Urban Forests

What is a simple action that homeowners can take to reduce stormwater runoff leaving their property? Plant a tree.
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 Trees and forests benefit air quality, biodiversity, neighbourhood aesthetics and also play an essential role in managing stormwater. Tree canopies reduce stormwater runoff by intercepting, capturing and storing rainfall and releasing water into the atmosphere through evapotranspiration. In urban and suburban settings, a single deciduous tree can intercept between 500-760 gallons (~1,800-2,800 L) per year, while a mature coniferous tree can intercept over 4,000 gallons (~15,000 L) per year (PA Trees). In addition, tree roots and leaf little help promote infiltration of runoff into the soil.

Source: http://bit.ly/IcxK5H

Trees also act as filters, taking up nutrients and contaminants from the ground that may otherwise directly enter natural water bodies, or end up in wastewater treatment plants. As we begin to remove forest canopy and replace it with lawns and impervious surfaces, we immediately have an impact on quality and quantity of stormwater runoff. 
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Urban Forests in Halifax Regional Municipality             
                                                               
In HRM, it is estimated that street trees provide about $2.1 million in stormwater reduction services annually (HRM). HRM is currently developing an Urban Forest Master Plan (UFMP) with the goal of ensuring a sustainable future for our urban forest. The plan contains an overview of the issues and opportunities regarding sustainable urban forest management in HRM. Neighbourhood Factsheets have also been developed that describe the species composition and age distribution of trees found in each neighbourhood, as well as targets for urban forest restoration. Take a look at the draft UFMP and Neighbourhood Factsheets here. 

Rain Catchment Workshop

Stormwater Management at Dalhousie University

A group of students enrolled in “Campus as a Living Lab”, a course at Dalhousie University that aims to engage students in efforts to “green” the campus and surrounding areas, have delved into the world of stormwater management. Students, Bridgette DeCoste, Tiara Pettinger, Robyn Pirie, Nicole Power, Michelle Simone and Paul Westlund, chose two areas on campus, the Dunn parking lot and the Grad House, to focus their research. The intention was to create transferable stormwater management designs that could be implemented by homeowners who are interested in managing stormwater on their properties. The students created three levels of increasingly complex designs for both sites and investigated five different management approaches; vegetated swales, permeable pavement, rain gardens, rain barrels, and French drains. The students then presented their designs to experts in the field, as well as with facilities management staff at Dalhousie to determine the most feasible and cost-effective approach to stormwater management on the two sites.

Here are graphics of the third designs for each location

Dunn Parking lot - featuring permeable pavement and vegetated swales

  

Grad House- featuring french drain, rain barrels and rain gardens

Click here to read the full report

The most interesting part about this report for the Ecology Action Centre is the transferability of the designs. Because each component of their designs is featured individually as well as a part of the whole system, the report contains a wealth of information directly relatable to any homeowner who’s looking into taking on some of these retrofits on their own properties. The report also contains several appendices including tables with a complete breakdown of all the costs associated with these retrofits, and a list of water-loving plants native to Nova Scotia, for installation in the rain gardens.

Thanks to all the students for their excellent work.