“Our street curbs flow like ephemeral creeks when it rains. So let's treat them like creeks, by planting the native vegetation you would naturally find growing along such local waterways. Then cut or eliminate the street curbs to allow the creek water to water the plants in flood-controlling, street-side rain gardens.
For every inch of rainfall...
• A 10-foot wide paved street will drain 27,800 gallons of runoff per mile
• A 30-foot wide paved street will drain 83,500 gallons of runoff per mile
For every 100 mm of rainfall...
• A 3-m wide paved street will drain 300,000 liters of runoff per kilometer
• A 9-m wide paved street will drain 900,000 liters of runoff per kilometer” -- Brad Lancaster, "Rainwater Harvesting for Drylands and Beyond, Volume 2"
Enough rain runs off my 38-foot wide neighborhood street to support over 400 native shade trees per mile, or one tree every 25 feet on both sides of the street.