Green Infrastructure: Designing with Best Water Management Practices to Conserve Resources

January 16, 2017

vaseyi, azaleas, mountains

Water is our most precious resource. We’ve all heard this phrase before, but it always seems the things that are a part of our lives every day are the things we most often take for granted. Access to clean water would not be possible without the services provided by the ecosystems that support our global habitat. Forests and soils provide filtration services, plants participate in the transpiration process, pulling water out of the soil and releasing it into the atmosphere through their leaves and needles. Perfectly balanced by nature over eons, these processes are now being disrupted by a changing climate and human development.

Weather and water are inextricably linked. As global temperatures rise, water evaporates from our oceans at a faster rate, which in turn causes an increase in frequency and intensity of storms. In addition, the expedited rate of evaporation also means weather events will result in more frequent of droughts and floods. In other words, we can expect to see longer periods of time without water and also experience  greater amounts of water in single weather events.

Water mitigation is important foremost for the purpose of water conservation and reduction of potential damage to both our landscapes and ecosystems. Water retention reduces the need for water elsewhere, which can be costly if the water source is monetized via a city water supply or a well supply, where energy is used to pump water on-site. Enhancing infiltration to utilize storm water runoff on site is beneficial for not only your gardens and cost reduction, but also prevent contamination of nearby streams and rivers. As storm water runs quickly over roads and land, it picks up contaminants and soil sediment that are then carried to water sources. Sedimentation is the number one cause of water pollution in North Carolina, which disrupts the balance of delicate aquatic ecosystems. With meteorologists predicting a greater amount of unpredictability in our weather patterns, employing water mitigation strategies helps us prepare for the unknown.

Over the past five years, SHR has implemented a number of water mitigation strategies to minimize the effects of drought and flooding in a changing climate. After the gardens were designed, SHR’s founders and staff began learning more about climate change and recognized the need to take action in order to adapt. As Executive Director Kelly Holdbrooks notes, “We don’t have to stay in the past and stay married to systems that don’t work. We can evolve.”

In order to formulate a plan on which best management practices would help SHR best address the changing weather patterns, Holdbrooks reached out to Gary Smith, the landscape architect who designed SHR’s Core Park. “Involving Gary allowed us to maintain the integrity of the master plan he created for SHR while adapting to changing weather patterns,” said Holdbrooks. In order to reduce the impact of garden trails that were not designed along contours (a practice which is now a fundamental principle taught in landscape design) SHR is considering the implementation of boardwalks to control erosion and storm water runoff as well as reduce the footprint on our native ecosystems.

At SHR, we currently apply two basic engineering principles to water mitigation: change the velocity in which water is moving across a landscape and/or change its direction.Executive Director Kelly Holdbrooks conducted 4-5 water mitigation studies over the course of 2012-2013 with the assistance of two consultants and staff to create the water mitigation strategy. Dr. Jon Calabria, ASLA, professor at the College of Environment and Design of the University of Georgia, recommended we build “hydra-humps,” or mounds of elevated soil. These mounds redirect the flow of water to an angle that is similar to where water would naturally flow, but steers it into areas that will not cause as much damage to plants or our trails. According to Director of Horticulture Eric Kimbrel, “We implemented hydra-humps back in 2013 when the rain was affecting our trails and gravel driveway.”

In areas where water is known to flow, SHR lines paths with stone to protect garden beds. These “dry creeks” help to capture storm water runoff during intense rainfall. According to Holdbrooks, “We created swales throughout the gardens to guide the storm water, some of which we have increased in size as well. We also placed large dead trees throughout our gardens in areas where the slope is higher than 5%. These logs help to slow down the run-off and protect our plants from getting the soil washed away or covered by other debris in the storm water runoff.”

Conversely, to mitigate times of drought as we had in 2016, our water mitigation strategies are focused on keeping water on site. Our primary method of keeping water on site is the Vaseyi Pond, which was engineered with a high degree of precision and passed by the Army Corps of Engineers to protect ecosystems downstream. While the pond is fed by a naturally-occurring stream, the gardens are engineered to send a majority of the water that lands on-site to the pond, where we collected it and use it for irrigation use. This highly-engineered water retention method is designed according to the scale of our gardens, but this water retention strategy can be calibrated to any size gardens, residential or commercial.

The Vaseyi Pond is also a water feature, which is inherently more valuable to the environment than just as a water mitigation or irrigation technique. The addition of a water source to any landscape or environment is highly beneficial in that it adds the number one component: water. Water is necessary for all living things; with the presence of water comes wildlife. At the pond, we have seen a massive increase in wildlife activity such as otters, bears, song birds, tree frogs, turtles, and a diversity of insect species. Lastly, water is used in design to create a connection to nature. Water is cleansing not only to our physical bodies but also to our mental and emotional bodies. The sound and sight of water is restorative.

Below are four specific water mitigation strategies that can be scaled used for residential and commercial applications:

• Utilize materials that don’t wash away, such as rock in dry beds for example. Use mulch during dry periods to slow the evaporation process.

• Collect water during the wetter spring months using water tanks, rain barrels and other forms of water retention.

• Consider designing water retention into the landscape. Water gardens can be an ornamental strategy to collect storm water while adding aesthetic value to the landscape.

• Evaluate using larger gutters and connecting those gutters to rain barrels, cisterns, and swales that feed the landscape when constructing home or consider upgrading if you’re in an area that gets high levels of precipitation.

The water cycle is a valuable ecosystem service that has been purifying our most precious resource for billions of years. All life on earth depends on clean water. Conservation and best management practices protects ecosystem services and saves money in the long run. While making these changes to existing gardens and landscapes now can be considered an investment, the return on invest will be tremendous in years to come.