Running any cable in a drainage channel is a daft idea. They need de-silting from time to time and that is likely to be done with a drop scraper with a metal blade. By the time that happens, the cable will be submerged in silt and will go unnoticed, so the blade will be dragged along the channel gouging through the sheath of the SWA. By the time the guy with the scraper notices, the cable will be as waterproof as a tea bag and he'll go nuts. "Could've b****y killed me, live cable hidden in there like that!" Even if the cable is indestructible, it'll stop the channel being scraped clean, would have to go down on hands and knees with a trowel and work round it. Mutual detrimental influence: Cable obstructs maintenance of channel, channel puts cable at risk of damage.
The ramp sounds like a possibility.