Although we had an unusually heavy rainfall in the winter of 2016 -17, we seem to be back in a serious drought cycle this year. In the recent past there has been talk about the possibility of California entering a mega drought that might last decades or even longer. From the study of submerged tree stumps in Lake Tahoe, climate researcher Susan Lindstrom found a dry spell that lasted 1,300 years before ending about 4,000 years ago. While we don’t know for sure what our next rainy season will bring, it is highly unlikely to eliminate the shortages in water supply we are facing. Consequently, we need to start looking more proactively at what we can do to conserve water in cities and on farms.
There are some very practical solutions we can begin to use around our homes that are not so costly. The cheapest approach is to direct roof and hardscape runoff water into dry wells scattered around our property where the water infiltrates into the ground. These dry wells can increase the water stored in subsoils on our properties and be available for trees to draw from as the weather warms.
For larger properties and residences, we can redirect the runoff from roofs and hardscape into temporary storage tanks that are much smaller than the long term storage tanks typically used. Instead of keeping the water stored for months in these containers, there is a pumping system that quickly supplies it to above ground sprinkler systems that cover landscaped areas. This kind of system would only be used when we are experiencing weak precipitation years so this collected water could supplement the rainfall. In 2015 we installed such a system at the Hollywood Hills residence of the young actress Alicia Silverstone. If the rains don't come this fall, her system will provide up to 50% of the shortfall.
To illustrate how a system like this could work, let’s take the example that we have a total of 3,000 square feet of residence footprint and hardscape surface that we can collect rainfall from and we have 3,000 square feet of landscape to irrigate. In this case, if we had only 6 inches of precipitation in a year, we could collect 6 inches of precipitation from our house and hardscape and redirect it to our landscape. With that supplementation, our landscape would receive the normal allotment of 12 inches of water over the rainy season. This would recharge the ground water table to normal and help trees and deep rooted shrubs weather our hot dry summers and falls better.
Pasadena, Altadena, South Pasadena, Sierra Madre,
San Marino, Arcadia, CA