The Library Garden Demonstrates Harvesting Rainwater
for Landscape Use
Rainwater harvesting is the capture,
diversion, and storage of rainwater for landscape irrigation and
other uses. Harvesting rainwater can reduce the use of drinking
water for landscape irrigation. Coupled with the use of native and
drought-tolerant plants, rainwater harvesting is an effective water
conservation tool because it provides ‘free’ water that is not from
the City’s municipal water supply.
There are many benefits to harvesting rainwater. Water harvesting
not only reduces dependence on groundwater and the amount of money
spent on water, but also reduces off-site flooding and erosion by
holding rainwater on the site.
Rainwater harvesting is appropriate for large scale landscapes
such as parks, schools, commercial sites, parking lots, and
apartment complexes, as well as small scale residential landscapes.
System design ranges from simple to complex. A rainfall water
harvesting system has three components: the supply (rainfall), the
demand (landscape water requirement), and the system that moves the
water to the plants. Storage is an additional element which is
The Library Garden demonstrates
rainwater harvesting by draining rainfall runoff from the adjacent
parking lots and directs it into a catchment area that is built of
boulders and concrete. The runoff is captured and used immediately
to water the high to moderate water use plants that are located in a
concave depression due south of the catchment area. Western River
Birch, horsetail, cattails, and irises are planted in the depression
or gully that runs north-south through the Library Garden.
"No Watering" Option
Although this is a controversial idea to some people, simply not
watering and relying on rainwater to irrigate a landscape is an
option. Having a rainfed-only versus an irrigated lawn has several
pros and cons as outlined in the tables. Motivations for this
approach are multiple:
- water conservation
- reduced water bills
- smaller quantities of lawn chemicals or none at all
- reduced labor and costs for landscape maintenance, and
- reduced adverse environmental effects.
To rely strictly on rainwater for irrigation is to accept the
fact that lawn grass naturally turns brown during hot, dry periods.
The reason that many lawns, particularly those with cool-season
grass species, look bright green under a broiling sun is that they
are kept that way artificially with supplemental irrigation.
Dormancy is nature’s mechanism to help grass survive heat and
drought; a lawn will “recover” with the return of rain and cooler