erosion.
As if this were not bad enough, embankment and dam designers often assume that the world’s weather won’t change when calculating how high a particular dam or embankment needs to be built. To call this sort of planning insufficient, in a warming world with increasingly erratic climatic conditions, is an understatement.
‘It is a policy disaster,’ says Himanshu Thakkar. ‘The Indian Government is trying to control floods through [building] dams and embankments. But it is not physically possible to control these floods. A better policy option would be catchment management through the creation of local water systems, wetland preservation, forest preservation, early warning systems and better drainage.’
What’s true in India is true elsewhere. The policy Thakkar outlines is the ‘soft path’ of flood management. Many planners have adopted this path, including river management agencies in Austria, China, France, Germany and the US. Instead of spending billions of dollars vainly trying to eradicate floods, these water managers recognize that floods will happen, and that we need to learn to live with them as best we can.
The way forward
Soft path flood management includes five key elements that can adapt to the vagaries of a changing climate: slowing the flood; improving emergency procedures; moving out of harm’s way; protecting vulnerable buildings and areas; and improving dam management procedures.
Slowing the flood involves restoring and preserving wetlands and flood plains that can absorb flood waters and discharge them slowly. It also requires improving urban drainage to prevent run-off driven flashfloods from metropolitan areas.
This is no pipedream. Napa, in California, has adopted a 10-year, $220 million project to restore wetlands, turn grazing lands into tidal marsh and replant native foliage to reduce riverbank erosion. Somewhat surprisingly, this plan received the blessings of the US Army Corps of Engineers.
Meanwhile, water managers in France’s Loire Valley and on the Drava River in Austria have adopted similar schemes. Even China is restoring 8,000 square miles of wetlands alongside the Yangtze River following a severe flood in 1998.
Improving emergency procedures should be a self-evident policy, but often is not. Although the Bangladesh Government is a proponent of dams and embankments, it has also adopted pre-emptive flood warning systems that have saved thousands of lives. Bangladesh recently installed long-range flood forecasting that enabled remote villages to evacuate with minimal loss of life.
In India some regions have taken matters into their own hands and adopted community-organized flood control systems. A 1,000-person strong, community flood-watch involving telephones and email has operated in India’s Ganga-Brahmaputra-Meghna basin for the past three years.
A key element of soft path flood management – getting out of the way – requires planning, regulation and enforcement. As floodplain development is restricted there also needs to be incentives for those living there to move. While it is not always possible to reduce the population of floodplains – think of the Ganges Delta – the fewer people at risk, the less destruction there will be. Over 100,000 businesses and homes were relocated to higher ground after the Mississippi River’s 1993 floods. In some cases entire towns moved. In others only the areas most at risk were relocated.
Raising valuable buildings on mounds or stilts can protect them, as has been done along the Russian River in northern California. Some urban areas use high-risk flood zones as sports fields that can be sacrificed in the event of a flood. Particularly vulnerable areas can be protected with the judicious use of well-maintained embankments.
Operating rules for dams should be developed with public input. They should be published and stringently enforced. A safety assessment of existing dams is also critical and the removal of unsafe dams needs to be a priority.
There is a growing consensus that flood mitigation is the most realistic form of flood management policy. But an iron triangle of politicians, bureaucrats and dam-builders remains. They promise salvation through embankments and dams whenever floods strike, even though such floods may have been worsened – or even caused – by those very dams and levees.
Global warming is changing that equation. UNICEF’s Indian Health Chief, Marzio Babill, told reporters after recent Indian floods that ‘the scale of the inundation is so vast, even communities that are used to coping with flooding were completely overwhelmed…We cannot continue to respond to these kinds of challenges with the same pace or technology that we did 10 years ago.’
He’s right. We can do better. Improving our ability to cope with floods now and in the future requires a more sophisticated approach. Soft path techniques can deliver a powerful one-two punch that not only reduces death and damage, but also develops a sustainable way to restore rivers, wetlands and ecosystems.
Tim Kingston is the media co-ordinator for International Rivers and has covered international politics and HIV/AIDS for many years.
See also Before the Deluge: Coping with Floods in a Changing Climate, published by International Rivers, Patrick McCully, www.internationalrivers.org
This article is from
the March 2008 issue
of New Internationalist.
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