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Designing effective stormwater management policies : the role of the urban forest and impervious cover in Vancouver, B.C. Lefrançois, Camille B.
Abstract
Cities across the world deal with issues of water quantity and quality due to stormwater runoff, and many of those problems are expected to increase with climate change. To address those problems, the use of urban forest to manage stormwater quantity and quality issues is becoming more common. However, the way trees and plants contribute to stormwater management varies significantly based on the local climate and topography. In this project, I investigate the role of the urban forest for stormwater management in a small sewershed in Vancouver, BC. The area is located in Hastings-Sunrise within the single-family residential zone and contains approximately 200 homes. I use the i-Tree Hydro hydrology and water quality model to quantify the effect of surface cover changes on the sewershed. I first test the effect of changes in tree canopy in comparison with changes in impervious cover. Then, I investigate the effect over time of a business as usual case where the properties build laneway houses and street trees mature, and of a possible future where the country lanes program is implemented, as well as a downspout disconnection policy. My results indicate that changes in impervious cover have an impact eleven times higher than changes in canopy cover on surface runoff. My scenarios show that the biggest factor affecting stormwater runoff quantity and quality is directly connected impervious areas. It is illustrated with the downspout disconnection scenarios, which generate a 65% reduction in surface runoff. However, the substantial decrease also results in an increase in pervious flow (saturated soils). Increases in tree canopy have a significant impact on the reduction of pervious flow. Overall, I found that the most effective change for stormwater management policies in Vancouver would be to reduce directly connected impervious areas. Policies recommending a reduction of these surfaces should also enhance the urban forest and consider engineered green infrastructure solutions to allow for sufficient infiltration and evapotranspiration. Tools such as i-Tree Hydro require a significant time investment, but can offer key informations for planners and decision-makers to inform decisions on the contribution of the urban forest and other surface covers to stormwater management.
Item Metadata
Title |
Designing effective stormwater management policies : the role of the urban forest and impervious cover in Vancouver, B.C.
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Creator | |
Date Issued |
2015-11
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Description |
Cities across the world deal with issues of water quantity and quality due to stormwater runoff, and many of
those problems are expected to increase with climate change. To address those problems, the use of urban
forest to manage stormwater quantity and quality issues is becoming more common. However, the way
trees and plants contribute to stormwater management varies significantly based on the local climate and
topography.
In this project, I investigate the role of the urban forest for stormwater management in a small sewershed in
Vancouver, BC. The area is located in Hastings-Sunrise within the single-family residential zone and contains
approximately 200 homes.
I use the i-Tree Hydro hydrology and water quality model to quantify the effect of surface cover changes on
the sewershed. I first test the effect of changes in tree canopy in comparison with changes in impervious cover.
Then, I investigate the effect over time of a business as usual case where the properties build laneway houses
and street trees mature, and of a possible future where the country lanes program is implemented, as well as a
downspout disconnection policy.
My results indicate that changes in impervious cover have an impact eleven times higher than changes in
canopy cover on surface runoff. My scenarios show that the biggest factor affecting stormwater runoff
quantity and quality is directly connected impervious areas. It is illustrated with the downspout disconnection
scenarios, which generate a 65% reduction in surface runoff. However, the substantial decrease also results
in an increase in pervious flow (saturated soils). Increases in tree canopy have a significant impact on the
reduction of pervious flow.
Overall, I found that the most effective change for stormwater management policies in Vancouver would be
to reduce directly connected impervious areas. Policies recommending a reduction of these surfaces should
also enhance the urban forest and consider engineered green infrastructure solutions to allow for sufficient
infiltration and evapotranspiration. Tools such as i-Tree Hydro require a significant time investment, but can
offer key informations for planners and decision-makers to inform decisions on the contribution of the urban
forest and other surface covers to stormwater management.
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Genre | |
Type | |
Language |
eng
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Series | |
Date Available |
2016-07-07
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivatives 4.0 International
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DOI |
10.14288/1.0300042
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URI | |
Affiliation | |
Peer Review Status |
Unreviewed
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Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Item Citations and Data
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International