The Rebel Faction

George Griffiths' A Honeymoon in Space (1900) describes the canals as the remnants of gulfs and straits "widened and deepened and lengthened by... Martian labour".
Edgar Rice Burroughs' influential A Princess of Mars (1912) describes an almost entirely desert Mars, with only one small body of liquid water on the surface (though swamps and forests appear in the sequels). The canals, or waterways as Burroughs calls them, are still irrigation works, but these are surrounded by wide cultivated tracts of farmland which make their visibility somewhat credible.

Otis Adelbert Kline's Outlaws of Mars (1933) has multiple parallel canals, surrounded by walls and terraces, and describes the construction of the canals by Martian machines.

In C. S. Lewis' Out of the Silent Planet (1938), the "canals" (handramit in Martian) are actually vast rifts in the surface of a nearly airless, desert Mars, in which the only breathable atmosphere and water have collected and where life is possible, the rest of Mars being entirely dead.