what is an impervious surface

3 min read 25-12-2024

Impervious surfaces are any surfaces that don't allow water to penetrate the ground. Instead, water runs off these surfaces, impacting our environment in various ways. Understanding what constitutes an impervious surface is crucial for managing stormwater runoff and protecting our ecosystems.

Defining Impervious Surfaces: What They Are and Aren't

Impervious surfaces are materials that prevent water infiltration into the soil. This contrasts with permeable surfaces like grass or soil, which absorb rainfall. Common examples include pavements, rooftops, and parking lots. The key characteristic is the prevention of water absorption.

Examples of Impervious Surfaces

Paved roads and sidewalks: Asphalt and concrete are prime examples, preventing water from seeping into the ground.
Building rooftops: Most building roofs, regardless of material (shingles, metal, etc.), prevent water infiltration.
Parking lots: Large expanses of asphalt or concrete are highly impervious.
Driveways: Similar to parking lots, driveways made of pavement significantly increase impervious area.
Patios and Decks: Many patio and deck materials are designed to shed water, making them impervious.
Sports fields (artificial turf): While some newer turf systems offer improved permeability, many traditional artificial turf fields are largely impervious.

The Environmental Impact of Impervious Surfaces

The widespread use of impervious surfaces has significant consequences for the environment. Increased runoff leads to several problems. These problems include flooding, water pollution, and ecosystem disruption.

Increased Stormwater Runoff and Flooding

When rainfall hits impervious surfaces, it cannot be absorbed. This leads to increased runoff, overwhelming drainage systems and causing floods, especially in urban areas. The sheer volume of water exceeds the capacity of natural systems to handle it.

Water Pollution

Runoff from impervious surfaces carries pollutants like oil, fertilizers, pesticides, and litter into waterways. This contaminated water harms aquatic life and compromises water quality. These pollutants are picked up as the water flows across these surfaces.

Changes to the Water Cycle

Reduced water infiltration disrupts the natural water cycle. Less water replenishes groundwater supplies. This can lead to decreased base flow in streams and rivers, impacting aquatic ecosystems.

Habitat Loss and Fragmentation

The expansion of impervious surfaces destroys natural habitats. This leads to habitat loss and fragmentation, negatively impacting biodiversity. Wildlife loses its homes and natural movement corridors.

Mitigating the Impact of Impervious Surfaces: Solutions and Strategies

Addressing the negative impacts of impervious surfaces requires a multi-pronged approach. Several strategies can help mitigate these effects. These methods aim to reduce runoff and improve water quality.

Permeable Pavement

Permeable pavement allows water to seep through, reducing runoff and recharging groundwater. This is a valuable alternative to traditional asphalt and concrete.

Green Roofs and Rain Gardens

Green roofs and rain gardens are designed to capture and absorb rainwater, reducing runoff volume and improving water quality. They act as natural filters.

Stormwater Management Systems

Implementing effective stormwater management systems is crucial for managing runoff. These systems can include detention basins, bioswales, and other engineered solutions.

Reduced Impervious Cover

Planning and development should aim to minimize the amount of impervious surfaces. This can involve incorporating green spaces, using smaller lots, and promoting mixed-use development.

Conclusion: The Importance of Considering Impervious Surfaces

Impervious surfaces are a significant factor in urban environmental challenges. Understanding their impact is crucial for developing sustainable urban environments. By implementing effective mitigation strategies, we can minimize the negative consequences of impervious surfaces and protect our valuable water resources and ecosystems. Reducing the impact requires a conscious effort from individuals, developers, and policymakers alike.