What is the purpose of a "drainage swale"?

A drainage swale is specifically designed to manage stormwater runoff effectively. This shallow, vegetated channel conveys surface water and allows it to infiltrate into the ground, reducing the amount of water flowing directly into storm drains or other drainage systems. The vegetation in the swale helps to filter pollutants from the runoff, stabilizes the soil, and promotes groundwater recharge. This functionality is critical for managing stormwater in a manner that minimizes flooding and protects water quality.

In comparison, while a channel designed for landscaping purposes or a decorative feature along roadways may look appealing, they do not serve the integral function of controlling and managing stormwater. Additionally, a solid barrier for protecting traffic from flooding does not facilitate drainage but instead may exacerbate runoff issues by obstructing water flow. Therefore, the primary role of a drainage swale is to provide an environmentally friendly approach to stormwater management, making the second option the most appropriate answer.