by Judith Curry
With the Ganges–Brahmaputra delta sinking, the race is on to protect millions of people from future flooding. – Quirin Schirmeier
Bangladesh is a poster child for ‘dangerous sea level rise.’ However, only a small fraction of the sea level rise can be attributed warming oceans (see this previous post). And the Bangladeshis seem to be doing a pretty good job of adaptation.
Nature has an excellent article: Floods: holding back the tide. Excerpts:
Scenes of disaster are not unusual in Bangladesh. About 6,000 square kilometers of the massive Ganges–Brahmaputra delta, the largest delta in the world, lies less than two metres above sea level. On average, 6,000 people in Bangladesh die each year in storms and floods. In April 1991, a single cyclone, the worst in recent decades, wiped out well over 100,000 lives in the delta and left millions of people homeless.
Risks are expected to climb. Global warming is raising sea levels around the planet by 2–3 millimetres each year. That only adds to bigger problems in the Ganges–Brahmaputra delta, which is sinking so rapidly that the local, relative sea level may be rising by up to 2 centimetres each year. And Bangladesh’s population of more than 150 million people is projected to grow by a further 50 million by 2050, putting more people in harm’s way.
The Ganges–Brahmaputra delta is the dumping ground of the Himalayas. As wind and rain erode the mountain range, massive rivers carry more than a billion tonnes of sediment into the Bay of Bengal each year; in some places, the layer deposited since the most recent ice age is more than one kilometre thick. As in all deltas, this loose material compacts easily, causing the land to sink slowly and the relative sea level to rise. In the past, sediment carried downstream each year would have refreshed the delta. But agriculture, industry and hydroelectric dams have diverted water and choked the flow of sediments, so the land is no longer being rebuilt.
Attempting to hold back the tide
From the Nature article:
Previous efforts at flood defence in Bangladesh have not solved the problems. In 1990, the first flood action plan called for barriers to be built along main rivers: in less than 10 years, some 3,500 kilometres of embankments sprang up. In 2000, the country’s focus shifted towards constructing more storm shelters and improving warning systems — but even so, about three-quarters of Bangladesh’s population remains exposed to severe flooding.
A big part of the problem is a lack of understanding of how the delta’s behaviour differs from one place to another. Embankments might work to some extent to protect the capital, Dhaka; but as Polder 32 demonstrates, they do not always do their job elsewhere
Some flood-control efforts might exacerbate the problems. UK geographers John Pethick at Newcastle University and Julian Orford at Queen’s University Belfast reported last year that water levels at some spots in the most vulnerable southwest are much higher than expected. They concluded that embankments along hundreds of tidal channels, some of which reach hundreds of kilometres inland, have vastly reduced the area of land covered by water at high tide. Because the water is less able to spread out, it shoots farther inland where it can. The result is a huge increase in tidal range in less-protected areas. Tide-gauge records from three locations in the southwest suggest a mean rate of relative sea-level rise of about 5 millimetres per year over the past 30 years, but some local spots have experienced an average annual high-water-level increase of 15–20 millimetres.
Other complicating factors are easier to assess and guard against. They found that the embankments that protect the land from the river and sea had also robbed it of fresh supplies of sediment: during the five decades of its existence, the polder had sunk by a full metre relative to the land outside the embankments because it was not being replenished. On top of that, Goodbred found, local shrimp farmers had drilled holes into the dikes to pipe salt water from coastal rivers into their hatcheries, weakening the barriers.
Although Cyclone Aila brought much suffering to the people, it helped to rescue the land a little. During the two years in which the dikes were broken, the polder rebounded with tens of centimetres of sediment deposited by daily tides. The mud caused havoc in the short term by flooding peoples’ floors and gardens, but offers the possibility of long-term sustainability for delta ground.
All this information will feed into the Delta Plan, which will be written over the next 2.5 years by a Dutch–Bangladeshi consortium of government departments, research organizations and engineering consultants. The Netherlands has pledged an initial €7 million (US$9.7 million) to develop the strategy.
The uncertainty in the science makes it difficult for policy-makers to see how much investment is justified, and what kind, says van Scheltinga. “We’re only beginning to understand how the delta works — but we know enough to do a bit better,” says Goodbred.
In rural coastal areas, Goodbred adds, one solution might be to return to the kind of low, flexible embankments that people in this region built before the 1960s. Locals could raise them in the dry season to keep salty water away, and cut them down in the wet season to allow sediment in. Tidal water must, from time to time, be allowed to flush embanked land, he says, to deposit sediment and thus prevent the polders from sinking over the long term. Homes in these polders, he notes, tend to be on land that sits half a metre or more above the polder basins, so would be protected from the influx.
There are cheaper options, he says. Scientists with the Bangladesh Rice Research Institute in Gazipur have developed salt-tolerant rice to grow in flood-prone plains. In large coastal cities, new homes and public infrastructure could be built on artificially raised land. Near the coast, conserving and planting trees could create a buffer against storm surges.
Adaptation – Bangladesh style
iied has a blog post on adaptation in Bangladesh – Reality check: climate change and the poor. Excerpts:
I was also struck by how the community — supported by the local nongovernmental organisation, GSK — has developed a range of strategies and activities to cope with longer floods, higher floodwater levels and the erosion that each year washes away more and more of their crop and homestead land into the nearby Padma River. There was no drama here. And I was deeply affected by the industrious positive way the people of Manikganj District meet these challenges and carry on with daily life.
Many families are moving their homesteads and fodder stores onto raised platforms to keep out of the rising floodwater. They have built small hills with corals and feed stations on top to keep their cattle dry. Similarly, they use chicken houses and portable ovens that can be picked up and moved to dry land during floods.
The ovens even work on the small banana tree rafts that the poorest have built and use during the three or so weeks when the floods force them out of their homes. Families pile goats and all their worldly possessions onto these rafts, and even sleep on them, until the water recedes. Other families have protected their possessions by piling firewood on their roof, or building platforms in their ceilings.
The community is also adapting their use of natural resources. They have built a raised well to stop the floods from polluting fresh groundwater, and we met the woman who manages it and ensures this water is distributed fairly in times of need. New drought- and flood-resistant crops have been planted in the floodplain, and the community also have a resources centre with posters on the walls and a meeting space to encourage learning about sound management of fisheries, forests and agricultural land.
World Resources Institute has a post Adapting to Climate Change in Bangladesh. Excerpts:
Yet, the first people who welcomed us into the village were a group of women that had formed a successful cooperative to address the challenges the floods have brought. Their model is dispersing loans to other women in the village from their collective savings and charging interest on them. Loans in turn are used to buy livestock and other assets that could improve income over the longer term.
Bangladesh Center for Advanced Studies (BCAS) and the Christian Commission for Development in Bangladesh (CCDB), two organizations active in the area, use this women’s collective to begin helping villages respond to the challenges associated with floods. With financial support from Norwegian Church Aid, these two organizations had identified 17 of the village’s poorest households and decided to raise the foundational platform, or plinth, of their houses by four feet to protect them from the flood waters. A few other households, after seeing the benefits of such raised plinths, in turn made their own investments to raise the plinths of their houses.
With their agricultural lands inundated for months, many households in the area also use a floating bed of compacted water hyacinths to grow vegetables, locally known as baira. These floating gardens fall and rise with the water level and can allow households to grow vegetables for consumption when the flood waters are high. Researchers from BCAS have devised ways to improve the design of such bairas to make them lighter and stay afloat for longer periods of time.
It was clear from our visit to Goalbari that diversifying the ways people could make a living when the area is under water was fundamental to their long-term adaptation. Developing ways for students to go to school and to keep schools open even during floods seemed equally important. Improving access to services for these communities, like drinking water, health facilities and other types of income generating activities were critical to improving people’s resilience to these weather related challenges.
Climate change and other weather related events do, however, present unique challenges that will require us to think in innovative ways. Often project and community-driven approaches like the interventions I mention above are critical to understanding local needs, keeping communities central to decision and planning processes. Yet, they alone are not able to address the greater landscape of environmental services that might be needed to contend with such challenges. For example, drainage issues, often one of the major causes of water logging in delta regions like Gopalgunj, can’t be solved by a narrow focus on communities and may need us to look at regional scales and subnational, national or sometimes even international processes. Similarly, local community-based approaches will also need to address other system-wide activities like access to markets, seasonal migration as an income diversifying source, and trade that could be important resilience-building activities .
Further description of the efforts at Mitradanga from Chimalaya:
By the time we arrive in Mitradanga it is late afternoon. The sun is beginning to dip over bamboo trellises that trail ripening squash over a mass of water hyacinth. Birds fly low over the surface of the water, black against a peach-pink sky.
It’s a dreamy scene, and I say as much to Shova Biswas, vice-president of the Sonalir Shopnaw (or Golden Dream) forum, who has emerged to greet us. ‘You should see it in the rainy season,’ she says flatly. I have come to the village during the two months of the year when land can be farmed and water is temporarily at bay.
The village sticks out on a thin raised finger of land surrounded by water, close to the Modhumoti river. Located on the intertidal floodplains of south-central Bangladesh in Gopalganj district, it’s facing a three-pronged attack from water-logging, floods and saltwater intrusion.
Shova picks out some of Mitradanga’s defences from our surroundings. The mudcaked men are climbing up out of paddy fields sown with indigenous deep-water and saline-resistant rice varieties; the ducks waddling into their coops are prodigious layers, whose eggs provide both nutrition and an income to plug the gap left by lower-yielding rice.
Houses and water pumps are mounted on to plinths built high enough to withstand floods for the next 30 years. Alongside them stand huge tanks to harvest salt-free, safe to drink rainwater from the skies.
Shova shows us the floating gardens – a strengthened version of traditional models. They are planted with new crops, such as turmeric intercropped with okra, cucumber and chillies.
Is it enough?
Chimalaya has an article – Ready or not: Can Bangladesh cope with climate change? Excerpts:
Major international organizations made the switch to ‘resilience’ from disaster management some years ago. CARE , Plan, Red Cross, Practical Action, Oxfam, Christian Aid, Action Aid and WWF all have ‘climate smart’ frameworks, and all are active in Bangladesh.
Practical Action has built multipurpose flood shelters in the north that lend full-scale protection to livestock and people, and have had huge successes growing pumpkins on sandbars; the United Nations Development Programme is trialing disaster-proof villages, ringed entirely by dykes, with houses mounted on concrete legs. Environmental challenges also drive great innovation in national NGOs. Shidhulai Swanirvar Sangstha has built a fleet of floating, solar-powered schools. Another outfit sails along the coast offering hospital services.
Bangladesh is awash with climate adaptation projects. But I am left wondering: what makes for success? And how do you know when you see it? In the capital Dhaka, I track down Bangladeshi scientist Saleemul Huq, leading climate adaptation expert, and author for the UN Intergovernmental Panel on Climate Change (IP CC).
The theory is, of course, that if you are well prepared you will suffer less. ‘In many ways Bangladesh is better adapted than even the US,’ he says. ‘Take Hurricane Katrina. That’s a technologically advanced and rich country watching the thing coming but not being able to protect its own citizens – particularly the poorer citizens.
‘I’ve been working on adaptation for the last 10 years in the Least Developed Countries of Africa and Asia, and Bangladesh is several steps ahead of anybody else.’
Bangladesh has certainly played its hand well on the international stage. Politicians have eloquently challenged Western nations to open up their borders to refugees. They write hardhitting op-eds in leading broadsheets and lay responsibility squarely at the feet of polluting nations. And they are at the front of the queue when it comes to adaptation funding.
Only, until now, very little has materialized – $18 million to be precise. Most of the money coughed up by industrialized nations has gone to large economies like China and India to finance ‘mitigation’ in the form of energy efficiency (translation: slightly less polluting coal-fired power stations than before).
The villagers have a solution. ‘Stop air pollution and give us financial help to survive this,’ they say. It resonates with UN climate negotiations: stop damaging, pay for the damage.
Shova has another suggestion: ‘Take us to your country if it gets bad here.’ Evan Sarkar prefers Canada: ‘They’ve got more space.’
Crop production is predicted to decrease by up to 32 per cent by 2050, by which time there will be an extra 130 million mouths to feed.
Bangladesh’s problem is primarily one of population – a very large and growing population with demands to feed more and more people places more people in the most flood – vulnerable regions (also most fertile)as they attempt to eke more productivity out of their limited land.
Climate change is a small part of their current problems, but but the Bangladeshis are concerned about future alarming prospects for their country – whether or not these concerns will be realized, remains to be seen.
Big engineering projects are often ineffective and sometimes do more harm than good; the approach being taken by the Dutch-Bangladesh consortium seems like a good one.
Bangladesh has been quite effective at playing the international aid game, which is now largely torqued from general development aid into climate-related aid – mitigation, adaptation, and reparations. Two points here: mitigation funding (largely going to China) is directly competing with adaptation aid, that is serving humanitarian and development needs that exist now. In terms of ‘bang per buck’, I suspect that that the adaptation funding, if wisely used, is money that is much better spent.
The adaptation measures being taken in Mitradanga are fascinating; not only are they effective, but they actually make sense in context of the local culture. The rest of the world can learn something from Bangladesh.