PREVENTING FLOODS1 IN CITIES
In recent years, cities all over the world have suffered badly from the effects of climate change. One of the worst effects is the powerful storms that can occur at any time of the year. Huge amounts of rain fall in a very short time, causing serious floods. As a result, cities are left without electricity for days or weeks, homes and businesses are destroyed, and lives are endangered2. According to experts, as climate change continues, storms will become more frequent and bring even greater amounts of rain.(lines 1–6)
Cities normally rely on drains3 to carry all the rain away from the streets. However, the drains are not built to cope with enormous amounts of rain that suddenly fill the streets. "Sometimes you get the amount of rain of several weeks in only a few hours," says engineer Anna Cooper. "And when rain cannot flow into the drains, it has nowhere else to go. This is because pavements4 and roads in most cities are made from concrete5 and asphalt6. These surfaces prevent rain from passing through them into the earth below, and the water that remains on them floods the streets and buildings."(lines 7–13)
Cities have therefore begun to use more effective methods of removing rain from the streets. One such method is to build roads and pavements using new materials7 with tiny holes in them. Through these holes, water can flow down into the earth below. "Today many cities are digging up old asphalt and concrete surfaces, and replacing them with the new materials," says Cooper. "This means that roads are closed for weeks or even months. Obviously, residents8 hate the noise, the dust and the traffic jams. But they know that when the work is finished, they'll be better protected against a very serious risk."(lines 14–20)
Some cities are also planting "rain gardens" – gardens that are specifically designed to absorb large amounts of rain quickly. Cities such as Portland in the USA have planted gardens in all available spaces. Other cities, such as Wuhan in China, use another method to achieve the same goal: They have covered the roofs of many buildings with earth and planted grass there. "All these 'green' roofs and rain gardens also attract birds and insects and help them survive in the urban environment," says Cooper. "And of course, green spaces are beautiful. So residents not only get greater safety but can also enjoy their city more."(lines 21–27)