|
A
low-cost depth logger was installed in the backyard
rain-garden. This has proved immensely valuable, allowing us to
re-evaluate the potential for vegetated infiltration systems as
stormwater retention devices in this catchment.
Although the underlying soils of the catchment have extremely low
infiltration capacity, the top soils allow substantial infiltration,
and, once established, the rain-garden plants allow substantial loss
of water through evapotransipiration.
As a
result, the rain-garden has performed much better than modelled,
overflowing only 7 times over 1 year (Figure 1). This system
overflows to the lawn, so it is unlikely that any overland flow was
generated from this property over the last year.
We have thus
demonstrated that a simple, cheap rain-garden covering about 3% of
its impervious catchment can restore the hydrology of a developed
area back to its pre-urban state, reducing the impact of the area to
receiving waters to zero.
This garden also
thrived during the very hot and dry January and February of 2009,
which can be seen in Figure 1 as the period of consistent draw down
resulting primarily from transpirational losses through the
plants. Such losses provide substantial cooling benefits to the
local urban microclimate. |
