Making the Most of Rainwater
By Virginia Hayes
Mother Nature is flirting with us as usual. A drizzle here,
false alarm on a thunderstorm over there — no real rain yet for the
new season, but it will come. Will you be ready? I’m not talking
about patching that leaky roof, cleaning the leaves out of the
gutters, or putting the lawn furniture in the garage. Are you ready
to reap the harvest of rainwater offered up for free? With more and
more of our urban world being paved or built over and increasing
numbers of people straining the limited resources available from
conventional sources of domestic water, it is high time we as
individuals got into the act of water conservation.
We all bask in the great weather that is the norm here on the
South Coast. Lots of sunny days also mean, however, that we live in
one of the drier regions of the country. Our local rainfall average
is less than 20 inches (depending on where you live). To cap it all
off, the rainy season is short, typically starting late in October
and finishing up in March. That also equates to a climate in which
the warmest months are the driest ones. This puts a strain on
gardens and gardeners alike. Just how do you go about saving the
most precious resource, water? There is a wealth of information
available to help you learn how to keep rain, first in your garden,
and then in our local aquifers. One of the most comprehensive
sources of practical instruction is the recently published book
Rainwater Harvesting for Drylands by Brad Lancaster.
This is actually the first volume in a three-volume set, but for
the beginning water harvester it will go a long way toward helping
you understand how some simple techniques can make a significant
change in the amount of water leaving your property. These methods
do not require expensive tools or materials. The first of eight
principles of rainwater harvesting, according to Lancaster, is to
“Begin with long and thoughtful observation.” The idea is to watch
how water moves over the land. What direction does it flow, what
obstacles does it encounter, and how does it react to those
obstacles? Only by beginning to understand the nature of water can
one hope to find ways to redirect it to benefit our environment and
us.
The other seven principles are equally logical. Since everyone
knows that water flows downward, principle number two is to “Start
at the highpoint of your watershed and work your way down.” You may
not have thought of your own garden as comprising a “watershed,”
but if you look at the roof of your domicile and the tallest trees
as the start of a raindrop’s journey toward the sea, you will see
another way to look at your surroundings. My favorite is the next
principle: “Start small and simple.” Keep reading and researching
and you will find your own comfort zone of change, but even the
smallest changes will be of benefit to you and the overall
environment.
The next four principles refer to more specific ways to look at
the flow of water to achieve your goals. Number four, “Spread and
infiltrate the water,” is a way to slow water down and give it a
chance to soak into the soil. In the short run, this nurtures your
landscape; in the long run, it replenishes the aquifers below.
Numbers five and six mitigate the destructive properties of water:
“Always plan for an overflow route, and manage that overflow as a
resource” and “maximize living and organic groundcover.” Both of
these rules will enable you to divert and use water to irrigate
your landscape before letting the excess water follow its
inevitable path. Principle number seven is “Maximize beneficial
relationships and efficiency by ‘stacking functions.’” This one
requires a little more thought and planning, and the book has lots
of great illustrations and plans that you can adapt to your own
situation. The eighth and last rule is as important as the first.
In order to make sure that you learn from your own situation, you
must “Continually reassess your system: the ‘feedback loop.’”
Again, observation is the key to success.
Throughout the book, Lancaster has supported his thesis by
summarizing his research in small sidebars with compelling
information. One such “box” reveals some interesting facts about
the efficiency of size in relation to the amount of water that can
be stored and used by damming up waterways. It turns out that
smaller is better. Large reservoirs are more disruptive to the
local ecosystem and its inhabitants (plants, animals, and people).
Also, in larger reservoirs, an increasing proportion of water is
lost to evaporation and to the soil than in smaller bodies of
water. According to the Centre for Science and Environment in
India, “In a drought-prone area where water is scarce, 10 tiny dams
with a catchment of 1 hectares (2.47 acres) each will collect much
more water than one larger dam with a catchment of 10 hectares.”
This should be an inspiration to small-scale water harvesters. In
even the smallest landscapes, significant gains can be made through
a human-scale endeavor.
The practicality of applying these concepts is not as daunting
as it might seem. One of the basics of diverting water is to move a
little earth this or that way to channel it where it can do the
most good. Small changes in grade can accomplish large results in
terms of redirecting storm water to your benefit. Some of the basic
techniques involve mounding up soil into berms perpendicular to the
slope (and water flow) to contain rainfall in a basin so that it
has a chance to percolate into the soil instead of rolling right
off. If you landscape these basins with plants, they can thrive on
the free irrigation to provide food, shade (to reduce heating costs
in your home), and habitat for other inhabitants of the ecosystem
such as beneficial insects and birds (these are the “stacking
functions” mentioned above). Many more easy-to-master techniques
will allow you to modify your landscape to maximize water retention
and utilization. Once you are hooked, you may want to progress to
the more detailed information in the other volumes.
One other source of good information and networking is through
Harvest H2O, the Online Rainwater Harvesting Community
(harvesth2o.com).