L10_GI

Green Infrastructure Overview

• Definition: Cost-effective, resilient approach to managing wet weather impacts, providing various community benefits.

• Contrast with Gray Infrastructure: Single-purpose, conventional systems (e.g., piped drainage) move urban stormwater away, while green infrastructure treats it at the source.

• Benefits: Environmental, social, and economic advantages from green infrastructure implementation.

Importance of Urban Stormwater Management

• Combined Systems: Urban areas often have combined sewer systems leading to overflow.

• Pollution Loading: Increased costs of solving issues with conventional engineering solutions prompts the need for green infrastructure.

• **Key Solutions: **Reduce stormwater quantity and slow its flow.

Features of Green Stormwater Infrastructure

Single Feature Installations

• Downspout Disconnection: Redirect roof drains to rain barrels or permeable surfaces.

• Rainwater Harvesting: Collection for later use, diminishing run-off especially in arid regions.

• Permeable Pavement: Allows rainwater infiltration and is cost-effective in high land-value areas.

• Green Roofs: Vegetated layers that allow rainfall infiltration and evapotranspiration.

• Detention Basins: Temporarily hold runoff before slowly releasing it.

• Raingardens: Vegetated basins collecting and absorbing runoff.

• Planter Boxes: Space-efficient solutions for runoff absorption in dense areas.

• Bioswales: Vegetated channels filtering stormwater while moving it between areas.

Green Roofs

Characteristics

• Extensive Green Roofs: Low-growing, lightweight, minimal maintenance; ideal for stormwater management.

• Intensive Green Roofs: Requires more structural support, accessible, and provides aesthetic benefits.

Benefits of Green Roofs

• Cooling Benefits: Reduced roof membrane temperatures and minimized heat flux in buildings.

• Runoff Impact Assessments: Varied impacts depending on seasons.

• Plant Contributions: Provide shading, enhance evapotranspiration, and contribute to building insulation.

Pollution Control

• Air Quality Benefits: Green infrastructure contributes to decreasing pollution in urban street canyons through enhanced deposition rates via vegetation.

• Design Considerations: Mixing heights and rough surfaces are crucial for improving air quality by dispersing pollutants.

Multifunctionality of Green Infrastructure

• Integrated Functions: Combines ecological, social, and economic benefits unlike isolated green spaces.

• Limitations: Small spaces may not provide for intense recreation needs or extensive habitats.

Strategic Planning of Green Infrastructure

• GIS-Based Approaches: Involves criteria such as stormwater management, air quality, and urban heat effects.

• Equity Considerations: Ensuring benefits accrue to all neighborhoods, particularly underserved communities.

Study Review Points

• Understand definitions, types, and goals of green infrastructure, emphasizing multifunctionality.

• Describe the influence of green roofs and walls on water, air, and energy dynamics in the city.

• Identify various Green Stormwater Infrastructure features and their applications in urban settings.