In a previous question I asked if a world similar to that envisioned in the Mars of Edgar Rice Burroughs / H G Wells could exist? And if so would canals be a practical way to make the planet habitable over the long term?
One of the potential issues identified with such a scenario was the prospect of salinization of the canals
How best can the Martians prevent salinization of their canal network? Pipes can be used in places but canals are needed for my story and for transportation. Assume that The Martians have modern twenty first century technology, plenty of money (hey it’s an existential threat to the civilization) and a lot of time (decades – centuries). Conveniently in the hemisphere and latitudes of interest it can be assumed that there is sufficient head of water and suitable gradient to generate a flow over a wide area of the canal network from the melt waters in the sub Artic regions to the dry by fertile land in the subtropics.