Water
Conservation.
EFFICIENT IRRIGATION
Efficient
Irrigation includes irrigation mechanical properties,
irrigation schedules, grade manipulation and runoff
management. Whatever irrigation practices are
implemented, they should ultimately provide water at but
not beyond soil absorption and plant transpiration
capacity. The irrigation necessary for an optimally
performing landscape varies by site and by
microclimate. Planned and formal gardens of the
southeast usually require human and/or mechanical
intervention to maintain proper plant irrigation
throughout the seasons. Woodlands, prairies, other
naturalized settings and certain foundational shrubs
present less demand for water and can be incorporated
into many design programs to maximize water economy.
Types of
Systems
Irrigation
systems are available in broadcast, mist and soaking
configurations in both elaborate and simple delivery
systems. The most efficient are the soaking systems
which apply water directly to the ground surface. They
allow the atmosphere a minimal chance of grabbing
moisture before the soil and roots have a chance to
absorb irrigated water.
In-ground
systems are more elaborate and include a network of
conduits which disperse water within the irrigated area
through strategically placed spray or mist heads or
perforated or permeable hose. These systems have one
benefit in common – they are all efficient in the sense
that they distribute water more evenly than above ground
systems, without incomplete or redundant coverage. Drip
systems are the most efficient of the three because air
exposure and thus evaporation are at a minimum at ground
level. Drip systems have the added advantage over spray
and mist heads in that water does not typically make
contact with plant foliage, thereby reducing the
potential for leaf fungus to develop, whereas spray and
mist heads create unnaturally sustained water contact
with plant foliage.
Above-ground systems tend to be less elaborate than
their in-ground counterparts. Portability is the common
attribute of above-ground systems. Oscillating and
rotating sprinklers, hand-held nozzles and perforated
hose have certain, limited advantages to in-ground
systems, namely lower cost and lack of installation
tasks. Perforated or permeable hose on the soil surface
is semi-permanent and may be automated. Hose layouts
can be configured to suit the individual plant design’s
distribution needs. Sprinklers are appropriate for
isolated needs but generally provide inefficient
distribution with incomplete or redundant coverage.
Best Times
to Water
The most
efficient time of day to water varies from season to
season but between 3 am and 8 am is the general range.
Water loss due to evaporation is up to 50% less at
night than during midday. Research indicates that as
long as the irrigation follows dew accumulation, rather
than preceding it, the proper balance between over
and under hydration can be maintained.[1] In any case, the roots must be able to absorb water
before the solar heat promotes evaporation and before
accumulation promotes fungal disease.
Runoff
Management
Site grade
is the ultimate correction for distribution efficiency,
if it is possible. Plant beds can often be positioned
to leverage site runoff. Grading equipment can
reposition earth to steer water runoff towards
established trees and shrubs or create new beds where
water naturally collects. Runoff management is often
created and maintained by constructing dry creeks and
dry ponds and planting materials in the surrounding area
which respond well to the conditions associated with
these features. Reshaping the path of gravity can
effectively redistribute rainfall according to the needs
of a professional landscape design as well as prevent
erosion and reduce waste of a natural resource.
Landry, Gilbert Jr., "Turfgrass Water
Management." The University of Georgia
College of Agricultural and Environmental
Sciences - Cooperative Extension Service.
April 2000. University of Georgia.
14 Feb. 2005.
<http://pubs.caes.uga.edu/caespubs/pubcd/L399.htm>
|
