Listen to part of a lecture in an environmental science class. Professor: Today we're discussing the role of wetlands in flood control. Many people think wetlands are just wastelands, but they serve a critical function. Wetlands act like natural sponges. They absorb excess rainwater and slowly release it over time, reducing the peak flow of rivers during storms. In the 1990s, the Mississippi River experienced devastating floods, partly because upstream wetlands had been drained for agriculture. When we remove wetlands, water moves faster into rivers, causing higher flood peaks. Conversely, restoring wetlands can mitigate flooding. For example, a study in Wisconsin found that a restored wetland reduced downstream flood damage by over 30%. However, wetlands are not a complete solution. They work best when combined with other strategies like levees and floodplain zoning. Also, wetland efficiency depends on soil type and vegetation. Sandy soils drain faster, while clay soils hold water longer. So, when planning restoration, we must consider local conditions. Overall, preserving and restoring wetlands is a cost-effective way to enhance community resilience against floods.
❓ 题目 What is the main purpose of the lecture?
A. A. To explain why wetlands are often considered wastelands
B. B. To describe the role of wetlands in flood control and the importance of their restoration
C. C. To compare different types of soil in wetland areas
D. D. To argue that levees are more effective than wetlands for flood prevention
✅ 正确答案
B. To describe the role of wetlands in flood control and the importance of their restoration