Development of a framework for the valuation of EcoSystem Services of Green Infrastructure

Abstract

With the rapid urban growth and development, the quality of green space available is consequently been degrading. Furthermore, many land characteristics have been altered such that the whole water cycle has been significantly changed. Some of the considerable adverse effects occur by these changes include the increase of runoff which can lead to flooding and the poor quality of receiving waters. Therefore, to improve the quality of the prevailing surface conditions whilst managing the stormwater, Green Infrastructure (GI) have been introduced which is becoming one of the promising practices of restoring the natural environment across many countries around the world. The term GI in the literature is commonly referred as Low Impact Development (LID), Best Management Practices (BMP), Sustainable Urban Drainage Systems (SUSD), Water Sensitive Urban Design (WSUD) and Low Impact Urban Design and Development (LIUDD) in different contexts (Eliot and Trowsdale, 2006). GI in broader terms can be defined as an "interconnected network of green space that conserves natural systems and provides assorted benefits to human populations" (McMahon and Benedict, 2006). GI can be grouped into two main categories structural and non-structural. The former include green roofs, rainwater tanks, wetlands, bio swales, pervious pavement, stormwater detention systems, planter boxes, cisterns, rain barrels and downspout disconnection amongst others. Nonstructural GI is designing the buildings or roads to minimize the imperviousness, improvement of the infiltration ability of soils by amending the properties and improving the vegetation of specific site or region. (Eliot and Trowsdale, 2006) Though GI is best known as an alternative to conventional stormwater management strategies, it has been proven that apart from managing stormwater GI can provide a wide range of benefits known as Eco-system Services (ESS) (CNT, 2009). Such benefits include reducing Urban Heat Island (UHI), improving air quality, saving the energy, climate change and adaptation, improving habitats and community livability amongst others. Currently, different countries across the world are committing investments on promoting the benefits of having GI within their communities and therefore it is very important to have a comprehensive study on the value of the ESS they can provide. Such holistic assessment will demonstrate to stakeholders as well as the general public that the application of GIs not only a stormwater management strategy but have many social and environmental benefits. Furthermore, when these benefits can be transferred into monetary value then wider community will appreciate the importance of GI implementation in their society.ESS of GI in six main initial categories. They are water, energy, air, UHI, climate change and community liveability. The ESS of GI can be studied in terms of environmental, economic and social benefits. Since the representation of benefit of each of the ESS in monetary terms can concentrate the results in to a final common resource unit, the economic benefits of these practices can produce are used for the cumulative valuation in the framework development. The valuation is done by using formulas adopted by different researchers in previous studies and applied for the conditions in Melbourne Australia. Melbourne is the second largest city in Australia with a highest rate of urban growth. Due to this scenario the green space available within the area is alarmingly degraded by creating the importance among professionals and government bodies in developing new ways to improve the region's natural environment. Therefore, the aim of this project is to develop a framework for valuing ESS of GI for Melbourne, Australia. The framework is then applied to a hypothetical case study with a green roof area of 300 square meters considering rainfall, temperature, and pricing for utilities in Melbourne area. The results of the ESS assessment indicates that a green roof located in Melbourne can approximately reduce 93 kiloliters of rainfall runoff per year and provide an economic benefit of 1245 AUD per annum by considering its energy, air quality and climate change benefits.