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Photo by Kris Wetherbee
Capturing excess rain prevents erosion and allows many options for creating and maintaining eye-catching landscapes. |
Plant a rain garden Before you dig, consider these three tips:
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Rainscaping
By managing storm runoff, you can lighten the load on local ecosystems and improve wildlife habitat
Rain is a natural and welcome part of the process for keeping plants happy and sustaining wildlife. But unless properly managed, the excess water that runs down driveways and sloping lawns can have a negative impact on local waterways and watersheds.
When it rains, water runs off our roofs, sidewalks, driveways, roads, parking lots and other impervious surfaces. The resulting runoff picks up and carries contaminants such as fertilizers, pesticides, de-icing salts, bacteria from animal waste, and petroleum products.
Ultimately this cocktail of contaminants ends up in local streams, rivers, lakes and other water bodies. However, there is an alternative approach to managing stormwater runoff and lightening the load on our local ecosystems.
Landscaping for rain
The benefits of rainwater harvesting include improved water quality, soil infiltration and wildlife habitat, along with reducing your community's carbon footprint. There are a variety of approaches you can use to help manage stormwater runoff and lighten the load on watersheds.
Collectively called "rainscaping," a term that evolved in the Mid-Atlantic region in the late 1990s, these techniques mimic natural processes by helping capture, divert and store rainwater for later use.
Rainscaping techniques range from straightforward solutions that include redirecting downspouts to garden beds, setting up rain barrels and cisterns, installing a French drain, digging a dry well, and planting a canopy of trees and shrubs, to progressive approaches such as rain gardens and rainwater harvesting water features.
Other factors to consider before deciding on which rainscaping techniques to implement include the volume and timing of rainfall, topography of your landscape, soil porosity and the size of your lot and roof. Identify any problem areas. For example, underground utilities could interfere where you dig. Decide whether your goal is to divert or spread out runoff or capture and reuse it to water your landscape.
Backyard rainscaping techniques
Rain barrels and cisterns: Commercial rain barrels typically hold 55 gallons of water. A cistern is a super-sized water tank made of concrete or other materials and holds from 1,000 to 10,000 gallons. Consider that a 1-inch rainfall on a 1,000-square-foot roof generates about 620 gallons of water. That amounts to an ample supply of rainwater to fill the birdbath, replenish water features and irrigate plants in containers and beds.
Dry wells and French drains: A dry well is a passive underground structure that receives water from one or more entry pipes or channels located at its top. The water is discharged through a number of small openings where it gradually dissipates into the ground. A French drain consists of a perforated pipe placed in a gravel-lined trench. The pipe is topped with a grate or filter fabric and covered with soil. Grass is often planted on top. Water from a French drain can also be directed to a dry well or rain garden.
Swales and vegetative filter strips: A grassed swale is similar to a French drain except the earthen channels are covered with a dense growth of hardy grasses or other low-growing vegetation. Grassed swales provide runoff control but may not be effective in regions with sandy soils. Vegetative filter strips are tightly planted in grass, but can include shrubs or woody plants. The strips run parallel to pavement, at least one foot from the edge, and are situated between the paved surface and a pond, wetland or other surface water collection system. Vegetative strips help reduce the influx of pollutants and sediment, but are less effective at removing soluble pollutants.
Permeable pavers and porous surfaces: This method provides the strength and stability of asphalt or concrete while allowing water to filter through the surface. The pavers, which are made with holes or larger aggregates that create voids within the system, help reduce runoff of pollutants and decrease summer heat levels. Examples include grass pavers, gravel pavers, interlocking concrete pavers created in grid-like fashion, and porous concrete. The type of paver determines how much water can soak through, though usually you can expect up to 80 percent water infiltration — sometimes more.
Rainwater harvesting water feature: This system combines a recirculating decorative water feature with a sub-surface rainwater harvesting collection system. The underground tank is connected to a high-pressure pump, so you can have access to the stored water and use it to hand water or irrigate the landscape. A water feature can also be installed on top of permeable pavers that collect the water and direct it to the storage system. Overflow can be directed to a rain garden or allowed to slowly percolate or soak into the soil.
Rain gardens: A rain garden is a natural or artificial saucer-shaped depression in the landscape. Its primary function is to slow down runoff, store it temporarily, and release it gradually so it has time to spread out and soak in, but rain gardens also filter sediment and pollutants while adding color and interest to the home landscape.
Keep in mind that certain rainscaping practices that work well in one area may perform poorly in another. It all depends on your site, climate and available conditions for installing each type of system. Once you know what works well in your area, you can combine several rainscaping methods to achieve your overall goal. — Kris Wetherbee