Hugelkultur (hill or mound gardening) is one of the ways to save water in the garden. Dig a small trench to define the area of the bed; then fill the bottom of the trench with bits of wood or logs; add layers of cardboard, compost, upturned turves and soil; and either make a level bed or an inverted V. A steeply sloped bed will need support with sticks.
Regenerative agriculture can restore degraded landscapes, even where all the trees have been cut down, as on the west coast of Saudi Arabia:-
And in Australia:-
And from gorse to forest in New Zealand:-
Restoring Scottish forest:-