How can we translate deserts into agricultural areas?

We should dig deep pits when planting trees in deserts. When we see wet sand, we should sow our tree or seed. So you dig a deep pit until you see the wet soils where it's important.

In order to find the seas in the deserts of the rivers, we should search for water with water search detectors. So maybe there are rivers flowing in the desert, but we may not know it.