When we cover our planet with concrete we do many things that we may not intentionally want to do.
Ground is cooled by stored water and when you cover it with concrete you keep any rain from entering the earth which waters roots, keeps the ground cool and refills the water table. Sending run off into the LA river diverts the needed water from the land where it is needed.
Plants do not need as much water as we give them and many folks over water their yards. Using water wisely and recycling could actually be better that covering your property with concrete.
Concrete holds and reflects heat which warms the environment.
Rebates motivate change but maybe not the best plans for nature. Quick and dirty solutions may not be the best solutions for water conservation.
Covering ground with plastic and then covering with rocks or gravel also keeps water from absorbing into the ground.