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Rising to Meet the Challenge; Delaware’s Communities Start a Path Forward to Improving Resiliency

Written on: March 13th, 2020 in OutreachWetland Restorations

Guest writer: Kelly Valencik, DNREC Delaware Coastal Programs

Communities Seeing Shifts in Mother Nature

South Bethany, DE flooding during a Nor'easter in October of 2019
South Bethany, DE flooding during a Nor’easter in October of 2019

Many communities throughout our state have already seen changes as a result of climate change- from shifting rainfall and storm patterns, to increased drought, to flooding from sea level rise. These consequences of the warming earth and ocean temperatures as a result of greenhouse gas emissions have brought long term community planning challenges to Delaware.

For example, residents in the City of Lewes, which sits next to the Delaware Bay in Sussex County, have noticed more and more disruptions to the typical rhythms of nature in their community. Now it’s not just the the big coastal storms or nor’easters that cause flooding issues, it is also the sunny day, strong or spring tides that are inundating sections of main roads that connect the downtown area to the major road arteries.

Other Delaware communities have experienced similar issues and and are looking for ways to tackle these problems now before they get worse, with the ultimate goal to reduce impacts to their residents. 

The Delaware Department of Natural Resources and Environmental Control (DNREC) wants to assist municipalities and communities across the state in becoming more prepared and resilient to any change that currently appears inevitable.

What is Community Resilience?

Community resilience is the ability to plan for and bounce back quickly from hazardous events. In the coastal context, the focus is on planning for more frequent and stronger storms, sea level rise, and other changing climate conditions so that communities are better able to recover when the event occurs.

Communities and local governments in Delaware have the opportunity to be proactive and play a leading role in preparing and responding to the impacts of severe weather and climate change because municipalities largely have the responsibility for planning their own future through land use decisions, building codes and design, and maintenance of infrastructure such as water and wastewater systems. Using these tools, municipalities can be vigilant in protecting and safeguarding people and habitats from harm.

What is Green Infrastructure and how does it Affect Community Resiliency?

Green infrastructure is a nature-based approach to address environmental challenges such as stormwater runoff, coastal flooding, erosion, and water and air pollution. It uses natural processes to manage water and improve environmental quality. These natural processes include using plants and soils to:

  • filter pollutants from surface and stormwater
  • improve infiltration of water into soil and groundwater
  • reduce the volume of stormwater during high-intensity events
  • moderate air and water temperatures by shading and through evapotranspiration by plants

Stormwater and Pervious vs. Impervious Surfaces

Impervious area verses pervious area
Impervious area verses pervious area (Graphic: A Guide to the Drainage Charge)

Stormwater refers to the rainwater that flows off of different surfaces after it falls to the ground. People commonly see stormwater running out of rooftop gutters and along the sides of streets during a rainstorm. The surfaces on which rainwater falls are classified into two categories:

  1. Pervious surfaces – surfaces that allow stormwater to seep into the earth like gardens, forests and grass
  2. Impervious surfaces – surfaces that don’t allow stormwater to seep into the earth like driveways, roads, sidewalks, and roof tops.

When land is developed, pervious surfaces (water infiltrating) are replaced with impervious surfaces (solid) which allows for a larger volume of stormwater to run off into storm drains and streams. This can cause more frequent flooding and can make coastal flooding or sea level rise inundation worse. In developed areas, stormwater is also more likely to pick up pollutants like gasoline residue, animal waste, and trash and carry them into streams, bays, and the ocean.

DNREC Green Infrastructure Primer for Delaware, Rain Gardens
A rain garden is a green infrastructure practice that mimics a wetland and is made from a shallow depression in the landscape with plants that allows the rainwater and stormwater to collect and infiltrate into the ground. Typically installed in community and residential areas, rain gardens are designed to hold rainwater in place, collect and filter stormwater through layers of mulch, soil, and plant root systems, and absorb and retain pollutants. (Image: DNREC Green Infrastructure Primer for Delaware)

Creating Solutions for Communities

Communities are working to improve their resiliency through the use of Best Management Practices (BMPs) to capture runoff from impervious areas, reduce flooding, and filter pollutants out of stormwater before it reaches important aquatic ecosystems, like wetlands, or recreational areas. Green infrastructure can be used in many different settings to act as a BMP that improves stormwater management and the infiltration of runoff.

For example, trees can be used in urban, suburban, and rural settings, in plantings of one or two trees, or in a 100-foot-wide forested buffer along a river shoreline. Their root systems help absorb precipitation and filter water runoff before it reaches open bodies of water. Rain gardens can act in similar way and help manage stormwater runoff from specific areas such as roofs and parking areas, while larger expanses of conserved or restored wetlands can provide flood retention, carbon storage, and wildlife habitat.

Project in Action

Delaware Coastal Municipality Locations
Delaware Coastal Municipality Locations (First component final report)

A Community-led Focus on Stormwater Management for Improving Resiliency

Last year the DNREC Delaware Coastal Program’s (DCP)’s Resilient Community Partnership (RCP) program worked with a group of coastal municipalities, the Cities of Lewes and Rehoboth, and the Towns of Henlopen Acres, Dewey Beach, Bethany Beach, South Bethany, and Fenwick Island, to conduct a study of impervious surface coverage. This study was done to find out what impacts the existing impervious surfaces in these cities and towns have on the stormwater management of precipitation and water quality.

These coastal communities face challenges on multiple fronts for addressing stormwater management including: tidal flooding, rapid population growth from tourism and development, a shallow groundwater table, and growing floodplain. The best path forward to consider all of these challenges to plan for their resident’s futures, was for all 7 of these communities to work together to gain an understanding of existing impervious surfaces and strategies for reducing said coverage.

Three components to this project were performed to address these multiple influences on stormwater management.

  1. First, the current (2016) and past (2007) amounts of impervious surfaces in the municipalities were determined using GIS and LiDAR with the assistance of the University of Delaware Department of Geography. This analysis included results for both private properties and municipal impervious surface areas.
  2. Second, the project contractors summarized current Best Management Practices (BMP) regarding stormwater infiltration across the state and region.
  3. Third, a final report that summarizes the Best Management Practices (BMP) for each municipality to control future impervious surfaces was created.

Many of the recommendations from this plan include methods of using green infrastructure at the municipal (or citywide level) and residential levels, and are now being considered for adoption in these communities. As a result, these communities are better prepared to react to address flooding and sea level rise concerns and have community specific nature-based solutions easily accessible to reduce the impact of impervious surfaces on their environment and water quality.

More Resources

  • The DNREC Delaware Coastal Programs office encourages stewardship of Delaware’s coastal and ocean resources by promoting informed, science-based decision making. Our office has produced tools and resources, informs local and regional planning, holds training workshops, conferences, and field demonstrations, and provides technical assistance to communities and coastal decision makers. Please visit our website for additional resources on planning and preparedness, mapping and data, and grants and funding programs.
  • Guidance on the use of Green Infrastructure is available through the DNREC Green Infrastructure Primer.
  • Additional Resilient Community Partnership project information and the full reports on the imperious surface coverage study conducted for the group of Delaware’s coastal communities can be accessed online
  • Please contact Kelly Valencik at kelly.valencik@delaware.gov for questions or additional details.

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