The water challenge 3

Dry rice

Farmers around the world are beginning to adopt rice production methods that require less water than the traditional paddy field. Seedlings are planted very young and the ground is kept moist rather than flooded. This not only reduces the amount of water needed to get a crop, but also the fertilizer and pesticide requirement. And it also reduces emissions of methane (a greenhouse gas associated with waterlogged ground) so it’s good for the climate as well as for human health.

Water quality

“I’m trying to improve water quality for 40,000 São Carlos inhabitants. At Universidade Federal de São Carlos, I study organisms in the ecosystem to determine water quality. I focus particularly on macroinvertebrates in sediments, because they are great indicators of the real condition of the water. Based on our findings, the city’s environmental ministry is restoring streams, which is more cost-efficient than treating the water, and prevents disease.” Amanda Baldochi Souza, Brazil

Rainwater harvest

“I designed a prototype rooftop rainwater harvesting system for drinking water using four layers of physical filtration: sand, gravel, sand with aluminium, and sulphate and activated carbon. A chemical filtration layer uses a chlorine gas pump. Finally, UV radiation kills bacteria. My goal is to save more than one fifth of rainwater runoff that would otherwise be wasted. Next I hope to raise the water quality to government standards, and scale things up.” Liu Zhihao, 17, Singapore

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