Your water needs might drop significantly once the forest is established. Depending on the trees, the established canopy might drop the evaporative losses dramatically.
Under the current models we send most of the rainfall immediately back into rivers + oceans. By creating inland forests we get mini little "oceans" to evaporate and move water for a 2nd rainfall. Each cycle the plants + ground hold onto a little, but mostly it can be evaporated and re-rained again and again. Deserts have the issue that they have little to hold onto the water, and to reevaporate it for subsequent rainfalls.
The right tarp or net that lets through the most useful wavelengths seems to help more than hurt.
A lot of places are starting to install solar over farm installations on a small scale. Yields are tending up while also generating electricity to run the operation
Or you burn natural gas to produce CO2 (and some water), but then your carbon sequestration goals go up in smoke...