This blog post was written by Mikala Newsom as part of the Spring 2018 UGA Urban Ecology class.
As watershed health continues to decline with increasing urbanization and population growth, it is necessary to adjust infrastructure in order to mitigate water quality issues. (Tolbert & Hanson et al. 2012) Currently, gray infrastructure is mainly used when dealing with water distribution and how it is transferred from human facilities back into the environment. Gray infrastructure been practiced since the industrial revolution and is the traditional way of building, which normally involves materials like steel and concrete (Tolbert & Hanson et al. 2012). These materials used are impervious, meaning that water cannot penetrate through it. Water must then go around it, which can lead to unequal water distribution and higher levels of runoff. If there are large storms events, flooding can occur since the water cannot be absorbed into the ground and must pass over this infrastructure. Due to this, the runoff can easily pick up contaminants on the way such as litter, excess nutrients, and oils and therefore polluting watersheds. This reason this type of infrastructure is more commonly used is because it is relatively cheap, easier to construct, and has been the norm for over a hundred years (Alberta Water Portal Society et al. 2017).
Within the past 40 years, a more sustainable approach to infrastructure that has risen is known as green infrastructure (Firehock et al. 2010). With increasing popularity, more are questioning in what ways is green infrastructure a better alternative to traditional gray infrastructure in relation to improving water quality and the health of watersheds. This type of infrastructure aims to mimic the natural environment and creates the least disruptive impact on water distribution and quality. For example, natural materials such as plants are used in this infrastructure to absorb water and reduce flooding. Permeable concrete was created to allow penetration of water into the ground rather than pooling polluted runoff on surfaces such as asphalt. Green spaces can be found in many different cities all over the world and can not only help with decreasing the chances of flooding by groundwater absorption, but also becomes a recreational area for the use all members of the community. The ecological footprint of green infrastructure is also notably less than gray infrastructure because it incorporates factors of the natural environment into building. This as an effect lets natural steps of the water cycle occur with minimal interruption (Ranjha et al. 2016).
Green infrastructure plan. Photo Credit: EPA
The more natural and renewable resources that can be used in infrastructure, usually the cheaper and more beneficial to the environment it will be (EPA et al. 2014). Green infrastructure can save energy, time, and resources. For example, green roofs are starting to be more commonly used. Green roofs are gardens that are planted on top of residential or commercial buildings that use plants to absorb rainfall and lessen the amounts of water and contaminants that normally come off of roofs. Rain barrels are also used frequently on top of buildings, as well as in residential backyards. They collect water from rain events which is then used to water plants or lawns. This decreases total water usage and increases the amount of water that can remain in ecosystems. Some of the materials used in the building of green infrastructure are completely renewable, such as plants. For example, certain plants known to filter water are placed in rain gardens located in areas where heavy volumes of water pass through and can effectively increase the quality of that water before it reaches the watershed (Ranjha et al. 2016). This is much cheaper than having a treatment plant clean the water before allowing it to go back into the watershed system (EPA et al. 2014).
Proctor creek rain garden runoff buffer. Photo Credit: Elizabeth Wilkes
Green infrastructure has multiple benefits that have been known to increase watershed health and overall water quality within communities (Tolbert & Hanson et al. 2012). In Syracuse, NY, a program called “Save the Rain” was created which involved over 180 green infrastructure projects in combined sewer watershed basins. This has saved the city 122 million gallons of water so far. They used infrastructure such as green roofs, green spaces, permeable concrete, rain gardens, and placing stormwater cisterns throughout the city. This has decreased the overall water usage and helped to increase the health of surrounding watersheds.
As previously mentioned, a type of green infrastructure is permeable surfaces, such as permeable concrete. This not only helps naturally direct water back into the ground, but majorly decreases flooding occurrences due to more natural absorption. Absorption of water through the ground, rather than straight to larger waterways, filters the water as it penetrates through the soil and moves down to the water table. This process decreases contaminants and excess nutrients in runoff water. This can be vastly important in areas like Atlanta, GA which uses combined sewer systems and often has sewage stormwater overflows that can potentially harm the water quality and health of watersheds. In Atlanta, rain gardens and transforming areas into green spaces have been a few ways the community has used green infrastructure to deal with flooding and protecting their watershed health. Many cities have already begun to instill the usage of green infrastructure, and many some places now receive funding to do so because of the environmental and economic benefits (Hirsch et al. 2017). In all, there are many benefits of green infrastructure, and the health of our watersheds will soon begin to greatly rely on it.
Proctor creek rain garden. Photo Credit: Gabby Gravel
References:
Alberta Water Portal Society. (2017). Introduction to green infrastructure and grey infrastructure. Retrieved from https://albertawater.com/green-vs-grey-infrastructure
Environmental Protection Agency. (2014, February). The economic benefits of infrastructure. Retrieved from https://www.epa.gov/green-infrastructure/economic-benefits-green-infrastructure-case-study-lancaster-pa
Firehock, Karen. (2010, January). A short history of the term green infrastructure and selected literature. Retrieved from http://www.gicinc.org/PDFs/GI%20History.pdf
Hirsch, Jennifer. (2017, October 25). The hidden power of equity in sustainable buildings. Retrieved from https://livingbuilding.kendedafund.org/2017/10/25/equity-petal-sustainable-building-georgia-tech/
Ranjha, Shikha. (2016). Green infrastructure: planning for sustainable and resilient urban environment. Retrieved from https://sustainabledevelopment.un.org/content/documents/95599_Ranjha_Green%20infrastructure_planning%20for%20sustainable%20and%20resilient%20urban%20environment.pdf
Tolbert, J. & Hanson, C. (2012, June 19). Green vs. Gray Infrastructure: When Nature Is Better than Concrete. Retrieved from http://www.wri.org/blog/2012/06/green-vs-gray-infrastructure-when-nature-better-concrete