Sand dams: low-tech weapons against climate change -

Sand dams and raised water pumps that dig deeper into the ground were just a couple of the low-tech ways of dealing with the consequences of climate change presented in Nairobi, Kenya recently.
Nearly 500 delegates took time off from the main programme of the annual UN conference on climate change to discuss the importance of preparing for global warming's inevitable effects, including longer periods of drought and more severe flooding.
Such events are inevitable due to the time lag between greenhouse gases entering the atmosphere, and their effects – especially on the oceans (see Ocean heat store makes climate change inevitable.
Gases already pumped into the atmosphere have yet to have their full impact, but some of those effects are now starting to be felt, says Saleemul Huq, director of the International Institute for Environment and Development’s climate change programme, and organiser of the Nairobi “adaptation days”.
It has been five years since Huq first launched the adaptation days. He believes the importance of adapting to climate change is finally gaining a following. Discussions of how to manage an adaptation fund that would finance projects in developing countries are high on the agenda of this year’s UN conference.
Sand dams
Several projects are already in place, many financed by non-governmental organisations. One of these, presented by Jeroen Aerts of the Institute for Environmental Studies in the Netherlands, involves building sand dams in the Kitui district of Kenya.
Sand dams, which are in fact made of concrete, are low walls placed across small rivers that cease to flow in the dry season. During the first two wet seasons of their existence, the space behind them fills up with sand, dragged down from the banks by erosion.
The sand retains 40% of its volume in water, protecting that water from evaporation. Wells are then dug into it, supplying local villagers during the subsequent dry season.
Aerts says there are now about 500 such dams in Kitui. For an initial one-off cost of $35 per person – supplied in materials and engineering support by the NGO Sasol – they keep locals supplied with drinking water year after year.
The idea of the dams goes back more than 2000 years, to the Babylonian era, Aerts explains. It was later picked up by the English who built sand dams in India and Kenya.
Raised pumps
India's local governments are wasting money by not integrating adaptation plans into their development projects, says Courtenay Cabot Venton of Environmental Resources Management, an environment consulting company in London, UK.
Cabot Venton presented an India-based project led by Tearfund, a UK NGO, with Indian partners in the states of Bihar and Andhra Pradesh. Workers there are helping prepare for annual floods which affected 21 million people in Bihar alone in 2004. Among other initiatives, they build water hand-pumps on raised platforms, designed to resist local flooding.
In Andhra Pradesh, which suffers from both floods and drought, the raised pumps also reach deeper into the ground so they do not run out during the dry months.
Cabot Venton says the Bihar government recently installed 30 low-lying hand pumps that were rendered useless at the first floods. By investing a little more money at the start and building higher pumps, the wells would have lasted longer. The cost to recover and repair the damaged pumps led to a government outlay three times greater than it would have cost to build the wells properly in the first place, she says.
Evacuation routes
The cost-benefit analysis Cabot Venton ran looked at how much money Tearfund put into pumps, evacuation routes, lifeboats and other disaster management measures. She then assessed the financial gains of this investment in terms of saved lives, avoided injuries, and tools and equipment that were not lost to the floods.
She estimates that Tearfund’s work resulted in 3.76 rupees of benefit for every rupee spent. “Even by putting in an extra bit upfront, you can get a lot more back in the end,” says Cabot Venton.
Also at the adaptation days, Angie Dazé of CARE Canada described how mountain communities in Tajikistan are using energy efficient stoves that both reduce the amount of fuel that is used and improve heating in schools.
Ranjashami Mohanraj of Bharathidasan University in India discussed efforts to minimise the stresses on the Noyyal river basin, which is suffering from lower levels of rainfall. These included making bricks from the sludge produced by the textile industry instead of dumping it into the river.