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Runoff as resource instead of problem

Deborah K. Rich, SF Gate, Special to The SF Chronicle
Saturday, December 6, 2008

"The first year we were here, the water would just sheet down from the property higher up the slope, and this area would be mud. I couldn't even walk out here; it was just slosh and goop," she said.

Her home is near Occidental in Sonoma County, which can receive 60 inches of rain a year. "My husband and I were wondering what we were going to do, and how we were going to figure this out."

Davison met a teacher at her sons' school whose husband, Erik Ohlsen, had recently launched Permaculture Artisans, a landscape design and installation business.

Permaculture - the word plays on "permanent culture" and "permanent agriculture" - strives for sustainability by incorporating ecological cycles and principles into land altered for human use. Ohlsen took his first permaculture class in 1999 from Brock Dolman, who directs the Water Institute at the Occidental Arts & Ecology Center.

Interaction with water in the landscape has become fundamental to Ohlsen's permaculture design practice.

"I was inspired by the concepts of water harvesting, ecological watershed management practices and erosion control and everything to do with water in Brock's course," Ohlsen said. The storm water that turned the property into muck could instead provide a foundation for the garden Davison wanted.

"The Davisons were clear that they wanted an ecological landscape that provided food for their family," Ohlsen said. "Water harvesting wasn't something they had foreknowledge of, but the way we design ecological gardens, water harvesting is always the first piece designed into the system."

Swales and berms
Ohlsen used a small excavator to build a series of parallel swales (a shallow ditch) and berms (a raised area adjacent to the swale) on contour (meaning that they lie across slope, their elevation remaining constant). He dug the first swale along the upper property line and the last where the property levels off.

Each swale is roughly 5 feet wide; its adjoining berm is 2 1/2 feet tall and 6 feet wide. A smaller berm lies across the end of each swale to prevent water from running out the end of the swale.

The swales and berms harvest rainwater by pooling and slowing the water on its downhill course, giving it time and space to soak into the soil. Rock-lined spillways connect the swales and allow water to flow from one to the next if the water pools in the swale more than 8 inches.

In the Davisons' loamy soil, all the rainwater will generally soak into the swale where it is caught, and water will spill from one swale to the next only during a very heavy rain. "We design for catastrophe," Ohlsen said of the oversize catchment systems. Encouraging Davison and her boys to work along with him, Ohlsen planted the berms with an eye toward both feeding the family and creating a self-sustaining ecosystem.

"We chose plants that provide multiple functions - for example, leguminous plants which can provide edible pods while, at the same time, fixing nitrogen in the soil and attracting beneficial insects and hummingbirds, which can then manage pests," Ohlsen said.

For entire article, please visit website.

Get out of the drain age, into the retain age

By Deborah K. Rich, SF Gate
Saturday, December 6, 2008

Embedded in both urban and suburban lot design is the "pave and pipe paradigm," according to Brock Dolman, director of the Occidental Arts & Ecology Center's Water Institute. It favors grading, piping and paving properties to drain away rainwater as quickly as possible.

But rapidly draining water off landscapes rather than allowing it the time and space to soak in causes a host of problems downstream and in the pipes. Culverts pour water into gullies and seasonal creeks, overloading and eroding the natural drainage area and rushing sediment into rivers, streams and estuaries, where it imperils fish.

Downspouts, gutters and sloping driveways conduct water into the storm water and sewer systems, which can dump raw sewage when overloaded. After we're finished draining our properties, we pay, increasingly dearly, to pipe water back into our homes and landscapes.

Dolman advocates replacing the "drain age" with a new "retain age," wherein we capture and store storm water for future use and resculpt yards and gardens to allow water to percolate into the ground.

To take a step into the retain age, consider harvesting rainwater from your roof and banking more water in your soil.

Harvesting roof water
Every inch of rainfall on 100 square feet of roof surface yields 55 to 60 gallons of water. For a 2,500-square-foot home, that translates to 1,375 to 1,500 gallons of water per inch of rain. This water can be caught and stored in above- or belowground cisterns and used for drinking, in-house nonpotable uses or irrigation, depending upon what filtration systems are installed and upon local regulations.

For entire article and web references on Water Harvesting, please go to website below.

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