Listen to part of a lecture in an environmental science class. The professor is discussing the role of wetlands in flood control.
Professor: Today, I want to talk about wetlands and their often underestimated role in flood mitigation. You might think that wetlands are just swampy, unproductive areas, but they act like natural sponges. When heavy rain falls, wetlands absorb and store excess water, gradually releasing it over time. This reduces the peak flow of rivers and streams, which helps prevent downstream flooding. For example, in the Mississippi River basin, studies have shown that the loss of wetlands has contributed to higher flood levels. In the 1990s, major floods caused billions of dollars in damage, and part of the reason was that many wetlands had been drained for agriculture or urban development. Conversely, in areas where wetlands remained intact, flood peaks were lower. It's not just about water storage—wetlands also slow down the water's velocity, allowing sediment to settle. This natural process can protect levees and infrastructure. So, preserving wetlands is not only an ecological concern but also a practical strategy for flood management.
❓ 题目 What is the main point the professor makes about wetlands?
A. Wetlands are ecologically valuable but have no impact on flooding.
B. Wetlands help reduce flood severity by absorbing and slowing water.
C. Wetlands are a major cause of river flooding in the Mississippi basin.
D. Wetlands should be drained to prevent flood damage.
✅ 正确答案
Wetlands help reduce flood severity by absorbing and slowing water.
