การฟัง TOEFL

🎧 บทถอดเสียง

Narrator: Listen to part of a lecture in an environmental science class. Professor: Today we're going to talk about a surprising solution to urban flooding: green roofs. Now, when it rains heavily in a city, the water has nowhere to go because of all the concrete and asphalt. This causes flash floods. Traditional solutions, like building bigger drains, are expensive and often insufficient. However, green roofs—roofs covered with vegetation and soil—can absorb a significant amount of rainwater. In fact, studies have shown that a green roof can retain up to 70% of rainfall during a moderate storm. The plants and soil act like a sponge, slowing down the release of water into the drainage system. This not only reduces the peak flow of water but also filters pollutants. Additionally, green roofs provide insulation, which lowers energy costs for the building. So, while the initial installation might be pricier than a standard roof, over time, the benefits outweigh the costs. Now, some critics argue that green roofs are too heavy and require extensive maintenance. But engineers have developed lightweight materials and drought-resistant plants, making green roofs viable even in arid climates. So, we're seeing more cities adopt this nature-based solution.