Tuesday, April 22, 2008

Landscaping as if Water Mattered

On this Earth Day, it's time to take another look at how our landscape choices are impacting the planet. Last year I posted a diary here taking our default landscape choice, the lawn, to task over its extreme dependency on petroleum, and accompanying waste of this dwindling resource. It is not only oil, however, that our landscapes waste. They waste productive human labor, money (over 45 billion dollars per year in the United States), fertilizers that could be better directed to crop production, but most of all, they waste and abuse water. Water is the basic resource upon which life depends, but our current landscape choices behave as if it were limitless. The current turf-dominated landscape both attempts to get rid of water, and to introduce it at the same time, thus contributing even further to squandering of water resources. Below the fold, we talk about how landscaping affects our water resources and explore sustainable, water conserving alternatives to the wasteful dominant landscape paradigm.

Water is a critical issue these days. Most of our surface and ground water is salty, polluted, or otherwise unfit for human consumption. Water shortages have led to conflicts, and open warfare. Large centralized corporations such as Bechtel in Bolivia have attempted to corner and privatize water, even making it illegal for individuals to harvest rainwater for their own use. In Colorado, archaic water laws also make it illegal for property owners to utilize rainwater collected on their own properties, citing the fact that it diminishes the downstream supply of water. Even in our neck of the woods, a contentious battle has been fought over access to the Great Lakes, where municipalities outside of the watershed boundary in sprawl suburbs in Waukesha County have attempted to gain use of Lake Michigan water to solve their water shortage and contamination issues. Much of this water use is a result of our water squandering, turf-centric landscape, and if more sustainable water use practices were adopted in our area, a reduction in the “need” for Lake Michigan water would definitely be a result.

Turf is wasteful of water due to its high water demand to remain green, but lack of tolerance to flooding. In many areas, even in the wetter eastern half of the country, droughts of several weeks to months occur in summer, causing the turf to go brown, which the suburban lawn fetishist finds unacceptable. To get the right moisture levels, expensive irrigation systems are built to pull out groundwater to water turf lawns and golf courses, while on the other hand, sites are graded and piped to get rid of excess rainfall as quickly as possible without allowing it to soak into the ground and recharge the aquifer. A combination of turf, asphalt roadways, rooftops, and other pavement such as sidewalks forces water to run off, intensifying flooding (runoff peak flow) and robbing local groundwater aquifers of their recharge water, which reduces base flow of streams (that flow that derives from ground water, not direct runoff of rainwater) , stressing water dependent ecosystems and human development dependent on these water resources. An extreme example of this is Atlanta, suffering from a long term drought exacerbated by poor land use practices that deplete and degrade local water resources.
According to Food not Lawns, 270 billion gallons of water is used every year in the U.S. to water turf grass. Up to 30 percent of water use in the eastern U.S. and 70 percent of water use in the more arid regions of the west are devoted to sustaining this landscape model. Think of this when considering piped irrigation just to keep your expanses of turf green.

A lack of familiarity with alternative, sustainable landscape models permeates the design and civil engineering community, and perpetuates the current model of water mismanagement, where rainwater is not thought of as a resource, but something to be removed from the site with all deliberate speed, in order to compensate for the poor absorptive capacity of shallow rooted lawn turf and accompanying impervious land surfaces to service vehicles. Turf grasses typically have root systems that penetrate less than 6 inches into the soil, in contrast with most native plants such as prairie plants and trees, which can have roots that penetrate 4 to 15 feet. Water is also contaminated for the downstream user through several pathways – the overuse of fertilizers and pesticides that are not taken up by the turf grass , the lack of a deep, complex root system and layering of vegetation , and erosion promoted by the shallow roots of the grass, which does a poor job of holding the soil, especially on slopes.
After leaving the turf lawn, road and roof at great speed, the water is often dumped into a centralized, highly engineered water management system, that is supported by commonly used hydrological (water) engineering models. These are designed to “meter” runoff to reduce pulses of stormwater and filter it before it enters the natural surface water system, but because of the lack of living components, often fail at these tasks, especially in water quality. Such systems begin where water is routed from lawns, streets and low areas into underground storm sewer pipes, that either empty into engineered detention basins, or directly into natural lakes and streams. In some areas, mainly large cities, the storm sewers are connected with the sanitary sewers, leading to even more surface water pollution problems during times of heavy rain. The infrastructure, requiring a good deal of pipes, excavation, and grading can be very expensive. Some developments use open ditches and swales instead of storm sewers, which do reduce the runoff somewhat, but would do better if native vegetation was used. These conventional practices leads to inappropriate land abuses such as these:

This dry detention basin with gravel filter does little to cleanse and infiltrate rain water before it enters the natural watershed.

To add insult to injury, detention basins such as these systems require expensive heavy equipment and engineering to install and the gravel lined drains are prone to clogging with sediment over the long term. Also, the dirty runoff water has little time to precipitate out sediment before it is directed into other surface waters. The runoff from the basin in the photograph travels directly to Delavan Lake via an underground storm sewer, thus contributing to pollution of an already overly nutrient-rich lake.

Other detention basins try to use rip-rap to solve erosion problems. This also fails to filter the water, can be expensive, and eventually these areas grow in with weeds and opportunistic vegetation, making scenes such as this even more hideous Examples of how turf grass fails to hold the soil are shown here in this photo of a collapsing stream bank and erosion by a school.

The monomaniacal devotion to turf leads to landscaping like this (extremely steep slope along highway with mowed grass). Research indicates that turf is a poor landscape choice on steep slopes, as runoff from it and leaching of chemicals is far greater for these areas than on a level surface
Research into the relative runoff of turf grasses versus native vegetation in my region has determined that wooded areas along Wisconsin lakes (warning, PDF) have at least ten times less runoff than turf areas. Native habitats also generate less than half the nitrogen and phosphorus leaching to the lakes as do the turf areas. Nitrogen and phosphorus are the principal nutrients that lead to imbalances in lakes causing excessive algae growth and sedimentation, “blue baby syndrome” from nitrates in the ground water, and overgrowth of weedy vegetation in and near the water. A study of a sustainably landscaped house in a suburb of Chicago (Elmhurst), showed that runoff volume is reduced by 50-80 percent by using native vegetation and other water-conserving landscape treatments relative to the standard turf model.
In a nutshell, our current landscape model wastes and pollutes surface and ground water, lead to conflicts over water usage and rights, push water quality problems on to others, worsen flooding problems, causes erosion, and destroys fish and wildlife habitat through degradation of lakes and streams. This model sends the water downstream or squanders it under our feet, making it a problem for someone else. Like most other “solutions” of the economic status quo, our current rape and scrape, green rug landscape model imposes great external costs to the rest of society.
Fortunately, there is a toolbox of solutions that address all the problems that our conventional landscape model visits upon our waters. A combination of new paradigms and old ideas which were used in previous times of scarcity to make our landscapes conserve and clean the water, and even provide on-site water to serve potable uses. The idea of this new paradigm is to trap the water on site for local usage, or return it to the groundwater for collective benefit, rather than to move it off at all deliberate speed.
Local sustainable landscape solutions for water conservation and filtration run the gamut from rain water harvesting systems such as cisterns to collect roof-top runoff, rain barrels (a smaller version of the cistern), French drains to direct runoff directly into the soil to help it absorb the water on-site, bioswales and rain gardens that utilize native plants to trap and absorb runoff waters, permeable pavement and pavers, and green roofs, which use soil and vegetation to absorb rainfall. Native deep rooted vegetation or drought adapted native plants (in the West) are used in lieu of grass where possible. Biofilter basins are use pollution-tolerant native wetland vegetation to filter and absorb rainwater from contaminated surfaces such as pavement. Even cultivated vegetables and fruit trees save water relative to the demands of lawn turf as part of a permaculture solution. Greywater systems also provide beneficial re-use of indoor wash water for landscape irrigation should the above solutions not provide enough water for on-site use. The house in Elmhurst Illinois uses nearly all of these water saving techniques, and the amazing result is that, relative to the conventional landscape, only 20 percent of the water leaves the site with the sustainable improvements.
Cisterns are an excellent way to conserve water in the landscape. For example, in our area, a 10,000 gallon cistern combined with the 37-inch annual average rainfall and a 2,000 square foot roof can provide enough water to serve the TOTAL annual water needs of a family of four with moderate water conservation (use of high efficiency appliances, and moderate landscape water demand). A one inch rainfall over the same 2000 square foot roof area generates 1,247 gallons of water! Some water –poor areas, such as on islands in the Caribbean, require rainwater harvesting systems for all new development, and the state of Texas actively promotes these systems and provides a free comprehensive how-to document on the Texas Water Development Board website (warning, PDF). . At least there is one good thing coming out of Texas, in spite of the fact that that state hatched the Bush Regime. Progressive landscape firms, especially on the west coast, are integrating and installing these systems in their landscape designs. An excellent example of a cistern system and other water conserving measures is the Chicago Center For Green Technology.
The Chicago Center for Green Technology and the 168 Elm Street Elmhurst property also utilize green, vegetated roofs. First popularized in Europe, American cities such as Chicago and New York are beginning to promote them. They consist of a layer of soil and vegetation on top of a membrane. These roofs provide the benefits of vegetation, including cooling and runoff reductions of up to 75 percent relative to conventional roofs. Properly designed and installed, they can outlast conventional rooftops. A green roof in Switzerland has lasted nearly 100 years.
The Elmhurst house and the Chicago Center for Green Technology also showcase the use of native vegetation in rain gardens and bio-swales to collect and infiltrate rain water. Sustainable residential developments such as Prairie Crossing in Grayslake, Illinois, and Tryon Farms, in Michigan City, Indiana integrate forest and prairie vegetation into their development, as well as bioswales, rain gardens, reduced or porous pavement, and greatly reduced or absent turf areas. At Prairie Crossing, roof and pavement runoff is routed through a series of vegetated treatments, starting with rain gardens, vegetated swales, biofilters, detention ponds, and finally to native vegetated swales exiting the property. By the time runoff water reaches the detention ponds at the last step of this “treatment train”, the water is so clean that it has allowed the community to introduce thriving populations of three endangered fish species endemic to northern Illinois that depend on clean surface waters, and are thus endangered for that reason as lakes are fouled by encroaching sprawl development. In areas where turf is desired for recreational purposes or for residential usage, strategically placed berms, or terraces, landscaped with trees, shrubs, perennials or native plants, can also slow down, trap and infiltrate turf runoff
Naturalized detention basins and native vegetated buffers along lakes and streams, the last step in the on-site water conservation and filtration system provide both beauty and water quality benefits relative to turfed waters edges. Research has indicated that native buffers at least 30 feet wide provide the greatest benefits to water quality. The complexity and deep roots of the native vegetation also provide a variety of nutrients that actually cycle into the water and benefit a diversity of aquatic life. Streams and lakes are not a closed system from the adjacent land, and nutrients and carbon cycle from land to water and vice versa. Preservation of native vegetation in and around ponds greatly improves water clarity by trapping sediments and absorbing nutrients from the adjacent land. The photos shown here show an obvious contrast between ponds bordered by native plants, and those with turf or rip-rap stone shorelines. “Neatness” of the landscape along ponds and streams does not translate to cleanliness of the water in them.
In concluding, there are a wide variety of tools to make our landscapes conserve and clean our water resources. The potential exists, if these are widely adapted, to reduce water usage in the landscape by a factor of at least 50%, and perhaps more, by adopting sustainable techniques as described above. These tools also greatly reduce the level of maintenance needed, especially that dependent on fossil fuels. There is hope to remake our landscape model to improve our waters, not degrade them.

Note: Most of the photographs of disastrous detention basins were taken near Williams Bay in our county, less than a mile from our house. The native planted detention ponds are located just south of the border, in Harvard at the defunct Motorola plant, and at the corner of Huntley and Randall Roads in Carpentersville, Illinois. It is ironic that Illinois native landscapes are ahead of the curve relative to our local area, when Wisconsin is supposed to be the leader in environmentalism!

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