In some desert areas there is no other use for the water because the aquifers are fragmented. People don't live there, you can't readily move the water to somew

In some desert areas there is no other use for the water because the aquifers are fragmented. People don't live there, you can't readily move the water to somewhere useful, and it won't flow anywhere useful on its own. Agriculture is a way to convert water into something easily transported. This doesn't apply to many places but in the desert Mountain West this is often the case. Also, while it may seem surprising, a few crops really thrive in the high desert e.g. onions.