Environmental design: learning to work with the natural water balance

Roy L Hales/ Cortes Currents - In a previous interview with the Quadra ICAN water security team, Bernie Amell said that development could take place in a manner that respects the natural water balance. Amell is co-owner of the environmental design firm Source2Source and a recognized authority in the design of constructed wetlands for water treatment, and in the restoration of streams and riparian habitats. One of his firm’s projects received a gold medal from the Canadian Society of Landscape Architects last year. Amell’s bio mentions over 135 restoration projects throughout Alberta and in British Columbia. He has presented his work at national and international water management professional conferences. Amell lives on Quadra Island and in today’s interview, he talks about learning to work with the natural water balance.

“Natural water balance is an idea that has been generated in the past 20 years by people in a stormwater management world,” he explained.

Prior to that, people simply built ditches or install pipes to drain away the excess water from areas where they wanted to build houses, businesses or cities.

Unfortunately, there were often consequences.

“It seems like you're not really doing much to the hydrology, but in fact you are. So, what has happened in the stormwater management world is to recognize that even fairly humble things that we all take for granted, like curbs on roads and roadside ditches and the ditches in farm fields and so on change the hydrology. Most human activities do,” explained Amell.

A roof has a hundred percent runoff and so does a parking area (after it's been used a few years).

“There is a whole set of fairly humble tools to maintain a natural water balance close to the point where that human impact has occurred,” said Amell.

It is relatively inexpensive to address the problem of water draining from a roof. Problems affecting multiple city blocks are fixable, but more expensive.

Remember that big circular water cycle that most of us learned about in elementary school?

“If you delve into the detail of how the rain falls on the ground, usually you just see the vegetation and the soil. There is a certain amount of the rainfall caught in the canopy that never actually makes it to the ground, called intercepted water. There's not much in this rainy season, but throughout the year it's probably 5% to 10%. Then there's a spongy layer of humus, leaves and everything and, surficial vegetation and routes that take a very high proportion of the water into the ground,“ said Amell. “Probably 50% of the water that falls in an area doesn't run off the land, it goes into the ground or its used by the vegetation on the property.”

Amell cited the Dillon Creek Wetland Restoration project, which helps filtrate the flow of nitrates into Gunflint Lake on Cortes Island, as an example of reversing the damages from human development.

On a smaller scale, a structured bed of earth with plants can address the problem of runoff from a roof.

“If you're dealing with a few acres of land around a house, you might just focus on biofilter beds because you could integrate it, say with a fruit orchard or something that will also benefit from having deeper rooted soil conditions,” explained Amell. “You have to deliberately create it. You've created the roof and the pavement that increases runoff from one area. You have to do some deliberation somewhere else. I call it countervailing effects. That's what the core of the natural water balance is about, understanding the kind of nitty gritty of the water cycle on your property. Then saying, ‘Okay, I've done inescapable things that effect it, what can I do to bring things back into balance?’”