According to the U.S Census Bureau, the urban population, at present, represents 80.7 percent of total U.S. population – densely developed residential, commercial and other nonresidential areas. There are 486 urbanized areas (50,000 or more people) and 3,087 urban clusters (2,500-50,000 people) nationwide. And according to the World Health Organization (WHO), the urban population in 2014 accounted for 54% of the total global population, up from 34% in 1960. Global urban population is expected to grow approximately 1.84% per year between 2015 and 2020, mostly in developing countries.
Increased urbanization and population growth in urban areas has exerted significant demand to expand and enhance water-infrastructure – water supplies, wastewater treatment and urban stormwater management. The characteristics of conventional urban water structure include: centralized and large systems serving large populations; dependency on water supplies from water sources outside urban areas; increasing wastewater generation and treatment; urban runoff discharge to surface waters and wastage; pipe networks providing potable water to consumers; and drainage networks transporting wastewater and stormwater runoff away from population centers. Major consequences of centralized water-infrastructure include surface water pollution, groundwater table decline/saltwater intrusion in urban and coastal aquifers. Furthermore, conventional/centralized urban water-infrastructures are highly energy dependent and consume 4-10% of the nation’s total energy use, mostly from fossil fuel -based sources.
To effectively address immediate and long-term problems of water management in urban areas, a significant need exists for a paradigm shift toward a holistic approach for sustainable water management in urban environments. Sustainable water management can be achieved by incorporating green decentralized water-infrastructure in urban water management. Green Water-Infrastructure (GWI) is defined as small-scale decentralized water systems that integrate locally available water and renewable energy resources for water treatment, water delivery and use at the local level anywhere within and urban environment. Locally available water resources may include captured rainwater (rooftop and other impervious surface runoff), greywater and black water, brackish and salt water. GWI may incorporate advanced small-scale water treatment technologies depending on anticipated water use. Renewable energy resources may include, but are not limited to, solar, wind, geothermal, bioenergy, and micro-hydro power.
In the U.S., at present, efforts are scattered, for both, promoting and implementing decentralized green water-infrastructure. The Green-Water Infrastructure Academy will bring together stakeholders and build partnerships between academia, government, businesses, nonprofits and private citizens in a cohesive fashion in order to promote green water-infrastructure research, education/outreach and implementation in urban environments.