Module 2: Motivations for the Grey-to-Green Transition
Module 2: Motivations for the Grey-to-Green Transition
Learning Objectives
- Examine the motivations behind green infrastructure systems and their potential for improving urban resilience to climate change and urban development.
It took the absence of forests in upstream areas and the consequent flooding of city streets and properties for scientists and engineers to understand that forests absorb significant amounts of rainfall, slowing its progression towards rivers and stream and transforming intense rainfall events into steady stream flow instead of rushing, erosive torrents. It took the creation of wide swaths of paved surfaces before anyone could measure the difference in temperature between urban areas and their surrounding wilds. It took the drying of wells and the rapid deterioration of surface water quality before we could understand that soils provide natural water filtration, capable of transforming impurities in contaminated surface water into healthy groundwater reserves and stream flows.
The density and infrastructure needs of urban centres make a complete transition to green infrastructure solutions challenging with today’s technology and materials. However GI systems can be strategically and successfully incorporated into existing grey infrastructure systems such as roads, buildings, cisterns, and sewers to augment the services provided by these traditional infrastructure systems. Green infrastructure implementation uses public spaces to greater effect in order to better serve communities and their surrounding environment and GI systems can also be the existing natural areas that provide services to communities which previously may have gone unnoticed. Recognizing these services can help protect these areas and prevent the need for grey infrastructures to replace the services that are lost by damaging them.
The increasing interest in green infrastructure systems has been driven by a variety of issues largely caused by urbanization and the corresponding loss of natural spaces due to conventional development. The concept of a “grey-to-green” transition to describe the growing interest in green infrastructure is helpful to describe the mindset needed for green infrastructure in urban and suburban environments to dismantle or augment hardscape surfaces to make room for natural systems that mitigate for the negative impacts of grey infrastructure impermeability. To date, green infrastructure systems are frequently used to support rather than supplant conventional grey infrastructure, however, the grey-to-green transition represents a shift in how governments at all levels see and manage for the community’s assets and priorities as much as it does a physical transformation of human-occupied spaces. It is the result of a growing recognition that green infrastructure systems have the capacity to replicate and/or augment the services that nature provides and help solve the issues exacerbated by our continued urbanization and the impacts o