Water in the Desert
Deserts have some water but the lands have been mismanaged such that there's no longer adequate vegetation and landscape features to adequately hold onto and use what little rain they do get. This can be reversed.
Check dams are porous dams intended to slow water in gullies or washes or wadis. In other words stream beds that are dry much of the year.
Deserts are prone to floods. When you do get rain, there's too little vegetation and poor soil conditions for readily soaking it up. This becomes a vicious cycle where soils and vegetation are damaged by rain and the landscape is eroded.
Both check dams and semicircular bunds slow down and capture water to begin the process of stopping this vicious cycle.
Here is a pdf on rock detention structures and this is a brief video about the worl of Cuenco Los Ojos.
From their website:
The two main methods include: trincheras (small rock dams) and gabions (wire cages filled with rocks) to restore riparian areas on a watershed scale.