Warning: This page is an edit and testing page use by the wiki authors. It is not a content page for the Manual. Information on this page may not be accurate and should not be used as guidance in managing stormwater.

Proposed portal for Green Infrastructure

  • Overview of green infrastructure
  • Stormwater management and green infrastructure
  • Green infrastructure and climate adaptation
  • Enhancing biodiversity with stormwater management
  • Benefit-costs of green infrastructure stormwater management
  • Case studies
  • Green Infrastructure resources
  • Links


Overview of green infrastructure

Green infrastructure is an approach to managing urban wet weather impacts that mimics, restores, or maintains natural hydrology. Green infrastructure includes a wide array of practices, including infiltrating, evapotranspiring, or harvesting and using stormwater. On a regional scale, green infrastructure is the preservation or restoration of natural landscape features, such as forests, floodplains and wetlands. On the local scale, green infrastructure consists of site and neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements and cisterns. Regional and local practices are coupled with policies such as infill and redevelopment that reduce overall imperviousness in a watershed.

This page provides a summary of green infrastructure, including a discussion of urban hydrology and water quality, an overview of green infrastructure practices, and benefits of green infrastructure. Links to other pages in the manual are provided at the end of this article.

Urban hydrology and water quality

schematic illustrating differences in the water budget between forested and urban watersheds
This schematic illustrates differences in the water budget between forested and urban land uses. In forested watersheds, the majority of annual precipitation infiltrates the soil and is subsequently lost to deep percolation or evapotranspiration. In an urban watershed, increases in impervious surfaces result in increasing amounts of water lost as surface runoff. This surface runoff typically discharges to lakes, rivers or wetlands. (Source: University of Washington)

The section called Overview of basic stormwater concepts provides an in-depth discussion of urban stormwater, including it's effects on hydrology and water quality. In a forested watershed, the majority of precipitation infiltrates the soil and subsequently percolates deeper into groundwater or is evapotranspired back to the atmosphere. As urban development increases, the paving of pervious surfaces (that is, surfaces able to soak water into the ground) with impervious roads, shopping centers, driveways and rooftops means less water soaks into the ground and more water runs off. The result is increased runoff volumes, increased peak runoff discharges, greater runoff velocities, increased flooding, increased scouring of streams and streambanks, and less subsurface flow to streams (baseflow). These processes dramatically change the morphology and biology of urban stream systems, to a point where they often can no longer support a viable biologic assemblage.

Water quality is also impacted. The water that washes over these new urban surfaces picks up materials laying upon those surfaces. The sediment from construction erosion, the oil, grease and metals from many automobiles, the fertilizer and pesticides from lawns, and many more new pollutants can adversely impact the receiving waters. There are several nonpoint sources of pollution, each with a distinct set of pollutants of concern. See the section on Pollutant fate and transport in stormwater infiltration systems to learn more about the transport and fate of pollutants in urban stormwater runoff.



Water is continually on the move on, above and below the surface of the earth. This movement is called the water cycle (AKA: hydrological cycle or H2O cycle). The water moves by the physical processes of evaporation, condensation, precipitation, infiltration, surface runoff, and subsurface flow. In doing so, the water goes through different phases: liquid, solid (ice) and vapor. To talk about the water cycle is to talk about:

  • The state of the water - liquid, solid (frozen) or gas (vapor)
  • where it is relative to the surface of the earth - below (ground water), on (surface water), above (humidity)
  • location (city , state, country, named ocean, etc.)

The total amount of water on earth is considered to have been more or less constant for hundreds of millions of years. What is not constant is the amount of water that is liquid, gas or solid that is below, on or above the surface at a particular location. Again in plain language less ice means more liquid water (higher sea levels) and / or more humidity. Pumping out groundwater means more surface water and / or more humidity. There are many scenarios which would illustrate how the balance in the water cycle changes yet the total amount of water on earth does not change.

Water is requirement for all known living organisms. The trick is to the water supporting life is the water has to be of a certain range quality. Fish needs some oxygen to be dissolved in the water to survive. Thousands of species of fish live in the saline oceans but humans cannot survive drinking ocean water because of the saline. Water quality is about the concentration of what is suspended or dissolved in the water. When we talk about water quality it is relative to ability to support various uses of the water. Water is an excellent solvent. The list of things that will dissolve in water is very long. Even many things that don't dissolve in water will suspend in water.

In the past several centuries, man has changed the natural hydrology by adding infrastructure. For example:

  • impervious surfaces such as roads, parking lots, buildings
  • drainage ditches
  • Drain tiles
  • cleared huge swaths of land
    • recreation
    • logging
    • agriculture
  • temperature (climate change)
  • and the like

The result of these activities has adversely affected the water quality and changed the hydrologic balance. The goal of Green infrastructure is to move back to a more natural hydrology while supporting the needs of our civilized world.

This portal has links to numerous articles relating to various aspects of using natural hydraulic methods to preserve and restore good water quality. In other words, this portal is about providing information about the use of green infrastructure.

Conceptually Green Infrastructure is about using natural hydrology and topography to benefit water quality. The articles below should help provide a base of high level information which is in turn linked to more detailed technical information to assist in creating "Green Infrastructure".

Introduction to pre-development hydrology

Introduction to Water quality

Resources

Green infrastructure: Back to basics


Green infrastructure - wikipedia

What is Green Infrastructure? - EPA

Green Infrastructure - Using natural systems to meet environmental challenges in urban, rural and coastal settings

Green Infrastructure Primer

Stormwater management: Low-impact development and green infrastructure


Blue-Green Cities

BlueGreenCities

Blue Green Dream

Sustainable Drain

Stormwater Australia

Save the rain

Professional Practice - Green Infrastructure - American Society of Landscape Architects

Sustainable drainage system

Green Infrastructure - City of Portland Oregon


Green Infrastructure and Climate Change: Collaborating to Improve Community Resiliency

Green Infrastructure, The Conservation Fund



Anne G. thoughts for Green Infrastructure Web Page in Stormwater Manual

Include:


'Definition of GI:' this is what’s in the manual now:

green infrastructure -means a wide array of practices at multiple scales that manage wet weather and that maintains or restores natural hydrology by infiltrating, evapotranspiring, or harvesting and using stormwater. On a regional scale, green infrastructure is the preservation or restoration of natural landscape features, such as forests, floodplains and wetlands, coupled with policies such as infill and redevelopment that reduce overall imperviousness in a watershed. On the local scale, green infrastructure consists of site and and neighborhood-specific practices, such as bioretention, trees, green roofs, permeable pavements and cisterns

Notice all the green call-out boxes for green infrastructure.

'GI BMP’s: '

  • Permeable pavement (link to page)
  • Green roofs (link to page)
  • Harvest and Use (link to page)
  • Trees (link to page)
  • Bioretention (link to page)
  • Infiltration


'GI and Climate Change/Adaptation/Resiliency'

The MPCA’s Stormwater Program has been addressing the issues related to climate change adaptation since 2005 with the first issuance of the Minnesota Stormwater Manual. It advanced the concept of treating water on site, using low impact design, and volume control best management practices (BMPs). Since then, stormwater permits have advanced these BMPs, and MPCA has worked to set goals and quantify credits for using these BMPs through the Minimal Impact Design Standards (MIDS) Project. Consistent with MIDS are BMPs that can increase infiltration and reduce runoff (including green infrastructure like rain gardens, urban forestry/trees, pervious pavement, swales, etc.) Local units of government have traditionally worked to get water off the landscape as quickly as possible. In the last couple of decades, the MPCA has started addressing pollutant and rate control. We are now beginning to address volume control. Volume control, and working to mimic natural hydrology, helps to result in less dramatic runoff events, which reduces stream erosion and scouring. Impervious surfaces are increasing faster than population growth. This increase in impervious surface coupled with larger storm events will have a significant impact on receiving waters. Stormwater capture and reuse is an opportunity to reduce runoff and reap benefits from heavier rainfalls while reducing demands on the potable water supply.

NOAA Atlas 14 updates are being utilized to more accurately reflect precipitation intensities and durations. NOAA Atlas 14 incorporates 50 additional years of data into the estimate of precipitation 27 intensity and durations, and could account for changes that may be related to climate change. These estimates, used as an engineering standard, are vital to ensure proper design of culverts, storm sewers, and water quality devices.

In August 2013, the reissued Municipal Separate Storm Sewer System (MS4) General Permit became effective, which regulates stormwater discharge from counties, cities, townships and other publicly owned entities in urbanized areas. The goal of the MS4 program is to prevent or reduce the discharge of pollutants to stormwater, and ultimately, surface waters. This permit’s provisions will help to address problems of erosion and water pollution associated with heavy precipitation events.

Portfolio of green infrastructure in Minnesota (by region)

Green Infrastructure in schools

'GI and health benefits:'

'GI and sustainable communities:' EPA: Enhancing Communities with Green Infrastructure: https://www.epa.gov/smartgrowth/enhancing-sustainable-communities-green-infrastructure

'Green Streets and Living Streets. City of North St. Paul: http://www.ci.north-saint-paul.mn.us/vertical/sites/%7B5F63881B-2F96-4032-818C-7F4AD3529485%7D/uploads/%7BAF05CD7B-64EC-4FA8-A5BF-55F91637C22A%7D.PDF and City of Maplewood: http://maplewoodmn.gov/1014/Living-Streets


'For municipalities: '

Integrating GI : EPA: GI Opportunities that Arise During Municipal Operations: https://www.epa.gov/sites/production/files/2015-09/documents/green_infrastructure_roadshow.pdf Meet permit requirements with GI:


'GI Costs/Benefits'


GI and brownfield development:


'Link to other reports:' EQB