Week 9 - Effectivity of Green Infrastructure

It has always been discussing how good green infrastructure is over the last decade.

What is green infrastructure? As defined by US Environmentel Protection Agency, "Green infrastructure is a cost-effective, resilient approach to managing wet weather impacts that provides many community benefits. While single-purpose gray stormwater infrastructure - conventional piped drainage and water treatment systems - is designed to move urban stormwater away from the built environment, green infrastructure reduces and treats stormwater at its source while delivering environmental, social, and economic benefits".

Green infrastructure can exist in various of forms in practice, including green roofs, tree planting, bio-retention & infiltration, permeable pavement, and water harvesting. General public is well aware of the loads of benefits of green infrastructure, including:-
_ The most significant one, reduces urban stormwater runoff, reduce water resource pollution

• Subsequently improves water quality and increases water supply
• Helps to reduce salt use and energy use
• Also improves air quality and reduces carbon dioxide in the atmosphere
• Improves thermal comfort as well as aesthetics for a city
• Also improves community livability, for example, providing more recreational spaces, urban agriculture, and reduces noise pollution

It is a good phenomenon that the general public knows the benefit of a sustainable movement, and most of them are being supportive. However, it makes me to think, that when one thing is being promoted, all the positives will be shown in front of everybody's faces, whilst the downsides are not being revealed to people's eyes. The question is, when we are trying to imply the idea into our living environment, just how effective it is in terms of workability and economics? Let's get real for a moment.

Getting on to the NYC 2010 Green Infrastructure Plan. Some green street in the US has been tested out for the workability of green infrastructure. One particular green street, has a false catch basin to capture excess rainwater and through the perforated pipes to feed  into vegetated area. Water samples has been taken and checked periodically from the pipe, to see if the pollutants have been filtered effectively from the soil and the plants. The result, without any mysteries, is negative. Since the city has been using fast-draining sandy soil in green infrastructures, it adds extra nutritions to the runoff. As well as, the fast draining is reducing filtration time to filter all the pollutants. The extra nutrition, with no doubt, is polluting local water supply. 

Green Street

There should be no surprise with this testing result. When looking through all the promotions of green infrastructure, there are heaps of information of how good it is, yet the negative sides are rarely mentioned. Or, let's not say the negative side, I would call it the "precautions" of implying green infrastructure. Nothing is absolutely good, there are certainly downsides when using it inappropriately. Just like the test on green streets in the US, if using wrong material, even the good move can become worse. 

Therefore, let's take it real. Not saying the idea of green infrastructure is deceptive, just that we all need to be careful in practising the new ideas, do not take everything for granted. 








Resources:
http://blogs.ei.columbia.edu/2013/10/31/just-how-effective-is-green-infrastructure/
https://www.epa.gov/green-infrastructure/what-green-infrastructure
http://www.cnt.org/sites/default/files/publications/CNT_Value-of-Green-Infrastructure.pdf