How to Stop Erosion on a Slope or Hill

If you have a slope or hill on your property, erosion can be a problem. Not only can erosion lead to contaminated drinking water, but it also strips topsoil and the nutrients it provides, so your grass or plants may not be able to thrive. Luckily, there are a few measures you can take to fix the issue. In this guide, we’ll explain how to stop erosion on a slope and include some tips you can use based on your specific property.

Why Is Erosion on a Slope a Problem? 

Erosion on a slope in your yard can present a few problems, most notably contaminated drinking water if you have a private well. Even if you rely on public water, erosion on a slope or hill can leave the soil unfit for growing grass, plants, and trees. Severe erosion can detract from your home’s curb appeal, leave your yard looking unkempt, and even lead to structural damage in some cases.

Signs of Erosion on a Hill

Erosion can be a surprisingly difficult issue to identify. If you notice the following issues on your slope, it might be a good time to regrade your yard or install erosion control.

• Exposed roots: Look for roots poking out of the ground around plants, shrubs, and even trees. Check for leaning trees on the slopetoo—this can indicate severe erosion.

• Soil channeling: If you don’t have ground cover on the slope, inspect the soil for channels after it rains.

• Cracks in the soil: Keep an eye out for cracks forming in the ground along the top edge of the slope. This suggests that large sections of soil are shifting downward.

• Soil deposits: Particularly after heavy rain, look for soil spilling over the bottom edge of the slope. This will be most obvious if the slope runs down to a sidewalk, walkway, or driveway.

• Poor plant growth: Erosion on a slope strips away healthy topsoil that holds key nutrients for plants and grass. Dying, discolored, or withering plants on a slope can all indicate erosion issues.

How to Prevent Erosion on a Slope

The best way to prevent erosion on a slope depends on your particular property and the intensity of the slope. Many homeowners will find that covering the area with mulch, landscaping rocks, deep-rooted vegetation, or ground cover plants will eliminate their erosion problems. You can fix more severe erosion issues by installing a drainage system or retaining wall.

Lay Down Mulch or Landscaping Rocks

One of the simplest methods you can use if your slope is 33% or lower is to cover the hill with mulch or landscaping rocks.

1. Pick up bags of mulch or have mulch or landscaping rocks delivered in bulk by a local supplier. Calculate how much mulch you need or how many cubic yards of rocks you’ll need before you buy to make sure you don’t miscalculate.

2. Remove weeds from the slope.

3. Consider putting landscape edging around the area where your mulch or landscaping rocks will sit to keep the material contained. This is especially important for keeping landscaping rocks in place.

4. Spread the substrate using an iron rake, aiming for a depth of 3 to 4 inches for mulch or 2 to 3 inches for landscaping rocks.

5. If you’re using mulch, lightly water the area to help the material settle.

Use Ground Cover Plants or Deep-Rooted Shrubs

Putting in ground cover vegetation and shrubs can help reduce erosion because the roots will hold the soil in place and protect it from movement.

1. Remove weeds from the slope.

2. Lightly till the soil if your slope is 33% or lower. Don’t till on steeper slopes, as this can make the erosion worse.

3. Purchase ground cover plants or shrubs with deep roots, and consider your climate when selecting plants.

4. Consider installing landscaping curbing where the ground cover will meet grass or garden beds to prevent overgrowth.

5. Put in the plants and water them to help stimulate root growth.

6. Continue to water daily until they’re well established.

Install an Erosion Control Blanket

An erosion blanket sits just on top of the soil, acting like mulch to keep the dirt below it in place but still allowing for runoff to pass over it.

1. Clear the entire slope of weeds and debris. Forestry mulching is a convenient way to get this done quickly.

2. Rake the soil level over the hill.

3. Dig a 6-inch trench along the top ridge of the slope, where the bottom levels out into flat ground.

4. Use ground staples to secure the erosion control blanket along the inside of the bottom trench. Follow manufacturer directions for staple placement and quantity.

5. Roll out the erosion blanket up the slope.

6. If you run out of blanket material, begin with another roll and overlap the upper portion 12 inches over the bottom portion.

7. You can cut holes in the blanket to work around shrubs or trees. Do your best to keep the hole as small as possible around the base of the plant.

8. Continue unrolling the blanket over the top ridge and then along the inside of the upper trench.

9. Secure the blanket over the slope and in the top ridge according to the manufacturer’s directions.

10. Consider laying down mulch over the fabric for a finished look.

Use Riprap Along Natural Bodies of Water

“Riprap” refers to a pile of rocks that can help disperse water that threatens the borders around ponds, lakes, and, especially, moving bodies of water, like oceans, rivers, and streams. It’s best to leave this method to professionals due to the weight of the rocks and the extra preparation required.

1. Ensure your slope is no greater than 33%. Hire a landscape grading company near you to grade the land to establish a proper slope if necessary.

2. Install an erosion control blanket over the soil according to the steps above or the manufacturer’s directions.

3. Install curbing, if necessary, to keep the rocks in place after installation.

4. Lay down the riprap and aim for an even covering at a depth of 6 to 18 inches. Most professionals use heavy equipment to move rocks into place quickly.

Install a Retaining Wall

A retaining wall can bridge the gap between a high and low point of the land to prevent runoff from flowing downward and causing erosion. Much like with riprap installation, it’s a good idea to hire a professional to avoid ongoing issues, but it is possible to DIY if you have experience. If your wall is more than 3 feet tall, it’s a good idea to hire a pro regardless of your experience.

1. Mark the location of the wall using landscaping paint.

2. Dig a trench where the wall will sit to a depth of around 6 inches. Make sure the entire length is perfectly level.

3. Lay down a bed of gravel inside the trench and aim for a uniform depth of 2 to 3 inches.

4. Use an iron rake to flatten the gravel, and check again for level.

5. Lay down the first layer of concrete blocks, checking for level as you go.

6. Lay down subsequent layers of concrete blocks and stagger the seams from layer to layer.

7. Use capstone blocks for the top layer, once again staggering the seams with the layer below.

Install an Exterior Drainage System

For more severe slopes and areas prone to heavy erosion, a drainage system like a French drain is a good option for rerouting water from the top of the slope to a safe spot on your property.

1. Mark the area along the top ridge of the slope where you plan to install the drain using landscaping paint.

2. Dig a trench inside your guidelines. Aim for a depth of 12 to 18 inches and a width of around 12 inches.

3. Use a level to get the base of the trench to slope gently toward one side. A slope of around 1% is ideal, so for every 10 feet of drainpipe, it should slope down about an inch.

4. Lay down landscaping fabric or a heavy-duty weed blanket inside the trench, leaving 2 to 3 inches of overhang on either side.

5. Put down an even layer of gravel to cover the bottom of the trench at a depth of about 3 inches. Double-check that your 1% slope remains.

6. Lay a perforated pipe inside the trench. If only one side of the pipe is perforated, make sure it’s facing upward.

7. Make pipe connections leading down a slope to an area of your property where it’s safe to dispose of the runoff the drain collects.

8. Fill the rest of the trench with gravel, leaving an inch or two at the top to backfill with soil.

9. Wrap the overhanging landscaping fabric over the bed of gravel.

10. Fill the rest of the trench with soil and gently compact the area.