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 RAINWATER
HARVESTING - CAPTURING AND USING PRECIPITATION
Even if arid and semi-arid regions, it rains from time to time.
If you have large amounts of impermeable surfaces on your lot,
such as bare ground or pavement, or if your roof has gutters
and downspouts, you may be able to capture some rain and direct
it to your landscaping. This can reduce your water bills from
irrigating.
An added benefit of rain water harvesting is that plants thrive
on it. Rainwater is very low in salts, and directing runoff
to plants can help leach out salts that accumulate from irrigation.
In addition, the lightning in thunderstorms creates a beneficial
form of nitrogen, which the rain washes out of the air.
Surface runoff can be directed to turfed
areas or shallow basins around trees and shrubs by contouring
the land surface. These contours need not be more than an
inch or two in height, and can have a barely perceptible slope,
so large amounts of earth-moving is not required. The goal
is to collect the runoff, direct it to where it can be of
use, and slow it down so it has time to soak into the ground.
This can reduce erosion on your property.
Although precipitation may occur sporadically,
desert storms can drop a great deal of water in a short time.
Therefore, you need to plan for your basins to overflow from
time to time.
Rain that falls onto roofs can not only
be directed to landscape plants, it can be stored in tanks
or rain barrels for later use. Such a system can be as simple
as a downspout feeding rain into a 55-gallon barrel. More
complex systems can include filters and pumps. Below-ground
cisterns can store both rooftop and surface runoff. Whether
investing in a rainwater storage system makes sense or not
will depend on the frequency and volume of rain as well as
its seasonal distribution, the size of your roof, your irrigation
needs, and other factors.
Note that if it hasn=t rained in quite some
time, the initial runoff from a roof or driveway can be loaded
with pollutants, including motor oil and bird droppings. Water
storage systems can be designed so that the initial runoff
is not stored.
Often, homeowners start their water
harvesting systems with a simple berm or contour to divert
runoff otherwise lost from their property into a tree basin.
Over time, more contours, mulching, and storage systems can
be gradually added.
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