Low Impact Development (LID) in Landscape Design

Low Impact Development (LID) stresses the role of rainwater and landforms in creating an environment that is sustainable. Sustainable landscaping strives to create beauty with the lowest possible impact on the natural environment within which it exists, and LID adds a strong emphasis on rainwater retention - preserving and enhancing the natural flow of water - to counteract the destructive water-wasteful practices humans have employed in the past.

Due to human fears about floods, city planners all over the world have developed extensive storm drainage systems that take rainwater straight to the sea. But recent droughts have caused a reconsideration of such systems. They are now being acknowledged as a way of throwing away rainwater, thereby preventing the earth from storing and utilizing it to support life.

In addition to rivers, earth's storage system includes underground storage basins called "aquafirs," which are normally filled by rain sinking down through the earth. Humans have blocked that replenishment, also, by covering the ground with concrete, asphalt, and buildings.

LID principles reverse both of these processes, encouraging water retention as a major part of sustainability. They can be applied to almost any kind of design, whether buildings, landscapes, storm drain systems, parks, transportation routes, or city streets.

Paying attention to the role of water availability and flow in a landscape, according to what normally accrues in a particular location, is the key to designing a sustainable landscape. Bioswales, pervious concrete, green roofs, detention basins, and rain barrels are all tools related to the use and sustainment of water in an area. Hence, all of them are resources that can be used in designing sustainable landscapes.

The Arizona Landscape Contractors Association offers annual awards to designers that best design creative landscapes that harmonize well with the environment. 

One of their recent winners, Enchanted Garden Landscapers (EGL), designed an exceptionally attractive water-saving landscape in the Arizona desert, based on the xeriscape concept (see photo). Xeriscape is a term used to describe a landscape especially designed around a minimal use of water (but it's also patented, hence is not as widely used now as it was). Below the photo of the winning landscape is another, similar project designed by EGL.

Here is an example of a LID community built in Brevard County, Florida. The semi-tropical area includes 1,000 acres of upland (high and hilly) and wetland preserves, with over 400 acres set aside to be enhanced specifically for the Florida scrub jay and gopher tortoise.They designed the housing development around keeping and improving habitat for the jay, paying attention to wildlife corridors, as well, so that animals could continue to migrate to and from feeding areas.

The developers built the community with the smallest possible destructive impact on the environment, preserving it for the exploration and pleasure of residents, including creating small lakes as an integral part of the wetlands.

The state of Washington appears to be one of the most active states in the United States in practicing LID designs. In Sammamish, Washington, a natural woodlands area, a team of developers created a city hall, police facility, civic plaza, skate park, and sports park on the upper ten acres of a 30 acre site. Of the remaining 20 acres below, they enhanced a protected wetland and built walking trails, picnic shelters, a play meadow, and a garden and orchard. Pavements in all areas were made permeable to allow rainwater to filter down into the soil. The city hall was awarded a LEED Silver rating.

An environment, planted or natural, should be able to sustain itself over time with a minimal amount of care. Sun, water, and soil are some of the environmental factors that affect what will grow in a particular area. The shape of the land and the insects and other wildlife in the area also affect what will grow and define what will be supported by it.

Different environments provide different sets of characteristics that can help or hurt a designer, depending on what the aim is. They will still need to be worked with, so aiming for sustainability encourages a designer to recognize, use, and often enhance whatever those characteristics are.

With a site that is located in a valley, water will flow downhill when it rains, which provides the potential to create a retention basin, natural lake, a rain garden, or at least to collect water in a cistern. With a site located in the foothills, you can expect some soil runoff as well. A retaining wall will hold it back, creating a bank that you can then plant.

The overall look of an environment is also a characteristic, which can be brought into your own home using local rocks and cultivars or native plant hybrids. These tools will help your landscape to be sustainable, blend with the environment, and still look residential.

Note that a 1,000 acre golf course built in the middle of the Nevada desert would NOT be sustainable, whether or not it was labeled as such.

In built-out areas like cities, existing buildings are considered part of the environment you will need to work with. The aim there would be to restore whatever could be restored to mimic a more natural eco-system.

For example, the City of Los Angeles is discussing a potential reconstruction of storm drains into open streams that meander throughout the city. The streams would be edged with bike and walking paths and native greenery. There is strong support among developers and the citizenry for such a project.

Many cities (such as Chicago) are building roof gardens on the tops of city buildings which are, in a sense, like the tops of mountains. Water pouring off a roof during a rainstorm mimics waterfalls flowing down a mountainside. It can be captured in pools to sink down slowly into the aquafir, or in barrels or buried cisterns to be saved for later use in a garden or park area. Low-lying areas in cities can sport rain gardens, which can be set up to mimic natural swamps.

When you design and plant for the native environment, you take advantage of the way local plants are naturally supported throughout the seasons. You save energy, work, and money in the long run by building a sustainable landscape with a year-round "shelf life," as opposed to replenishing plants every time the weather or water availability changes.

And just as nature modifies and shapes itself differently over time, so a new landscape doesn't have to be built overnight.

There will be no need anymore to spend money to go up into the mountains to experience the real natural environment, when you have a built one right where you are. Using sustainable landscape design, you will have created a new vacation spot right at home. You will be attracting back wildlife and birds that used to live there, making it feel "wild" once again. You can take your time, enjoy the process of creation, and when you need a break go watch a movie instead of leaving town . . . unless you like to hike.