Agriculture Reference
In-Depth Information
Rain
Evapotranspiration
Living Roof
Stormwater mitigation
tool to minimize runoff
and contaminant
generation
Evapotranspiration
Stormwater Control Measure
Retains and detains runoff,
reduces contaminant
concentrations and loads
Evaporation
Reduced sewer
di
scharge
Vegetated Ground Cover
Reduces runoff velocity
and promotes in
ltration
Groundwater recharge
Receiving
water
Separate
storm sewer
Figure 1.1
Living roofs: a tool and
system component
quantity. From a philosophical and technical perspective, prevention (source
control limiting runoff- or contaminant-generating surfaces) is more effective
than a “cure” (capture and treat) (National Research Council 2009).
Thoughtfully designed living roofs provide an excellent opportunity to effec-
tively prevent or signiicantly dampen runoff generation from the traditionally
impervious rooftop, yet form does not always complement function. The land-
scape architect's objective is to make these planted spaces visually attractive,
accessible, noticeable (or invisible) and usable as well as maintainable from an
environmentally responsible standpoint. Clients are heavily inluenced by garden
design magazine images in their perception of living roof appearance. Landscape
architects are pressured to produce a “green” roof appearance foremost for the
client, whereas lack of connection to the ground means that living roofs are
extreme places, (hu)man-made and artiicial - thus potentially requiring signii-
cant intervention. Designers need to responsibly balance appearance with the
long-term environmental beneits, where the premise of the living roof assembly
and runoff mitigation capacity might (or should) override the appearance. Explor-
ing the interdependence of the visual impact and technical goals (namely storm-
water management) of a living roof is the premise of the design considerations
suggested in this topic.
While the premise of this topic focuses on effective design of living roofs inte-
grated in an urban water system, we would be remiss to overlook mention of
additional or complementary roles a living roof might fulill. A review of almost
any information on the beneits of living roofs list contributions such as extend-
ing the roof's life, energy demand reduction, urban heat island mitigation,
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