By Dr. Tyler A. Groh, Penn State Extension

Flooding after a large rainfall is often a concern for anyone with a waterfront property. With over 86,000 miles of streams in Pennsylvania, there are many areas that can be impacted when water levels rise.

On September 1st, 2021, the storm remnants of Hurricane Ida came through much of Pennsylvania, dumping more than 8 inches of rain in some areas. This flood potential raised a concern for us and prompted a trip to our recent planting along Spring Creek to assess any potential damage to the vegetation.

I made the trip from State College to our planting in Dauphin County the day after the Ida rain event.

This trip was not without its stress since flooding was everywhere, and I had to make sure I could safely get to the site and back out again that day.

Quick Tip: if there is ever standing water across a road, even if it only looks like an inch or two, turn around. It does not take much water to lift a vehicle and provide a dangerous situation for the driver inside.

Also, water across a road can be deceptively deep.

For more information on how to assess flood levels of streams from the comfort of your home, please see this Online Mapping Tool article.

Once I made it to our planting site, I immediately went to the highest elevation of the site to inspect the current water elevation of Spring Creek.

By the time I arrived, the water had receded back within its banks and I knew it was safe to venture out into our planting.

Since I am still not as familiar with this site and I came after the flood took place, I had to look for signs on the land to gauge how high the flood waters rose.

Tall grasses close to the water's edge provide a clear visual of recent flooding. These grasses will bend over in the direction of stream flow during a flood. This is perhaps easiest to see later in the growing season when the grasses are tallest.

Upon first assessment, I thought our planting was at a high enough elevation where the flood waters did not reach the trees and shrubs that we planted.

However, as I walked further into the planting, I noticed that a portion of the buffer site was slightly lower in elevation and had signs of significant flooding and even had a fair amount of standing water.

This observation got me thinking about plant selection for this site and other streamside locations.

When first planting a streamside garden, it is common to put water loving vegetation directly next to the stream itself. However, you may also have areas furthest away from the stream that are better suited for water loving plants too.

These plants like having water around their roots for a longer duration and can better survive flooding, even at greater frequencies.

Moral of the story: the days after flood waters recede are a good time to look for the lowest portions of your property that may be wetter for longer.

In addition to tall grasses being flattened, there are other visual signs you can look for that indicate the extent of a recent flood.

Our Spring Creek planting site is surrounded by agricultural fields on both sides of the creek. These fields are much higher in elevation than our planted vegetation.

While I was there, I looked at the soybeans in the field, and the ones closest to me looked like they had brown leaves. This brown color came from sediment that was deposited by the flood waters.

There was a very obvious line within the field where the brown colored soybeans stopped and the green soybeans started again. This line was the maximum flood elevation.

Further, debris on tree branches like that shown in the photo below will allow for visual inspection of flood levels. This debris floated down stream during a flood and was caught by the tree as the water receded.

My main concern for going out to our Spring Creek buffer planting after the Ida floods was to check up on the trees and shrubs we planted. I wanted to make sure that we did not lose any vegetation and that our tree tubes and stakes were not broken off.

Floods have great energy and may carry heavy debris that could flatten planted vegetation and the tubes that protect it. It is considered necessary maintenance to identify any broken or bent tubes shortly after a flood to prevent permanent damage to the vegetation.

Thankfully only two of our tubes were slightly bent. To correct them, I carefully pulled the stake and tube out of the ground (making sure to not harm the tree inside), straightened the tube and pushed its bottom edge into the soil to ensure proper tube-soil contact, and proceeded to pound in the stake to resecure the tube.

This easy fix will help protect the planted trees.

All things considered, our Spring Creek planting site was minimally impacted by the floods from Ida.

This flood event provided some great insight into the hydrology of the site (what areas are the wettest) without harming the planted vegetation too much.

Stay tuned on what we discover next at the side of Spring Creek. In the meantime, if you missed the first to articles in this series, please visit them via the links below.

Previous Articles On Spring Creek:

-- At the Side of Spring Creek: An Introduction

-- At the Side of Spring Creek: Pitfalls

(Reprinted from Penn State Extension Watershed Winds newsletter.  Click Here to sign up for your own copy.)

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[Posted: September 20, 2021]

9/27/2021