The desert has water, it is just that you can't see it
and most of the time you can't get to it. But sometimes
you can both see and get at it.
The well. It is a collapsed sinkhole formed when
underground waterflows eroded the overlying
strata, forming a cavity. When the cavity grew
big enough to not be able to support the top,
it fell down, leaving a water-filled hole in the
middle of the desert.
The hole seen from the opposite rim. Note the houses
built into the wall - it was a popular way
among the people living here of building houses that
were well-protected and warm.