Botanica Atlanta | Landscape Design, Construction & Maintenance

The moment rain touches down on a typical building, mankind has fundamentally altered the natural water cycle of a site. Our roofs are successful at creating dry living spaces inside, but by sheltering from precipitation, rooftops incidentally collect and concentrate stormwater. For most buildings in the United States, a storm promises a gathering of rainwater in roof gutters and -- shortly thereafter -- a surging outfall at each downspout location.

Image: Grifos

Though most builders still send stormwater down the pipe as if it's a nuisance, there's a steadily growing movement to rethink this water once it reaches the landscape. Many local governments, realizing the toll that concentrated stormwater volumes take on infrastructure, encourage "downspout disconnection." Rainwater harvesting, mostly in the form of rain barrels, has become nearly ubiquitous in the suburbs of America.

Images: Clean Air Gardening, Improvements Catalog, and Eric Hoffabee

It's certainly good news that every homeowner and building manager can "do their small part" to reduce development's overall impact on the environment, and due to their small size and low cost, these downspout interventions commonly take the form of DIY tinkers. Grassroots green-engineering is a beautiful thing from a social and ecological perspective, but from a designer's view, these small-scale retrofits often appear clunky, feeble, and incongruous with both the architecture and the landscape.

Images: ChannelGuard, InvisaFlow, and Marine Leroux

For example: all three of the splash-pads photographed above show a marked improvement over conventional downspout treatment. In each case, a retained strip of loose stones likely slows down stormwater runoff, prevents soil erosion, and encourages some amount of infiltration of stormwater into the planting soil. Despite the environmental benefits, each of these examples introduces materials that seem unharmonious with the site. These "orphan" materials match neither the landscape nor the building and exhibit high visual contrast. These splash-pads appear as an afterthought, and attract more attention than their builders probably sought.

Images: David R. J. K, Antalya Real Estate, and Evergreen Landscape

These next three examples (above) are more successful. These downspout treatments each achieve better harmony with their surroundings by evoking the natural stone of the landscape edging or the brick of the building face. Quiet, graceful integration of stormwater infrastructure into the landscape surface is a noble goal, but sometimes a solution can be buried from sight altogether.

Images: Keith Board, Phillip's Garden, and Jennifer Connell

Stormwater design gets most exciting, though, when the travel of runoff is expressed unabashedly in the landscape. At many contemporary sites a visitor can observe rainwater in motion and trace its path across the landscape.

Images: San Francisco Better Streets, Zahradní Nábytek, and It's a Green Life

Next time rain falls, put on a jacket and take a walk around your home, office, or school. Are there missed opportunities to reduce your building's environmental impact? Can these same opportunities be leveraged even further into a landscape expression that is educational, ecorevelatory, or artful?

Image: Rob Faulkner

Rain falls from the sky and onto landscapes of the Southeast on more than one-hundred days each year. That averages out to almost one out of every three days that your garden receives precipitation, and I find that most landscapes fail to reach their grand potential on these days. Rainfall is something ephemeral, natural, and beautiful. More importantly, rain is something that is absolutely critical to your garden’s soil health and your plants’ survival.

In the civilized world of man – where cold is blocked by synthetic-lined jackets, heat is doused by air conditioning systems, and the sun’s rays are blocked by rooftops and polarized glass – we tend to associate the occurrence of rain with feelings of discomfort and inconvenience.

Image: Bruno Hautzenberger

To plants, however, rainfall is quite the opposite. When the first plump, wet drop of a coming storm falls onto a plant’s leaf, it is a moment to celebrate. As the raindrop’s mile-long freefall ends abruptly by crashing into a leaf, the shaking of that leaf might as well be a ringing dinner bell. Precipitation provides a plant with sustenance, and an ample rainstorm ensures a plant’s survival for days, if not weeks.

So how can you properly honor a rain event in your garden? Unfortunately, the typical solution that is employed on most properties involves collecting the stormwater into drains and quickly channeling this fluid into underground pipes that spit it directly into the local storm sewer. Though this default strategy does accomplish one necessary task – the protection of your house from flooding – the solution lacks creativity and it certainly far from natural. Failing to wisely control and harness the sometimes violent accumulation and movement of rainwater can lead to the erosion of your garden’s soil and can have a larger scale detrimental impact on the ecological health of your local streams and rivers.

Images: Sam Valentine, Jeff Curtis, Avis Adams, and Thiago Souto

Artistic downspouts and rain-chains are excellent ways to delineate the path of water as it flows from your roof to your landscape.

Collecting this water for use, also known as “rainwater harvesting,” is one excellent strategy for conscientiously dealing with precipitation on your property, but harvesting your fallen rain is more than just a courtesy to your local environment. These rain catchment systems – which can range from a simple rain barrel connected to one of your existing downspouts to complex underground cisterns and irrigation systems – can help your garden survive through periods of drought and even government-enforced watering bans. (For more detailed information on rain water harvesting, study up on earlier Botanica Atlanta posts categorized under Water Management, including “Planning for a Dry Summer” and “Harvesting Rain Water”.)

Images: Lady Bird Johnson Wildflower Center and Local Ecology

I advise a combined strategy of exhibiting rainwater and harvesting it in your garden, as exemplified by the Lady Bird Johnson Wildflower Center. A research unit of the University of Texas at Austin, the Center is a pioneering agency in a region where rainfall is only a fraction of that in the Southeast. The Wildflower Center surely practices what they preach, and their facilities include a water harvesting system that collects 10,200 gallons of useful water for each inch of rainfall. Furthermore, one of the architectural centerpieces of their garden is an aqueduct that is cleverly designed to double as a vine-covered arbor. An example such as this one, along with historic design precedents like Spanish runnel irrigation, offers plenty of design inspiration for collecting rainwater and delivering it to needy plants, while at the same time visually demarcating the journey that this precious liquid takes through your landscape.

If you have a 2,000 square-foot single story home in northern Georgia, your rooftop will intercept more than 62,000 gallons of water in an average year. What do you plan to do with yours? With so many options available, I advise that you not just let it go down the drain.

Author: Sam Valentine, BLA, LEED AP

Atlanta recently got over 25 inches of rain and many residents experienced the ravages of our floodwaters in some way or another. High volume preciptation created problems with both pooling water and fast moving water, both problems that can be managed in the landscape.

Site grading is the most elemental of drainage strategies homeowners can use to control the flow of water across their properties from areas of undesirable over-saturation to collection areas for later use or to municipal stormwater systems. Generally houses should be sited so that stormwater drains away from the house.

If downspouts create pooling or erode the soil, or if high volumes of water enter from a neighboring property, dry creek beds can be used to direct rainwater off the property or to a collection area such as a dry pond, retention pond or rainwater harvesting cistern. Dry creek beds can be designed and specified to compliment the aethetics of your landscape and add a new dimension to your site vistas.

Photo Credit: Sturgis Rock Solid Solutions

French drains are appropriate for controlling excessive moisture around foundations, where hardscapes and softscapes create pooling and where grade depressions create ponding in undesirable locations. French drains are basically just trenches filled with gravel. Sometimes drainage pipe is installed. French drains act as disguised dry creek beds, and can transport water under turf or other landscape features.

Including native wetland plants in high moisture areas can also control water excesses on site. Winterberry hollies, inkberry, florida anise, willows, red dogwoods, birches, cedars, horsetail, ornamental grasses, lillies, and rose mallow are all species native to Georgia which can withstand or even thrive in excessive moisture.

If the recent rains pointed out site drainage issues on your property, talk to a qualified landscape designer for advice about how to manage drainage, even harness excessive water on your property for asethetic or functional gain.

Although the recent rains have alleviated the severe drought of 2007/8, the Atlanta area will still get dry months, and planning for a dry summer should start now. 

In recent years, because of the drought, a number of innovations in water saving systems have taken place.  The most common one is a simple rain barrel.  These have come a long way from the old fashioned wooden barrel that collected water on rural properties.  Fiskars have come onto the market with very acceptable designs that are easy to install and are available at larger hardware stores.

The barrels come complete with hardware, so that all you need to do is assemble and install.  Locate the collection system near a downspout, and on a level spot.  The assembly does require that you saw into the downspout at two different places so that the diverter hose can be inserted.  The hose carries water coming down the spout and into the barrel.  When the barrel is full, the hose becomes inactive and water continues down the spout to the ground drainage system.

The biggest drawback with the system as it stands right now is that the only outlet is a spigot.  This is fine for a watering can to refresh hanging baskets, but not so great for larger areas which need a soaker hose or other method of water delivery.  Putting a tap with a hose attachment onto the barrel is not difficult, but you will have to purchase the parts such as an outlet tap, connector, washers etc.

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A Fiskars Water Collection System modified with a hose outlet as well as the spigot fixture.

By the middle of this season, a new version of the Fiskars rain collection system will be on the market, which includes a modified tap that has the threading to attach a hose.

For larger, more complex water collection systems you can use cisterns and underground tanks. For more about these systems visit www.atlantarainharvest.com .

Drainage patterns in your garden can negatively effect the optimal use of water. 

Most modern homes have a system that is geared to carrying water away from the whole area, reducing ponding and preventing dampness around basement areas. That is a fine model for flood prone areas and areas that do not suffer from regular droughts, but not so good for Atlanta which is facing a second year of watering restrictions. Learning how to change the drainage patterns can ensure that more water stays on your lot, and less is diverted to the storm sewers.

The drainage on your property can be adjusted such that it can help conserve the water that we do get, and in many cases this water, particularly from spring and summer storms, can be stored for later, drier periods. Knowing how to capture the water and effectively distribute it may need a professional, but there are some things that a homeowner can do to adjust the flow patterns such that they are more beneficial to the landscape as a whole.

Identifying Low Points

When heavy rains occur, even if they only last a few minutes, it becomes obvious where your low points are.  Look for standing water just after the storm.  You can also see grass lying down in the direction of flow when fast moving water passes over it.  This will indicate the direction of drainage.

Generally you will find the low spot and drainage areas are at the corner of the property, or a group of properties.  Placing a collection system at this point will stop the water leaving your property.  Underground cisterns are a convenient way to store this excess water. With a pump installed, the stored water can be distributed as needed.

Altering the Flow Pattern

Water that leaves the property by running along the back lot line can be retained on the property if the flow pattern is adjusted.  Just as ancient irrigation systems were made to channel water in a specific direction, modern landscape design can also be designed to retain water and drain it to a designated place. 

Altering the overall flow of the lot, by creating swales and hills, will divert the storm water effectively, but it is wise to get professional advice prior to major reworking.  Draining too much storm water towards your home can cause major structural problems.

Small scale trenches and channels through a vegetable bed are quite within the scope of a homeowner. Instead of using boards to retain soil in a raised bed, trench around the bed and heap the soil to the middle, thus giving a channel around the edge of the area to retain, and distribute, storm water when it occurs.

Knowing how to change the drainage pattern will make the best use of rainwater and help ensure that your garden gets the maximum amount of water available.

Perennial beds are best watered with soaker hoses.

A tremendous amount of water is wasted when people water their gardens. Most of the wasted water either goes to run off or is evaporated. Neither of these are any use to the landscape. Picking the right sort of water method for your garden depends on what you are growing.

Overhead Sprinklers

Overhead sprinklers are the worst culprit as they fling water in every direction and on a hot day the tiny droplets evaporate before they reach the ground. However, sprinklers are probably the best method of watering newly laid turf or lawns. To maximize the water getting onto the surface, water very early in the morning when the temperatures are coolest. Cool air temperatures cannot hold as much water as hot air and the addition of sprinkler-driven water will result in much more getting onto the lawn where it is needed.

Overhead sprinklers are not the way to go with herbaceous borders. Getting the leaf surface wet can lead to mildew problems particularly in humid weather. Much less water actually reaches the surface from sprinklers and as the plant needs moisture at the root level, you will need to run the water for much longer.

Soaker Hoses

Soaker hoses are made from a sponge like material that allows water to ?leak? out. If placed carefully and covered with mulch, these will irrigate the surrounding 3 ? 6 inches. This type of hose is great for irrigating a large perennial bed where you want to get water to the roots of many items in the same general area.

Drip Irrigation

This method of watering is great for things that are spread apart. A shrub bed would be the ideal situation where individual shrubs are several feet apart. Each shrub needs water but the area between the shrubs does not. Drip irrigation carries water along a pipe and diverts it to a few discrete areas. One t-junction will send water to each shrub. This makes watering more targeted and thus more useful for the specific landscape.

Whichever sort of landscape you have, you can mix and match the irrigation to suit the area that you need to irrigate.

For more ideas on efficient irrigation visit: http://atlantawaterharvest.com.

Rain barrels are probably the most common way capture water from a storm to use in the landscape. There are many situations though where a homeowner wants to save water, but they also want discrete collection containers.

The main source of collectible water is from downspouts.  Rain that falls onto the roof follows down the slope of the roof line and is diverted into the gutters, then into the downspout. From there the water is taken away from the foundation and usually drained into storm sewers. Older homes could find that the water is diverted to a low spot on the property which floods when you get heavy storms.

This water is the prime source of collectible landscape water. 

When designing a rainwater capture system for your landscape there are a few considerations, the prime one being ? where do you want to water?  If your favorite perennial border is 75 feet from the collection point, you will need hoses or even buckets to get it from the point of collection to the point of use. This is the major drawback with rain barrels. A rain barrel is collecting at the base of the downspout, which is next to the house.  For foundation plantings and things close by this is an adequate source of supplemental water.  However, for plants on the far side of a pool, you would have to string ugly hoses around the pool to water the landscape, and that is not quite so convenient.

This is where alternative collection sites need to be sited.  Funneling the water from the house to a distant collection point needs to be designed carefully.  Water can easily be backed up and cause your basement to fail.  Remembering that water needs to flow downhill is critical, and for most landscapes this requires the collection tank to be sited below ground.  Capacity of the tanks will vary but even fountains can be sustained by larger tanks. 

Once you have the collection side of the operation organized, then you can deal with the delivery.  Unless your garden is down hill from the tank, you need to use a pump to get the water to where you want it. A simple sump pump mechanism will work to evacuate the water from the cistern, but a stronger pump is required if you want sufficient pressure to carry the water along soaker hoses and around the garden.  A tap that has a hose nozzle fixture is the most convenient and this requires an electrical line for power.  Simply activate the pump to get the water flowing through your hoses.

Overall water collection for use in the landscape is not only needed on those hot dry summer days, but with the environmental and climate concerns being important too, having someway to sustain a landscape without using public water is imperative.

For more information on storing water in cisterns check: http://atlantawaterharvest.com/