A more permaculture approach would be to decrease run-off rates / increase infiltration capacity of soils over the entire region -- almost by definition permaculture isn't big on massive terraforming projects.
I was responding to the specifics of the parent comment -- the suggestion to build reservoirs and lakes, which are necessarily large cost, time-consuming, high-impact, often high-maintenance, logistically challenging activities in comparison to, for example, simpler methods of improving temporary slowing and long-term infiltration and holding capacity features of soils.
I'm thinking of very effective but definitely small scale activities -- one or two people with a small dozer or bobcat over a few days -- to install contour or keyline swales and bunds, erect fencing to exclude wild animals or livestock from sensitive areas, re-seeding / re-planting with more appropriate species, and so on.
I guess it's a semantic question at some point -- but I think that because you _can_ apply these activities over an entire region doesn't necessarily make it a massive terraforming project, nor more importantly does it necessarily need to be.
Massive projects engender feelings of helplessness and a kind of 'responsibility abrogation' for many individuals, often including an assumption that government and/or big-business are necessary to manage them, that it will be extremely costly, that it will take many years or decades to implement, and longer yet to have an effect. (And, if we're being cynical, a tacit assumption that it probably won't work anyway.)