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Piedmont vs. Coastal Plain Wetlands: A tale of two regions

Written on: September 16th, 2019 in Outreach

by Erin Dorset & Kenny Smith, DNREC Wetlands Monitoring & Assessment Program

If you spend a lot of time traveling around Delaware, you’ll notice that northern Delaware is very different from the rest of the state. That’s because Delaware is made up of two distinct geologic regions. The northernmost part of Delaware is within the Piedmont region, while the rest of Delaware lies within the Coastal Plain region.

The Coastal Plain is relatively flat and is characterized by small hills, gradual slopes, and sandy or silty stream beds. In contrast, the Piedmont region tends to have bigger rolling hills, steeper slopes, some small cliffs, and stream beds with more rocks, much like a lot of Pennsylvania.

What does this have to do with wetlands, you ask?

Flat wetlands

Landscape characteristics play a big role in determining what kinds of wetlands occur in different areas. So, there tend to be differences in the wetlands in the Piedmont and Coastal Plain regions. Through our years as wetland scientists, doing fieldwork all over Delaware, we have made some first-hand observations about wetlands in these two geologic regions. For example, we have seen that flat wetlands are one of Delaware’s most common wetland types in the Coastal Plain, yet they are fairly uncommon and often smaller in size in the Piedmont because of more varied terrain.

Riverine wetlands

Another observation that we’ve made is that riverine wetlands are often larger in the Coastal Plain. Streams and rivers in that region typically have gradual banks, allowing water to easily overflow into floodplain areas. In contrast, riverine wetlands that we’ve seen in the Piedmont region are often smaller, and many waterways do not have any riverine wetlands along them at all. This is because stream banks tend to be higher and steeper, and streams are often found at the bottoms of slopes, so flood waters do not cover as much land when the banks overflow. The slope of the land also tends to drain water off more quickly, so floodplain areas may not stay wet for as long.

Beautiful riverine wetlands in the northern Piedmont region (left) and central Coastal Plain region (right) of Delaware. Notice the rocky bottom and sharp slopes in the image on the left, and the river banks with very gradual slops in the image on the right.

Seepage wetlands

A closed-canopy seepage wetland in northern Delaware.
A closed-canopy seepage wetland in northern Delaware.

Yet another thing that we have noticed is that seepage wetlands are more common in the Piedmont region than in the Coastal Plain. Seepage wetlands are wetlands formed in places where groundwater comes out onto the surface year-round or nearly year-round. Some of them are closed-canopy seeps, meaning that they are within the forest and create the headwaters of some streams. They are usually dominated by skunk cabbage and are small and narrow in size and shape. Others are open-canopy seeps, which are wet meadows fed by closed-canopy seeps. These have few trees and shrubs and a wide variety of herbaceous plants. Seepage wetlands tend to form at the bases of slopes, which is why they are prevalent in the Piedmont region and are not as common in the Coastal Plain.

Check them out!

Curious about making some of your own observations? Check out some of these parks and forests that will let you compare and contrast the Piedmont and Coastal Plain regions of Delaware!

Piedmont region

Coastal Plain region


Protected: Spartina: A Name of the Past

Written on: December 5th, 2019 in Outreach

There is no excerpt because this is a protected post.

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Sassafras Landing: A living shoreline demonstration

Written on: September 16th, 2019 in Living Shorelines

On a warm July morning not long after the official start of summer, some 2 dozen volunteers gathered at Sassafras Landing, an unimproved boat launch popular with kayakers and duck hunters inside the Delaware Division of Fish and Wildlife’s Assawoman Wildlife Area (AWA) near Frankford. Their mission: transplant nearly 5,200 plugs of native marsh grass onto what otherwise appeared to be a pristine white sand beach.

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Confessions of Seasonal: Everlasting impressions

Written on: September 16th, 2019 in Wetland Assessments

Wetlands work is not for the faint of heart. I won’t sugar coat it for you. Its dirty. Its messy. Oftentimes pretty buggy (even though we really lucked out this year). Yep. Wetlands can be all of those things. But – they are also so much more.

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Pole Replacement Spawns Marsh Recovery Data

Written on: September 6th, 2019 in Wetland Assessments

When a power company needed to replace a utility pole in a wetland area that was a part of a national vegetation monitoring program within the Delaware National Estuarine Research Reserve (DNERR), staff at the Reserve worked closely with the power company and with other state agencies to maintain the integrity of the datasets being collected, but also took the opportunity to begin a study on how the marsh would recover naturally from the disturbance.

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Wetlands are Magicians of Water Quality Improvement

Written on: May 15th, 2019 in Outreach

by Alison Rogerson, Wetland Monitoring and Assessment Program In our Wetland Monitoring and Assessment Program we speak so often about the ecosystem services that wetlands provide or the beneficial functions wetlands perform daily.  We rattle them off in varying order “provide vital habitat for plants and wildlife, improve water quality, protect our coasts, act like […]

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Delaware’s Freshwater Mussels

Written on: May 14th, 2019 in Wetland Animals

Guest writer: Clare Sevcik, DNREC’s Nonpoint Source Program There are so many charismatic animals that make Delaware waterways their home. Most people living in Delaware can easily recognize a few of the most popular species: bald eagles, osprey, blue crabs, horseshoe crabs, beavers, river otters, and many more. But there are many more animals living […]

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Wetland Monitoring and Assessment Program: Celebrating 20 years

Written on: May 14th, 2019 in Wetland Assessments

by Alison Rogerson, Wetland Monitoring & Assessment Program Our Roots In 1998 the Delaware Department of Natural Resources and Environmental Control’s (DNREC) Environmental Scientist, Amy Jacobs (now with The Nature Conservancy), took part in a grant project held by the Delaware chapter of The Nature Conservancy and the Smithsonian Environmental Research Center. This project developed […]

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Birding in Delaware’s Wetlands

Written on: May 8th, 2019 in Wetland Animals

by Erin Dorset, Wetland Monitoring & Assessment Program Birding is always exciting in Delaware. While some bird species are year-round residents, many others are migrants traveling along the Atlantic Flyway. This keeps things interesting, as it allows birders to see a very wide variety of species throughout the year. A lot of these awesome birds […]

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Wetlands are like sponges, how?

Written on: March 11th, 2019 in Outreach

by Brittany Haywood, DNREC Wetland Monitoring and Assessment Program One part of our job is going out into the public and explaining simply our research and the benefits of wetlands.  We often use the saying, “wetlands are like sponges” to describe their ability to absorb water, but recently we’ve been asked exactly how that is […]

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Delaware Wetland Management & Assessment Program