How Do I Address Hillside Erosion?

February 20, 2012 Dave Marciniak 0 Comments

Water can cause a lot of damage. Any time you have a slope you have the potential for water and erosion issues, and it’s my job as a landscape designer to address identify and address these issues. There is no one size fits all solution to erosion issues, but we can start by understanding the causes of erosion.

Two factors that I look at when resolving an erosion issue are volume of water and velocity of water. Sometimes the problem is volume: there is so much water being dumped in one spot that it’s going to have destructive force. I’ve seen this with water rushing off the end of a driveway, or if there are several downspouts dumping in the same area.

Velocity is an issue with a steep slope. It can also be an issue with a long slope where the volume and momentum of the water build up. We actually encountered this at one of the estate properties I designed. The slope looked pretty gentle but it was so long, and the underlying soil was such hard clay, that the water washed out all the beds every time it rained.

How do we deal with these issues? If at all possible, the first place to look is where the water is entering the slope. Can we redirect it, or can we at least disperse it so that the force is spread more evenly over a larger area? From there we can also look at solutions that will slow the water flow.

A lot of people say “I need a retaining wall to slow the water flowing down this hill.” Ok, that might work; more often, I see walls that don’t do a darn thing to slow the water. Surface water just rockets over the top of the wall, which can make a pretty waterfall – but it accomplishes nothing. This is why the right design begins with a detailed analysis, including documenting grades and elevations. In many cases a wall (which is an expensive solution) isn’t actually required.

To finish the project we still need to make sure that the slope is stabilized. Plant material is what we’re talking about. If the slope is gentle enough and it can be maintained, turfgrass is an inexpensive and effective choice. Various groundcovers can be used for lower maintenance, and I’ve even designed hillside gardens with a mix of trees, shrubs, and perennials.

If you have an erosion or drainage issue that needs addressed, you need the services of an experienced design professional. Contact me to start the process.

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