In undeveloped coastal areas, the average amount of runoff is about fifteen percent but when we pave, roof, cement and make other impermeable additions to the landscape, that runoff number rises to between fifty and seventy-five percent.
That extra water burdens the system. The old philosophy was to push the water towards the ocean as quickly as possible. It seemed that the ocean was capable of absorbing this. Now, we see that the volumes are overwhelming the natural cycle. The best way to deal is to retain water on property.
Landscpeonline.com, a trade press for landscape contractors, showcased this project at the San Francisco 49ers stadium. Their bio-retention system collects and treats runoff for a five acre parking lot.
This was a huge project: it involved five workers and they completed the work in over three hundred hours.
Of course, most suburban and urban gardens won't require such extensive solutions. The first level is to use native plants. Their water profile can be so much lower than conventional planting.
So, plant natives! Conserve and retain water!