Instead of planting front-yard trees on a mound and directing rainwater past vegetation and straight out to the gutter, let's put the rain to work for us! By planting native vegetation and fruit trees in basins (in arid and semi-arid climates like the CA Bay Area), and by directing rain from the gutters, paths, and driveways into these basins, we can save thousands of gallons of water every year. Not only that, we can also shade and cool our homes, produce abundant food, AND filter and clean the water through the living soil before it goes out to the waterways. This is permaculture in action: taking care of the earth while taking care of people!
In this next diagram, see how an integrated urban/suburban water harvesting system maximizes the efficient use of rainfall. Notice the rainwater tank to the left of the house, with the overflow directed to a nearby tree, and notice how all the sidewalks and paths are used to direct water to the rest of the landscape.
And finally, here is a picture of a young drought-tolerant pineapple guava tree (feijoa sellowiana) sitting in a basin, a perfect choice for an edible, drought tolerant California garden. The basin is dug out to the eventual dripline of the tree, and during a rain shower, the water from the gutters can be directed straight into the basin. After a year or two, this tree may not need more than a couple supplemental waterings per year!
These diagrams are borrowed from Brad Lancaster's incredible book, Rainwater Harvesting for Drylands and Beyond, Volume 1. Do yourself a big favor and purchase this book from Brad's website: http://www.harvestingrainwater.com/