I live in a desert climate where irrigation - sprinkler systems/drip lines are widely used. I'm not here to defend water wasters, however, some people do their best to use water in a fairly responsible manner. E.g. drip lines deliver water precisely where it's needed for less waste, automatic sprinklers run before dawn to limit evaporation, sensors can be used to water only when necessary. So, while water is being used in a arid climate, there are ways it can be done in a more responsible manner. Some cities even have regulations enforcing the above. Seems to me like common sense, but you know what they say about that.
About 75% of my yard is hardscape, with a small amount of grass, plants and trees. As with all things in life, there are trade-offs. For example, having shade trees around your home minimizes the amount of electricity you need to cool it. Having grass in a hot climate keeps your yard/patio cooler than hardscape. Plants and bushes provide habitat, shade and water sources for birds, lizards and other wildlife. Flowering plants provide pollen for local bee populations (currently dying at an alarming rate). If everyone suddently stopped watering, my bet is that there would be a ripple effect of consequences. Don't know exactly what or how bad, but it seems every action in nature has an equal an opposite reaction.
Several years ago, the History Channel had a show called "Life After People" where experts speculated what would happen to Earth if people unexpectedly vanished. I know you were being serious, but we all need humor, so here's my comedic attempt to speculate on your question:
Day 1 - Without a release, water pressure builds to dangerous levels until toilets everywhere erupt, injuring millions and providing fodder for America's Funniest Home Videos for years to come.
Day 2 - Early morning joggers suddenly no longer get back spackle from running through puddles. Stock prices for Shout and Asics plummet as clothes and shoes are no longer ruined.
Day 5 - Humidity levels plummet. Severe dry skin, cracked elbows and chapped lips cause a run on Aveno and Lubriderm - supplies run dangerously low. Martial law is delcared. Dry eyes wreak havoc on internet gamers staying up late playing Halo 4.
Day 10 - Lawns are brown. Dads everywhere are forced to ride their mowers around the neighborhood to avoid screaming kids who "just want them to set up the slip and slide." What, can't hear you...the mowers too loud...
Day 30 - Without flowers, bees die in droves. Honey becomes the new currency of the post-irrigated world.
Day 90 - Without bees, all crops die and huge dust storms envelope the Earth. Swiffer cleans up...literally, as people use their cloths as masks.
Day 180 - Temperatures plummet; surprisingly, Vanilla Ice becomes popular again as our morale wanes.
Day 1240 - Life on Earth ends except for those preppers everyone made fun of on Nat Geo. Who's laughing now! They go deep undergound for years. A small group of politicians find a way to survive on the surface.
802,701 A.D. - The preppers emerge as the working class Morlocks and the politicians as the lazy and ineffectual leisured class Eloi - which is the only thing in the world not to change at all!
You see, harsh consequences await. Ha!
