Latest update 22nd June 2016.
Drought is a recurring feature of Melbourne’s climate, but the longest one I have experienced was the "Millennium Drought" which lasted 13 years from 1997 to 2009.
Melbourne’s topography includes mountains mainly to the east which provide protected rainwater catchments and supply Melbourne’s network of reservoirs (capacity over 1.8 million mega litres) with fresh clean rainwater (unfortunately treated with fluoride and chlorine before distribution).
Melbourne’s water storage dropped to an all time low of 25.6% of capacity in 2009. Water restrictions were imposed progressively by the state government until finally, in the last few years of the drought, domestic consumption was restricted to 155 litres per person per day.
This meant that without sensible irrigation measures most gardens would simply die. Many people turned to decorative gravel instead of lawns, and used succulent and native Australian plants to keep water use to a minimum. Many just gave up.
My wife and I place a fairly high value on growing nourishing organic food, and having a little bit of nature in our garden. With the help of three rainwater storage tanks (7500 litres total), and drip irrigation, our garden survived the drought.
In 2010 I retired and since then I have found time to research ways to further drought proof our garden. I discovered raised garden beds with built-in water tanks. They are commonly known as wicking beds and were originally developed by Colin Austin, a retired Australian engineer living in Queensland. I decided to call my version the Garden Ecobed.
After a couple of years experimenting with Ecobins, I built my first Ecobed in May 2012, and since then after trying several different design options, I settled on the "Garden Ecobed" as the ideal model for my backyard. I now have 4 of them in a 4 year crop rotation.
Ecobeds only use as much water as the plants and soil organisms need for transpiration and growth. When I built my first Garden Ecobed after enriching and mulching the soil, I left it for a month so the worms and microbes could get busy before I planted my first crop. During this time water consumption was very low.
After I planted my first crop, water consumption increased, and as the plants grew bigger, demand grew proportionately. When the crop was harvested, water consumption returned to its previous low level.
Even under extreme conditions (windy weather with temperatures around 40 deg C is not unusual in a Melbourne summer), an Ecobed full of tall legumes only needed refilling every 5-6 days. The other Ecobeds lasted 7 days or more.
To me this is reasonably indicative that plant growth and transpiration make up nearly all the water consumed in an efficient Ecobed, and I believe my edible garden is now as water conserving as I can make it.
My edible garden includes:-
3...Larger drip line irrigated fruit tree and herb beds.