Hilly mountain to capture rainwater?

I am looking at some land in the desert that is very hilly.  It is about 6,000 feet up, so high to begin with.  Out of 10 acres, there is probably 3 that are reasonably flat.  If I buy land like this, I was thinking I could use some of the inclines, hills and small valleys as natural collection "panels" and aquifers to direct water to where I want it for household use.  My first thought would be to try to develop some really healthy ground cover on the slopes to hold the soil in place.  Any thoughts about doing this?

Hey Tom, Have a look at this grass. Amazing reputation. With roots that grow vertically down up to two meters, can survive water logged or in drought. excellent soil erosion control or reclaiming. http://www.theherbcottage.com/may-2015-vetiver-grass-of-many-uses/