Flood Control with Plants (Irene Survivors One Year On)

Just over a year ago, this was the scene near our farm pond and stream after Hurricane Irene’s path of destruction swept through:

Large areas of gardens were washed away entirely, or covered with 3-6″ of sand and gravel from the floodwaters.

Right afterwards, I wrote the article  “Irene-Proof Native Plants” naming the plants that seemed to best survive the damage. Little bluestem (Schizachyrium scoparium), a short grass native to most of the US, took 1st prize. The plants were flattened (below), but their strong and deep root systems held on tight against the floodwater – can you see the tiny young (2nd year) bluestem seedling flattened against the rocks down below on the right?

Plants with strong root systems bind soil together and prevent erosion during heavy rains

Today, the area has recovered, and the resilient little bluestem and New England asters are in their full glory again. Cinnamon fern, turtlehead and garden phlox also staged a healthy comeback. Even “baby bluestem” came back and strong and tall. The others? Well, if they didn’t pass the flood test, I won’t be replacing them…

Damage? What damage? Little bluestem and New England Aster came back and bloomed beautifully after being buried underneath several inches of sand and gravel. Self-seeding annuals such as cleome and browallia (both non-native) also popped up and flowered, all on their own. Thank you mother nature for helping out!

If you witnessed any of the damage from Hurricanes Irene or Katrina, you ‘ve seen how heavy rain combined with poor drainage and a lack of vegetation can cause catastrophic damage to lower-lying areas. If you’re in a flood-prone area near a river or stream, there’s not much that you can do as an individual to prevent your own property from flooding – but there’s plenty we can all do to help prevent worse damage downstream.

Here’s an urgent message from the natural world: Get out there and plant stuff! Just by adding a variety of hardy perennials, shrubs and trees to your property, you’ll be doing your part to control flood damage – any size mixed planting will help slow down (or re-route to another area) surface flooding – and the tangled mass of root systems in a densely planted area also help keep soil and sediment from washing away and joining the floodwaters.

In built-up areas with lots of pavement and very few plants and trees, heavy rains can turn into uncontrollable floods that can quickly rip through roads and other structures in its path:

A few hours of heavy rain caused a flood that gouged a 2′ trench in this road.

Whether or not you live right on the water or some ways uphill, choose plants that are both native to both your local region (New England, Gulf Coast, Pacific Northwest, etc.) AND your own particular site conditions (sunny slope, moist shade etc). Not just beneficial as storm damage control, locally native plants are key to supporting natural communities of birds, beneficial insects and other wildlife that have evolved over long periods to depend upon certain plants for survival. Plus, if sited correctly, regionally native plants should not require watering or fertilizing once established – which means fewer fertilizer chemicals washing into nearby waters.

Here in the hills and valleys of southern New England, most of us live “upstream” from a major river or coastal bay. During heavy rains, lawn and farm fertilizers, animal manure, even motor oils & fluids from driveways and roads get washed into nearby streams, ponds and rivers – eventually ending up in either Long Island Sound or the bays of Cape Cod, Narragansett and Boston. It’s not hard to to see the problem these excessive nutrients cause — dead fish and toxic algae blooms that close our beaches in the summer, and the increasing cost of municipal wastewater treatment (a cost we all bear as taxpayers).

What if your property is mostly pavement and lawn? Even more reason to replace part (or all!) of your lawn with plantings of native shrubs and trees that will soak up rainwater and feed wildlife. Consider converting paved driveways and walkways with permeable surfaces that allow water to drain slowly on site, instead of washing away into storm drains — which generally empty into the nearest river.

Tough native plants on the edges of ponds help prevent shoreline erosion and supports healthy local wildlife communities at the same time.

Whatever our nationality or religion or political views, I think we can all agree that our planet has but a finite source of water and that we all rely on this water remaining clean and healthy. Technology may help us clean polluted wastewater and remove salt from seawater, but nothing can replace the natural filtering provided by mother nature herself with plants, trees and an almost infinite array of microbiota (underground and aquatic).

Plants on the edge of farm ponds are especially important for filtering agricultural nutrients before they reach the water.

In a time of increasing anxiety about the future, I urge you to consider the larger world in your landscaping choices, because what happens in our back yards impacts all of us. You may feel like your effort is just a tiny drop in the bucket, but small measures add up, and we just can’t wait for our leaders to take action to protect the natural resources we all depend upon. One backyard at a time, let’s do what we can to mitigate the damage caused by the once unusual but now frighteningly common “extreme weather events” we are experiencing. We all share this planet, and we will all benefit.

© 2012, Ellen Sousa. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us