Climate change is fueling more intense weather and compounding the impact of hazards that communities are dealing with already, such as flooding and heat waves. Aging infrastructure and stronger, more frequent storms are a rising challenge to communities around the globe as they seek to rapidly adapt to a changing world. This “new normal” is constantly testing traditional ideas on hazard mitigation and how communities recover from natural disasters.
Knowing that every $1 spent on mitigation at the local level saves $6 on recovery efforts , communities are looking for economically viable mitigation solutions.
Projects that restore and/or emulate natural systems to increase human, ecosystem, and infrastructure resilience to climate impacts - often referred to as Green Infrastructure or Nature-based Solutions (NBS) - can reduce damage from natural hazards as well as (or better than) traditional engineered projects, often at less cost.
In its simplest terms, green infrastructure is an approach to stormwater management and flood mitigation that provides areas for water to soak into the ground, or evaporate back into the air, rather than forming runoff and leading to flooding.
Nature-based solutions refer to managed landscape strategies designed to mimic nature by creating holistic and integrated solutions that provide essential services like a clean water supply, drought mitigation, and flood control. Research shows that nature-based solutions can provide more co-benefits to a community than traditional forms of gray infrastructure, while also reducing overall costs to build and maintain over the life of the system.
In the past, the main goal of managing stormwater was to drain it as quickly as possible. With the advent of Low Impact Development (LID) and Green Infrastructure (GI), rainwater is treated as a resource and not as a waste product. This approach reduces the impact of development on receiving streams and on increasing flood risk.
As communities historically developed, the number of impervious surfaces such as roads, sidewalks, and parking lots within the community increased. These surfaces are referred to as impervious because they do not allow rainwater to soak into the ground. Community flood risk increases as the area of impervious surface increases. Since rainwater falling on impervious surfaces cannot soak into the ground, it must either run off of that surface or collect in low-lying areas.
LID/GI uses natural features and engineered controls to reduce runoff volume through infiltration, evapotranspiration, or rainwater harvesting. For example, stream buffer planting slows down and infiltrates runoff, keeping stream banks stable. Healthy vegetation, groundwater recharge, and wildlife habitat are side benefits that create more livable communities.
KAMM’s LID Information document
Why is There a Need for Green Infrastructure?
Most communities have some type of stormwater collection system comprised of storm drains and pipes. These systems are referred to as grey infrastructure because they are constructed of man-made materials and are engineered and designed to collect water and move rainwater rapidly out of the community. However, these systems are often undersized and outdated compared to the increases in impervious surfaces within the community over time. As these grey infrastructure systems become overwhelmed, they are no longer able to collect additional stormwater runoff. That excess runoff then flows across the surface of the community and collects in low-lying areas, leading to localized flooding.
Stormwater runoff in urban areas is also a major cause of water pollution. As rainwater runs off the ground, it can collect and carry trash, bacteria, and heavy metals. These pollutants are ultimately carried to local streams and rivers. As high volumes of runoff enter local streams, there is also a rapid increase in the water levels in those streams. This increases the impacts of localized flooding, streambank erosion, destruction of property, and in some cases flash flooding. Increases in impervious surface area means that even smaller storm events can lead to flooding because the overall volume of stormwater runoff increases.
Natural infrastructure - These projects restore or use existing natural systems and landscapes (such as forests, floodplains, and wetlands) to increase resilience to climate impacts. Natural infrastructure projects often support habitat restoration as described below.
Urban focus - Nature-based solutions, such as increasing tree canopies, can be incorporated into urban environments to improve resilience to climate impacts such as extreme heat and flooding.
Habitat restoration - Natural habitats preserved or restored to protect biodiversity and improve habitat health can mitigate climate impacts.
Flood prevention - Nature-based solutions can help mitigate flooding cost-effectively by absorbing and reducing runoff.
Water quality - Nature-based solutions that reduce runoff and increase filtration minimize pollution and improve water quality. In addition, clean water improves the effectiveness of nature-based solutions along riverine areas, which allows the solutions to better support climate adaptation and mitigation.
Pollution abatement - Several types of pollution, especially air, water, and soil pollution, can be reduced through nature-based solutions. Pollution abatement with nature-based solutions, such as planting and maintaining trees and enhancing soil quality, also serves as a mechanism for climate adaptation (i.e., water storage) and mitigation (i.e., carbon sequestration).
Disaster mitigation - Nature-based solutions aid in disaster mitigation by helping communities prepare for, cope with, and recover from disasters, including slow-onset events such as droughts.
Nature-based Solutions Approach
Nature-based solutions are locally appropriate, cost-effective practices that mimic or support natural processes (like restoring floodplains to help store excess flood waters) while simultaneously providing economic, social, and environmental benefits.
Why take a nature-based approach?
With the increase in frequency and duration of severe weather events becoming the new normal, communities are facing growing pressure to develop strategies that protect vulnerable populations and infrastructure from flooding and other water quantity issues.
Extreme rain events can exacerbate runoff of water quality-degrading pollutants, such as sediments and nutrients. Nature-based solutions that provide filtration of pollutants from stormwater runoff may also slow quick flowing water and improve water infiltrating into the soil, thereby reducing erosion and flooding while simultaneously protecting water quality and controlling water quantity.
By supporting the natural sponge-like function of soil, for example, such actions can also help combat drought conditions by maintaining moisture in the ground.
Living shorelines, restored wetlands, reforestation projects, and green (vegetative) roofs are just a few examples of nature-based solutions. They provide multiple environmental, economic, and social benefits, including carbon sequestration, which is a key tool for reducing greenhouse gas emissions.
Key Terminology
Nature-based solution: locally appropriate, cost-effective actions that mimic or support natural processes while simultaneously providing economic, social, and environmental benefits.
Green Infrastructure: a type of nature-based practice that uses natural hydrological processes and natural elements such as soil and plants to capture stormwater and reduce flows to sewer systems or to surface water.
Low-impact Development: a planning and design approach to manage stormwater runoff using green infrastructure.
Co-benefit: shorthand for “collaborative benefit”, which are the multiple, sometimes multidisciplinary, benefits that arise from a singular practice
Ecosystem service: benefits people obtain from ecosystems (e.g., food, water, oxygen)
Ecosystem-based management: an integrated management approach that considers the multiple and varied interactions within an ecosystem
Hazard Mitigation Plan: federally mandated plan that aims to abate and prevent the impact of natural hazards, like floods, drought, tornados, and mudslides
Community Rating System: a voluntary, incentive-based community program that recognizes, encourages, and rewards local floodplain management activities that exceed the minimum standards of the National Flood Insurance Program
Watershed Management Plan: flexible framework that addresses water quality issues in each watershed
Green Infrastructure Examples
Green infrastructure - Typically, green infrastructure is a built or engineered solution such as a green roof or bioswale. See examples below.
Downspout disconnection - This simple practice reroutes rooftop drainage pipes from draining rainwater into the storm sewer to draining it into rain barrels, cisterns, or permeable areas. It can be used to store stormwater and/or allow stormwater to infiltrate into the soil.
Rainwater harvesting systems collect and store rainfall for later use. When designed appropriately, they slow and reduce runoff and provide a source of water. This practice is particularly valuable in arid regions, where it could reduce demands for increasingly limited water supplies.
Rain gardens are versatile features that can be installed in almost any unpaved space. Also known as bioretention, or micro-bioretention cells, these shallow, vegetated basins collect and absorb runoff from rooftops, sidewalks, and streets. This practice mimics natural hydrology by infiltrating, evaporating, and transpiring stormwater runoff.
Utilizing Rainwater and Gravity: A Guide to Rain Gardens
Bioswales are vegetated, mulched, or xeriscaping channels that provide stormwater treatment and retention as it moves from one place to another. Vegetated swales slow, infiltrate, and filter stormwater flows. As linear features, they are particularly well suited to being placed along streets and parking lots.
Permeable Pavement infiltrates, treats, and/or stores rainwater where it falls. It can be made of pervious concrete, porous asphalt, or permeable interlocking pavers. This practice could be particularly cost effective where land values are high and flooding or icing is a problem.
Green roofs are covered with growing media and vegetation that enable rainfall infiltration and evapotranspiration of stored water. They are particularly cost-effective in dense urban areas where land values and stormwater management costs are likely to be high.
Urban tree canopy – Trees reduce and slow stormwater by intercepting precipitation in their leaves and branches. Many cities have set tree canopy goals to restore some of the benefits of trees that were lost when the areas were developed. Homeowners, businesses and community groups can participate in planting and maintaining trees throughout the urban environment.
Planter Boxes are urban rain gardens with vertical walls and either open or closed bottoms. They collect and absorb runoff from roofs, sidewalks, parking lots, and streets and are ideal for space-limited school sites in dense urban areas.
EPA: Soak Up the Rain
Resources for Residents:
What You Can Do
Disconnect Downspouts
Green Roofs
Permeable Pavement
Rain Barrels
Rain Gardens
Trees
EFCN’s Green Infrastructure Webinar: Green Infrastructure 101
Green Infrastructure is critical to addressing urgent and interrelated water, wastewater, and stormwater infrastructure challenges. GI has not, however, been widely adapted in U.S. municipalities - particularly in small, rural, and tribal communities - due to political barriers, misconceptions, and lack of knowledge or resources to successfully implement GI. In this introductory webinar, we kick off our 10-part series with an overview of basic GI concepts, terminology, and funding sources; as well as challenges and opportunities facing communities and practitioners in the field of GI.
View Recording
Presentation Slides
Integrated Asset Management Framework: Combining Green and Gray Assets
Green Stormwater Infrastructure Maintenance and Contractor Coordination – Manual & Video Series
Bernalillo County Passive Rainwater Harvesting Guide
Nature-Based Solutions, Climate Change & Future Conditions
BRIC and FMA Program Webinar Series | July 28, 2021
BRIC FY21 Climate Webinar 7.28.21
Welcome and Introduction
Kayed Lakhia, AIA, NCARB, LEED AP, CFM, FEMA
BRIC’s Overview on Nature Based Solutions
Camille Crain, FEMA
Climate Change with Future Conditions
Josh Murphy, National Oceanic and Atmospheric Administration (NOAA)
Nature Based Mitigation
Sarah Murdock, The Nature Conservancy
Building Community Resilience with Nature-Based Solutions
FEMA published Building Community Resilience with Nature-Based Solutions . It highlights five key strategies for implementing successful nature-based solution projects to advance natural hazard mitigation and climate adaptation:
- Building Strong Partnerships
- Engaging the Whole Community
- Matching Project Size With Desired Goals and Benefits
- Maximizing Benefits
- Designing for the Future
KAMM’s Nature-Based Solutions in Kentucky Information document
Audio stories: How Thrive New Orleans works to make residents safer with green infrastructure
In a new two-part audio and print series, Eve Abrams, a radio producer, writer and audio documentarian in New Orleans, examines the impact of the climate resiliency and racial equity work of Thrive New Orleans. The stories illustrate how Thrive is creating a pipeline of economic opportunity in the city with its climate resiliency training program and how its work is making residents’ homes and lives safer through green infrastructure. In audio interviews, hear from New Orleans residents and training program graduates about Thrive’s work rebuilding residential landscapes to prevent the devastating consequences of flooding.
Part 1: Working with water
Part 2: Living with Water
Green Infrastructure Wizard Connects Communities to Resources
Green infrastructure uses natural landscapes to manage water and provide environmental and community benefits. EPA’s Green Infrastructure Wizard, or GIWiz, provides access to tools and resources that can support and promote water management and community planning decisions.
GIWiz offers access to a repository of EPA-sourced Green Infrastructure tools and resources designed to support and promote sustainable water management and community planning decisions. The tools and resources available through GIWiz will help analyze problems, understand management options, calculate design parameters, analyze costs and benefits, evaluate tradeoffs, engage stakeholders, and/or develop education and outreach campaigns.
Users can produce customized reports that include links to the resources they want to use.
Step-by-Step Guide to Integrating Community Input into Green Infrastructure Projects
Many communities are turning to green infrastructure to reduce flooding, clean and conserve water, and provide recreational and other benefits. But how can local governments ensure they’re meeting the needs of the community? The Step-by-Step Guide to Integrating Community Input into Green Infrastructure Projects shows how.
The guide provides details and tips to help local governments as they move through the decision-making process in eight easy-to-digest steps. While the guide is directed largely at local governments, it could also be a useful resource for other groups such as community and nonprofit organizations that are looking to implement green infrastructure projects in their communities.
For additional information, visit ELI’s Green Infrastructure Program.
A Guide to FEMA’s Community Rating System for Conservation Practitioners
Nature-based solutions—such as open space protection and wetland restoration— can effectively reduce flood risk and are creditable components of the CRS. The conservation community can and should partner with municipalities to plan and design “nature-based solutions” that restore and protect natural areas, reduce flood risk and earn citizens a discount on their flood insurance rate.
Green Infrastructure Maintenance Costs
Green Infrastructure: Cost-effective solutions to flooding
To help communities weigh strategies for reducing flood risks, Headwaters Economics researched green infrastructure solutions with low maintenance costs. These low-cost practices may help communities use existing land assets to protect public infrastructure, private property, and lives. The cost estimates are based on industry-standard unit costs for construction in the Midwest. Geographic variability in construction costs and inflation will affect which solutions are ultimately the most cost-effective.
Communities can use maintenance cost data to help evaluate potential green infrastructure projects. Understanding long-term costs can be especially important when the maintenance of green infrastructure will require interdepartmental collaboration.
2022 GI Maintenance Costs
Recommendations
Communities may also consider the following recommendations:
1. Consider hybrid green-grey projects. For example, rain gardens can slow down stormwater and provide access to subsoils for water to seep into while also diverting excess water to grey infrastructure such as gutters to reduce the risk of localized flooding.
2. Incentivize green infrastructure through regulations and redevelopment. Stormwater management plans, standards, and subdivision regulations can inadvertently incentivize gutters and pipes instead of green infrastructure solutions like bioswales. Regulations and ordinances can be modified to prioritize green infrastructure. Communities can also work to incorporate green infrastructure into repair, upgrade, and redevelopment projects. For individuals, local governments can incentivize and provide information to property owners and property managers on lawn and landscaping alternatives that are responsive to the regional climate and weather patterns.
3. Plan for alternative funding streams for maintenance of green infrastructure. The type of skilled manual labor required to maintain green infrastructure is often different than that needed to maintain grey infrastructure. For example, green infrastructure may require annual landscaping crews on staff, whereas grey infrastructure is often maintained less frequently by contract road and construction crews. Communities need to plan for green infrastructure maintenance as an ongoing expense that requires a steady revenue stream, as opposed to planning for large capital expenditures for grey infrastructure maintenance. Programs that incentivize community monitoring of various types of green and grey infrastructure can support accounting for maintenance as a regular expense. The National Flood Insurance Program’s Community Rating System is an example of a program that incentivizes this work.
4. Adapt and re-use community assets. Property prone to flooding can be a great place to install green infrastructure. Green infrastructure can help reduce flood risk from localized stormwater management to an interconnected stream-side system. In cases where local governments have acquired low-lying land via property buy-outs and restrictive covenants limit redevelopment, green infrastructure can create a park-like asset out of a neighborhood eyesore.
5. Enhance wildlife habitat in public spaces and parks with green infrastructure. The diversity of native plants and improved water quality can support habitat connectivity to facilitate wildlife movement, nesting, food, shelter, and shade; increase wildlife viewing opportunities, and help reduce the urban heat island effect by lowering temperatures. Communities can use tools like Neighborhoods at Risk to identify locations where green infrastructure would help combat urban heat and mitigate flood risk for the most vulnerable populations.
Green Infrastructure & Managing Flood Risk
Heavy downpours have increased in frequency and intensity worldwide in the last 50 years. They are expected to become more frequent and intense as global temperatures continue to rise. As a result, the risk of flooding is likely to increase dramatically across the United States.
The average 100-year floodplain is projected to increase 45 percent by the year 2100, while the annual damages from flooding are predicted to increase by $750 million. Among the types of flooding that will likely become more frequent are localized floods and riverine floods. Localized flooding happens when rainfall overwhelms the capacity of urban drainage systems, while riverine flooding happens when river flows exceed the capacity of the river channel.
By reducing stormwater runoff and protecting floodplains, green infrastructure can help manage both localized and riverine floods. In areas impacted by localized flooding, green infrastructure practices absorb rainfall, preventing water from overwhelming pipe networks and pooling in streets or basements.
Green infrastructure practices that enhance infiltration include rain gardens, bioswales, and permeable pavements. In areas impacted by riverine flooding, green infrastructure, open space preservation, and floodplain management can all complement gray infrastructure approaches. These practices reduce the volume of stormwater that flows into streams and rivers, protecting the natural function of floodplains, and reducing the damage to infrastructure and property.
Flood Avoidance Green Infrastructure
To address the impacts of excess stormwater, the U.S. Environmental Protection Agency (EPA) evaluated potential scenarios for managing stormwater from new development and redevelopment. The purpose of this study is to examine one of these impacts: flood loss avoidance. This study generated an estimate of the monetary value of flood loss avoidance that could be achieved by using distributed stormwater controls to capture a specified volume of runoff.
This stormwater management approach retains on-site small storm events to simulate predevelopment runoff conditions. This approach is referred to as Low Impact Development (LID) or Green Infrastructure (GI) for stormwater management and is an integrated approach that uses site planning and small engineered stormwater controls spatially distributed throughout a development site to capture runoff as close as possible to where it is generated. In this document, the term Green Infrastructure is used for bioretention filters, landscaped roofs, rainwater cisterns, and infiltration trenches as examples of stormwater controls commonly found in GI applications. These controls infiltrate and evapotranspiration runoff, or capture and store rain for beneficial uses like landscape irrigation and other non-potable uses. The approach in this study considered the application of GI only to new development and redevelopment, not as retrofits to mitigate the impact of existing imperviousness.
The study approach consists of estimating flood depths and the associated flood losses with and without GI. The benefits are the losses that are avoided by watershed-wide implementation of GI. In this report, the terms “damages” and “flood losses” are used interchangeably. The timeframe of analysis is from 2020 to 2040. The extent of GI application assumed for this study is small initially, because the assumption in this study is that GI would be implemented only on new development and redevelopment starting in 2020. The extent of GI application, and the associated benefits, would increase with development over time. Therefore, maximum benefits are realized in 2040, the last year of this study period. At the time of this report, several states have already adopted on-site retention practices; therefore, benefits of wider adoption nationwide are the focus of this study (i.e., the study focuses on areas that have not adopted retention policies to date).
Flood Loss Avoidance Benefits of Green Infrastructure for Stormwater Management
Reducing Damage from Localized Flooding: A Guide for Communities This guide was produced by the Federal Emergency Management Agency to help U.S. cities, towns, villages, and counties reduce damage, disruption, and public and private costs caused by localized flooding within their jurisdictions.
A Flood of Benefits – Using Green Infrastructure to Reduce Flood Risk This report describes how restoration or conservation of forests, wetlands, rivers, and floodplains can reduce flood risk while supporting an array of other benefits.
GI In Community Parks
Green Infrastructure in Parks
Planning for Equity in Parks with Green Infrastructure
From the APA and National Recreation and Park Association (NRPA). Planners and park professionals routinely incorporate green infrastructure principles into the planning and design of public parks. This approach can be a powerful tool to improve the environmental quality of parks, engage and empower nearby communities, and provide social equity benefits.
Resource Guide for Planning, Designing and Implementing: Green Infrastructure in Parks
This Resource Guide for Planning, Designing and Implementing Green Infrastructure in Parks builds on the success of park and green infrastructure initiatives throughout the United States. The 48-page Guide provides basic principles, inspiration, and ideas that can help planners, designers, and decision-makers equitably integrate green. The Guide was developed partnership between the National Recreation and Park Association (NRPA) and the American Planning Association (APA), with support from the Low Impact Development Center Inc. (LID Center), stormwater infrastructure into parks and park systems across the country.
Parks and Green Stormwater Infrastructure | City Parks Alliance
Parks have great potential for green stormwater infrastructure. Green stormwater infrastructure (GSI) manages runoff naturally, reducing flooding and pollution while enhancing urban resilience, creating green spaces, spurring jobs, and improving public health.
WHY GREEN STORMWATER IN PARKS IS A WIN-WIN FOR URBAN RESILIENCE
Additional Resources
Saving the Rain: Green Stormwater Solutions for Congregations
- Educate the congregation
- Identify champions
- Organize working groups
- Partner with local governments
- Identify green infrastructure opportunities at their places of worship
Catalyzing Green Infrastructure on Private Property
The NRDC and the New York University Stern Center for Sustainable Business have released a report with recommendations for stimulating wide spread use of green infrastructure on private property to help reduce stormwater runoff from existing development. The report presents an innovative approach to a large-scale green infrastructure grant program, which can be adapted by cities around the US, which engages the private sector, community-based organizations, and the affordable housing sector.
The report offers ways to leverage green infrastructure retrofit efforts with other local green building and sustainability initiatives. The report is based on over 250 expert interviews, stakeholder meetings, and the work of a NRDC finance analyst working from the offices of the NYC Dept. of Environmental Protection.
Regional Resilience Tool Kit Presentation - EPA released its Regional Resilience Toolkit, for addressing regional resilience planning needs to address hazards from natural disasters and is working with a handful of pilot communities.
Regional Resilience Tool Kit
Two Webcasts: Lessons Learned Integrating Water Quality and Nature Based Approaches for Hazard Mitigation Webinar and Building Resilient Communities with Green Infrastructure and Hazard Mitigation Planning Webcast— EPA and FEMA worked with three regions – Ashland OR, Albany NY, and the Commonwealth of MA – to pilot projects that have successfully integrated watershed planning, green infrastructure practices and source water protection into FEMA hazard mitigation plans.
Including Watershed Planning and Green Infrastructure into State Hazard Mitigations Plans— EPA fact sheet on the four main benefits of integrating planning and resources for getting started.
Strategically Placing Green Infrastructure: Cost-Effective Land Conservation in the Floodplain —This paper estimates the flood damage and costs that can be avoided by preventing development of floodplain parcels in the East River watershed of Wisconsin’s Lower Fox River Basin. The analysis demonstrates how to use a geographic-information-based model to estimate the benefits of green infrastructure in reducing flood damage, compare the benefits to the costs, and target investments to develop cost-effective nonstructural flood damage mitigation policies.
Naturally Resilient Communities
Economic Assessment of Green Infrastructure Strategies for Climate Change Adaptation: Pilot Studies in the Great Lakes Region —This National Oceanic and Atmospheric Administration study assesses stormwater management practices that can help communities reduce flooding by capturing, storing, or absorbing more water from precipitation events.
Planning for Flood Recovery and Long-Term Resilience in Vermont - This report describes strategies that communities can use to become more flood resilient, including:
- conserving land in flood-prone areas
- directing new development to safer areas
- using green infrastructure practices to manage stormwater.
EPA Green Streets Handbook
Green Streets Handbook Released earlier in 2021 is a 116-page handbook from the Environmental Protection Agency (EPA) that provides a systematic process for reducing the impervious surface footprint of public rights-of-ways and associated off-street surface parking areas.
The EPA handbook is intended to assist state and local transportation agencies, municipal officials, designers, stakeholders, and others to select, design, and implement site design strategies as well as green infrastructure practices for roads, alleys, and parking lots.
Link to to Green Streets Handbook.
Resilience Matters: Collective Action for Healthier Communities from Island Press Urban Resilience
Nature-Based Solutions in Kentucky: New Ways to Keep Water and Nutrients on our Farms, in our Garden
Kentuckians can protect downstream neighbors and wildlife by using innovative natural approaches to mitigate floods and prevent erosion. Increasingly, community planners and risk managers transform rural, suburban and urban landscapes into places where stormwater flows into constructed wetlands, vegetated swales, or rain gardens rather than directly into waterways or onto streets. In addition to keeping water close by for future use, diverting rain helps keep soils and associated nutrients in place. As our weather swings between periods of drought and short bouts of intense rain, the need for these kinds of strategies increases. By capturing rainwater and keeping it near at hand, we can help mitigate floods downstream and improve our ability to keep livestock, crops and gardens watered during dry periods. We can also keep soil and nutrients on our farms and in our neighborhoods.
KAMM’s Funding GI Information document