The new report, "Green Infrastructure: Lessons from Science and Practice" evaluates and begins to address green infrastructure information needs. The report is intended to help researchers identify and overcome information gaps, and as a resource for managers determining the most appropriate green infrastructure designs for their landscape and climate.
Green infrastructure is an emerging engineering approach used to address stormwater and water quality challenges in urban areas using cost-effective technologies, which also provide environmental, social, and economic benefits.
Despite the growing interest in green infrastructure for stormwater management, information is limited on its design, implementation, operation and performance.
The limited information available indicates that there are substantial differences in function and performance among different green infrastructure designs.
Bioretention cells, green roofs and porous pavement provided the most stormwater loss benefit.
Swales , detention ponds and media filters were not effective at water removal, but accomplish stormwater management by providing additional stormwater storage capacity.
The importance of considering site-specific performance of different technologies was underscored by the outcome that average retention performance differs more by sites than by events within a given green infrastructure technology.
The water retention capacity of bioretention cells and green roofs can be diminished under cold season conditions, but given appropriate design and operation, green infrastructure can still process stormwater effectively during winter conditions.
Green infrastructure technologies can also remove contaminants in stormwater. Virtually all green stormwater technologies are effective at removal of suspended solids, with mean removals ranging from 71% for bioretention cells to 33% for wetlands.
Bioretention cells, media filters, detention ponds and retention ponds retain modest quantities of total nitrogen and total phosphorus. In contrast, swales, porous pavement, wetlands and green roofs retain minimal quantities of these nutrients, with some systems releasing quantities to downstream water, likely due to the application of fertilizer to biological systems.
Stormwater structures do not seem to retain chloride, but the do generally effectively retain the trace metals lead and cadmium.
Key factors enabling the adoption of green infrastructure programs include:
- Strong local leadership and entrepreneurship
- Collaboration with multiple and diverse community groups and stakeholders
- Learning from the experiences of other green infrastructure adopting communities
- Consideration of social benefits related to green infrastructure technologies
Barriers that discourage the adoption of green infrastructure programs include:
- Concern about cost-effectiveness, including operation and maintenance costs
- Lack of interdepartmental coordination and funding
- Inadequate technical capacity and expertise