By creating channels

Water is the essential element for life by excellence and abundance since the dawn of time, but it has become a luxury for all but the poorest people. Hydropolis offers an alternative to the use of fresh water, but also a new way of life completely different based on the sea water. Using it in purely artificial and independent oasis helping countries this way that are located in “water-stressed” areas.
The aim of this project is to propose a scheme that is based in developing the biggest necessary activities for the human race around salt water: the production of energy, housing, agriculture and ecological restoration. Aquaculture will be possible thanks to the contribution of seawater. This scheme will meanwhile be reproduced to infinity in space but also in time as long as the intake of sea water is possible.
http://www.evolo.us/architecture/hydropolis-is-a-city-designed-to-transform-sea-water-into-fresh-water-in-arid-countries/