What is an Impervious (or Impermeable) Surface?

When we talk about urban planning or environmental conservation, you might hear the term “impervious surface.” So, what does it mean? Simply put, an impervious surface is any surface that does not allow water to pass through it. Think of it as a barrier that keeps rainwater from soaking into the ground.

Common examples of impervious surfaces include asphalt roads, concrete sidewalks, and roofs. These materials are great for constructing durable infrastructure, but they have a downside: they prevent water from naturally infiltrating the soil. This can lead to problems like increased runoff and flooding, as well as reduced groundwater recharge.

Why Should We Care?

1. Flooding: When it rains, water can’t seep through impervious surfaces and ends up running off into storm drains. This can overwhelm drainage systems and cause flooding, especially in urban areas with lots of concrete and asphalt.

2. Water Pollution: As runoff flows over impervious surfaces, it picks up pollutants like oil, grease, and heavy metals. This polluted runoff eventually makes its way into rivers and lakes, harming aquatic life and affecting water quality.

3. Heat Island Effect: Impervious surfaces absorb and retain heat, which can raise temperatures in urban areas. This phenomenon, known as the "heat island effect," makes cities hotter than surrounding rural areas.

Real-Life Examples

1. Green Roofs: In cities like Portland, Oregon, green roofs are becoming popular. These roofs are covered with vegetation, allowing water to be absorbed and reducing runoff. They also help to cool buildings and improve air quality.

2. Permeable Pavements: Some cities have started using permeable pavements, which allow water to flow through the surface and into the ground. This technology is used in parking lots and sidewalks to reduce runoff and manage stormwater more effectively.

3. Rain Gardens: In places like Minneapolis, Minnesota, rain gardens are used to capture and absorb rainwater. These gardens are planted with native plants and designed to slow down and filter runoff, preventing it from reaching storm drains.

How Does This Fit Into Our Self-Sustainable City Project?

In our self-sustainable city project, managing impervious surfaces is crucial. We incorporate permeable materials for driveways and walkways to allow water to naturally seep into the ground. This helps reduce runoff, prevent flooding, and support groundwater recharge. Additionally, green roofs and rain gardens are integral parts of our design, contributing to a healthier, more resilient urban environment.

What do you think about the impact of impervious surfaces on our environment? Have you seen any innovative solutions in your area? Share your thoughts or ask questions in the comments below!