Ensuring we get enough rainfall

We need to retain a certain amount of open space with trees and foliage which all help to produce rain. One of the islands of Hawaii had to import certain trees to help them with their water situation - I don't want to see this island being a total concrete block with not enough sustainable natural/environmental ways to manage our natural water supply. Maybe also reinforcing the fact that water is a precious commodity and should be treated with respect and used wisely. Just my thoughts.