How to control an eroding landscape
By Scarlett Steer, Minine’s Plants
Erosion on major building sites is a relatively common sight around the BVI, but we should not be too quick to assign fault with construction alone. Our own homes and gardens can also play a role. Heavy weather or excess landscape irrigation causes runoff from our gardens, driveways and parking lots. Topsoil—brimming with valuable microorganisms and nutrients—is washed away. Included in this mix are often contaminants such as fertilizers and pesticides. Not the ideal combination to end up in ones drinking water. But help is at hand. There are more than a few options to help avoid this potential unhappy event – some DIY affairs and others that require proper landscape architect design and execution.
A rock garden used against erosion at one of Necker Island’s guest houses. All photos by Scarlett Steer.
On The Incline
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Grass: Various species of grass provide good protection against erosion. Grass is inexpensive and grows well. Ryegrass, for instance, is often planted to help reestablish hillsides devastated by wildfires in California. Your local landscape company or the Ministry of Agriculture are the best sources of information on the best grass to choose for your particular area.
Grass and rock used near an eroding landscape.
Mulch: A much-loved friend of the landscaper, this erosion prevention tool also absorbs moisture and releases it into the ground slowly and steadily without washing anything away. Mulch can take the form of bark chips, wood pulp, straw, leaves and cuttings, and/or sawdust, and provides a starter environment your plants will love you for.
Matting: Erosion control matting works well to help plants take root on precipitous terrain. This woven fabric is generally made up of organic materials such as jute, straw, wood, coconut, coir and mulches, held together by synthetic mesh straw filament. Erosion control matting comes with extra added bonuses for your garden. These include: the absorption of very heavy rainfall, the moderation of soil temperature, and the preservation of soil moisture. This matting is also very natural in appearance blending nicely in to your planters and beds.
Baffles and Boulders: Not to be confused with a berm, landscape baffles are small terraces that run parallel across medium-sloped inclines to hold soil, mulch and plants in place and to prevent erosion.
A beautiful cactus walkway lined into an eroding landscape.
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The inclusion of small rock gardens or bigger boulders in your landscaping not only helps to control erosion by impeding the flow of water, but can also add wonderful texture to a landscape. Barriers like rails or timbers can be placed to overlap at right angles. These, along with the baffles, hinder and divert the flow of water during heavy rains preventing it from running directly downhill. These types of barriers work best on mild slopes.
Terraced hillsides: The terrace made an appearance many moons ago in the agricultural practice of terracing a sloping site. In gardening, a terrace began as an element where a raised flat section overlooks a prospect, and made its debut in the ancient Persian gardening tradition. It is thought that the Hanging Gardens of Babylon, one of the Seven Wonders of the Ancient World (and the only one that may have been mythical), were thought to have employed the terrace system; built on a man-made mountain with vast slabs of stone used to prevent erosion. Today terraces have been adapted to both control runoff and help planted areas retain water more effectively. Terraces should be wide and deep enough that their forward edge is protected from erosion. They should also slope a little to prevent water from gathering at the back of the terrace.
Riprap and Gabions: Gabions (from Italian gabbione meaning “big cage”) are wire cages filled with a variety of rock types, commonly granite or limestone. Riprap is rough, loose stone, usually granite, which is either set into or scattered loosely onto a slope. Riprap also slows and diverts flowing water. It is effective but can often look somewhat bleak as part of a landscape. Strategically planted groundcovers or rock garden plants between the stones can soften this effect. Riprap lined swales can be designed to carry runoff to stable outlets. These swales require proper design and careful engineering, taking building codes into consideration.
Plants: Plants can either stand alone or be incorporated into any of the erosion control techniques mentioned above. When plants are established, the roots help anchor the soil. Getting them established, however, is the tricky part and requires some elbow grease in the early stages. Certain plants fare better on slopes than others, and it is best to consult your local landscape company before spending your money. If you want to install irrigation on a planted slope, make sure that the system’s water pressure is adequate to water the entire area.
Go native. Incorporate the native plants and trees on your property into your landscape design. Indigenous plants and trees are masters in erosion control tool. They are already adapted to their environment, are deep-rooted and hardy. Space other plants out appropriately to allow for proper root structures and soil to absorb runoff.
Erosion, at best, an eyesore; at worst, a serious threat to our community and economy. But again, even as individual owners of relatively small parcels of land, we still have the clout to make a difference no matter how small. And your local landscaper is here to help.
