Green infrastructure, also known as Low Impact Development (LID) and Natural Infrastructure, includes rain gardens, porous pavement, green roofs, parks, bio-swales, and rainwater harvesting. Green infrastructure addresses stormwater pollution by capturing rain on or near where it falls, preventing the rain from carrying runoff from dirty streets to local waterways and oceans, instead storing the rain or allowing it to naturally filter back into the ground. These sustainable practices not only restore the health of local waterways, but also beautify neighbourhoods, cool and cleanse the air, reduce asthma and heat-related illnesses and save on heating/cooling energy costs—usually at the same or lower cost than a purely “traditional” gray infrastructure solution. UBC Innovations in Stormwater Management Video Series introduces the emergence of innovative designs and approaches to urban stormwater management using green infrastructure focusing on property level, neighbourhood level and watershed level scales.
Green infrastructure and LID
Green infrastructure and LID imitates the natural hydrology (or movement of water) of the site by managing rainfall where it falls, and uses design techniques that allow infiltration, and that filter, store, evaporate, and detain runoff close to its source. Using these techniques will help to protect and restore creeks, and create a more livable community.
LID practices, such as the examples listed below, offer great potential to help our region manage development and stormwater runoff more effectively. Green Infrastructure and LID can be used in new developments or as part of a re-development project.
Green Infrastructure and LID helps:
- Create areas for infiltration. Rain is able to soak into the ground; soil and plants remove pollutants. Stormwater infrastructure is less burdened, flooding is reduced and creeks have more consistent volume and speed of flow year round.
- Protect the environment. LID techniques help to remove pollutants from stormwater, reduce the overall volume of stormwater, manage high storm flows and help protect water quality in creeks and the ocean.
- Reduce flooding and protect property. Reducing impervious surfaces, increasing vegetation, and dispersing and infiltrating rainwater results in less runoff, reducing the likelihood of flooding from storms.
- Help the economy. Developers and builders can also save money because LID projects in many cases are less expensive to build, saving money on overall development costs and protecting your property.
- Provide cost-effective alternatives to system upgrades. Land developed prior to the 1990s usually provides little, if any, stormwater treatment. In many cases, LID systems, such as bioretention, are much less expensive to use than costly stormwater vaults or land-consuming stormwater ponds.
- Create greener communities. LID projects leave more trees and plants and have less impervious surfaces, which makes for greener developments and communities.
- Increase public safety. One of the hallmarks of LID is “green streets”. Studies show that when vehicle traffic is slowed, there are fewer pedestrian accidents and fatalities.
Rainwater Management Techniques Used in the CRD
Bioretention Ponds & Rain gardens
Planters, rain gardens, bioswales and bioretention ponds are depressed landscapes designed to collect, filter and sometimes convey or detain stormwater. Stormwater has time to drop out sediments and filter back into the ground, akin to the natural hydrological cycle.
Creek Restoration & Naturescaping
Native plants thrive in our climate and rainfall patterns. They rarely need irrigation once established. They need little or no fertilizer or pesticide, which has benefits for stormwater quality. Restoring ditches and creeks or bringing them back out of pipes where they have been buried allows them to perform more naturally when it rains. Restoration even allows us to use some low lying riparian areas for flood storage once again.
The vegetation planted on a green roof and the soil it grows in, absorb rain and reduce the amount of runoff leaving a building site. Green roofs help insulate the buildings below, cool and cleanse the air, provide micro-habitat for birds and insects, and provide attractive spaces for building users and nicer views for those who overlook the roofscape of a town.