After years of drought, followed by devastating wildfires and recent heavy rainstorms, the hilly areas of the Western states suffer from soil erosion. Many of the hills that remain need soil erosion stabilization.
In the case of Northern California communities, the fires wiped out so much vegetation. The hills were left bare of trees, shrubs, and grasses. The rains swept away valuable topsoil. Some homes lost purchase and slid away with the loose soil. Now, instead of feeling relief that the drought may have ended, heavy rain brings fear of slope erosion, mudslides, and flooding.
What are 5 ways to prevent erosion?
There are simple and more complex ways to stop soil erosion. The methods will depend on the current condition of the slope. Is it an especially steep slope? Is the slope bare due to fire and soil loss or are you preparing to prevent soil erosion before it starts?
So, what is the best material to stop erosion?
Plants are a natural for erosion control.
Vegetation, whether in the form of native grasses, ground cover or trees, can provide a root system that will hold soil in place. In fact, a variety of plants in combination, and native to your particular area, work best. Using plants for erosion control can prove to be the cheapest and most efficient way to prevent further damage.
If you don’t plan on hiring a landscape architect, your local garden store can advise you on the best native plants for erosion control. Ground cover is a good place to start. You’ll want a ground cover that spreads quickly so the plant root can begin forming a natural, mat-like system to hold the soil.
Trees, while slower growing, provide a deeper root system to hold the soil in place. Ecologists recommend them for erosion control. In addition, trees create a canopy of leaf cover that reduces the velocity of a downpour and protects the ground from heavy rain and water runoff.
If you are concerned that the erosion on your slope has left little topsoil to promote plant growth you may want to try other options. You might add mulch to the bare soil as another method to retain the soil that is left and support vegetation growth.
Man-made Materials to Stop Erosion
Erosion control blankets work well on steep slopes damaged by fire or heavy rains, or both. Compost erosion control blankets provide a nutrient rich growing medium for vegetation to take hold. A compost erosion control blanket is also thin enough for the seeds contained within to sprout and grow into the soil beneath. They are a great option for very steep slopes that could prove difficult to plant through more conventional methods.
Turf reinforcement mats can be used when a slope also contains water drainage conditions too severe for erosion control blankets. They are designed to ensure that plants have a better chance of holding on when soil is at risk of washing away. They are made of non-degradable, synthetic material, a fiber mesh that comes in a variety of thicknesses to serve as seedbed and soil covers. Plants grow up through these mats, so the vegetation is supported.
Adapting by Design
What if your slope is so steep and damaged by runoff channels that plants have too hard a time taking hold? If you want an immediate solution, the creation of drainage ditches can help to prevent soil erosion. Just like the installation of a French drain can keep standing water away from a building, a drainage ditch will divert water down a slope through gravity. You also have the option of using gutters or pipes to carry the water down the slope.
If you are seeking a more permanent, foolproof option, cutting a series of stepped areas, called terracing the slope, could prove to be your best solution. In some countries, farmers have been using this method for centuries to create more space to grow food.
Engineering a terraced hillside
Terracing is definitely a serious project; one that should not be undertaken without an understanding of the process, appropriate materials and the permitting needed. A terraced hillside can be utilitarian or more design conscious. This is where a landscape architect could be a great partner in creating a beautiful, and efficient terraced hillside.
The regular intervals cut out of the face of the slope create swales that can be used for planting. In that way, the terraced outcroppings are designed to capture rainwater runoff and preventing soil erosion. The terraced area can provide an interesting landscape for planting vegetation whether decorative or for a backyard vegetable garden.
Some slopes require other types of erosion control like the option to build retaining walls. While a terraced slope is done in a series of level outcroppings (swales) that can contain soil for planting, retaining walls are near-vertical or vertical structures.
Retaining walls are often created after cutting into a hillside or slope to create space for a patio or other outdoor living space. A retaining wall is designed to keep or retain the soil on the other side from slipping, thereby preventing erosion. The wall needs to be strong enough to keep the soil in place, even when the soil becomes saturated with water. To divert water away from the wall through proper drainage is essential. You don’t have to have a master’s degree in engineering to construct a retaining wall, but it wouldn’t hurt. This is not a job for the average DYI’er.
The variety of retaining walls
The most common for residential use is a gravity wall. Most often they are built of heavy material like concrete or stone. They may also be built at a slight angle, using their weight and setback to provide leverage and heft to keep the hillside in place.
Buttressed retaining walls are tall, vertical walls that are anchored into the hillside with steel rods or counterforts. The wall itself is usually made of concrete or some other strong material. The counterforts are meant to reduce the bending stresses that can occur in the wall slabs.
Green retaining walls are the choice for homeowners that need a retaining wall for a gentler slope and don’t want the look of concrete or stone. Green retaining walls are made from honeycomb cells designed to be embedded in the slope and then planted. The combination of the honeycomb cells, soil and vegetation provide soil erosion prevention.
If you are worried about slope erosion or simply want to protect your hillside and home from the changes climate change may bring, contact us today. One of your professionals can help you assess your specific needs and provide tailored solutions.